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Xiao G, Zhang X, Tang H, Huang W, Chen Y, Zhuang C, Chen B, Yang L, Chen Y, Yan G, Wu R. Deep learning for dense Z-spectra reconstruction from CEST images at sparse frequency offsets. Front Neurosci 2024; 17:1323131. [PMID: 38249588 PMCID: PMC10796656 DOI: 10.3389/fnins.2023.1323131] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2023] [Accepted: 12/13/2023] [Indexed: 01/23/2024] Open
Abstract
A direct way to reduce scan time for chemical exchange saturation transfer (CEST)-magnetic resonance imaging (MRI) is to reduce the number of CEST images acquired in experiments. In some scenarios, a sufficient number of CEST images acquired in experiments was needed to estimate parameters for quantitative analysis, and this prolonged the scan time. For that, we aim to develop a general deep-learning framework to reconstruct dense CEST Z-spectra from experimentally acquired images at sparse frequency offsets so as to reduce the number of experimentally acquired CEST images and achieve scan time reduction. The main innovation works are outlined as follows: (1) a general sequence-to-sequence (seq2seq) framework is proposed to reconstruct dense CEST Z-spectra from experimentally acquired images at sparse frequency offsets; (2) we create a training set from wide-ranging simulated Z-spectra instead of experimentally acquired CEST data, overcoming the limitation of the time and labor consumption in manual annotation; (3) a new seq2seq network that is capable of utilizing information from both short-range and long-range is developed to improve reconstruction ability. One of our intentions is to establish a simple and efficient framework, i.e., traditional seq2seq can solve the reconstruction task and obtain satisfactory results. In addition, we propose a new seq2seq network that includes the short- and long-range ability to boost dense CEST Z-spectra reconstruction. The experimental results demonstrate that the considered seq2seq models can accurately reconstruct dense CEST images from experimentally acquired images at 11 frequency offsets so as to reduce the scan time by at least 2/3, and our new seq2seq network contributes to competitive advantage.
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Affiliation(s)
- Gang Xiao
- School of Mathematics and Statistics, Hanshan Normal University, Chaozhou, China
| | - Xiaolei Zhang
- Department of Radiology, Second Affiliated Hospital of Shantou University Medical College, Shantou, China
| | - Hanjing Tang
- College of Engineering, Shantou University, Shantou, China
| | - Weipeng Huang
- Medical Imaging Center, Jieyang People's Hospital, Jieyang, China
| | - Yaowen Chen
- College of Engineering, Shantou University, Shantou, China
| | - Caiyu Zhuang
- Department of Radiology, Second Affiliated Hospital of Shantou University Medical College, Shantou, China
| | - Beibei Chen
- Department of Radiology, Second Affiliated Hospital of Shantou University Medical College, Shantou, China
| | - Lin Yang
- Department of Radiology, Second Affiliated Hospital of Shantou University Medical College, Shantou, China
| | - Yue Chen
- Department of Radiology, Second Affiliated Hospital of Shantou University Medical College, Shantou, China
| | - Gen Yan
- Department of Radiology, Second Affiliated Hospital of Xiamen Medical College, Xiamen, China
| | - Renhua Wu
- Department of Radiology, Second Affiliated Hospital of Shantou University Medical College, Shantou, China
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2
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Zhuang C, Chen B, Wu S, Xu L, Zhang X, Zheng X, Chen Y, Geng Y, Guan J, Lin Y, Wilman AH, Wu R. Repurposing of the PET Probe Prototype PiB for Label and Radiation-Free CEST MRI Molecular Imaging of Amyloid. ACS Chem Neurosci 2023; 14:4344-4351. [PMID: 38061891 PMCID: PMC10741654 DOI: 10.1021/acschemneuro.3c00539] [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: 08/16/2023] [Revised: 11/21/2023] [Accepted: 11/22/2023] [Indexed: 12/21/2023] Open
Abstract
