1
|
Sun PZ. Quasi-steady-state (QUASS) reconstruction enhances T 1 normalization in apparent exchange-dependent relaxation (AREX) analysis: A reevaluation of T 1 correction in quantitative CEST MRI of rodent brain tumor models. Magn Reson Med 2024; 92:236-245. [PMID: 38380727 PMCID: PMC11055669 DOI: 10.1002/mrm.30056] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2023] [Revised: 01/26/2024] [Accepted: 02/04/2024] [Indexed: 02/22/2024]
Abstract
PURPOSE The apparent exchange-dependent relaxation (AREX) analysis has been proposed as an effective means to correct T1 contribution in CEST quantification. However, it has been recognized that AREX T1 correction is not straightforward if CEST scans are not performed under the equilibrium condition. Our study aimed to test if quasi-steady-state (QUASS) reconstruction could boost the accuracy of the AREX metric under common non-equilibrium scan conditions. THEORY AND METHODS Numerical simulation and in vivo scans were performed to assess the AREX metric accuracy. The CEST signal was simulated under different relaxation delays, RF saturation amplitudes, and durations. The AREX was evaluated as a function of the bulk water T1 and labile proton concentration using the multiple linear regression model. AREX MRI was also assessed in brain tumor rodent models, with both apparent CEST scans and QUASS reconstruction. RESULTS Simulation showed that the AREX calculation from apparent CEST scans, under non-equilibrium conditions, had significant dependence on labile proton fraction ratio, RF saturation time, and T1. In comparison, QUASS-boosted AREX depended on the labile proton fraction ratio without significant dependence on T1 and RF saturation time. Whereas the apparent (2.7 ± 0.8%) and QUASS MTR asymmetry (2.8 ± 0.8%) contrast between normal and tumor regions of interest (ROIs) were significant, the difference was small. In comparison, AREX contrast between normal and tumor ROIs calculated from the apparent CEST scan and QUASS reconstruction was 3.8 ± 1.1%/s and 4.4 ± 1.2%/s, respectively, statistically different from each other. CONCLUSIONS AREX analysis benefits from the QUASS-reconstructed equilibrium CEST effect for improved T1 correction and quantitative CEST analysis.
Collapse
Affiliation(s)
- Phillip Zhe Sun
- Department of Radiology and Imaging Sciences, Emory University School of Medicine, Atlanta, GA
- Winship Cancer Institute, Emory University, Atlanta, GA
- Primate Imaging Center, Emory National Primate Research Center, Emory University, Atlanta, GA
| |
Collapse
|
2
|
Jin T, Wang J, Chung J, Hitchens TK, Sun D, Mettenburg J, Wang P. Amide proton transfer MRI at 9.4 T for differentiating tissue acidosis in a rodent model of ischemic stroke. Magn Reson Med 2024. [PMID: 38923094 DOI: 10.1002/mrm.30194] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2023] [Revised: 04/08/2024] [Accepted: 05/24/2024] [Indexed: 06/28/2024]
Abstract
PURPOSE Differentiating ischemic brain damage is critical for decision making in acute stroke treatment for better outcomes. We examined the sensitivity of amide proton transfer (APT) MRI, a pH-weighted imaging technique, to achieve this differentiation. METHODS In a rat stroke model, the ischemic core, oligemia, and the infarct-growth region (IGR) were identified by tracking the progression of the lesions. APT MRI signals were measured alongside ADC, T1, and T2 maps to evaluate their sensitivity in distinguishing ischemic tissues. Additionally, stroke under hyperglycemic conditions was studied. RESULTS The APT signal in the IGR decreased by about 10% shortly after stroke onset, and further decreased to 35% at 5 h, indicating a progression from mild to severe acidosis as the lesion evolved into infarction. Although ADC, T1, and T2 contrasts can only detect significant differences between the IGR and oligemia for a portion of the stroke duration, APT contrast consistently differentiates between them at all time points. However, the contrast to variation ratio at 1 h is only about 20% of the contrast to variation ratio between the core and normal tissues, indicating limited sensitivity. In the ischemic core, the APT signal decreases to about 45% and 33% of normal tissue level at 1 h for the normoglycemic and hyperglycemic groups, respectively, confirming more severe acidosis under hyperglycemia. CONCLUSION The sensitivity of APT MRI is high in detecting severe acidosis of the ischemic core but is much lower in detecting mild acidosis, which may affect the accuracy of differentiation between the IGR and oligemia.
Collapse
Affiliation(s)
- Tao Jin
- Department of Radiology, University of Pittsburgh, Pittsburgh, Pennsylvania, USA
| | - Jicheng Wang
- Department of Urology, University of Pittsburgh, Pittsburgh, Pennsylvania, USA
| | - Julius Chung
- Department of Radiology, University of Pittsburgh, Pittsburgh, Pennsylvania, USA
| | - T Kevin Hitchens
- Department of Neurobiology, University of Pittsburgh, Pittsburgh, Pennsylvania, USA
| | - Dandan Sun
- Department of Neurology, University of Pittsburgh, Pittsburgh, Pennsylvania, USA
| | - Joseph Mettenburg
- Department of Radiology, University of Pittsburgh, Pittsburgh, Pennsylvania, USA
| | - Ping Wang
- Department of Radiology, University of Pittsburgh, Pittsburgh, Pennsylvania, USA
| |
Collapse
|
3
|
Chung J, Sun D, Hitchens TK, Modo M, Bandos A, Mettenburg J, Wang P, Jin T. Dual contrast CEST MRI for pH-weighted imaging in stroke. Magn Reson Med 2024; 91:357-367. [PMID: 37798945 PMCID: PMC10872804 DOI: 10.1002/mrm.29842] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2023] [Revised: 07/30/2023] [Accepted: 08/05/2023] [Indexed: 10/07/2023]
Abstract
PURPOSE pH enhanced (pHenh ) CEST imaging combines the pH sensitivity from amide and guanidino signals, but the saturation parameters have not been optimized. We propose pHdual as a variant of pHenh that suppresses background signal variations, while enhancing pH sensitivity and potential for imaging ischemic brain injury of stroke. METHODS Simulation and in vivo rodent stroke experiments of pHenh MRI were performed with varied RF saturation powers for both amide and guanidino protons to optimize the contrast between lesion/normal tissues, while simultaneously minimizing signal variations across different types of normal tissues. In acute stroke, contrast and volume ratio measured by pHdual imaging were compared with an amide-CEST approach, and perfusion and diffusion MRI. RESULTS Simulation experiments indicated that amide and guanidino CEST signals exhibit unique sensitivities across different pH ranges, with pHenh producing greater sensitivity over a broader pH regime. The pHenh data of rodent stroke brain demonstrated that the lesion/normal tissue contrast was maximized for an RF saturation power pair of 0.5 μT at 2.0 ppm and 1.0 μT at 3.6 ppm, whereas an optimal contrast-to-variation ratio (CVR) was obtained with a 0.7 μT saturation at 2.0 ppm and 0.8 μT at 3.6 ppm. In acute stroke, CVR optimized pHenh (i.e., pHdual ) achieved a higher sensitivity than the three-point amide-CEST approach, and distinct patterns of lesion tissue compared to diffusion and perfusion MRI. CONCLUSION pHdual MRI improves the sensitivity of pH-weighted imaging and will be a valuable tool for assessing tissue viability in stroke.
Collapse
Affiliation(s)
- Julius Chung
- Department of Radiology, University of Pittsburgh, Pittsburgh, Pennsylvania
| | - Dandan Sun
- Department of Neurology, University of Pittsburgh, Pittsburgh, Pennsylvania
| | - T. Kevin Hitchens
- Department of Neurobiology, University of Pittsburgh, Pittsburgh, Pennsylvania
| | - Michel Modo
- Department of Radiology, University of Pittsburgh, Pittsburgh, Pennsylvania
| | - Andriy Bandos
- Department of Biostatistics, University of Pittsburgh, Pittsburgh, Pennsylvania
| | - Joseph Mettenburg
- Department of Radiology, University of Pittsburgh, Pittsburgh, Pennsylvania
| | - Ping Wang
- Department of Radiology, University of Pittsburgh, Pittsburgh, Pennsylvania
| | - Tao Jin
- Department of Radiology, University of Pittsburgh, Pittsburgh, Pennsylvania
| |
Collapse
|
4
|
Wu Q, Qi Y, Gong P, Huang B, Cheng G, Liang D, Zheng H, Sun PZ, Wu Y. Fast and robust pulsed chemical exchange saturation transfer (CEST) MRI using a quasi-steady-state (QUASS) algorithm at 3 T. Magn Reson Imaging 2024; 105:29-36. [PMID: 37898416 DOI: 10.1016/j.mri.2023.10.009] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2023] [Revised: 10/21/2023] [Accepted: 10/22/2023] [Indexed: 10/30/2023]
Abstract
Chemical exchange saturation transfer (CEST) has emerged as a powerful technique to image dilute labile protons. However, its measurement depends on the RF saturation duration (Tsat) and relaxation delay (Trec). Although the recently developed quasi-steady-state (QUASS) solution can reconstruct equilibrium CEST effects under continuous-wave RF saturation, it does not apply to pulsed-CEST MRI on clinical scanners with restricted hardware or specific absorption rate limits. This study proposed a QUASS algorithm for pulsed-CEST MRI and evaluated its performance in muscle CEST measurement. An approximated expression of a steady-state pulsed-CEST signal was incorporated in the off-resonance spin-lock model, from which the QUASS pulsed-CEST effect was derived. Numerical simulation, creatine phantom, and healthy volunteer scans were conducted at 3 T. The CEST effect was quantified with asymmetry analysis in the simulation and phantom experiments. CEST effects of creatine, amide proton transfer, phosphocreatine, and combined magnetization transfer and nuclear Overhauser effects were isolated from a multi-pool Lorentzian model in muscles. Apparent and QUASS CEST measurements were compared under different Tsat/Trec and duty cycles. Paired Student's t-test was employed with P < 0.05 as statistically significant. The simulation, phantom, and human studies showed the strong impact of Tsat/Trec on apparent CEST measurements, which were significantly smaller than the corresponding QUASS CEST measures, especially under short Tsat/Trec times. In comparison, the QUASS algorithm mitigates such impact and enables accurate CEST measurements under short Tsat/Trec times. In conclusion, the QUASS algorithm can accelerate robust pulsed-CEST MRI, promising the efficient detection and evaluation of muscle diseases in clinical settings.
Collapse
Affiliation(s)
- Qiting Wu
- Paul C. Lauterbur Research Center for Biomedical Imaging, Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences, Shenzhen, Guangdong, China; Medical AI Lab, School of Biomedical Engineering, Medical School, Shenzhen University, Shenzhen, Guangdong, China
| | - Yulong Qi
- Department of Medical Imaging, Peking University Shenzhen Hospital, Shenzhen, Guangdong, China
| | - Pengcheng Gong
- Paul C. Lauterbur Research Center for Biomedical Imaging, Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences, Shenzhen, Guangdong, China
| | - Bingsheng Huang
- Medical AI Lab, School of Biomedical Engineering, Medical School, Shenzhen University, Shenzhen, Guangdong, China
| | - Guanxun Cheng
- Department of Medical Imaging, Peking University Shenzhen Hospital, Shenzhen, Guangdong, China
| | - Dong Liang
- Paul C. Lauterbur Research Center for Biomedical Imaging, Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences, Shenzhen, Guangdong, China
| | - Hairong Zheng
- Paul C. Lauterbur Research Center for Biomedical Imaging, Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences, Shenzhen, Guangdong, China
| | - Phillip Zhe Sun
- Department of Radiology and Imaging Sciences, Emory University School of Medicine, Atlanta, GA, USA
| | - Yin Wu
- Paul C. Lauterbur Research Center for Biomedical Imaging, Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences, Shenzhen, Guangdong, China.
| |
Collapse
|
5
|
Zhao J, Wu G, Wu Q, Gong P, Kuang J, Zheng H, Sun PZ, Li Y, Wu Y. A Pilot Study of Ratiometric Creatine CEST MRI Assessment of Rabbit Skeletal Muscle Energy Metabolism at 3 T. J Magn Reson Imaging 2024; 59:201-208. [PMID: 37246769 DOI: 10.1002/jmri.28832] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2023] [Revised: 05/17/2023] [Accepted: 05/17/2023] [Indexed: 05/30/2023] Open
Abstract
BACKGROUND pH MRI may provide useful information to evaluate metabolic disruption following ischemia. Radiofrequency amplitude-based creatine chemical exchange saturation transfer (CrCEST) ratiometric MRI is pH-sensitive, which could but has not been explored to examine muscle ischemia. PURPOSE To investigate skeletal muscle energy metabolism alterations with CrCEST ratiometric MRI. STUDY TYPE Prospective. ANIMAL MODEL Seven adult New Zealand rabbits with ipsilateral hindlimb muscle ischemia. FIELD STRENGTH/SEQUENCE 3 T/two MRI scans, including MRA and CEST imaging, were performed under two B1 amplitudes of 0.5 and 1.25 μT after 2 hours of hindlimb muscle ischemia and 1 hour of reperfusion recovery, respectively. ASSESSMENT CEST effects of two energy metabolites of creatine and phosphocreatine (PCrCEST) were resolved with the multipool Lorentzian fitting approach. The pixel-wise CrCEST ratio was quantified by calculating the ratio of the resolved CrCEST peaks under a B1 amplitude of 1.25 μT to those under 0.5 μT in the entire muscle. STATISTICAL TESTS One-way ANOVA and Pearson's correlation. P < 0.05 was considered statistically significant. RESULTS MRA images confirmed the blood flow loss and restoration in the ischemic hindlimb at the ischemia and recovery phases, respectively. Ischemic muscles exhibited a significant decrease of PCr at the ischemia (under both B1 amplitudes) and recovery phases (under B1 amplitude of 0.5 μT) and significantly increased CrCEST from normal tissues at both phases (under both B1 levels). Specifically, CrCEST decreased, and PCrCEST increased with the CrCEST ratio. Significantly strong correlations were observed among the CrCEST ratio, and CrCEST and PCrCEST under both B1 levels (r > 0.80). DATA CONCLUSION The CrCEST ratio altered substantially with muscle pathological states and was closely related to CEST effects of energy metabolites of Cr and PCr, suggesting that the pH-sensitive CrCEST ratiometric MRI is feasible to evaluate muscle injuries at the metabolic level. EVIDENCE LEVEL 2 TECHNICAL EFFICACY STAGE: 1.
Collapse
Affiliation(s)
- Jialei Zhao
- Paul C. Lauterbur Research Center for Biomedical Imaging, Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences, Shenzhen, Guangdong, China
| | - Gang Wu
- Department of Radiology, Tongji Hospital of Tongji College of Huazhong University of Science and Technology, Wuhan, Hubei, China
| | - Qiting Wu
- Paul C. Lauterbur Research Center for Biomedical Imaging, Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences, Shenzhen, Guangdong, China
| | - Pengcheng Gong
- Paul C. Lauterbur Research Center for Biomedical Imaging, Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences, Shenzhen, Guangdong, China
| | - Junfeng Kuang
- Paul C. Lauterbur Research Center for Biomedical Imaging, Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences, Shenzhen, Guangdong, China
| | - Hairong Zheng
- Paul C. Lauterbur Research Center for Biomedical Imaging, Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences, Shenzhen, Guangdong, China
| | - Phillip Zhe Sun
- Department of Radiology and Imaging Sciences, Emory University School of Medicine, Atlanta, Georgia, USA
| | - Ye Li
- Paul C. Lauterbur Research Center for Biomedical Imaging, Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences, Shenzhen, Guangdong, China
| | - Yin Wu
- Paul C. Lauterbur Research Center for Biomedical Imaging, Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences, Shenzhen, Guangdong, China
| |
Collapse
|
6
|
Foo LS, Larkin JR, Sutherland BA, Ray KJ, Yap WS, Goh CH, Hum YC, Lai KW, Harston G, Tee YK. Investigation of relayed nuclear Overhauser enhancement effect at -1.6 ppm in an ischemic stroke model. Quant Imaging Med Surg 2023; 13:7879-7892. [PMID: 38106293 PMCID: PMC10722023 DOI: 10.21037/qims-23-510] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2023] [Accepted: 08/28/2023] [Indexed: 12/19/2023]
Abstract
Background When an ischemic stroke happens, it triggers a complex signalling cascade that may eventually lead to neuronal cell death if no reperfusion. Recently, the relayed nuclear Overhauser enhancement effect at -1.6 ppm [NOE(-1.6 ppm)] has been postulated may allow for a more in-depth analysis of the ischemic injury. This study assessed the potential utility of NOE(-1.6 ppm) in an ischemic stroke model. Methods Diffusion-weighted imaging, perfusion-weighted imaging, and chemical exchange saturation transfer (CEST) magnetic resonance imaging (MRI) data were acquired from five rats that underwent scans at 9.4 T after middle cerebral artery occlusion. Results The apparent diffusion coefficient (ADC), cerebral blood flow (CBF), and apparent exchange-dependent relaxations (AREX) at 3.5 ppm and NOE(-1.6 ppm) were quantified. AREX(3.5 ppm) and NOE(-1.6 ppm) were found to be hypointense and exhibited different signal patterns within the ischemic tissue. The NOE(-1.6 ppm) deficit areas were equal to or larger than the ADC deficit areas, but smaller than the AREX(3.5 ppm) deficit areas. This suggested that NOE(-1.6 ppm) might further delineate the acidotic tissue estimated using AREX(3.5 ppm). Since NOE(-1.6 ppm) is closely related to membrane phospholipids, NOE(-1.6 ppm) potentially highlighted at-risk tissue affected by lipid peroxidation and membrane damage. Altogether, the ADC/NOE(-1.6 ppm)/AREX(3.5 ppm)/CBF mismatches revealed four zones of increasing sizes within the ischemic tissue, potentially reflecting different pathophysiological information. Conclusions Using CEST coupled with ADC and CBF, the ischemic tissue may thus potentially be separated into four zones to better understand the pathophysiology after stroke and improve ischemic tissue fate definition. Further verification of the potential utility of NOE(-1.6 ppm) may therefore lead to a more precise diagnosis.
Collapse
Affiliation(s)
- Lee Sze Foo
- Lee Kong Chian Faculty of Engineering and Science, Universiti Tunku Abdul Rahman, Kajang, Malaysia
| | - James R. Larkin
- Department of Oncology, Cancer Research UK and Medical Research Council Oxford Institute for Radiation Oncology, University of Oxford, Oxford, UK
| | - Brad A. Sutherland
- Tasmanian School of Medicine, College of Health and Medicine, University of Tasmania, Hobart, Australia
| | - Kevin J. Ray
- Department of Oncology, Cancer Research UK and Medical Research Council Oxford Institute for Radiation Oncology, University of Oxford, Oxford, UK
| | - Wun-She Yap
- Lee Kong Chian Faculty of Engineering and Science, Universiti Tunku Abdul Rahman, Kajang, Malaysia
| | - Choon-Hian Goh
- Lee Kong Chian Faculty of Engineering and Science, Universiti Tunku Abdul Rahman, Kajang, Malaysia
| | - Yan Chai Hum
- Lee Kong Chian Faculty of Engineering and Science, Universiti Tunku Abdul Rahman, Kajang, Malaysia
| | - Khin Wee Lai
- Faculty of Engineering, Department of Biomedical Engineering, University of Malaya, Kuala Lumpur, Malaysia
| | - George Harston
- Acute Stroke Service, Oxford University Hospitals National Health Service Foundation Trust, Oxford, UK
| | - Yee Kai Tee
- Lee Kong Chian Faculty of Engineering and Science, Universiti Tunku Abdul Rahman, Kajang, Malaysia
| |
Collapse
|
7
|
Wu L, Lu D, Sun PZ. Comparison of model-free Lorentzian and spinlock model-based fittings in quantitative CEST imaging of acute stroke. Magn Reson Med 2023; 90:1958-1968. [PMID: 37335834 PMCID: PMC10538953 DOI: 10.1002/mrm.29772] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2023] [Revised: 05/14/2023] [Accepted: 06/01/2023] [Indexed: 06/21/2023]
Abstract
PURPOSE CEST MRI detects complex tissue changes following acute stroke. Our study aimed to test if spinlock model-based fitting of the quasi-steady-state (QUASS)-reconstructed equilibrium CEST MRI improves the determination of multi-pool signal changes over the commonly-used model-free Lorentzian fitting in acute stroke. THEORY AND METHODS Multiple three-pool CEST Z-spectra were simulated using Bloch-McConnell equations for a range of T1 , relaxation delay, and saturation times. The multi-pool CEST signals were solved from the simulated Z-spectra to test the accuracy of routine Lorentzian (model-free) and spinlock (model-based) fittings without and with QUASS reconstruction. In addition, multiparametric MRI scans were obtained in rat models of acute stroke, including relaxation, diffusion, and CEST Z-spectrum. Finally, we compared model-free and model-based per-pixel CEST quantification in vivo. RESULTS The spinlock model-based fitting of QUASS CEST MRI provided a nearly T1 -independent determination of multi-pool CEST signals, advantageous over the fittings of apparent CEST MRI (model-free and model-based). In vivo data also demonstrated that the spinlock model-based QUASS fitting captured significantly different changes in semisolid magnetization transfer (-0.9 ± 0.8 vs. 0.3 ± 0.8%), amide (-1.1 ± 0.4 vs. -0.5 ± 0.2%), and guanidyl (1.0 ± 0.4 vs. 0.7 ± 0.3%) signals over the model-free Lorentzian analysis. CONCLUSION Our study demonstrated that spinlock model-based fitting of QUASS CEST MRI improved the determination of the underlying tissue changes following acute stroke, promising further clinical translation of quantitative CEST imaging.
Collapse
Affiliation(s)
- Limin Wu
- Massachusetts General Hospital, Harvard Medical School, Boston, MA
| | - Dongshuang Lu
- Massachusetts General Hospital, Harvard Medical School, Boston, MA
| | - Phillip Zhe Sun
- Massachusetts General Hospital, Harvard Medical School, Boston, MA
- Emory National Primate Research Center, Emory University, Atlanta GA
- Department of Radiology and Imaging Sciences, Emory University School of Medicine, Atlanta GA
| |
Collapse
|
8
|
Maxouri O, Bodalal Z, Daal M, Rostami S, Rodriguez I, Akkari L, Srinivas M, Bernards R, Beets-Tan R. How to 19F MRI: applications, technique, and getting started. BJR Open 2023; 5:20230019. [PMID: 37953866 PMCID: PMC10636348 DOI: 10.1259/bjro.20230019] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2023] [Revised: 07/26/2023] [Accepted: 08/01/2023] [Indexed: 11/14/2023] Open
Abstract
Magnetic resonance imaging (MRI) plays a significant role in the routine imaging workflow, providing both anatomical and functional information. 19F MRI is an evolving imaging modality where instead of 1H, 19F nuclei are excited. As the signal from endogenous 19F in the body is negligible, exogenous 19F signals obtained by 19F radiofrequency coils are exceptionally specific. Highly fluorinated agents targeting particular biological processes (i.e., the presence of immune cells) have been visualised using 19F MRI, highlighting its potential for non-invasive and longitudinal molecular imaging. This article aims to provide both a broad overview of the various applications of 19F MRI, with cancer imaging as a focus, as well as a practical guide to 19F imaging. We will discuss the essential elements of a 19F system and address common pitfalls during acquisition. Last but not least, we will highlight future perspectives that will enhance the role of this modality. While not an exhaustive exploration of all 19F literature, we endeavour to encapsulate the broad themes of the field and introduce the world of 19F molecular imaging to newcomers. 19F MRI bridges several domains, imaging, physics, chemistry, and biology, necessitating multidisciplinary teams to be able to harness this technology effectively. As further technical developments allow for greater sensitivity, we envision that 19F MRI can help unlock insight into biological processes non-invasively and longitudinally.
Collapse
Affiliation(s)
| | | | | | | | | | - Leila Akkari
- Division of Tumor Biology and Immunology, Oncode Institute, The Netherlands Cancer Institute, Amsterdam, The Netherlands
| | | | - René Bernards
- Division of Molecular Carcinogenesis, Oncode Institute, The Netherlands Cancer Institute, Amsterdam, The Netherlands
| | | |
Collapse
|
9
|
Petratou D, Gjikolaj M, Kaulich E, Schafer W, Tavernarakis N. A proton-inhibited DEG/ENaC ion channel maintains neuronal ionstasis and promotes neuronal survival under stress. iScience 2023; 26:107117. [PMID: 37416472 PMCID: PMC10320524 DOI: 10.1016/j.isci.2023.107117] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2022] [Revised: 03/28/2023] [Accepted: 06/09/2023] [Indexed: 07/08/2023] Open
Abstract
The nervous system participates in the initiation and modulation of systemic stress. Ionstasis is of utmost importance for neuronal function. Imbalance in neuronal sodium homeostasis is associated with pathologies of the nervous system. However, the effects of stress on neuronal Na+ homeostasis, excitability, and survival remain unclear. We report that the DEG/ENaC family member DEL-4 assembles into a proton-inactivated sodium channel. DEL-4 operates at the neuronal membrane and synapse to modulate Caenorhabditis elegans locomotion. Heat stress and starvation alter DEL-4 expression, which in turn alters the expression and activity of key stress-response transcription factors and triggers appropriate motor adaptations. Similar to heat stress and starvation, DEL-4 deficiency causes hyperpolarization of dopaminergic neurons and affects neurotransmission. Using humanized models of neurodegenerative diseases in C. elegans, we showed that DEL-4 promotes neuronal survival. Our findings provide insights into the molecular mechanisms by which sodium channels promote neuronal function and adaptation under stress.
Collapse
Affiliation(s)
- Dionysia Petratou
- Institute of Molecular Biology and Biotechnology, Foundation for Research and Technology, Heraklion, 70013 Crete, Greece
- Department of Basic Sciences, Medical School, University of Crete, Heraklion, 71003 Crete, Greece
| | - Martha Gjikolaj
- Institute of Molecular Biology and Biotechnology, Foundation for Research and Technology, Heraklion, 70013 Crete, Greece
- Department of Basic Sciences, Medical School, University of Crete, Heraklion, 71003 Crete, Greece
| | - Eva Kaulich
- Neurobiology Division, MRC Laboratory of Molecular Biology, Cambridge Biomedical Campus, CB2 0QH Cambridge, UK
| | - William Schafer
- Neurobiology Division, MRC Laboratory of Molecular Biology, Cambridge Biomedical Campus, CB2 0QH Cambridge, UK
| | - Nektarios Tavernarakis
- Institute of Molecular Biology and Biotechnology, Foundation for Research and Technology, Heraklion, 70013 Crete, Greece
- Department of Basic Sciences, Medical School, University of Crete, Heraklion, 71003 Crete, Greece
| |
Collapse
|
10
|
Igarashi T, Kim H, Sun PZ. Detection of tissue pH with quantitative chemical exchange saturation transfer magnetic resonance imaging. NMR IN BIOMEDICINE 2023; 36:e4711. [PMID: 35141979 PMCID: PMC10249910 DOI: 10.1002/nbm.4711] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/08/2021] [Revised: 02/03/2022] [Accepted: 02/05/2022] [Indexed: 05/12/2023]
Abstract
Chemical exchange saturation transfer (CEST) magnetic resonance imaging (MRI) has emerged as a novel means for sensitive detection of dilute labile protons and chemical exchange rates. By sensitizing to pH-dependent chemical exchange, CEST MRI has shown promising results in monitoring tissue statuses such as pH changes in disorders like acute stroke, tumor, and acute kidney injury. This article briefly reviews the basic principles for CEST imaging and quantitative measures, from the simplistic asymmetry analysis to multipool Lorentzian decoupling and quasi-steady-state reconstruction. In particular, the advantages and limitations of commonly used quantitative approaches for CEST applications are discussed.
Collapse
Affiliation(s)
- Takahiro Igarashi
- Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA
| | - Hahnsung Kim
- Department of Radiology and Imaging Sciences, Emory University School of Medicine, Atlanta, GA
- Yerkes Imaging Center, Yerkes National Primate Research Center, Emory University, Atlanta, GA
| | - Phillip Zhe Sun
- Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA
- Department of Radiology and Imaging Sciences, Emory University School of Medicine, Atlanta, GA
- Yerkes Imaging Center, Yerkes National Primate Research Center, Emory University, Atlanta, GA
| |
Collapse
|
11
|
Heo HY, Tee YK, Harston G, Leigh R, Chappell M. Amide proton transfer imaging in stroke. NMR IN BIOMEDICINE 2023; 36:e4734. [PMID: 35322482 PMCID: PMC9761584 DOI: 10.1002/nbm.4734] [Citation(s) in RCA: 12] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/02/2021] [Revised: 03/04/2022] [Accepted: 03/21/2022] [Indexed: 05/23/2023]
Abstract
Amide proton transfer (APT) imaging, a variant of chemical exchange saturation transfer MRI, has shown promise in detecting ischemic tissue acidosis following impaired aerobic metabolism in animal models and in human stroke patients due to the sensitivity of the amide proton exchange rate to changes in pH within the physiological range. Recent studies have demonstrated the possibility of using APT-MRI to detect acidosis of the ischemic penumbra, enabling the assessment of stroke severity and risk of progression, monitoring of treatment progress, and prognostication of clinical outcome. This paper reviews current APT imaging methods actively used in ischemic stroke research and explores the clinical aspects of ischemic stroke and future applications for these methods.
Collapse
Affiliation(s)
- Hye-Young Heo
- Division of MR Research, Department of Radiology, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
- F.M. Kirby Research Center for Functional Brain Imaging, Kennedy Krieger Institute, Baltimore, Maryland, USA
| | - Yee Kai Tee
- Lee Kong Chian Faculty of Engineering and Science, University Tunku Abdul Rahman, Malaysia
| | - George Harston
- Acute Stroke Programme, Oxford University Hospitals NHS Foundation Trust, Oxford, UK
| | - Richard Leigh
- Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| | - Michael Chappell
- Radiological Sciences, Mental Health and Clinical Neurosciences, School of Medicine, University of Nottingham, Nottingham, UK
- Nottingham Biomedical Research Centre, Queen’s Medical Centre, University of Nottingham, Nottingham, United Kingdom, UK
| |
Collapse
|
12
|
Yong X, Lu S, Hsu YC, Fu C, Sun Y, Zhang Y. Numerical fitting of Extrapolated semisolid Magnetization transfer Reference signals: Improved detection of ischemic stroke. Magn Reson Med 2023; 90:722-736. [PMID: 37052377 DOI: 10.1002/mrm.29660] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2022] [Revised: 03/09/2023] [Accepted: 03/18/2023] [Indexed: 04/14/2023]
Abstract
PURPOSE To propose a novel Numerical fitting method of the Extrapolated semisolid Magnetization transfer Reference (NEMR) signal for quantifying the CEST effect. THEORY AND METHODS Modified two-pool Bloch-McConnell equations were used to numerically fit the magnetization transfer (MT) and direct water saturation (DS) signals at far off-resonance frequencies, which was subsequently extrapolated into the frequency range of amide proton transfer (APT) and nuclear Overhauser enhancement (NOE) pools. Then the subtraction of the fitted two-pool z-spectrum and the experimentally acquired z-spectrum yielded APT# and NOE# signals mostly free of MT and DS contamination. Several strategies were used to accelerate the NEMR fitting. Furthermore, the proposed NEMR method was compared with the conventional extrapolated semisolid magnetization transfer reference (EMR) and magnetization transfer ratio asymmetry (MTRasym ) methods in simulations and stroke patients. RESULTS The combination of RF downsampling, MT lineshape look-up table, and conversion of MATLAB code to C code accelerated the NEMR fitting by over 2700-fold. Monte-Carlo simulations showed that NEMR had higher accuracy than EMR and eliminated the requirement of the steady-state condition. In ischemic stroke patients, the NEMR maps at 1 μT removed hypointense artifacts seen on EMR and MTRasym images, and better depicted stroke lesions than EMR. For NEMR, NOE# yielded significantly (p < 0.05) stronger signal contrast between stroke and normal tissues than APT# at 1 μT. CONCLUSION The proposed NEMR method is suitable for arbitrary saturation settings and can remove MT and DS contamination from the CEST signal for improved detection of ischemic stroke.
Collapse
Affiliation(s)
- Xingwang Yong
- Key Laboratory for Biomedical Engineering of Ministry of Education, Department of Biomedical Engineering, College of Biomedical Engineering & Instrument Science, Zhejiang University, Hangzhou, Zhejiang, China
| | - Shanshan Lu
- The First Affiliated Hospital of Nanjing Medical University, Nanjing, Jiangsu, China
| | - Yi-Cheng Hsu
- MR Collaboration, Siemens Healthcare Ltd., Shanghai, China
| | - Caixia Fu
- Siemens Shenzhen Magnetic Resonance Ltd., Shenzhen, Guangdong, China
| | - Yi Sun
- MR Collaboration, Siemens Healthcare Ltd., Shanghai, China
| | - Yi Zhang
- Key Laboratory for Biomedical Engineering of Ministry of Education, Department of Biomedical Engineering, College of Biomedical Engineering & Instrument Science, Zhejiang University, Hangzhou, Zhejiang, China
| |
Collapse
|
13
|
Wu Y, Sun PZ. Demonstration of pH imaging in acute stroke with endogenous ratiometric chemical exchange saturation transfer magnetic resonance imaging at 2 ppm. NMR IN BIOMEDICINE 2023; 36:e4850. [PMID: 36259279 DOI: 10.1002/nbm.4850] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/14/2022] [Revised: 10/11/2022] [Accepted: 10/11/2022] [Indexed: 06/16/2023]
Abstract
pH change is often considered a hallmark of metabolic disruption in diseases such as ischemic stroke and cancer. Chemical exchange saturation transfer (CEST) MRI, particularly amide proton transfer (APT), has emerged as a noninvasive pH imaging approach. However, there are changes in multipool CEST effects besides APT MRI. Our study investigated radiofrequency (RF) amplitude-based ratiometric CEST pH imaging in acute stroke. Briefly, adult male Wistar rats underwent CEST MRI under two RF saturation (B1 ) levels of 0.75 and 1.5 μT following middle cerebral artery occlusion. Magnetization transfer (MT), direct water saturation, CEST at 2 ppm (CEST@2 ppm), amine (2.75 ppm), and APT (3.5 ppm) effects were resolved with the multipool Lorentzian fitting approach. The ratiometric analysis was measured in the ischemic lesion and the contralateral normal area, which was also correlated with pH-specific MT and the relaxation normalized APT (MRAPT) index. MT, amine CEST effect, and their respective ratiometric indices did not show significant changes in ischemic regions (p > 0.05), as expected. Whereas APT decreased in the ischemic lesion for B1 of 1.5 μT (p < 0.01), the correlation between the amide ratio with MRAPT index was moderate (r = 0.52, p = 0.02). By comparison, the ischemic tissue showed a significantly increased CEST@2 ppm for both saturation levels from the contralateral normal area (p ≤ 0.01). Importantly, the CEST@2 ppm ratio decreased in the ischemic lesion (p < 0.01), which highly correlated with the MRAPT index (r = 0.93, p < 0.001). To summarize, our study demonstrated the feasibility of endogenous CEST@2 ppm ratiometric imaging of pH upon acute stroke, promising to detect pH changes in metabolic diseases.