Positron emission tomography (PET) probes are specific and sensitive while suffering from radiation risk. It is worthwhile to explore the chemical emission saturation transfer (CEST) effects of the probe prototypes and repurpose them for CEST imaging to avoid radiation. In this study, we used 11C-PiB as an example of a PET probe for detecting amyloid and tested the feasibility of repurposing this PET probe prototype, PiB, for CEST imaging. After optimizing the parameters through preliminary phantom experiments, we used APP/PS1 transgenic mice and age-matched C57 mice for in vivo CEST magnetic resonance imaging (MRI) of amyloid. Furthermore, the pathological assessment was conducted on the same brain slices to evaluate the correlation between the CEST MRI signal abnormality and β-amyloid deposition detected by immunohistochemical staining. In our results, the Z-spectra revealed an apparent CEST effect that peaked at approximately 6 ppm. APP/PS1 mice as young as 9 months injected with PiB showed a significantly higher CEST effect compared to the control groups. The hyperintense region was correlated with the Aβ deposition shown by pathological staining. In conclusion, repurposing the PET probe prototype for CEST MRI imaging is feasible and enables label- and radiation-free detection of the amyloid while maintaining the sensitivity and specificity of the ligand. This study opens the door to developing CEST probes based on PET probe prototypes.
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Affiliation(s)
- Caiyu Zhuang
- Department
of Radiology, Second Affiliated Hospital, Shantou University Medical College, Shantou 515041, China
- Department
of Radiology, First Affiliated Hospital, Shantou University Medical College, Shantou 515041, China
| | - Beibei Chen
- Department
of Radiology, Second Affiliated Hospital, Shantou University Medical College, Shantou 515041, China
| | - Shuohua Wu
- Department
of Radiology, Second Affiliated Hospital, Shantou University Medical College, Shantou 515041, China
| | - Liang Xu
- Department
of Medical Imaging, Seventh Affiliated Hospital, Sun Yat-sen University, Shenzhen 518107, China
| | - Xiaolei Zhang
- Department
of Radiology, Second Affiliated Hospital, Shantou University Medical College, Shantou 515041, China
| | - Xinhui Zheng
- Department
of Radiology, Second Affiliated Hospital, Shantou University Medical College, Shantou 515041, China
| | - Yue Chen
- Department
of Radiology, Second Affiliated Hospital, Shantou University Medical College, Shantou 515041, China
| | - Yiqun Geng
- Laboratory
of Molecular Pathology, Shantou University
Medical College, Shantou 515041, China
| | - Jitian Guan
- Department
of Radiology, Second Affiliated Hospital, Shantou University Medical College, Shantou 515041, China
| | - Yan Lin
- Department
of Radiology, Second Affiliated Hospital, Shantou University Medical College, Shantou 515041, China
- Provincial
Key Laboratory for Breast Cancer Diagnosis and Treatment, Shantou 515041, China
| | - Alan H. Wilman
- The Department
of Biomedical Engineering, University of
Alberta, Edmonton, Alberta T6G 1H9, Canada
| | - Renhua Wu
- Department
of Radiology, Second Affiliated Hospital, Shantou University Medical College, Shantou 515041, China
- Provincial
Key Laboratory for Breast Cancer Diagnosis and Treatment, Shantou 515041, China
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3
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Kim H, Park S, Hu R, Hoang KB, Sun PZ. 3D CEST MRI with an unevenly segmented RF irradiation scheme: A feasibility study in brain tumor imaging. Magn Reson Med 2023; 90:2400-2410. [PMID: 37526017 PMCID: PMC10586718 DOI: 10.1002/mrm.29810] [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: 12/02/2022] [Revised: 06/17/2023] [Accepted: 07/08/2023] [Indexed: 08/02/2023]
Abstract
PURPOSE To integrate 3D CEST EPI with an unevenly segmented RF irradiation module and preliminarily demonstrate it in the clinical setting. METHODS A CEST MRI with unevenly segmented RF saturation was implemented, including a long primary RF saturation to induce the steady-state CEST effect, maintained with repetitive short secondary RF irradiation between readouts. This configuration reduces relaxation-induced blur artifacts during acquisition, allowing fast 3D spatial coverage. Numerical simulations were performed to select parameters such as flip angle (FA), short RF saturation duration (Ts2), and the number of readout segments. The sequence was validated experimentally with data from a phantom, healthy volunteers, and a brain tumor patient. RESULTS Based on the numerical simulation and l-carnosine gel phantom experiment, FA, Ts2, and the number of segments were set to 20°, 0.3 s, and the range from 4 to 8, respectively. The proposed method minimized signal modulation in the human brain images in the kz direction during the acquisition and provided the blur artifacts-free CEST contrast over the whole volume. Additionally, the CEST contrast in the tumor tissue region is higher than in the contralateral normal tissue region. CONCLUSIONS It is feasible to implement a highly accelerated 3D EPI CEST imaging with unevenly segmented RF irradiation.