Collapse
Affiliation(s)
- Yin Wu
- Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital and Harvard Medical School, Charlestown, Massachusetts, USA
- Paul C. Lauterbur Research Centre for Biomedical Imaging, Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences, Shenzhen, Guangdong, China
| | - Phillip Zhe Sun
- Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital and Harvard Medical School, Charlestown, Massachusetts, USA
- Department of Radiology and Imaging Sciences, Emory University School of Medicine, Atlanta, Georgia, USA
- Imaging Center, Emory National Primate Research Center, Emory University, Atlanta, Georgia, USA
| |
Collapse
|
14
|
Sun PZ. Demonstration of accurate multi-pool chemical exchange saturation transfer MRI quantification - Quasi-steady-state reconstruction empowered quantitative CEST analysis. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2023; 348:107379. [PMID: 36689786 PMCID: PMC10023465 DOI: 10.1016/j.jmr.2023.107379] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/16/2022] [Revised: 01/05/2023] [Accepted: 01/15/2023] [Indexed: 05/18/2023]
Abstract
Chemical exchange saturation transfer (CEST) MRI is sensitive to dilute labile protons and microenvironment properties, yet CEST quantification has been challenging. This difficulty is because the CEST measurement depends not only on the underlying CEST system but also on the scan protocols, including RF saturation amplitude, duration, and repetition time. In addition, T1 normalization is not straightforward under non-equilibrium conditions. Recently, a quasi-steady-state (QUASS) algorithm was established to reconstruct the desired equilibrium state from experimental measurements. Our study aimed to determine the accuracy of spinlock-model-based multi-pool CEST quantification using numerical simulations and phantom experiments. In short, CEST Z-spectra were simulated for a representative 3-pool model, and CEST amplitudes were solved with spinlock model-based multi-pool fitting and assessed as a function of RF saturation time (Ts), repetition time (TR), and T1. Although the apparent CEST signals showed significant T1 dependence, such relationships were not observed following QUASS reconstruction. To test the accuracy of T1 correction, a multi-vial phantom of nicotinamide and creatine was doped with manganese chloride, resulting in T1 ranging from 1 s to beyond 2 s. The multi-labile signals determined from the routine measurements showed significant dependence on Ts, TR, and T1. In contrast, CEST signals from the QUASS reconstruction showed consistent quantification independent of such variables. To summarize, our study demonstrated that accurate CEST quantification is feasible in multi-pool CEST systems with the spinlock-model-based fitting of QUASS CEST MRI.
Collapse
Affiliation(s)
- Phillip Zhe Sun
- Primate Imaging Center, Emory National Primate Research Center, Emory University, Atlanta, GA, United States; Department of Radiology and Imaging Sciences, Emory University School of Medicine, Atlanta, GA, United States.
| |
Collapse
|
15
|
Chung J, Jin T. Average saturation efficiency filter ASEF-CEST MRI of stroke rodents. Magn Reson Med 2023; 89:565-576. [PMID: 36300851 PMCID: PMC9757140 DOI: 10.1002/mrm.29463] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2022] [Revised: 07/29/2022] [Accepted: 08/29/2022] [Indexed: 12/13/2022]
Abstract
PURPOSE The average saturation efficiency filter (ASEF) is a novel method of improving the specificity of CEST; however, there is a mismatch between the magnetization transfer (MT) effect under high-duty cycle and low-duty cycle pulse trains. We explore measures of mitigation and the sensitivity and potential of ASEF imaging in phantoms and stroke rats. METHODS Simulation and nicotinamide phantoms in denatured protein were used to investigate the effect of different average saturation powers and MT pool parameters on matching coefficients used for correction as well as the ASEF ratio signal and baseline. Then, in vivo studies were performed in stroke rodents to further investigate the sensitivity and fidelity of ASEF ratio spectra. RESULTS Simulation and studies of nicotinamide phantoms show that the matching coefficient needed to correct the baseline MT mismatch is strongly dependent on the average saturation power. In vivo studies in stroke rodents show that the matching coefficient required to correct the baseline MT mismatch is different for normal versus ischemic tissue. Thus, a baseline correction was performed to further suppress the residue MT mismatch. After correction of the mismatch, ASEF ratio achieved comparable contrast at 3.6 ppm between normal and ischemic tissue when compared to the apparent amide proton transfer (APT*) approach. Moreover, contrasts for 2.0 and 2.6 ppm were also ascertainable from the same spectra. CONCLUSION ASEF can improve the CEST signal specificity of slow exchange labile protons such as amide and guanidyl, with small loss to sensitivity. It has strong potential in the CEST imaging of various diseases.
Collapse
Affiliation(s)
- Julius Chung
- Department of Radiology, University of Pittsburgh, Pittsburgh, Pennsylvania, USA
| | - Tao Jin
- Department of Radiology, University of Pittsburgh, Pittsburgh, Pennsylvania, USA
| |
Collapse
|
16
|
Sun PZ. Quasi-steady-state amide proton transfer (QUASS APT) MRI enhances pH-weighted imaging of acute stroke. Magn Reson Med 2022; 88:2633-2644. [PMID: 36178234 PMCID: PMC9529238 DOI: 10.1002/mrm.29408] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2022] [Revised: 07/15/2022] [Accepted: 07/19/2022] [Indexed: 02/01/2023]
Abstract
PURPOSE Chemical exchange saturation transfer (CEST) imaging measurement depends not only on the labile proton concentration and pH-dependent exchange rate but also on experimental conditions, including the relaxation delay and radiofrequency (RF) saturation time. Our study aimed to extend a quasi-steady-state (QUASS) solution to a modified multi-slice CEST MRI sequence and test if it provides enhanced pH imaging after acute stroke. METHODS Our study derived the QUASS solution for a modified multislice CEST MRI sequence with an unevenly segmented RF saturation between image readout and signal averaging. Numerical simulation was performed to test if the generalized QUASS solution corrects the impact of insufficiently long relaxation delay, primary and secondary saturation times, and multi-slice readout. In addition, multiparametric MRI scans were obtained after middle cerebral artery occlusion, including relaxation and CEST Z-spectrum, to evaluate the performance of QUASS CEST MRI in a rodent acute stroke model. We also performed Lorentzian fitting to isolate multi-pool CEST contributions. RESULTS The QUASS analysis enhanced pH-weighted magnetization transfer asymmetry contrast over the routine apparent CEST measurements in both contralateral normal (-3.46% ± 0.62% (apparent) vs. -3.67% ± 0.66% (QUASS), P < 0.05) and ischemic tissue (-5.53% ± 0.68% (apparent) vs. -5.94% ± 0.73% (QUASS), P < 0.05). Lorentzian fitting also showed significant differences between routine and QUASS analysis of ischemia-induced changes in magnetization transfer, amide, amine, guanidyl CEST, and nuclear Overhauser enhancement (-1.6 parts per million) effects. CONCLUSION Our study demonstrated that generalized QUASS analysis enhanced pH MRI contrast and improved quantification of the underlying CEST contrast mechanism, promising for further in vivo applications.
Collapse
Affiliation(s)
- Phillip Zhe Sun
- Athinoula A Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Boston, MA
- Imaging Center, Emory National Primate Research Center, Emory University, Atlanta GA
- Department of Radiology and Imaging Sciences, Emory University School of Medicine, Atlanta GA
| |
Collapse
|
17
|
Chen X, Zhang J, Wang K. Inhibition of intracellular proton-sensitive Ca 2+-permeable TRPV3 channels protects against ischemic brain injury. Acta Pharm Sin B 2022; 12:2330-2347. [PMID: 35646518 PMCID: PMC9136580 DOI: 10.1016/j.apsb.2022.01.001] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2021] [Revised: 11/18/2021] [Accepted: 12/02/2021] [Indexed: 11/24/2022] Open
Abstract
Ischemic brain stroke is pathologically characterized by tissue acidosis, sustained calcium entry and progressive cell death. Previous studies focusing on antagonizing N-methyl-d-aspartate (NMDA) receptors have failed to translate any clinical benefits, suggesting a non-NMDA mechanism involved in the sustained injury after stroke. Here, we report that inhibition of intracellular proton-sensitive Ca2+-permeable transient receptor potential vanilloid 3 (TRPV3) channel protects against cerebral ischemia/reperfusion (I/R) injury. TRPV3 expression is upregulated in mice subjected to cerebral I/R injury. Silencing of TRPV3 reduces intrinsic neuronal excitability, excitatory synaptic transmissions, and also attenuates cerebral I/R injury in mouse model of transient middle cerebral artery occlusion (tMCAO). Conversely, overexpressing or re-expressing TRPV3 increases neuronal excitability, excitatory synaptic transmissions and aggravates cerebral I/R injury. Furthermore, specific inhibition of TRPV3 by natural forsythoside B decreases neural excitability and attenuates cerebral I/R injury. Taken together, our findings for the first time reveal a causative role of neuronal TRPV3 channel in progressive cell death after stroke, and blocking overactive TRPV3 channel may provide therapeutic potential for ischemic brain injury.
Collapse
|
18
|
Nouri-Vaskeh M, Khalili N, Sadighi A, Yazdani Y, Zand R. Biomarkers for Transient Ischemic Attack: A Brief Perspective of Current Reports and Future Horizons. J Clin Med 2022; 11:jcm11041046. [PMID: 35207321 PMCID: PMC8877275 DOI: 10.3390/jcm11041046] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2022] [Revised: 02/09/2022] [Accepted: 02/16/2022] [Indexed: 02/05/2023] Open
Abstract
Cerebrovascular disease is the leading cause of long-term disability in the world and the third-leading cause of death in the United States. The early diagnosis of transient ischemic attack (TIA) is of great importance for reducing the mortality and morbidity of cerebrovascular diseases. Patients with TIA have a high risk of early subsequent ischemic stroke and the development of permanent nervous system lesions. The diagnosis of TIA remains a clinical diagnosis that highly relies on the patient's medical history assessment. There is a growing list of biomarkers associated with different components of the ischemic cascade in the brain. In this review, we take a closer look at the biomarkers of TIA and their validity with a focus on the more clinically important ones using recent evidence of their reliability for practical usage.
Collapse
Affiliation(s)
- Masoud Nouri-Vaskeh
- Tropical and Communicable Diseases Research Centre, Iranshahr University of Medical Sciences, Iranshahr 7618815676, Iran;
- Network of Immunity in Infection, Malignancy and Autoimmunity, Universal Scientific Education and Research Network, Tehran 1419733151, Iran
| | - Neda Khalili
- School of Medicine, Tehran University of Medical Sciences, Tehran 1449614535, Iran;
- Cancer Immunology Project (CIP), Universal Scientific Education and Research Network (USERN), Tehran 1419733151, Iran
| | - Alireza Sadighi
- Neuroscience Institute, Geisinger Health System, Danville, PA 17822, USA;
| | - Yalda Yazdani
- Immunology Research Center, Tabriz University of Medical Sciences, Tabriz 5165665931, Iran;
| | - Ramin Zand
- Neuroscience Institute, Geisinger Health System, Danville, PA 17822, USA;
- Neuroscience Institute, Pennsylvania State University, State College, PA 16801, USA
- Correspondence: or ; Tel.: +1-570-808-7330; Fax: +1-570-808-3209
| |
Collapse
|
19
|
Sun PZ. Consistent depiction of the acidic ischemic lesion with APT MRI-Dual RF power evaluation of pH-sensitive image in acute stroke. Magn Reson Med 2022; 87:850-858. [PMID: 34590730 PMCID: PMC8627494 DOI: 10.1002/mrm.29029] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2021] [Revised: 07/31/2021] [Accepted: 09/09/2021] [Indexed: 02/03/2023]
Abstract
PURPOSE Amide proton transfer-weighted (APTw) MRI provides a non-invasive pH-sensitive image, complementing perfusion and diffusion imaging for refined stratification of ischemic tissue. Although the commonly used magnetization transfer (MT) asymmetry (MTRasym ) calculation reasonably corrects the direct RF saturation effect, it is susceptible to the concomitant semisolid macromolecular MT contribution. Therefore, this study aimed to compare the performance of MTRasym and magnetization transfer and relaxation-normalized APT (MRAPT) analyses under 2 representative experimental conditions. METHODS Multiparametric MRI scans were performed in a rodent model of acute stroke, including relaxation, diffusion, and Z spectral images under 2 representative RF levels of 0.75 and 1.5 µT. Both MTRasym and MRAPT values in the ischemic diffusion lesion and the contralateral normal areas were compared using correlation and Bland-Altman tests. In addition, the acidic lesion volumes were compared. RESULTS MRAPT measurements from the diffusion lesion under the 2 conditions were highly correlated (R2 = 0.97) versus MTRasym measures (R2 = 0.58). The pH lesion sizes determined from MRAPT analysis were in good agreement (178 ± 43 mm3 vs. 186 ± 55 mm3 for B1 of 0.75 and 1.5 µT, respectively). CONCLUSIONS The study demonstrated that MRAPT analysis could be generalized to moderately different RF amplitudes, providing a more consistent depiction of acidic lesions than the MTRasym analysis.
Collapse
Affiliation(s)
- Phillip Zhe Sun
- Athinoula A Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Boston, MA,Yerkes Imaging Center, Yerkes National Primate Research Center, Emory University, Atlanta GA,Department of Radiology and Imaging Sciences, Emory University School of Medicine, Atlanta GA,Corresponding Author: Phillip Zhe Sun, Ph.D., Department of Radiology and Imaging Sciences, Emory University School of Medicine, 954 Gatewood Road NE, Atlanta, GA 30329, Phone: (404) 727-7786; (404) 712-1667,
| |
Collapse
|
20
|
Zhao Y, Chen Y, Chen Y, Zhang L, Wang X, He X. A Fully Convolutional Network (FCN) based Automated Ischemic Stroke Segment Method using Chemical Exchange Saturation Transfer Imaging. Med Phys 2022; 49:1635-1647. [PMID: 35083756 DOI: 10.1002/mp.15483] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2021] [Revised: 12/26/2021] [Accepted: 01/02/2022] [Indexed: 11/11/2022] Open
Abstract
BACKGROUND Chemical exchange saturation transfer (CEST) MRI is a promising imaging modality in ischemic stroke detection for its sensitivity in sensing post-ischemic pH alteration. However, the accurate segmentation of pH-altered regions remains difficult due to the complicated sources in water signal changes of CEST MRI. Meanwhile, manual localization and quantification of stroke lesions are laborious and time-consuming, which cannot meet the urgent need for timely therapeutic interventions. PURPOSE The goal of this study was to develop an automatic lesion segmentation approach of ischemic region based on CEST MR images. A novel segmentation framework based on fully convolutional neural network was investigated for our task. METHODS Z-spectra from 10 rats were manually labeled as ground truth and split into two datasets, where the training dataset including 3 rats was used to generate a segmentation model, and the remaining rats were used as test datasets to evaluate the model's performance. Then a 1-D fully convolutional neural network equipped with bottleneck structures was set up, and a Grad-CAM approach was used to produce a coarse localization map, which can reflect the relevancy to the 'ischemia' class of each pixel. RESULTS As compared with the ground truth, the proposed network model achieved satisfying segmentation results with high values of evaluation metrics including specificity (SPE), sensitivity (SEN), accuracy (ACC), and Dice similarity coefficient (DSC), especially in some intractable situations where conventional MRI modalities and CEST quantitative method failed to distinguish between ischemic and normal tissues, and the model with augmentation was robust to input perturbations. The Grad-CAM maps performed clear tissue change distributions and interpreted the segmentations, and showed a strong correlation with the quantitative method, gave extended thinking to the function of networks. CONCLUSIONS The proposed method can segment ischemia region from CEST images, with the Grad-CAM maps give access to interpretative information about the segmentations, which demonstrates great potential in clinical routines. This article is protected by copyright. All rights reserved.