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Affiliation(s)
- Hahnsung Kim
- Emory National Primate Research Center, Emory University, Atlanta GA
- Department of Radiology and Imaging Sciences, Emory University School of Medicine, Atlanta GA
| | - Suhyung Park
- Department of Computer Engineering, Chonnam National University, South Korea
- Department of ICT Convergence System Engineering, Chonnam National University, South Korea
| | - Ranliang Hu
- Department of Radiology and Imaging Sciences, Emory University School of Medicine, Atlanta GA
| | - Kimberly B Hoang
- Department of Neurosurgery, Emory University School of Medicine, Atlanta GA
| | - Phillip Zhe Sun
- Emory National Primate Research Center, Emory University, Atlanta GA
- Department of Radiology and Imaging Sciences, Emory University School of Medicine, Atlanta GA
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4
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Dhakan C, Anemone A, Ventura V, Carella A, Corrado A, Pirotta E, Villano D, Romdhane F, Gammaraccio F, Aime S, Longo DL. Assessing the Therapeutic Efficacy of Proton Transport Inhibitors in a Triple-Negative Breast Cancer Murine Model with Magnetic Resonance Imaging-Chemical Exchange Saturation Transfer Tumor pH Imaging. Metabolites 2023; 13:1161. [PMID: 37999256 PMCID: PMC10673543 DOI: 10.3390/metabo13111161] [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: 10/09/2023] [Revised: 11/06/2023] [Accepted: 11/14/2023] [Indexed: 11/25/2023] Open
Abstract
Proton transporters play a key role in maintaining the acidic tumor microenvironment; hence, their inhibition has been proposed as a new therapeutic treatment, although few methods can accurately assess their effect in vivo. In this study, we investigated whether MRI-CEST (Magnetic Resonance Imaging-Chemical Exchange Saturation Transfer) tumor pH imaging can be a useful tool to evaluate in vivo the therapeutic efficacy of several Proton Pump Inhibitors (PPIs) in breast cancer. Cell viability and extracellular pH assays were carried out in breast cancer cells cultured at physiological pH (7.4) or acid-adapted (pH of 6.5 and 6.8) following the exposure to inhibitors of V-ATPase (Lansoprazole, Esomeprazole) or NHE1 (Amiloride, Cariporide) at several concentrations. Next, triple-negative breast cancer 4T1 tumor-bearing mice were treated with Lansoprazole or Amiloride and MRI-CEST tumor pH imaging was utilized to assess the in vivo efficacy. Only Lansoprazole induced, in addition to breast cancer cell toxicity, a significant inhibition of proton extrusion. A significant reduction in tumor volume, prolonged survival, and increase in extracellular tumor pH after 1 and 2 weeks were observed after Lansoprazole treatment, whereas no significant changes were detected upon Amiloride treatment. Our results suggested that MRI-CEST tumor pH imaging can monitor the therapeutic efficacy of PPIs in breast cancer murine models.