Collapse
Affiliation(s)
- Yingcheng Zhao
- Xi'an Key Lab of Radiomics and Intelligent Perception, School of Information Sciences and Technology, Northwest University, Xi'an, Shaanxi, 710069, China
| | - Yibing Chen
- Xi'an Key Lab of Radiomics and Intelligent Perception, School of Information Sciences and Technology, Northwest University, Xi'an, Shaanxi, 710069, China
| | - Yanrong Chen
- Xi'an Key Lab of Radiomics and Intelligent Perception, School of Information Sciences and Technology, Northwest University, Xi'an, Shaanxi, 710069, China
| | - Lihong Zhang
- College of Computer Science and Technology (Software College), Henan Polytechnic University, Jiaozuo, Henan, 454003, China
| | - Xiaoli Wang
- Department of Medical Imaging, Weifang Medical University, Weifang, 261053, China
| | - Xiaowei He
- Xi'an Key Lab of Radiomics and Intelligent Perception, School of Information Sciences and Technology, Northwest University, Xi'an, Shaanxi, 710069, China
| |
Collapse
|
21
|
Chen S, Liu X, Lin J, Mei Y, Deng K, Xue Q, Song X, Xu Y. Application of amide proton transfer imaging for the diagnosis of neonatal hypoxic-ischemic encephalopathy. Front Pediatr 2022; 10:996949. [PMID: 36440343 PMCID: PMC9691961 DOI: 10.3389/fped.2022.996949] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/18/2022] [Accepted: 10/25/2022] [Indexed: 11/13/2022] Open
Abstract
OBJECTIVE This study aimed to evaluate cerebral amide proton transfer signal intensity (SI) among controls, hypoxic-ischemic encephalopathy (HIE) neonates with normal conventional magnetic resonance imaging (HIE/MRI-) findings, and HIE neonates with abnormal conventional MRI (HIE/MRI+) findings. METHODS Forty neonates diagnosed with neonatal HIE and sixteen normal neonates were evaluated. All neonates underwent conventional MRI scans and APT imaging. Cerebral APT SIs were compared to identify cerebral regions with significant APT changes among sixteen controls, thirteen HIE/MRI- patients, and twenty-seven HIE/MRI+ patients. RESULTS Significantly increased APT SIs were observed in the HIE/MRI- group compared with controls, in the left insula, right occipital lobe, left cingulate gyrus (posterior part), and corpus callosum. Significantly increased APT SIs were found in the HIE/MRI+ group compared with controls, in the right anterior temporal lobe (medial part), anterior parts of the right parahippocampal and ambient gyri, left superior temporal gyrus (middle part), left insula, left cingulate gyrus (posterior part), and right lentiform nucleus. No significant APT SI differences were observed in the cerebellum and brainstem among the three groups. CONCLUSION Amide proton transfer imaging plays an important role in detecting hypoxic-ischemic encephalopathy regardless of conventional MRI findings. Changes in APT signal intensity may provide important insights into the characterization of the cerebral internal environment. This study suggests that APT imaging could be used as a complement to conventional MRI in the detection of hypoxic-ischemic encephalopathy in clinical practice.
Collapse
Affiliation(s)
- Sijin Chen
- Department of Medical Imaging Center, Nanfang Hospital, Southern Medical University, Guangzhou, China.,Department of Obstetrics & Gynecology, Nanfang Hospital Baiyun Branch, Southern Medical University, Guangzhou, China
| | - Xilong Liu
- Department of Medical Imaging Center, Nanfang Hospital, Southern Medical University, Guangzhou, China
| | - Jie Lin
- Department of Medical Imaging Center, Nanfang Hospital, Southern Medical University, Guangzhou, China
| | - Yingjie Mei
- School of Biomedical Engineering, Southern Medical University, Guangzhou, China
| | - Kan Deng
- C&TS MR Clinical Science, Philips Healthcare, Guangzhou, China
| | - Qiao Xue
- Helong Street Community Health Service Center, Guangzhou, China
| | - Xiaoyan Song
- Department of Neonatology, Nanfang Hospital, Southern Medical University, Guangzhou, China
| | - Yikai Xu
- Department of Medical Imaging Center, Nanfang Hospital, Southern Medical University, Guangzhou, China
| |
Collapse
|
22
|
Guo Z, Meng Z, Mu R, Qin X, Zhuang Z, Zheng W, Liu F, Zhu X. Amide Proton Transfer MRI Could Be Used to Evaluate the Pathophysiological Status of White Matter Hyperintensities. J Magn Reson Imaging 2021; 56:301-309. [PMID: 34854519 DOI: 10.1002/jmri.28013] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2021] [Revised: 11/21/2021] [Accepted: 11/24/2021] [Indexed: 12/19/2022] Open
Abstract
BACKGROUND The pathophysiology of white matter hyperintensities (WMH) remains unclear, investigations of amide proton transfer (APT) signals in WMH disease may provide relevant pathophysiological information. PURPOSE To evaluate the APT signals differences and heterogeneity of WMH and adjacent normal-appearing white matter (NAWM) at different Fazekas grades and different locations. STUDY TYPE Prospective. POPULATION In all, 180 WMH patients (age, 40-76; male/female, 77/103) and 59 healthy controls (age, 42-70; male/female, 23/36). FIELD STRENGTH/SEQUENCE A 3 T; 3D fluid-attenuated inversion recovery (FLAIR), 3D APT-weighted (APTw). ASSESSMENT The mean APTw values (APTwmean ) and the APTw signals heterogeneity (APTwmax-min ) among different grades WMH and NAWM and the APTwmean of the same grade deep WMH (DWMH) and paraventricular WMH (PWMH) were calculated and compared. Regions of interests were delineated on WMH lesions, NAWM and healthy white matter. STATISTICAL TESTS One-way analysis of variance (ANOVA); independent sample t test; Chi-square test. Significance level: P < 0.05. RESULTS APTwmean among different grade WMH (from grade 0 to 3, 0.58 ± 0.14% vs. 0.29 ± 0.23% vs. 0.37 ± 0.24% vs. 0.61 ± 0.22%, respectively) were significantly different except between grade 1 and 2 (P = 0.27) and between grade 0 and 3 (P = 0.97). The differences in APTwmean between WMH and NAWM were significant (WMH vs. NAWM from grade 1 to 3, 0.29% ± 0.23% vs. 0.55% ± 0.27%; 0.37% ± 0.24% vs. 0.59% ± 0.22%; 0.61% ± 0.22% vs. 0.42% ± 0.24%, respectively). Lower APTwmean values were found only in grade 3 NAWM than other grades NAWM and controls. The APTwmax-min values of grade 1-3 WMH (0.38% ± 0.27% vs. 0.51% ± 0.31% vs. 0.67% ± 0.34%, respectively) were significantly different. Higher APTmean values were found only in grade 2 PWMH (0.47% ± 0.22% vs. 0.32% ± 0.24%). DATA CONCLUSION Significant differences of APT signals were found in WMH of different Fazekas grades and different locations. EVIDENCE LEVEL 2 TECHNICAL EFFICACY: Stage 3.
Collapse
Affiliation(s)
- Zixuan Guo
- Department of Medical Imaging, Guilin Medical University, Guilin, China.,Department of Medical Imaging, Nanxishan Hospital of Guangxi Zhuang Autonomous Region, Guilin, China
| | - Zhuoni Meng
- Department of Medical Imaging, Guilin Medical University, Guilin, China.,Department of Medical Imaging, Nanxishan Hospital of Guangxi Zhuang Autonomous Region, Guilin, China
| | - Ronghua Mu
- Department of Medical Imaging, Guilin Medical University, Guilin, China.,Department of Medical Imaging, Nanxishan Hospital of Guangxi Zhuang Autonomous Region, Guilin, China
| | - Xiaoyan Qin
- Department of Medical Imaging, Nanxishan Hospital of Guangxi Zhuang Autonomous Region, Guilin, China
| | - Zeyu Zhuang
- Department of Medical Imaging, Guilin Medical University, Guilin, China.,Department of Medical Imaging, Nanxishan Hospital of Guangxi Zhuang Autonomous Region, Guilin, China
| | - Wei Zheng
- Department of Medical Imaging, Guilin Medical University, Guilin, China.,Department of Medical Imaging, Nanxishan Hospital of Guangxi Zhuang Autonomous Region, Guilin, China
| | - Fuzhen Liu
- Department of Medical Imaging, Nanxishan Hospital of Guangxi Zhuang Autonomous Region, Guilin, China
| | - Xiqi Zhu
- Department of Medical Imaging, Nanxishan Hospital of Guangxi Zhuang Autonomous Region, Guilin, China
| |
Collapse
|
23
|
Kakkar P, Kakkar T, Patankar T, Saha S. Current approaches and advances in the imaging of stroke. Dis Model Mech 2021; 14:273651. [PMID: 34874055 PMCID: PMC8669490 DOI: 10.1242/dmm.048785] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022] Open
Abstract
A stroke occurs when the blood flow to the brain is suddenly interrupted, depriving brain cells of oxygen and glucose and leading to further cell death. Neuroimaging techniques, such as computed tomography and magnetic resonance imaging, have greatly improved our ability to visualise brain structures and are routinely used to diagnose the affected vascular region of a stroke patient's brain and to inform decisions about clinical care. Currently, these multimodal imaging techniques are the backbone of the clinical management of stroke patients and have immensely improved our ability to visualise brain structures. Here, we review recent developments in the field of neuroimaging and discuss how different imaging techniques are used in the diagnosis, prognosis and treatment of stroke. Summary: Stroke imaging has undergone seismic shifts in the past decade. Although magnetic resonance imaging (MRI) is superior to computed tomography in providing vital information, further research on MRI is still required to bring its full potential into clinical practice.
Collapse
Affiliation(s)
- Pragati Kakkar
- Leeds Institute of Cardiovascular and Metabolic Medicine, Faculty of Medicine and Health, University of Leeds, Leeds LS2 9JT, UK
| | - Tarun Kakkar
- Leeds Institute of Cardiovascular and Metabolic Medicine, Faculty of Medicine and Health, University of Leeds, Leeds LS2 9JT, UK
| | | | - Sikha Saha
- Leeds Institute of Cardiovascular and Metabolic Medicine, Faculty of Medicine and Health, University of Leeds, Leeds LS2 9JT, UK
| |
Collapse
|
24
|
Cheung J, Doerr M, Hu R, Sun PZ. Refined Ischemic Penumbra Imaging with Tissue pH and Diffusion Kurtosis Magnetic Resonance Imaging. Transl Stroke Res 2021; 12:742-753. [PMID: 33159656 PMCID: PMC8102648 DOI: 10.1007/s12975-020-00868-z] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2020] [Revised: 10/14/2020] [Accepted: 10/18/2020] [Indexed: 12/19/2022]
Abstract
Imaging has played a vital role in our mechanistic understanding of acute ischemia and the management of acute stroke patients. The most recent DAWN and DEFUSE-3 trials showed that endovascular therapy could be extended to a selected group of late-presenting stroke patients with the aid of imaging. Although perfusion and diffusion MRI have been commonly used in stroke imaging, the approximation of their mismatch as the penumbra is oversimplified, particularly in the era of endovascular therapy. Briefly, the hypoperfusion lesion includes the benign oligemia that does not proceed to infarction. Also, with prompt and effective reperfusion therapy, a portion of the diffusion lesion is potentially reversible. Therefore, advanced imaging that provides improved ischemic tissue characterization may enable new experimental stroke therapeutics and eventually further individualize stroke treatment upon translation to the clinical setting. Specifically, pH imaging captures tissue of altered metabolic state that demarcates the hypoperfused lesion into ischemic penumbra and benign oligemia, which remains promising to define the ischemic penumbra's outer boundary. On the other hand, diffusion kurtosis imaging (DKI) differentiates the most severely damaged and irreversibly injured diffusion lesion from the portion of diffusion lesion that is potentially reversible, refining the inner boundary of the penumbra. Altogether, the development of advanced imaging has the potential to not only transform the experimental stroke research but also aid clinical translation and patient management.
Collapse
Affiliation(s)
- Jesse Cheung
- Emory College of Arts and Sciences, Emory University, Atlanta, GA, 30329, USA
- Yerkes Imaging Center, Yerkes National Primate Research Center, Emory University, Atlanta, GA, 30329, USA
| | - Madeline Doerr
- Yerkes Imaging Center, Yerkes National Primate Research Center, Emory University, Atlanta, GA, 30329, USA
- Dartmouth College, Hanover, NH, 03755, USA
| | - Ranliang Hu
- Department of Radiology and Imaging Sciences, Emory University School of Medicine, 1364 Clifton RD NE, Atlanta, GA, 30322, USA
| | - Phillip Zhe Sun
- Yerkes Imaging Center, Yerkes National Primate Research Center, Emory University, Atlanta, GA, 30329, USA.
- Department of Radiology and Imaging Sciences, Emory University School of Medicine, 1364 Clifton RD NE, Atlanta, GA, 30322, USA.
| |
Collapse
|
25
|
Hampton DG, Goldman-Yassen AE, Sun PZ, Hu R. Metabolic Magnetic Resonance Imaging in Neuroimaging: Magnetic Resonance Spectroscopy, Sodium Magnetic Resonance Imaging and Chemical Exchange Saturation Transfer. Semin Ultrasound CT MR 2021; 42:452-462. [PMID: 34537114 DOI: 10.1053/j.sult.2021.07.003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Magnetic resonance (MR) is a powerful and versatile technique that offers much more beyond conventional anatomic imaging and has the potential of probing in vivo metabolism. Although MR spectroscopy (MRS) predates clinical MR imaging (MRI), its clinical application has been limited by technical and practical challenges. Other MR techniques actively being developed for in vivo metabolic imaging include sodium concentration imaging and chemical exchange saturation transfer. This article will review some of the practical aspects of MRS in neuroimaging, introduce sodium MRI and chemical exchange saturation transfer MRI, and highlight some of their emerging clinical applications.
Collapse
Affiliation(s)
- Daniel G Hampton
- Department of Radiology and Imaging Sciences, Emory University School of Medicine, Atlanta, GA.
| | - Adam E Goldman-Yassen
- Department of Radiology and Imaging Sciences, Emory University School of Medicine, Atlanta, GA
| | - Phillip Zhe Sun
- Department of Radiology and Imaging Sciences, Emory University School of Medicine, Atlanta, GA; Yerkes Imaging Center, Yerkes National Primate Research Center, Emory University, Atlanta, GA
| | - Ranliang Hu
- Department of Radiology and Imaging Sciences, Emory University School of Medicine, Atlanta, GA
| |
Collapse
|
26
|
Sun PZ. Quasi-steady-state chemical exchange saturation transfer (QUASS CEST) MRI analysis enables T 1 normalized CEST quantification - Insight into T 1 contribution to CEST measurement. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2021; 329:107022. [PMID: 34144360 PMCID: PMC8316384 DOI: 10.1016/j.jmr.2021.107022] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/04/2021] [Revised: 05/29/2021] [Accepted: 06/07/2021] [Indexed: 05/26/2023]
Abstract
Chemical exchange saturation transfer (CEST) MRI depends not only on the labile proton concentration and exchange rate but also on relaxation rates, particularly T1 relaxation time. However, T1 normalization has shown to be not straightforward under non-steady-state conditions and in the presence of radiofrequency spillover effect. Our study aimed to test if the combined use of the new quasi-steady-state (QUASS) analysis and inverse CEST calculation facilitates T1 normalization for improved CEST quantification. The CEST signal was simulated with Bloch-McConnell equations, and the apparent CEST, QUASS CEST, and the inverse CEST effects were calculated. T1-normalized CEST effects were tested for their specificity to the underlying CEST system (i.e., labile proton ratio and exchange rate). CEST experiments were performed from a 9-vial phantom of independently varied concentrations of creatine (20, 40, and 60 mM) and manganese chloride (20, 30, and 40 µM) under a range of RF saturation amplitudes (0.5-4 µT) and durations (1-4 s). The simulation showed that while T1 normalization of the apparent CEST effect was subject to noticeable T1 contamination, the T1-normalized inverse QUASS CEST effect had little T1 dependence. The experimental data were analyzed using a multiple linear regression model, showing that T1-normalized inverse QUASS analysis significantly depended on creatine concentration and saturation power (P < 0.05), not on manganese chloride concentration and saturation duration, advantageous over other CEST indices. The QUASS CEST algorithm reconstructs the steady-state CEST effect, enabling T1-normalized inverse CEST effect calculation for improved quantification of the underlying CEST system.
Collapse
Affiliation(s)
- Phillip Zhe Sun
- Yerkes Imaging Center, Yerkes National Primate Research Center, Emory University, Atlanta, GA, United States; Department of Radiology and Imaging Sciences, Emory University School of Medicine, Atlanta GA, United States.
| |
Collapse
|
27
|
Foo LS, Harston G, Mehndiratta A, Yap WS, Hum YC, Lai KW, Mohamed Mukari SA, Mohd Zaki F, Tee YK. Clinical translation of amide proton transfer (APT) MRI for ischemic stroke: a systematic review (2003-2020). Quant Imaging Med Surg 2021; 11:3797-3811. [PMID: 34341751 DOI: 10.21037/qims-20-1339] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2020] [Accepted: 03/22/2021] [Indexed: 12/15/2022]
Abstract
Amide proton transfer (APT) magnetic resonance imaging (MRI) is a pH-sensitive imaging technique that can potentially complement existing clinical imaging protocol for the assessment of ischemic stroke. This review aims to summarize the developments in the clinical research of APT imaging of ischemic stroke after 17 years of progress since its first preclinical study in 2003. Three electronic databases: PubMed, Scopus, and Cochrane Library were systematically searched for articles reporting clinical studies on APT imaging of ischemic stroke. Only articles in English published between 2003 to 2020 that involved patients presenting ischemic stroke-like symptoms that underwent APT MRI were included. Of 1,093 articles screened, 14 articles met the inclusion criteria with a total of 282 patients that had been scanned using APT imaging. Generally, the clinical studies agreed APT effect to be hypointense in ischemic tissue compared to healthy tissue, allowing for the detection of ischemic stroke. Other uses of APT imaging have also been investigated in the studies, including penumbra identification, predicting long term clinical outcome, and serving as a biomarker for supportive treatment monitoring. The published results demonstrated the potential of APT imaging in these applications, but further investigations and larger trials are needed for conclusive evidence. Future studies are recommended to report the result of asymmetry analysis at 3.5 ppm along with the findings of the study to reduce this contribution to the heterogeneity of experimental methods observed and to facilitate effective comparison of results between studies and centers. In addition, it is important to focus on the development of fast 3D imaging for full volumetric ischemic tissue assessment for clinical translation.
Collapse
Affiliation(s)
- Lee Sze Foo
- Lee Kong Chian Faculty of Engineering and Science, Universiti Tunku Abdul Rahman, Kajang, Malaysia
| | | | - Amit Mehndiratta
- Centre for Biomedical Engineering, Indian Institute of Technology Delhi, New Delhi, India.,Department of Biomedical Engineering, All India Institute of Medical Sciences, New Delhi, India
| | - Wun-She Yap
- Lee Kong Chian Faculty of Engineering and Science, Universiti Tunku Abdul Rahman, Kajang, Malaysia
| | - Yan Chai Hum
- Lee Kong Chian Faculty of Engineering and Science, Universiti Tunku Abdul Rahman, Kajang, Malaysia
| | - Khin Wee Lai
- Faculty of Engineering, Department of Biomedical Engineering, University of Malaya, Kuala Lumpur, Malaysia
| | | | - Faizah Mohd Zaki
- Department of Radiology, Universiti Kebangsaan Malaysia Medical Center (UKMMC), Kuala Lumpur, Malaysia
| | - Yee Kai Tee
- Lee Kong Chian Faculty of Engineering and Science, Universiti Tunku Abdul Rahman, Kajang, Malaysia
| |
Collapse
|
28
|
Four Decades of Ischemic Penumbra and Its Implication for Ischemic Stroke. Transl Stroke Res 2021; 12:937-945. [PMID: 34224106 DOI: 10.1007/s12975-021-00916-2] [Citation(s) in RCA: 37] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2021] [Revised: 05/10/2021] [Accepted: 05/12/2021] [Indexed: 12/15/2022]
Abstract
The ischemic penumbra defined four decades ago has been the main battleground of ischemic stroke. The evolving ischemic penumbra concept has been providing insight for the development of vascular and cellular approaches as well as diagnostic tools for the treatment of ischemic stroke. rt-PA thrombolytic therapy to prevent the transition of ischemic penumbra to core has been approved for acute ischemic stroke within 3 h and was later recommended to extend to 4.5 h after symptom onset. Mechanical thrombectomy was introduced for the treatment of acute ischemic stroke with a therapeutic window of up to 24 h after stroke onset. Multiple modalities brain imaging techniques have been developed that provide guidance to define ischemic penumbra for reperfusion therapy in clinical practice. Cellular and molecular dissection of ischemic penumbra has been providing targets for the development of neuroprotective therapy for ischemic stroke. However, the dynamic nature of ischemic penumbra implicates that infarct core eventually expands into penumbra over time without reperfusion, dictating relative short therapeutic windows and limiting the impact of current reperfusion intervention. Entering the 5th decade since the introduction, ischemic penumbra remains the main focus of ischemic stroke research and clinical practice. In this review, we summarized the evolving ischemic penumbra concept and its implication in the development of vascular and cellular interventions as well as diagnostic tools for acute ischemic stroke. In addition, we discussed future perspectives on expansion of the campaign beyond ischemic penumbra to develop treatment for ischemic stroke.
Collapse
|
29
|
Chung JJ, Jin T. Low duty cycle pulse trains for exchange rate insensitive chemical exchange saturation transfer MRI. Magn Reson Med 2021; 86:2542-2551. [PMID: 34196028 DOI: 10.1002/mrm.28896] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2020] [Revised: 04/29/2021] [Accepted: 06/02/2021] [Indexed: 12/22/2022]
Abstract
PURPOSE To introduce and validate a pulse scheme that uses low duty cycle trains of π-pulses to achieve saturation that is relatively insensitive to exchange rate yet linearly dependent on labile proton concentration. METHODS Simulations were performed to explore the exchange rate sensitivity of π-pulse trains and continuous wave chemical exchange saturation transfer (CEST) signals. Creatine phantoms with varying pH and varying concentrations were imaged to demonstrate pH insensitivity and concentration dependence of low duty cycle π-pulse saturation. RESULTS Simulations show decreasing the duty cycle of π-pulse saturation decreases peak sensitivity to exchange rate, and this range of insensitivity can be tuned to different exchange rates through average B1 power. The range of insensitivity is unaffected by changes in relaxation and magnetization transfer, while the sensitivity of CEST signal maintains linear dependence on labile proton concentration. Under B1, avg = 0.48 μT, 30 mM creatine with pHs ranging between 6.36 and 8.21 exhibited CEST contrast ranging between ~6 and 11% under continuous wave and ~4% across all pHs using 10% duty cycle π-pulses. Imaging these phantoms using duty cycles of 5, 10, 25, and 50% showed decreasing pH sensitivity with decreased duty cycle. Creatine phantoms with varied concentrations and pHs reveal that π-pulse train saturation exhibited stricter correlation to concentration at lower DCs. CONCLUSION Low DC π-pulse train is an easy-to-implement way of providing labile proton concentration-dependent CEST MRI signal that is insensitive to exchange rate. This approach can be useful in studies where a change of chemical exchange rate may interfere with accurate assessments of physiology or pathology.
Collapse
Affiliation(s)
- Julius Juhyun Chung
- Department of Radiology, University of Pittsburgh, Pittsburgh, Pennsylvania, USA
| | - Tao Jin
- Department of Radiology, University of Pittsburgh, Pittsburgh, Pennsylvania, USA
| |
Collapse
|
30
|
Foo LS, Larkin JR, Sutherland BA, Ray KJ, Yap WS, Hum YC, Lai KW, Manan HA, Sibson NR, Tee YK. Study of common quantification methods of amide proton transfer magnetic resonance imaging for ischemic stroke detection. Magn Reson Med 2021; 85:2188-2200. [PMID: 33107119 DOI: 10.1002/mrm.28565] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2020] [Revised: 09/30/2020] [Accepted: 10/02/2020] [Indexed: 12/14/2022]
Abstract
PURPOSE To assess the correlation and differences between common amide proton transfer (APT) quantification methods in the diagnosis of ischemic stroke. METHODS Five APT quantification methods, including asymmetry analysis and its variants as well as two Lorentzian model-based methods, were applied to data acquired from six rats that underwent middle cerebral artery occlusion scanned at 9.4T. Diffusion and perfusion-weighted images, and water relaxation time maps were also acquired to study the relationship of these conventional imaging modalities with the different APT quantification methods. RESULTS The APT ischemic area estimates had varying sizes (Jaccard index: 0.544 ≤ J ≤ 0.971) and had varying correlations in their distributions (Pearson correlation coefficient: 0.104 ≤ r ≤ 0.995), revealing discrepancies in the quantified ischemic areas. The Lorentzian methods produced the highest contrast-to-noise ratios (CNRs; 1.427 ≤ CNR ≤ 2.002), but generated APT ischemic areas that were comparable in size to the cerebral blood flow (CBF) deficit areas; asymmetry analysis and its variants produced APT ischemic areas that were smaller than the CBF deficit areas but larger than the apparent diffusion coefficient deficit areas, though having lower CNRs (0.561 ≤ CNR ≤ 1.083). CONCLUSION There is a need to further investigate the accuracy and correlation of each quantification method with the pathophysiology using a larger scale multi-imaging modality and multi-time-point clinical study. Future studies should include the magnetization transfer ratio asymmetry results alongside the findings of the study to facilitate the comparison of results between different centers and also the published literature.
Collapse
Affiliation(s)
- Lee Sze Foo
- Department of Mechatronics and Biomedical Engineering, Lee Kong Chian Faculty of Engineering and Science, Universiti Tunku Abdul Rahman, Kajang, Selangor, Malaysia
| | - James R Larkin
- Department of Oncology, Cancer Research UK and Medical Research Council Oxford Institute for Radiation Oncology, University of Oxford, Oxford, United Kingdom
| | - Brad A Sutherland
- Tasmanian School of Medicine, College of Health and Medicine, University of Tasmania, Hobart, Tasmania, Australia
- Acute Stroke Programme, Radcliffe Department of Medicine, University of Oxford, Oxford, United Kingdom
| | - Kevin J Ray
- Department of Oncology, Cancer Research UK and Medical Research Council Oxford Institute for Radiation Oncology, University of Oxford, Oxford, United Kingdom
| | - Wun-She Yap
- Department of Electrical and Electronic Engineering, Lee Kong Chian Faculty of Engineering and Science, Universiti Tunku Abdul Rahman, Kajang, Selangor, Malaysia
| | - Yan Chai Hum
- Department of Mechatronics and Biomedical Engineering, Lee Kong Chian Faculty of Engineering and Science, Universiti Tunku Abdul Rahman, Kajang, Selangor, Malaysia
| | - Khin Wee Lai
- Department of Biomedical Engineering, Faculty of Engineering, University of Malaya, Jalan Universiti, Kuala Lumpur, Malaysia
| | - Hanani Abdul Manan
- Department of Radiology, Universiti Kebangsaan Malaysia Medical Centre, Kuala Lumpur, Malaysia
| | - Nicola R Sibson
- Department of Oncology, Cancer Research UK and Medical Research Council Oxford Institute for Radiation Oncology, University of Oxford, Oxford, United Kingdom
| | - Yee Kai Tee
- Department of Mechatronics and Biomedical Engineering, Lee Kong Chian Faculty of Engineering and Science, Universiti Tunku Abdul Rahman, Kajang, Selangor, Malaysia
| |
Collapse
|
31
|
Sun PZ. Quasi-steady-state CEST (QUASS CEST) solution improves the accuracy of CEST quantification: QUASS CEST MRI-based omega plot analysis. Magn Reson Med 2021; 86:765-776. [PMID: 33749052 DOI: 10.1002/mrm.28744] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2020] [Revised: 01/27/2021] [Accepted: 01/31/2021] [Indexed: 12/11/2022]
Abstract
PURPOSE CEST MRI omega plot quantifies the labile proton fraction ratio (fr ) and exchange rate (ksw ), yet it assumes long RF saturation time (Ts) and relaxation delay (Td). Our study aimed to test if a quasi-steady-state (QUASS) CEST analysis that accounts for the effect of finite Ts and Td could improve the accuracy of CEST MRI quantification. METHODS We modeled the MRI signal evolution using a typical CEST EPI sequence. The signal relaxes toward its thermal equilibrium following the bulk water relaxation rate during Td, and then toward its CEST steady state following the spin-lock relaxation rate during Ts from which the QUASS CEST effect is derived. Both fr and ksw were solved from simulated conventional apparent CEST and QUASS CEST MRI. We also performed MRI experiments from a Cr-gel phantom under serially varied Ts and Td times from 1.5 to 7.5 s. RESULTS Simulation showed that, although ksw could be slightly overestimated (3%-15%) for the range of Ts and Td, fr could be substantially underestimated by as much as 67%. In contrast, the QUASS solution provided accurate ksw and fr determination within 2%. The CEST MRI experiments confirmed that the QUASS solution enabled robust quantification of ksw and fr , superior over the omega plot analysis based on the conventional apparent CEST MRI measurements. CONCLUSIONS The QUASS CEST MRI algorithm corrects the effect of finite Ts and Td times on CEST measurements, thereby allowing robust and accurate CEST quantification.
Collapse
Affiliation(s)
- Phillip Zhe Sun
- Yerkes Imaging Center, Yerkes National Primate Research Center, Emory University, Atlanta, Georgia, USA.,Department of Radiology and Imaging Sciences, Emory University School of Medicine, Atlanta, Georgia, USA
| |
Collapse
|
32
|
Sun PZ. Quasi-steady state chemical exchange saturation transfer (QUASS CEST) analysis-correction of the finite relaxation delay and saturation time for robust CEST measurement. Magn Reson Med 2021; 85:3281-3289. [PMID: 33486816 DOI: 10.1002/mrm.28653] [Citation(s) in RCA: 26] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2020] [Revised: 11/28/2020] [Accepted: 11/30/2020] [Indexed: 12/11/2022]
Abstract
PURPOSE CEST provides a MR contrast mechanism sensitizing to the exchange between dilute labile and bulk water protons. However, the CEST effect depends on the RF saturation duration and relaxation delay, which need to be long to reach its steady state. Our study aims to estimate the QUAsi-Steady State (QUASS) CEST signal from experiments with shorter saturation and relaxation delay times. METHODS The evolution of the CEST signal was modeled as a function of the bulk water longitudinal relaxation rate during the relaxation delay (Td) and spin-lock relaxation rate during the RF saturation (Ts), from which the QUASS CEST effect is solved. Numeric simulations were programmed to compare the apparent CEST and QUASS CEST effects as a function of Ts and Td times. We also performed CEST MRI experiments from a creatine-gel pH phantom under serially varied Ts and Td times. RESULTS The numeric simulation showed that although the apparent CEST effect depends on Td and Ts, the QUASS CEST solution has little dependence. Phantom results showed that the routine CEST pH contrast could be described by a nonlinear regression model (ie, Δ C E S T R = Δ C E S T R eq app 1 - e - R 1 ρ app · t ). We had Δ C E S T R eq app = 3.90 ± 0.03 % (P < 5e-8) and R 1 ρ app = 0.62 ± 0.02 s - 1 (P < 5e-6). For the QUASS CEST analysis, we modeled the pH contrast as Δ C E S T R = Δ C E S T R eq QUASS + s · t , using a linear regression model. We had Δ C E S T R eq QUASS = 3.63 ± 0.01 % (P < 5e-9) and s = - 0.02 ± 0.00 % / s (P < 0.01), the slope of which is minimal. CONCLUSIONS The QUASS CEST algorithm provides a post-processing solution that facilitates robust CEST measurement.
Collapse
Affiliation(s)
- Phillip Zhe Sun
- Yerkes Imaging Center, Yerkes National Primate Research Center, Emory University, Atlanta, Georgia, USA.,Department of Radiology and Imaging Sciences, Emory University School of Medicine, Atlanta, Georgia, USA
| |
Collapse
|
33
|
Kim H, Krishnamurthy LC, Sun PZ. Brain pH Imaging and its Applications. Neuroscience 2021; 474:51-62. [PMID: 33493621 DOI: 10.1016/j.neuroscience.2021.01.026] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2020] [Revised: 01/12/2021] [Accepted: 01/13/2021] [Indexed: 12/14/2022]
Abstract
Acid-base homeostasis and pH regulation are critical for normal tissue metabolism and physiology, and brain tissue pH alters in many diseased states. Several noninvasive tissue pH Magnetic Resonance (MR) techniques have been developed over the past few decades to shed light on pH change during tissue function and dysfunction. Nevertheless, there are still challenges for mapping brain pH noninvasively at high spatiotemporal resolution. To address this unmet biomedical need, chemical exchange saturation transfer (CEST) MR techniques have been developed as a sensitive means for non-invasive pH mapping. This article briefly reviews the basic principles of different pH measurement techniques with a focus on CEST imaging of pH. Emerging pH imaging applications in the tumor are provided as examples throughout the narrative, and CEST pH imaging in acute stroke is discussed in the final section.