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Affiliation(s)
- Chetan Dhakan
- Institute of Biostructures and Bioimaging (IBB), National Research Council of Italy (CNR), Via Nizza 52, 10126 Turin, Italy
| | - Annasofia Anemone
- Department of Molecular Biotechnology and Health Sciences, University of Turin, Via Nizza 52, 10126 Turin, Italy
| | - Vittoria Ventura
- Department of Molecular Biotechnology and Health Sciences, University of Turin, Via Nizza 52, 10126 Turin, Italy
| | - Antonella Carella
- Institute of Biostructures and Bioimaging (IBB), National Research Council of Italy (CNR), Via Nizza 52, 10126 Turin, Italy
| | - Alessia Corrado
- Institute of Biostructures and Bioimaging (IBB), National Research Council of Italy (CNR), Via Nizza 52, 10126 Turin, Italy
| | - Elisa Pirotta
- Institute of Biostructures and Bioimaging (IBB), National Research Council of Italy (CNR), Via Nizza 52, 10126 Turin, Italy
| | - Daisy Villano
- Department of Molecular Biotechnology and Health Sciences, University of Turin, Via Nizza 52, 10126 Turin, Italy
| | - Feriel Romdhane
- Institute of Biostructures and Bioimaging (IBB), National Research Council of Italy (CNR), Via Nizza 52, 10126 Turin, Italy
| | - Francesco Gammaraccio
- Department of Molecular Biotechnology and Health Sciences, University of Turin, Via Nizza 52, 10126 Turin, Italy
| | - Silvio Aime
- IRCCS SynLAB SDN, Via Gianturco 113, 80143 Naples, Italy
| | - Dario Livio Longo
- Institute of Biostructures and Bioimaging (IBB), National Research Council of Italy (CNR), Via Nizza 52, 10126 Turin, Italy
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5
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Sun PZ. Numerical simulation-based assessment of pH-sensitive chemical exchange saturation transfer MRI quantification accuracy across field strengths. NMR IN BIOMEDICINE 2023; 36:e5000. [PMID: 37401645 DOI: 10.1002/nbm.5000] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/16/2023] [Revised: 04/27/2023] [Accepted: 06/12/2023] [Indexed: 07/05/2023]
Abstract
Chemical exchange saturation transfer (CEST) MRI detects dilute labile protons via their exchange with bulk water, conferring pH sensitivity. Based on published exchange and relaxation properties, a 19-pool simulation was used to model the brain pH-dependent CEST effect and assess the accuracy of quantitative CEST (qCEST) analysis across magnetic field strengths under typical scan conditions. First, the optimal B1 amplitude was determined by maximizing pH-sensitive amide proton transfer (APT) contrast under the equilibrium condition. Apparent and quasi-steady-state (QUASS) CEST effects were then derived under the optimal B1 amplitude as functions of pH, RF saturation duration, relaxation delay, Ernst flip angle, and field strength. Finally, CEST effects, particularly the APT signal, were isolated with spinlock model-based Z-spectral fitting to evaluate the accuracy and consistency of CEST quantification. Our data showed that QUASS reconstruction significantly improved the consistency between simulated and equilibrium Z-spectra. The residual difference between QUASS and equilibrium CEST Z-spectra was, on average, 30 times less than that of the apparent CEST Z-spectra across field strengths, saturation, and repetition times. Also, the spinlock fitting of the QUASS CEST effect significantly reduced the residual errors 9-fold. Furthermore, the isolated APT amplitude from QUASS reconstruction was consistent and higher than the apparent CEST analysis under nonequilibrium conditions. To summarize, this study confirmed that QUASS reconstruction facilitates accurate determination of the CEST system under different scan protocols across field strengths, with the potential to help standardize CEST quantification.