Collapse
Affiliation(s)
- Hahnsung Kim
- Yerkes Imaging Center, Yerkes National Primate Research Center, Emory University, Atlanta, GA, United States; Department of Radiology and Imaging Sciences, Emory University School of Medicine, Atlanta, GA, United States
| | - Lisa C Krishnamurthy
- Center for Visual and Neurocognitive Rehabilitation, Atlanta VA, Decatur, GA, United States; Department of Physics & Astronomy, Georgia State University, Atlanta, GA, United States
| | - Phillip Zhe Sun
- Yerkes Imaging Center, Yerkes National Primate Research Center, Emory University, Atlanta, GA, United States; Department of Radiology and Imaging Sciences, Emory University School of Medicine, Atlanta, GA, United States.
| |
Collapse
|
34
|
Wu L, Jiang L, Sun PZ. Investigating the origin of pH-sensitive magnetization transfer ratio asymmetry MRI contrast during the acute stroke: Correction of T 1 change reveals the dominant amide proton transfer MRI signal. Magn Reson Med 2020; 84:2702-2712. [PMID: 32416012 DOI: 10.1002/mrm.28313] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2020] [Revised: 03/22/2020] [Accepted: 04/17/2020] [Indexed: 12/12/2022]
Abstract
PURPOSE Amide proton transfer (APT) MRI is promising to serve as a surrogate metabolic imaging biomarker of acute stroke. Although the magnetization transfer ratio asymmetry (MTRasym ) has been used commonly, the origin of pH-weighted MRI effect remains an area of investigation, including contributions from APT, semisolid MT contrast asymmetry, and nuclear Overhauser enhancement effects. Our study aimed to determine the origin of pH-weighted MTRasym contrast following acute stroke. METHODS Multiparametric MRI, including T1 , T2 , diffusion and Z-spectrum, were performed in rats after middle cerebral artery occlusion. We analyzed the conventional Z-spectrum I Δ ω I 0 and the apparent exchange spectrum R ex Δ ω , being the difference between the relaxation-scaled inverse Z-spectrum and the intrinsic spinlock relaxation rate R 1 · cos 2 θ · I 0 I Δ ω - R 1 ρ Δ ω . The ischemia-induced change was calculated as the spectral difference between the diffusion lesion and the contralateral normal area. RESULTS The conventional Z-spectrum signal change at -3.5 ppm dominates that at +3.5 ppm (-1.16 ± 0.39% vs. 0.76 ± 0.26%, P < .01) following acute stroke. In comparison, the magnitude of ΔRex change at 3.5 ppm becomes significantly larger than that at -3.5 ppm (-2.80 ± 0.40% vs. -0.94 ± 0.80%, P < .001), with their SNR being 7.0 and 1.2, respectively. We extended the magnetization transfer and relaxation normalized APT concept to the apparent exchange-dependent relaxation image, documenting an enhanced pH contrast between the ischemic lesion and the intact tissue, over that of MTRasym . CONCLUSION Our study shows that after the relaxation-effect correction, the APT effect is the dominant contributing factor to pH-weighted MTRasym following acute stroke.
Collapse
Affiliation(s)
- Limin Wu
- Neuroscience Center and Department of Pediatrics, Massachusetts General Hospital and Harvard Medical School, Charlestown, Massachusetts, USA
| | - Liang Jiang
- Department of Otolaryngology, Head and Neck Surgery, Affiliated Hospital of Southwestern Medical University, Luzhou, Sichuan, China.,Yerkes Imaging Center, Yerkes National Primate Research Center, Emory University, Atlanta, Georgia, USA
| | - Phillip Zhe Sun
- Yerkes Imaging Center, Yerkes National Primate Research Center, Emory University, Atlanta, Georgia, USA.,Department of Radiology and Imaging Sciences, Emory University School of Medicine, Atlanta, Georgia, USA.,Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital and Harvard Medical School, Charlestown, Massachusetts, USA
| |
Collapse
|
35
|
Sun PZ. Demonstration of magnetization transfer and relaxation normalized pH-specific pulse-amide proton transfer imaging in an animal model of acute stroke. Magn Reson Med 2020; 84:1526-1533. [PMID: 32080897 DOI: 10.1002/mrm.28223] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2019] [Revised: 01/12/2020] [Accepted: 01/29/2020] [Indexed: 12/14/2022]
Abstract
PURPOSE pH-weighted amide proton transfer (APT) MRI is promising to serve as a new surrogate metabolic imaging biomarker for refined ischemic tissue demarcation. APT MRI with pulse-RF irradiation (pulse-APT) is an alternative to the routine continuous wave (CW-) APT MRI that overcomes the RF duty cycle limit. Our study aimed to generalize the recently developed pH-specific magnetization transfer and relaxation-normalized APT (MRAPT) analysis to pulse-APT MRI in acute stroke imaging. METHODS Multiparametric MRI, including CW- and pulse-APT MRI scans, were performed following middle cerebral artery occlusion in rats. We calculated pH-sensitive MTRasym and pH-specific MRAPT contrast between the ipsilateral diffusion lesion and contralateral normal area. RESULTS An inversion pulse of 10 to 15 ms maximizes the pH-sensitive MRI contrast for pulse-APT MRI. The contrast-to-noise ratio of pH-specific MRAPT effect between the contralateral normal area and ischemic lesion from both methods are comparable (3.25 ± 0.65 vs. 3.59 ± 0.40, P > .05). pH determined from both methods were in good agreement, with their difference within 0.1. CONCLUSIONS Pulse-APT MRI provides highly pH-specific mapping for acute stroke imaging.
Collapse
Affiliation(s)
- Phillip Zhe Sun
- Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital and Harvard Medical School, Boston, MA.,Yerkes Imaging Center, Yerkes National Primate Research Center, Emory University, Atlanta, GA.,Department of Radiology and Imaging Sciences, Emory University School of Medicine, Atlanta, GA
| |
Collapse
|
36
|
Melingi SB, Vijayalakshmi V. A Hybrid Approach for Sub-Acute Ischemic Stroke Lesion Segmentation Using Random Decision Forest and Gravitational Search Algorithm. Curr Med Imaging 2020; 15:170-183. [PMID: 31975663 DOI: 10.2174/1573405614666180209150338] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2017] [Revised: 01/17/2018] [Accepted: 01/29/2018] [Indexed: 11/22/2022]
Abstract
BACKGROUND The sub-acute ischemic stroke is the most basic illnesses reason for death on the planet. We evaluate the impact of segmentation technique during the time of breaking down the capacities of the cerebrum. OBJECTIVE The main objective of this paper is to segment the ischemic stroke lesions in Magnetic Resonance (MR) images in the presence of other pathologies like neurological disorder, encephalopathy, brain damage, Multiple sclerosis (MS). METHODS In this paper, we utilize a hybrid way to deal with segment the ischemic stroke from alternate pathologies in magnetic resonance (MR) images utilizing Random Decision Forest (RDF) and Gravitational Search Algorithm (GSA). The RDF approach is an effective machine learning approach. RESULTS The RDF strategy joins two parameters; they are; the number of trees in the forest and the number of leaves per tree; it runs quickly and proficiently when dealing with vast data. The GSA algorithm is utilized to optimize the RDF data for choosing the best number of trees and the number of leaves per tree in the forest. CONCLUSION This paper provides a new hybrid GSA-RDF classifier technique to segment the ischemic stroke lesions in MR images. The experimental results demonstrate that the proposed technique has the Root Mean Square Error (RMSE), Mean Absolute Percentage Error (MAPE), and Mean Bias Error (MBE) ranges are 16.5485 %, 7.2654 %, and 2.4585 %individually. The proposed RDF-GSA algorithm has better precision and execution when compared with the existing ischemic stroke segmentation method.
Collapse
Affiliation(s)
- Sunil Babu Melingi
- Department of Electronics and Communication Engineering, Pondicherry Engineering College (PEC), Puducherry, India
| | - V Vijayalakshmi
- Department of Electronics and Communication Engineering, Pondicherry Engineering College (PEC), Puducherry, India
| |
Collapse
|
37
|
Zhang L, Zhao Y, Chen Y, Bie C, Liang Y, He X, Song X. Voxel-wise Optimization of Pseudo Voigt Profile (VOPVP) for Z-spectra fitting in chemical exchange saturation transfer (CEST) MRI. Quant Imaging Med Surg 2019; 9:1714-1730. [PMID: 31728314 DOI: 10.21037/qims.2019.10.01] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Background Chemical exchange saturation transfer (CEST) MRI is a promising approach for detecting biochemical alterations in cancers and neurological diseases, but the quantification can be challenging. Among numerous quantification methods, Lorentzian difference (LD) is relatively simple and widely used, which employs Lorentzian line-shape as a reference to describe the direct saturation (DS) of water and takes account of difference against experimental CEST spectra data. However, LD often overestimates CEST and nuclear overhauser enhancement (NOE) effects. Specifically, for fast-exchanging CEST species require higher saturation power (B1_sat) or in the presence of strong magnetization transfer (MT) contrast, Z-spectrum appears more like a Gaussian line-shape rather than a Lorentzian line-shape. Methods To improve the conventional LD analysis, the present study developed and validated a novel fitting algorithm through a linear combination of Gaussian and Lorentzian function as the reference spectra, namely, Voxel-wise Optimization of Pseudo Voigt Profile (VOPVP). The experimental Z-spectra were pre-fitted with Gaussian and Lorentzian method independently, in order to determine Lorentzian proportionality coefficient (a). To further compensate for the line-shape changes under different B1_sat's, a B1-dependent adjustment was applied to the experimental Z-spectra (Z_exp) according to the prior knowledge learned from 5-pool Bloch equation-based simulations at a range of B1_sat's. Then, the obtained Z-spectra (Z_B1adj) was fitted by the previously defined VOPVP function. Considering the asymmetric component of MT, the positive- and negative-side of Z-spectra were fitted separately, while the middle part (-0.6 to 0.6 ppm, consisted primarily of DS) was fitted using Lorentzian function. Finally, the difference between Z_VOPVP and Z_exp was defined as the CEST and NOE contrast. To validate our VOPVP method, an extensive simulation of CEST Z-spectra was performed using 5-pool model and 6-pool model with greater MT component. Results In comparison with LD approach, VOPVP exhibited lower sum of squares due to error (SSE) and higher goodness of fit (R-square) for the experimental Z-spectra at all B1_sat. Moreover, the results indicated that VOPVP fitting improved the overestimated contributions from amide proton transfer (APT) and NOE through LD at all B1_sat. Despite that the relationship for B1-dependent adjustment was pre-determined using a single 5-pool model, the VOPVP fittings obtained accurate quantification for multiple 6-pool models with a range of T1w's and T2w's. The robustness of VOPVP fitting was also proved by simulations using 3T parameters. Furthermore, we assessed VOPVP in vivo in a glioblastoma-bearing mouse. Compared to LD maps, VOPVP quantification maps displayed higher contrast-to-noise ratio between tumor and normal contralateral tissue for APT, glutamate and nuclear overhauser effect (NOE), when B1_sat >1 µT. Conclusions As an improvement of LD method, VOPVP fitting can serve as a simple, robust and more accurate approach for quantifying CEST and NOE contrast.
Collapse
Affiliation(s)
- Lihong Zhang
- School of Information Science and Technology, Northwest University, Xi'an 710127, China
| | - Yingcheng Zhao
- School of Information Science and Technology, Northwest University, Xi'an 710127, China
| | - Yanrong Chen
- School of Information Science and Technology, Northwest University, Xi'an 710127, China
| | - Chongxue Bie
- School of Information Science and Technology, Northwest University, Xi'an 710127, China
| | - Yuhua Liang
- School of Information Science and Technology, Northwest University, Xi'an 710127, China
| | - Xiaowei He
- School of Information Science and Technology, Northwest University, Xi'an 710127, China
| | - Xiaolei Song
- School of Information Science and Technology, Northwest University, Xi'an 710127, China
| |
Collapse
|
38
|
Sun PZ. Fast correction of B 0 field inhomogeneity for pH-specific magnetization transfer and relaxation normalized amide proton transfer imaging of acute ischemic stroke without Z-spectrum. Magn Reson Med 2019; 83:1688-1697. [PMID: 31631414 DOI: 10.1002/mrm.28040] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2019] [Revised: 09/17/2019] [Accepted: 09/23/2019] [Indexed: 01/04/2023]
Abstract
PURPOSE The magnetization transfer and relaxation normalized amide proton transfer (MRAPT) analysis is promising to provide a highly pH-specific mapping of tissue acidosis, complementing commonly used CEST asymmetry analysis. We aimed to develop a fast B0 inhomogeneity correction algorithm for acute stroke magnetization transfer and relaxation normalized amide proton transfer imaging without Z-spectral interpolation. METHODS The proposed fast field inhomogeneity correction describes B0 artifacts with linear regression. We compared the new algorithm with the routine interpolation correction approach in CEST imaging of a dual-pH phantom. The fast B0 correction was further evaluated in amide proton transfer imaging of normal and acute stroke rats. RESULTS Our phantom data showed that the proposed fast B0 inhomogeneity correction significantly improved pH MRI contrast, recovering over 80% of the pH MRI contrast-to-noise-ratio difference between the raw magnetization transfer ratio asymmetry and that using the routine interpolation-based B0 correction approach. In normal rat brains, the proposed fast B0 correction improved pH-specific MRI uniformity across the intact tissue, with the ratio of magnetization transfer and relaxation normalized amide proton transfer ratio being 10% of that without B0 inhomogeneity correction. In acute stroke rats, fast B0 inhomogeneity-corrected pH MRI reveals substantially improved pH lesion conspicuity, particularly in regions with nonnegligible B0 inhomogeneity. The pH MRI contrast-to-noise ratio between the ipsilateral diffusion lesion and contralateral normal tissue improved significantly with fast B0 correction (from 1.88 ± 0.48 to 2.20 ± 0.44, P < .01). CONCLUSIONS Our study established an expedient B0 inhomogeneity correction algorithm for fast pH imaging of acute ischemia.
Collapse
Affiliation(s)
- Phillip Zhe Sun
- Department of Radiology, Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts.,Yerkes Imaging Center, Yerkes National Primate Research Center, Emory University, Atlanta, Georgia.,Department of Radiology and Imaging Sciences, Emory University School of Medicine, Atlanta, Georgia
| |
Collapse
|
39
|
Sun PZ. Development of intravoxel inhomogeneity correction for chemical exchange saturation transfer spectral imaging: a high-resolution field map-based deconvolution algorithm for magnetic field inhomogeneity correction. Magn Reson Med 2019; 83:1348-1355. [PMID: 31628765 DOI: 10.1002/mrm.28015] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2019] [Revised: 09/04/2019] [Accepted: 09/05/2019] [Indexed: 12/12/2022]
Abstract
PURPOSE CEST MRI is sensitive to dilute proteins/peptides and microenvironmental properties yet susceptible to magnetic field inhomogeneity. We aimed to develop a high-resolution field map-based CEST intravoxel inhomogeneity correction (CIVIC) algorithm for CEST Z-spectral imaging. METHODS The proposed CIVIC approach treats the intravoxel inhomogeneity as a point spread function and applies the deconvolution algorithm to reconstruct the original Z-spectrum. We simulated the effect of B0 field inhomogeneity on CEST measurement and tested the efficacy of the proposed CIVIC algorithm. We also performed CEST MRI on a dual-pH Creatine-gel phantom under varied field homogeneity conditions and compared the CEST MRI contrast-to-noise ratio from the raw Z-spectrum, water saturation shift referencing, and the proposed CIVIC methods. RESULTS The numerical simulation showed that the CIVIC algorithm remains effective even in the case of symmetric field dispersion with a 0 mean shift. The experimental results confirmed that the proposed CIVIC method substantially improves the CEST MRI contrast-to-noise ratio under different field homogeneity conditions. CONCLUSION Our study established a new intravoxel B0 inhomogeneity correction algorithm, promising to facilitate CEST spectral imaging in challenging experimental conditions.
Collapse
Affiliation(s)
- Phillip Zhe Sun
- Yerkes Imaging Center, Yerkes National Primate Research Center, Emory University, Atlanta, Georgia.,Department of Radiology and Imaging Sciences, Emory University School of Medicine, Atlanta, Georgia
| |
Collapse
|
40
|
Bie C, Liang Y, Zhang L, Zhao Y, Chen Y, Zhang X, He X, Song X. Motion correction of chemical exchange saturation transfer MRI series using robust principal component analysis (RPCA) and PCA. Quant Imaging Med Surg 2019; 9:1697-1713. [PMID: 31728313 PMCID: PMC6828584 DOI: 10.21037/qims.2019.09.14] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2019] [Accepted: 09/10/2019] [Indexed: 12/28/2022]
Abstract
BACKGROUND Chemical exchange saturation transfer (CEST) MRI requires the acquisition of multiple saturation-weighted images and can last several minutes. Misalignments among these images, which are often due to the inevitable motion of the subject, will corrupt CEST contrast maps and result in large quantification errors. Therefore, the registration of the CEST series is critical. However, registration is challenging since common intensity-based registration algorithms may fail to differentiate CEST signals from motion artifacts. Herein, we studied how different patterns of motion affect CEST quantification and proposed a cascaded two-step registration scheme by utilizing features extracted from the entire Z-spectral image series instead of direct registration to a single image. METHODS The proposed approach is conducted in two stages: during the first coarse registration, the Z-spectral image series is decomposed by robust principal component analysis (RPCA) to separate CEST contrast from motion. The recomposed image series using only the low-rank component, which contains minimized motion, are averaged to generate a reference for the alignment of the image series. To further remove residual misalignments, the coarse registration is followed by a refinement stage, which uses PCA iteratively to generate motionless synthetic reference series with the first few principal components (PCs) that correspond to CEST contrast. In the end, the quality check is performed to exclude the images with unsuccessful registration. RESULTS The proposed registration scheme (RPCA + PCA_R) was assessed by both phantom experiments and in vivo data of tumor-bearing mouse brain, with simulated random rigid motion in different patterns applied to the acquired static Z-spectral image series. For comparison, previous correction schemes using an explicit image [either S0 or Ssat(∆ω)] as registration reference were also performed, named as S0_R and Ssat_R respectively. To illustrate the advantage of combination of RPCA and PCA, registration was also exploited using either only the RPCA-based method (RPCA_R) or only the PCA-based one (PCA_R). Compared with the above four methods, RPCA + PCA_R allowed for more accurate correction of the corrupted Z-spectral images, exhibiting smaller MTRasym(∆ω) error maps and lower residual Z-spectra referring to the static data. Among all the five correction methods, the corrected Z-spectral image series by RPCA + PCA_R and the resulting MTRasym(∆ω) maps achieved the highest correlation coefficients (CC) with respect to the static ones. CONCLUSIONS The registration scheme of RPCA + PCA_R provides robust motion correction between two specific Z-spectral images and among an entire image series, through extraction of the static component from the entire Z-spectra set and inclusion of a PCA-based refinement step. Therefore, this method can help improve CEST acquisition and quantification.
Collapse
Affiliation(s)
- Chongxue Bie
- School of Information Science and Technology, Northwest University, Xi'an 710127, China
| | - Yuhua Liang
- School of Information Science and Technology, Northwest University, Xi'an 710127, China
| | - Lihong Zhang
- School of Information Science and Technology, Northwest University, Xi'an 710127, China
| | - Yingcheng Zhao
- School of Information Science and Technology, Northwest University, Xi'an 710127, China
| | - Yanrong Chen
- School of Information Science and Technology, Northwest University, Xi'an 710127, China
| | - Xueru Zhang
- School of Information Science and Technology, Northwest University, Xi'an 710127, China
| | - Xiaowei He
- School of Information Science and Technology, Northwest University, Xi'an 710127, China
| | - Xiaolei Song
- School of Information Science and Technology, Northwest University, Xi'an 710127, China
| |
Collapse
|
41
|
Pradhan D, Tambe V, Raval N, Gondalia P, Bhattacharya P, Kalia K, Tekade RK. Dendrimer grafted albumin nanoparticles for the treatment of post cerebral stroke damages: A proof of concept study. Colloids Surf B Biointerfaces 2019; 184:110488. [PMID: 31541894 DOI: 10.1016/j.colsurfb.2019.110488] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2019] [Revised: 08/23/2019] [Accepted: 09/01/2019] [Indexed: 01/08/2023]
Abstract
Stroke is the second largest disease of mortality. The biggest hurdle in designing effective brain drug delivery systems is offered by the blood-brain barrier (BBB), which is highly impermeable to many drugs. Albumin nanoparticles (NP) have gained attention due to their multiple ligand binding sites and long circulatory half-life. Citicoline (CIT) is reported to enhance the acetylcholine secretion in the brain and also helps in membrane repair and regeneration. However, the poor BBB permeation of CIT results in lower levels of CIT in the brain. This demands the development of a suitable delivery platform to completely realize the therapeutic benefit of CIT in stroke therapy. This investigation reports the synthesis and characterization of second generation (2.0 G) dendrimer Amplified Albumin (dAA) biopolymer by FTIR, MALDI-TOF, and surface charge (mV). Further, the synthesized biopolymer has been utilized to develop a CIT nanoformulation using a commercially translatable one-pot process. Release of CIT from biopolymer was performed within an acetate buffer at pH 5 and Phosphate buffer at pH 7.4. Further, we investigated the ability of biopolymer to permeate BBB by in vitro permeability assay in bEnd.3 cells. MTT assay of CIT-dAA-NP, CIT-ANP, and 2.0 G PAMAM dendrimers was performed in bEnd.3 cells. Therapeutic efficacy of the synthesized biopolymer was determined by VEGF gene expression within an in vitro hypoxia model in PC12 cells. Thus, this investigation resulted in biopolymers that can be used to deliver any therapeutic agent by altering the permeability of the BBB. Also, cationization by dendrimer grafting is one such strategy that may be used to cationize any other negatively charged polymer, such as albumin. The synthesized biopolymer is not limited to deliver molecules to the brain, but can also be used to increase the loading of negatively-charged drug molecules, siRNA, or any other oligonucleotide.
Collapse
Affiliation(s)
- Deepak Pradhan
- National Institute of Pharmaceutical Education and Research (NIPER) - Ahmedabad, An Institute of National Importance, Government of India, Department of Pharmaceuticals, Ministry of Chemicals and Fertilizers, Palaj, Opp. Air Force Station, Gandhinagar, 382355, Gujarat, India
| | - Vishakha Tambe
- National Institute of Pharmaceutical Education and Research (NIPER) - Ahmedabad, An Institute of National Importance, Government of India, Department of Pharmaceuticals, Ministry of Chemicals and Fertilizers, Palaj, Opp. Air Force Station, Gandhinagar, 382355, Gujarat, India
| | - Nidhi Raval
- National Institute of Pharmaceutical Education and Research (NIPER) - Ahmedabad, An Institute of National Importance, Government of India, Department of Pharmaceuticals, Ministry of Chemicals and Fertilizers, Palaj, Opp. Air Force Station, Gandhinagar, 382355, Gujarat, India
| | - Piyush Gondalia
- National Institute of Pharmaceutical Education and Research (NIPER) - Ahmedabad, An Institute of National Importance, Government of India, Department of Pharmaceuticals, Ministry of Chemicals and Fertilizers, Palaj, Opp. Air Force Station, Gandhinagar, 382355, Gujarat, India
| | - Pallab Bhattacharya
- National Institute of Pharmaceutical Education and Research (NIPER) - Ahmedabad, An Institute of National Importance, Government of India, Department of Pharmaceuticals, Ministry of Chemicals and Fertilizers, Palaj, Opp. Air Force Station, Gandhinagar, 382355, Gujarat, India
| | - Kiran Kalia
- National Institute of Pharmaceutical Education and Research (NIPER) - Ahmedabad, An Institute of National Importance, Government of India, Department of Pharmaceuticals, Ministry of Chemicals and Fertilizers, Palaj, Opp. Air Force Station, Gandhinagar, 382355, Gujarat, India
| | - Rakesh K Tekade
- National Institute of Pharmaceutical Education and Research (NIPER) - Ahmedabad, An Institute of National Importance, Government of India, Department of Pharmaceuticals, Ministry of Chemicals and Fertilizers, Palaj, Opp. Air Force Station, Gandhinagar, 382355, Gujarat, India.
| |
Collapse
|
42
|
Wang E, Wu Y, Cheung JS, Igarashi T, Wu L, Zhang X, Sun PZ. Mapping tissue pH in an experimental model of acute stroke - Determination of graded regional tissue pH changes with non-invasive quantitative amide proton transfer MRI. Neuroimage 2019; 191:610-617. [PMID: 30753926 DOI: 10.1016/j.neuroimage.2019.02.022] [Citation(s) in RCA: 40] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2018] [Revised: 02/05/2019] [Accepted: 02/08/2019] [Indexed: 12/20/2022] Open
Abstract
pH-weighted amide proton transfer (APT) MRI is sensitive to tissue pH change during acute ischemia, complementing conventional perfusion and diffusion stroke imaging. However, the currently used pH-weighted magnetization transfer (MT) ratio asymmetry (MTRasym) analysis is of limited pH specificity. To overcome this, MT and relaxation normalized APT (MRAPT) analysis has been developed that to homogenize the background signal, thus providing highly pH conspicuous measurement. Our study aimed to calibrate MRAPT MRI toward absolute tissue pH mapping and determine regional pH changes during acute stroke. Using middle cerebral artery occlusion (MCAO) rats, we performed lactate MR spectroscopy and multi-parametric MRI. MRAPT MRI was calibrated against a region of interest (ROI)-based pH spectroscopy measurement (R2 = 0.70, P < 0.001), showing noticeably higher correlation coefficient than the simplistic MTRasym index. Capitalizing on this, we mapped brain tissue pH and semi-automatically segmented pH lesion, in addition to routine perfusion and diffusion lesions. Tissue pH from regions of the contralateral normal, perfusion/diffusion lesion mismatch and diffusion lesion was found to be 7.03 ± 0.04, 6.84 ± 0.10, 6.52 ± 0.19, respectively. Most importantly, we delineated the heterogeneous perfusion/diffusion lesion mismatch into perfusion/pH and pH/diffusion lesion mismatches, with their pH being 7.01 ± 0.04 and 6.71 ± 0.12, respectively (P < 0.05). To summarize, our study calibrated pH-sensitive MRAPT MRI toward absolute tissue pH mapping, semi-automatically segmented and determined graded tissue pH changes in ischemic tissue and demonstrated its feasibility for refined demarcation of heterogeneous metabolic disruption following acute stroke.
Collapse
Affiliation(s)
- Enfeng Wang
- Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital and Harvard Medical School, Charlestown, MA, USA; Department of Radiology, 3rd Affiliated Hospital, Zhengzhou University, Henan, China
| | - Yin Wu
- Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital and Harvard Medical School, Charlestown, MA, USA; Paul C. Lauterbur Research Centre for Biomedical Imaging, Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences, Shenzhen, Guangdong, China
| | - Jerry S Cheung
- Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital and Harvard Medical School, Charlestown, MA, USA
| | - Takahiro Igarashi
- Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital and Harvard Medical School, Charlestown, MA, USA
| | - Limin Wu
- Neuroscience Center and Department of Pediatrics, Massachusetts General Hospital and Harvard Medical School, Charlestown, MA, USA
| | - Xiaoan Zhang
- Department of Radiology, 3rd Affiliated Hospital, Zhengzhou University, Henan, China
| | - Phillip Zhe Sun
- Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital and Harvard Medical School, Charlestown, MA, USA.
| |
Collapse
|
43
|
Zhou J, Heo HY, Knutsson L, van Zijl PCM, Jiang S. APT-weighted MRI: Techniques, current neuro applications, and challenging issues. J Magn Reson Imaging 2019; 50:347-364. [PMID: 30663162 DOI: 10.1002/jmri.26645] [Citation(s) in RCA: 199] [Impact Index Per Article: 39.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2018] [Revised: 12/26/2018] [Accepted: 12/27/2018] [Indexed: 02/06/2023] Open
Abstract
Amide proton transfer-weighted (APTw) imaging is a molecular MRI technique that generates image contrast based predominantly on the amide protons in mobile cellular proteins and peptides that are endogenous in tissue. This technique, the most studied type of chemical exchange saturation transfer imaging, has been used successfully for imaging of protein content and pH, the latter being possible due to the strong dependence of the amide proton exchange rate on pH. In this article we briefly review the basic principles and recent technical advances of APTw imaging, which is showing promise clinically, especially for characterizing brain tumors and distinguishing recurrent tumor from treatment effects. Early applications of this approach to stroke, Alzheimer's disease, Parkinson's disease, multiple sclerosis, and traumatic brain injury are also illustrated. Finally, we outline the technical challenges for clinical APT-based imaging and discuss several controversies regarding the origin of APTw imaging signals in vivo. Level of Evidence: 3 Technical Efficacy Stage: 3 J. Magn. Reson. Imaging 2019;50:347-364.
Collapse
Affiliation(s)
- Jinyuan Zhou
- Division of MR Research, Department of Radiology, Johns Hopkins University, Baltimore, Maryland, USA.,F.M. Kirby Research Center for Functional Brain Imaging, Kennedy Krieger Institute, Baltimore, Maryland, USA
| | - Hye-Young Heo
- Division of MR Research, Department of Radiology, Johns Hopkins University, Baltimore, Maryland, USA.,F.M. Kirby Research Center for Functional Brain Imaging, Kennedy Krieger Institute, Baltimore, Maryland, USA
| | - Linda Knutsson
- Division of MR Research, Department of Radiology, Johns Hopkins University, Baltimore, Maryland, USA.,Department of Medical Radiation Physics, Lund University, Lund, Sweden
| | - Peter C M van Zijl
- Division of MR Research, Department of Radiology, Johns Hopkins University, Baltimore, Maryland, USA.,F.M. Kirby Research Center for Functional Brain Imaging, Kennedy Krieger Institute, Baltimore, Maryland, USA
| | - Shanshan Jiang
- Division of MR Research, Department of Radiology, Johns Hopkins University, Baltimore, Maryland, USA.,F.M. Kirby Research Center for Functional Brain Imaging, Kennedy Krieger Institute, Baltimore, Maryland, USA
| |
Collapse
|
44
|
Zhou IY, Lu D, Ji Y, Wu L, Wang E, Cheung JS, Zhang XA, Sun PZ. Determination of multipool contributions to endogenous amide proton transfer effects in global ischemia with high spectral resolution in vivo chemical exchange saturation transfer MRI. Magn Reson Med 2019; 81:645-652. [PMID: 30058148 PMCID: PMC6258351 DOI: 10.1002/mrm.27385] [Citation(s) in RCA: 37] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2017] [Revised: 04/26/2018] [Accepted: 05/08/2018] [Indexed: 12/31/2022]
Abstract
PURPOSE Chemical exchange saturation transfer (CEST) MRI has been used for quantitative assessment of dilute metabolites and/or pH in disorders such as acute stroke and tumor. However, routine asymmetry analysis (MTRasym ) may be confounded by concomitant effects such as semisolid macromolecular magnetization transfer (MT) and nuclear Overhauser enhancement. Resolving multiple contributions is essential for elucidating the origins of in vivo CEST contrast. METHODS Here we used a newly proposed image downsampling expedited adaptive least-squares fitting on densely sampled Z-spectrum to quantify multipool contribution from water, nuclear Overhauser enhancement, MT, guanidinium, amine, and amide protons in adult male Wistar rats before and after global ischemia. RESULTS Our results revealed the major contributors to in vivo T1 -normalized MTRasym (3.5 ppm) contrast between white and gray matter (WM/GM) in normal brain (-1.96%/second) are pH-insensitive macromolecular MT (-0.89%/second) and nuclear Overhauser enhancement (-1.04%/second). Additionally, global ischemia resulted in significant changes of MTRasym , being -2.05%/second and -1.56%/second in WM and GM, which are dominated by changes in amide (-1.05%/second, -1.14%/second) and MT (-0.88%/second, -0.62%/second). Notably, the pH-sensitive amine and amide effects account for nearly 60% and 80% of the MTRasym changes seen in WM and GM, respectively, after global ischemia, indicating that MTRasym is predominantly pH-sensitive. CONCLUSION Combined amide and amine effects dominated the MTRasym changes after global ischemia, indicating that MTRasym is predominantly pH-sensitive and suitable for detecting tissue acidosis following acute stroke.
Collapse
Affiliation(s)
- Iris Yuwen Zhou
- Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital and Harvard Medical School, Charlestown, MA, USA
| | - Dongshuang Lu
- Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital and Harvard Medical School, Charlestown, MA, USA
| | - Yang Ji
- Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital and Harvard Medical School, Charlestown, MA, USA
| | - Limin Wu
- Neuroscience Center and Department of Pediatrics, Massachusetts General Hospital and Harvard Medical School, Charlestown, MA, USA
| | - Enfeng Wang
- Department of Radiology, 3rd Affiliated Hospital, Zhengzhou University, Henan China
| | - Jerry S. Cheung
- Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital and Harvard Medical School, Charlestown, MA, USA
| | - Xiao-An Zhang
- Department of Radiology, 3rd Affiliated Hospital, Zhengzhou University, Henan China
| | - Phillip Zhe Sun
- Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital and Harvard Medical School, Charlestown, MA, USA
- Yerkes Imaging Center, Yerkes National Primate Research Center, Emory University, Atlanta, GA, USA
- Department of Radiology, Emory University School of Medicine, Atlanta, GA, USA
| |
Collapse
|
45
|
Lin G, Zhuang C, Shen Z, Xiao G, Chen Y, Shen Y, Zong X, Wu R. APT Weighted MRI as an Effective Imaging Protocol to Predict Clinical Outcome After Acute Ischemic Stroke. Front Neurol 2018; 9:901. [PMID: 30405523 PMCID: PMC6205981 DOI: 10.3389/fneur.2018.00901] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2018] [Accepted: 10/05/2018] [Indexed: 11/13/2022] Open
Abstract
To explore the capability of the amide-proton-transfer weighted (APTW) magnetic resonance imaging (MRI) in the evaluation of clinical neurological deficit at the time of hospitalization and assessment of long-term daily functional outcome for patients with acute ischemic stroke (AIS). We recruited 55 AIS patients with brain MRI acquired within 24-48 h of symptom onset and followed up with their 90-day modified Rankin Scale (mRS) score. APT weighted MRI was performed for all the study subjects to measure APTW signal quantitatively in the acute ischemic area (APTWipsi) and the contralateral side (APTWcont). Change of the APT signal between the acute ischemic region and the contralateral side (ΔAPTW) was calculated. Maximum APTW signal (APTWmax) and minimal APTW signal (APTWmin) were also acquired to demonstrate APTW signals heterogeneity (APTWmax-min). In addition, all the patients were divided into 2 groups according to their 90-day mRS score (good prognosis group with mRS score <2 and poor prognosis group with mRS score ≥2). In the meantime, ΔAPTW of these groups was compared. We found that ΔAPTW was in good correlation with National Institutes of Health Stroke Scale (NIHSS) score (R 2 = 0.578, p < 0.001) and 90-day mRS score (R 2 = 0.55, p < 0.001). There was significant difference of ΔAPTW between patients with good prognosis and patients with poor prognosis. Plus, APTWmax-min was significantly different between two groups. These results suggested that APT weighted MRI could be used as an effective tool to assess the stroke severity and prognosis for patients with AIS, with APTW signal heterogeneity as a possible biomarker.