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Affiliation(s)
- Phillip Zhe Sun
- Primate Imaging Center, Emory National Primate Research Center, Emory University, Atlanta, Georgia, USA
- Department of Radiology and Imaging Sciences, Emory University School of Medicine, Atlanta, Georgia, USA
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6
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Cohen O, Otazo R. Global deep learning optimization of chemical exchange saturation transfer magnetic resonance fingerprinting acquisition schedule. NMR IN BIOMEDICINE 2023; 36:e4954. [PMID: 37070221 PMCID: PMC10896067 DOI: 10.1002/nbm.4954] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/05/2023] [Revised: 04/10/2023] [Accepted: 04/11/2023] [Indexed: 05/06/2023]
Abstract
Chemical exchange saturation transfer (CEST) MRI is a promising molecular imaging technique but suffers from long scan times and complicated processing. CEST was recently combined with magnetic resonance fingerprinting (MRF) to address these shortcomings. However, the CEST-MRF signal depends on multiple acquisition and tissue parameters so selecting an optimal acquisition schedule is challenging. In this work, we propose a novel dual-network deep learning framework to optimize the CEST-MRF acquisition schedule. The quality of the optimized schedule was assessed in a digital brain phantom and compared with alternate deep learning optimization approaches. The effect of schedule length on the reconstruction error was also investigated. A healthy subject was scanned with optimized and random schedules and with a conventional CEST sequence for comparison. The optimized schedule was also tested in a subject with metastatic renal cell carcinoma. Reproducibility was assessed via test-retest experiments and the concordance correlation coefficient calculated for white matter (WM) and grey matter (GM). The optimized schedule was 12% shorter but yielded equal or lower normalized root mean square error for all parameters. The proposed optimization also provided a lower error compared with alternate methodologies. Longer schedules generally yielded lower error. In vivo maps obtained with the optimized schedule showed reduced noise and improved delineation of GM and WM. CEST curves synthesized from the optimized parameters were highly correlated (r = 0.99) with measured conventional CEST. The mean concordance correlation coefficient in WM/GM for all tissue parameters was 0.990/0.978 for the optimized schedule but only 0.979/0.975 for the random schedule. The proposed schedule optimization is widely applicable to MRF pulse sequences and provides accurate and reproducible tissue maps with reduced noise at a shorter scan time than a randomly generated schedule.
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Affiliation(s)
- Ouri Cohen
- Department of Medical Physics, Memorial Sloan Kettering Cancer Center, New York, New York, USA
| | - Ricardo Otazo
- Department of Medical Physics, Memorial Sloan Kettering Cancer Center, New York, New York, USA
- Department of Radiology, Memorial Sloan Kettering Cancer Center, New York, New York, USA
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7
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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.
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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
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8
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Zhang Y, Zu T, Liu R, Zhou J. Acquisition sequences and reconstruction methods for fast chemical exchange saturation transfer imaging. NMR IN BIOMEDICINE 2023; 36:e4699. [PMID: 35067987 DOI: 10.1002/nbm.4699] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/09/2021] [Revised: 01/02/2022] [Accepted: 01/17/2022] [Indexed: 05/23/2023]
Abstract
Chemical exchange saturation transfer (CEST) imaging is an emerging molecular magnetic resonance imaging (MRI) technique that has been developed and employed in numerous diseases. Based on the unique saturation transfer principle, a family of CEST-detectable biomolecules in vivo have been found capable of providing valuable diagnostic information. However, CEST MRI needs a relatively long scan time due to the common long saturation labeling module and typical acquisition of multiple frequency offsets and signal averages, limiting its widespread clinical applications. So far, a plethora of imaging schemes and techniques has been developed to accelerate CEST MRI. In this review, the key acquisition and reconstruction methods for fast CEST imaging are summarized from a practical and systematic point of view. The first acquisition sequence section describes the major development of saturation schemes, readout patterns, ultrafast z-spectroscopy, and saturation-editing techniques for rapid CEST imaging. The second reconstruction method section lists the important advances of parallel imaging, compressed sensing, sparsity in the z-spectrum, and algorithms beyond the Fourier transform for speeding up CEST MRI.