Collapse
Affiliation(s)
- Guisen Lin
- Department of Medical Imaging, The Second Affiliated Hospital, Medical College of Shantou University, Shantou, China
| | - Caiyu Zhuang
- Department of Medical Imaging, The Second Affiliated Hospital, Medical College of Shantou University, Shantou, China
| | - Zhiwei Shen
- Department of Medical Imaging, The Second Affiliated Hospital, Medical College of Shantou University, Shantou, China
| | - Gang Xiao
- Department of Mathematics and Statistics, Hanshan Normal University, Chaozhou, China
| | - Yanzi Chen
- Department of Medical Imaging, The Second Affiliated Hospital, Medical College of Shantou University, Shantou, China
| | - Yuanyu Shen
- Department of Medical Imaging, The Second Affiliated Hospital, Medical College of Shantou University, Shantou, China
| | - Xiaodan Zong
- Department of Medical Imaging, The Second Affiliated Hospital, Medical College of Shantou University, Shantou, China
| | - Renhua Wu
- Department of Medical Imaging, The Second Affiliated Hospital, Medical College of Shantou University, Shantou, China.,Provincial Key Laboratory of Medical Molecular Imaging, Shantou, China
| |
Collapse
|
46
|
Cohen O, Huang S, McMahon MT, Rosen MS, Farrar CT. Rapid and quantitative chemical exchange saturation transfer (CEST) imaging with magnetic resonance fingerprinting (MRF). Magn Reson Med 2018; 80:2449-2463. [PMID: 29756286 DOI: 10.1002/mrm.27221] [Citation(s) in RCA: 76] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2017] [Revised: 03/19/2018] [Accepted: 03/25/2018] [Indexed: 01/19/2023]
Abstract
PURPOSE To develop a fast magnetic resonance fingerprinting (MRF) method for quantitative chemical exchange saturation transfer (CEST) imaging. METHODS We implemented a CEST-MRF method to quantify the chemical exchange rate and volume fraction of the Nα -amine protons of L-arginine (L-Arg) phantoms and the amide and semi-solid exchangeable protons of in vivo rat brain tissue. L-Arg phantoms were made with different concentrations (25-100 mM) and pH (pH 4-6). The MRF acquisition schedule varied the saturation power randomly for 30 iterations (phantom: 0-6 μT; in vivo: 0-4 μT) with a total acquisition time of ≤2 min. The signal trajectories were pattern-matched to a large dictionary of signal trajectories simulated using the Bloch-McConnell equations for different combinations of exchange rate, exchangeable proton volume fraction, and water T1 and T2 relaxation times. RESULTS The chemical exchange rates of the Nα -amine protons of L-Arg were significantly (P < 0.0001) correlated with the rates measured with the quantitation of exchange using saturation power method. Similarly, the L-Arg concentrations determined using MRF were significantly (P < 0.0001) correlated with the known concentrations. The pH dependence of the exchange rate was well fit (R2 = 0.9186) by a base catalyzed exchange model. The amide proton exchange rate measured in rat brain cortex (34.8 ± 11.7 Hz) was in good agreement with that measured previously with the water exchange spectroscopy method (28.6 ± 7.4 Hz). The semi-solid proton volume fraction was elevated in white (12.2 ± 1.7%) compared to gray (8.1 ± 1.1%) matter brain regions in agreement with previous magnetization transfer studies. CONCLUSION CEST-MRF provides a method for fast, quantitative CEST imaging.
Collapse
Affiliation(s)
- Ouri Cohen
- Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital and Harvard Medical School, Charlestown, Massachusetts
| | - Shuning Huang
- Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital and Harvard Medical School, Charlestown, Massachusetts
| | - Michael T McMahon
- F.M. Kirby Research Center for Functional Brain Imaging, Kennedy Krieger Institute, Baltimore, Maryland.,Department of Radiology, Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - Matthew S Rosen
- Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital and Harvard Medical School, Charlestown, Massachusetts.,Department of Physics, Harvard University, Cambridge, Massachusetts
| | - Christian T Farrar
- Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital and Harvard Medical School, Charlestown, Massachusetts
| |
Collapse
|
47
|
Yin J, Sun H, Wang Z, Ni H, Shen W, Sun PZ. Diffusion Kurtosis Imaging of Acute Infarction: Comparison with Routine Diffusion and Follow-up MR Imaging. Radiology 2018; 287:651-657. [PMID: 29558293 DOI: 10.1148/radiol.2017170553] [Citation(s) in RCA: 41] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Purpose To determine the relationship between diffusion-weighted imaging (DWI) and diffusion kurtosis imaging (DKI) in patients with acute stroke at admission and the tissue outcome 1 month after onset of stroke. Materials and Methods Patients with stroke underwent DWI (b values = 0, 1000 sec/mm2 along three directions) and DKI (b values = 0, 1000, 2000 sec/mm2 along 20 directions) within 24 hours after symptom onset and 1 month after symptom onset. For large lesions (diameter ≥ 1 cm), acute lesion volumes at DWI and DKI were compared with those at follow-up T2-weighted imaging by using Spearman correlation analysis. For small lesions (diameter < 1 cm), the number of acute lesions at DWI and DKI and follow-up T2-weighted imaging was counted and compared by using the McNemar test. Results Thirty-seven patients (mean age, 58 years; range, 35-82 years) were included. There were 32 large lesions and 138 small lesions. For large lesions, the volumes of acute lesions on kurtosis maps showed no difference from those on 1-month follow-up T2-weighted images (P = .532), with a higher correlation coefficient than those on the apparent diffusion coefficient and mean diffusivity maps (R2 = 0.730 vs 0.479 and 0.429). For small lesions, the number of acute lesions on DKI, but not on DWI, images was consistent with that on the follow-up T2-weighted images (P = .125). Conclusion DKI complements DWI for improved prediction of outcome of acute ischemic stroke. © RSNA, 2018.
Collapse
Affiliation(s)
- Jianzhong Yin
- From the Departments of Radiology (J.Y., H.N., W.S.) and Neurology (Z.W.), Tianjin First Central Hospital, Tianjin, China; Department of Medicine, Tianjin Medical University, Tianjin, China (H.S.); and Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital and Harvard Medical School, 149 13th St, Room 2301 CNY, Charlestown, MA 02129 (P.Z.S.)
| | - Haizhen Sun
- From the Departments of Radiology (J.Y., H.N., W.S.) and Neurology (Z.W.), Tianjin First Central Hospital, Tianjin, China; Department of Medicine, Tianjin Medical University, Tianjin, China (H.S.); and Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital and Harvard Medical School, 149 13th St, Room 2301 CNY, Charlestown, MA 02129 (P.Z.S.)
| | - Zhiyun Wang
- From the Departments of Radiology (J.Y., H.N., W.S.) and Neurology (Z.W.), Tianjin First Central Hospital, Tianjin, China; Department of Medicine, Tianjin Medical University, Tianjin, China (H.S.); and Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital and Harvard Medical School, 149 13th St, Room 2301 CNY, Charlestown, MA 02129 (P.Z.S.)
| | - Hongyan Ni
- From the Departments of Radiology (J.Y., H.N., W.S.) and Neurology (Z.W.), Tianjin First Central Hospital, Tianjin, China; Department of Medicine, Tianjin Medical University, Tianjin, China (H.S.); and Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital and Harvard Medical School, 149 13th St, Room 2301 CNY, Charlestown, MA 02129 (P.Z.S.)
| | - Wen Shen
- From the Departments of Radiology (J.Y., H.N., W.S.) and Neurology (Z.W.), Tianjin First Central Hospital, Tianjin, China; Department of Medicine, Tianjin Medical University, Tianjin, China (H.S.); and Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital and Harvard Medical School, 149 13th St, Room 2301 CNY, Charlestown, MA 02129 (P.Z.S.)
| | - Phillip Zhe Sun
- From the Departments of Radiology (J.Y., H.N., W.S.) and Neurology (Z.W.), Tianjin First Central Hospital, Tianjin, China; Department of Medicine, Tianjin Medical University, Tianjin, China (H.S.); and Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital and Harvard Medical School, 149 13th St, Room 2301 CNY, Charlestown, MA 02129 (P.Z.S.)
| |
Collapse
|
48
|
JOURNAL CLUB: Evaluation of Diffusion Kurtosis Imaging of Stroke Lesion With Hemodynamic and Metabolic MRI in a Rodent Model of Acute Stroke. AJR Am J Roentgenol 2018; 210:720-727. [PMID: 29470156 DOI: 10.2214/ajr.17.19134] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
OBJECTIVE Diffusion kurtosis imaging (DKI) has emerged as a new acute stroke imaging approach, augmenting routine DWI. Although it has been shown that a diffusion lesion without kurtosis abnormality is more likely to recover after reperfusion, whereas a kurtosis lesion shows poor response, little is known about the underlying pathophysiologic profile of the kurtosis lesion versus the kurtosis lesion-diffusion lesion mismatch. MATERIALS AND METHODS We performed multiparametric MRI, including arterial spin labeling, pH-sensitive amide proton transfer, and DKI, in a rodent model of acute stroke caused by embolic middle cerebral artery occlusion. Diffusion and kurtosis lesions were semiautomatically segmented, and multiparametric MRI indexes were compared among the kurtosis lesion, diffusion lesion, kurtosis lesion-diffusion lesion mismatch, and the contralateral normal tissue area. RESULTS We confirmed a significant difference between diffusion lesion and kurtosis lesion volumes (mean [± SD] volume, 151 ± 65 vs 125 ± 47 mm3; p < 0.05). Although ischemic lesions have significantly reduced cerebral blood flow compared with contralateral normal tissue, we did not find a significant difference in cerebral blood flow between the kurtosis lesion and the kurtosis lesion-diffusion lesion mismatch (mean cerebral blood flow, 0.53 ± 0.10 vs 0.47 ± 0.14 mL/g of tissue per minute; p > 0.05). Of importance, the pH of the kurtosis lesion was significantly lower than that of the lesion mismatch (mean pH, 6.81 ± 0.08 vs 6.89 ± 0.09; p < 0.01). CONCLUSION The present study confirms that DKI provides an expedient approach for refining the heterogeneous DWI lesion that is associated with graded metabolic derangement, which is promising for improving the infarction core definition and ultimately helping to guide stroke treatment.
Collapse
|
49
|
Zhou IY, Wang E, Cheung JS, Lu D, Ji Y, Zhang X, Fulci G, Sun PZ. Direct saturation-corrected chemical exchange saturation transfer MRI of glioma: Simplified decoupling of amide proton transfer and nuclear overhauser effect contrasts. Magn Reson Med 2017; 78:2307-2314. [PMID: 29030880 PMCID: PMC5744877 DOI: 10.1002/mrm.26959] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2017] [Revised: 09/15/2017] [Accepted: 09/16/2017] [Indexed: 12/27/2022]
Abstract
PURPOSE Chemical exchange saturation transfer (CEST) MRI has shown promise in tissue characterization in diseases like stroke and tumor. However, in vivo CEST imaging such as amide proton transfer (APT) MRI is challenging because of concomitant factors such as direct water saturation, macromolecular magnetization transfer, and nuclear overhauser effect (NOE), which lead to a complex contrast in the commonly used asymmetry analysis (MTRasym). Here, we propose a direct saturation-corrected CEST (DISC-CEST) analysis for simplified decoupling and quantification of in vivo CEST effects. METHODS CEST MRI and relaxation measurements were carried out on a classical 2-pool creatine-gel CEST phantom and normal rat brains (N = 6) and a rat model of glioma (N = 8) at 4.7T. The proposed DISC-CEST quantification was carried out and compared with conventional MTRasym and the original three-offset method. RESULTS We demonstrated that the DISC-CEST contrast in the phantom had much stronger correlation with MTRasym than the three-offset method, which showed substantial underestimation. In normal rat brains, the DISC-CEST approach revealed significantly stronger APT effect in gray matter and higher NOE effect in white matter. Furthermore, the APT and NOE maps derived from DISC-CEST showed significantly higher APT effect in the tumors than contralateral normal tissue but no apparent difference in NOE. CONCLUSION The proposed DISC-CEST method, by correction of nonlinear direct water saturation effect, serves as a promising alternative to both the commonly used MTRasym and the simplistic three-offset analyses. It provides simple yet reliable in vivo CEST quantification such as APT and NOE mapping in brain tumor, which is promising for clinical translation. Magn Reson Med 78:2307-2314, 2017. © 2017 International Society for Magnetic Resonance in Medicine.
Collapse
Affiliation(s)
- Iris Yuwen Zhou
- Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital and Harvard Medical School, Charlestown, MA, USA
| | - Enfeng Wang
- Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital and Harvard Medical School, Charlestown, MA, USA
- Department of Radiology, 3 Affiliated Hospital, Zhengzhou University, Henan, China
| | - Jerry S Cheung
- Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital and Harvard Medical School, Charlestown, MA, USA
| | - Dongshuang Lu
- Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital and Harvard Medical School, Charlestown, MA, USA
| | - Yang Ji
- Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital and Harvard Medical School, Charlestown, MA, USA
| | - Xiaoan Zhang
- Department of Radiology, 3 Affiliated Hospital, Zhengzhou University, Henan, China
| | - Giulia Fulci
- Molecular Neuro-oncology Laboratories, Department of Neurosurgery, Massachusetts General Hospital and Harvard Medical School, Boston, MA 02124, USA
| | - Phillip Zhe Sun
- Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital and Harvard Medical School, Charlestown, MA, USA
| |
Collapse
|
50
|
Wang E, Wu Y, Cheung JS, Zhou IY, Igarashi T, Zhang X, Sun PZ. pH imaging reveals worsened tissue acidification in diffusion kurtosis lesion than the kurtosis/diffusion lesion mismatch in an animal model of acute stroke. J Cereb Blood Flow Metab 2017; 37:3325-3333. [PMID: 28752790 PMCID: PMC5624397 DOI: 10.1177/0271678x17721431] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Diffusion weighted imaging (DWI) has been commonly used in acute stroke examination, yet a portion of DWI lesion may be salvageable. Recently, it has been shown that diffusion kurtosis imaging (DKI) defines the most severely damaged DWI lesion that does not renormalize following early reperfusion. We postulated that the diffusion and kurtosis lesion mismatch experience heterogeneous hemodynamic and/or metabolic injury. We investigated tissue perfusion, pH, diffusion, kurtosis and relaxation from regions of the contralateral normal area, diffusion lesion, kurtosis lesion and their mismatch in an animal model of acute stroke. Our study revealed significant kurtosis and diffusion lesion volume mismatch (19.7 ± 10.7%, P < 0.01). Although there was no significant difference in perfusion and diffusion between the kurtosis lesion and kurtosis/diffusion lesion mismatch, we showed lower pH in the kurtosis lesion (pH = 6.64 ± 0.12) from that of the kurtosis/diffusion lesion mismatch (6.84 ± 0.11, P < 0.05). Moreover, pH in the kurtosis lesion and kurtosis/diffusion mismatch agreed well with literature values for regions of ischemic core and penumbra, respectively. Our work documented initial evidence that DKI may reveal the heterogeneous metabolic derangement within the commonly used DWI lesion.
Collapse
Affiliation(s)
- Enfeng Wang
- 1 Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Boston, USA.,2 Department of Radiology, Third Affiliated Hospital, Zhengzhou University, Zhengzhou, China
| | - Yin Wu
- 1 Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Boston, USA.,3 Paul C. Lauterbur Research Centre for Biomedical Imaging, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen, China
| | - Jerry S Cheung
- 1 Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Boston, USA
| | - Iris Yuwen Zhou
- 1 Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Boston, USA
| | - Takahiro Igarashi
- 1 Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Boston, USA
| | - XiaoAn Zhang
- 2 Department of Radiology, Third Affiliated Hospital, Zhengzhou University, Zhengzhou, China
| | - Phillip Zhe Sun
- 1 Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Boston, USA
| |
Collapse
|