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Affiliation(s)
- 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
- Cancer Center, Zhejiang University, Hangzhou, Zhejiang, China
| | - Tao Zu
- Key Laboratory for Biomedical Engineering of Ministry of Education, Department of Biomedical Engineering, College of Biomedical Engineering & Instrument Science, Zhejiang University, Hangzhou, Zhejiang, China
| | - Ruibin Liu
- Key Laboratory for Biomedical Engineering of Ministry of Education, Department of Biomedical Engineering, College of Biomedical Engineering & Instrument Science, Zhejiang University, Hangzhou, Zhejiang, China
| | - Jinyuan Zhou
- Department of Radiology, Johns Hopkins University, Baltimore, Maryland, USA
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9
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Sun PZ. Generalization of quasi-steady-state reconstruction to CEST MRI with two-tiered RF saturation and gradient-echo readout-Synergistic nuclear Overhauser enhancement contribution to brain tumor amide proton transfer-weighted MRI. Magn Reson Med 2023; 89:2014-2023. [PMID: 36579767 DOI: 10.1002/mrm.29570] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2022] [Revised: 12/13/2022] [Accepted: 12/14/2022] [Indexed: 12/30/2022]
Abstract
PURPOSE While amide proton transfer-weighted (APTw) MRI has been adopted in tumor imaging, there are concurrent APT, magnetization transfer, and nuclear Overhauser enhancement changes. Also, the APTw image is confounded by relaxation changes, particularly when the relaxation delay and saturation time are not sufficiently long. Our study aimed to extend a quasi-steady-state (QUASS) solution to determine the contribution of the multipool CEST signals to the observed tumor APTw contrast. METHODS Our study derived the QUASS solution for a multislice CEST-MRI sequence with an interleaved RF saturation and gradient-echo readout between signal averaging. Multiparametric MRI scans were obtained in rat brain tumor models, including T1 , T2 , diffusion, and CEST scans. Finally, we performed spinlock model-based multipool fitting to determine multiple concurrent CEST signal changes in the tumor. RESULTS The QUASS APTw MRI showed small but significant differences in normal and tumor tissues and their contrast from the acquired asymmetry calculation. The spinlock model-based fitting showed significant differences in semisolid magnetization transfer, amide, and nuclear Overhauser enhancement effects between the apparent and QUASS CEST MRI. In addition, we determined that the tumor APTw contrast is due to synergistic APT increase (+3.5 ppm) and NOE decrease (-3.5 ppm), with their relative contribution being about one third and two thirds under a moderate B1 of 0.75 μT at 4.7 T. CONCLUSION Our study generalized QUASS analysis to gradient-echo image readout and quantified the underlying tumor CEST signal changes, providing an improved elucidation of the commonly used APTw MRI.
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Affiliation(s)
- Phillip Zhe Sun
- Emory Primate Imaging Center, Emory National Primate Research Center, Emory University, Atlanta, Georgia, USA.,Department of Radiology and Imaging Sciences, Emory University School of Medicine, Atlanta, Georgia, USA
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10
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Bo S, Zhang D, Ma M, Mo X, Stabinska J, McMahon MT, Shi C, Luo L. Acyl Hydrazides and Acyl Hydrazones as High-Performance Chemical Exchange Saturation Transfer MRI Contrast Agents. Pharmaceuticals (Basel) 2023; 16:ph16050639. [PMID: 37242423 DOI: 10.3390/ph16050639] [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: 03/13/2023] [Revised: 04/17/2023] [Accepted: 04/20/2023] [Indexed: 05/28/2023] Open
Abstract
Chemical exchange saturation transfer (CEST) MRI is a versatile molecular imaging approach that holds great promise for clinical translation. A number of compounds have been identified as suitable for performing CEST MRI, including paramagnetic CEST (paraCEST) agents and diamagnetic CEST (diaCEST) agents. DiaCEST agents are very attractive because of their excellent biocompatibility and potential for biodegradation, such as glucose, glycogen, glutamate, creatine, nucleic acids, et al. However, the sensitivity of most diaCEST agents is limited because of small chemical shifts (1.0-4.0 ppm) from water. To expand the catalog of diaCEST agents with larger chemical shifts, herein, we have systematically investigated the CEST properties of acyl hydrazides with different substitutions, including aromatic and aliphatic substituents. We have tuned the labile proton chemical shifts from 2.8-5.0 ppm from water while exchange rates varied from ~680 to 2340 s-1 at pH 7.2, which allows strong CEST contrast on scanners down to B0 = 3 T. One acyl hydrazide, adipic acid dihydrazide (ADH), was tested on a mouse model of breast cancer and showed nice contrast in the tumor region. We also prepared a derivative, acyl hydrazone, which showed the furthest shifted labile proton (6.4 ppm from water) and excellent contrast properties. Overall, our study expands the catalog of diaCEST agents and their application in cancer diagnosis.
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Affiliation(s)
- Shaowei Bo
- Department of Medical Imaging, The Affiliated Guangdong Second Provincial General Hospital of Jinan University, Guangzhou 510317, China
| | - Dong Zhang
- Medical Imaging Center, The First Affiliated Hospital of Jinan University, Guangzhou 510632, China
| | - Mengjie Ma
- Medical Imaging Center, The First Affiliated Hospital of Jinan University, Guangzhou 510632, China
| | - Xukai Mo
- Medical Imaging Center, The First Affiliated Hospital of Jinan University, Guangzhou 510632, China
| | - Julia Stabinska
- The Russell H. Morgan Department of Radiology and Radiological Science, The Johns Hopkins University School of Medicine, Baltimore, MD 21287, USA
- F.M. Kirby Research Center for Functional Brain Imaging, Kennedy Krieger Institute, Baltimore, MD 21287, USA
| | - Michael T McMahon
- The Russell H. Morgan Department of Radiology and Radiological Science, The Johns Hopkins University School of Medicine, Baltimore, MD 21287, USA
- F.M. Kirby Research Center for Functional Brain Imaging, Kennedy Krieger Institute, Baltimore, MD 21287, USA
| | - Changzheng Shi
- Medical Imaging Center, The First Affiliated Hospital of Jinan University, Guangzhou 510632, China
| | - Liangping Luo
- Department of Medical Imaging, The Affiliated Guangdong Second Provincial General Hospital of Jinan University, Guangzhou 510317, China
- Medical Imaging Center, The First Affiliated Hospital of Jinan University, Guangzhou 510632, China
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11
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Nakaoka R, Kato K, Yamamoto K, Yasui H, Matsumoto S, Kirilyuk IA, Khramtsov VV, Inanami O, Hirata H. Electron Paramagnetic Resonance Implemented with Multiple Harmonic Detections Successfully Maps Extracellular pH In Vivo. Anal Chem 2023; 95:3940-3950. [PMID: 36725678 PMCID: PMC9979135 DOI: 10.1021/acs.analchem.2c03194] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Extracellular acidification indicates a metabolic shift in cancer cells and is, along with tissue hypoxia, a hallmark of tumor malignancy. Thus, non-invasive mapping of extracellular pH (pHe) is essential for researchers to understand the tumor microenvironment and to monitor tumor response to metabolism-targeting drugs. While electron paramagnetic resonance (EPR) has been successfully used to map pHe in mouse xenograft models, this method is not sensitive enough to map pHe with a moderate amount of exogenous pH-sensitive probes. Here, we show that a modified EPR system achieves twofold higher sensitivity by using the multiple harmonic detection (MHD) method and improves the robustness of pHe mapping in mouse xenograft models. Our results demonstrate that treatment of a mouse xenograft model of human-derived pancreatic ductal adenocarcinoma cells with the carbonic anhydrase IX (CAIX) inhibitor U-104 delays tumor growth with a concurrent tendency toward further extracellular acidification. We anticipate that EPR-based pHe mapping can be expanded to monitor the response of other metabolism-targeting drugs. Furthermore, pHe monitoring can also be used for the development of improved metabolism-targeting cancer treatments.
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Affiliation(s)
- Ririko Nakaoka
- Division
of Bioengineering and Bioinformatics, Graduate School of Information
Science and Technology, Hokkaido University, North 14, West 9, Kita-ku, Sapporo060-0814, Japan
| | - Kazuhiro Kato
- Laboratory
of Radiation Biology, Graduate School of Veterinary Medicine, Hokkaido University, North 18, West 9, Kita-ku, Sapporo060-0818, Japan
| | - Kumiko Yamamoto
- Laboratory
of Radiation Biology, Graduate School of Veterinary Medicine, Hokkaido University, North 18, West 9, Kita-ku, Sapporo060-0818, Japan
| | - Hironobu Yasui
- Laboratory
of Radiation Biology, Faculty of Veterinary Medicine, Hokkaido University, North 18, West 9, Kita-ku, Sapporo060-0818, Japan
| | - Shingo Matsumoto
- Division
of Bioengineering and Bioinformatics, Faculty of Information Science
and Technology, Hokkaido University, North 14, West 9, Kita-ku, Sapporo060-0814, Japan
| | - Igor A. Kirilyuk
- N.N.
Vorozhtsov Novosibirsk Institute of Organic Chemistry, 9, Ac. Lavrentieva Ave., Novosibirsk630090, Russia
| | - Valery V. Khramtsov
- Department
of Biochemistry and Molecular Medicine, and In Vivo Multifunctional
Magnetic Resonance Center, West Virginia
University Robert C. Byrd Health Sciences Center, 1 Medical Center Drive, Morgantown, West Virginia26506, United States
| | - Osamu Inanami
- Laboratory
of Radiation Biology, Faculty of Veterinary Medicine, Hokkaido University, North 18, West 9, Kita-ku, Sapporo060-0818, Japan
| | - Hiroshi Hirata
- Division
of Bioengineering and Bioinformatics, Faculty of Information Science
and Technology, Hokkaido University, North 14, West 9, Kita-ku, Sapporo060-0814, Japan,
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12
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Jardim-Perassi BV, Irrera P, Lau JYC, Budzevich M, Whelan CJ, Abrahams D, Ruiz E, Ibrahim-Hashim A, Damgaci Erturk S, Longo DL, Pilon-Thomas SA, Gillies RJ. Intraperitoneal Delivery of Iopamidol to Assess Extracellular pH of Orthotopic Pancreatic Tumor Model by CEST-MRI. CONTRAST MEDIA & MOLECULAR IMAGING 2023; 2023:1944970. [PMID: 36704211 PMCID: PMC9836819 DOI: 10.1155/2023/1944970] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/29/2022] [Revised: 11/05/2022] [Accepted: 12/06/2022] [Indexed: 01/07/2023]
Abstract
The extracellular pH (pHe) of solid tumors is often acidic, as a consequence of the Warburg effect, and an altered metabolic state is often associated with malignancy. It has been shown that acidosis can promote tumor progression; thus, many therapeutic strategies have been adopted against tumor metabolism; one of these involves alkalinization therapies to raise tumor pH to inhibit tumor progression, improve immune surveillance, and overcome resistance to chemotherapies. Chemical exchange saturation transfer-magnetic resonance imaging (CEST-MRI) is a noninvasive technique that can measure pH in vivo using pH-sensitive contrast agents. Iopamidol, an iodinated contrast agent, clinically used for computed tomography (CT), contains amide group protons with pH-dependent exchange rates that can reveal the pHe of the tumor microenvironment. In this study, we optimized intraperitoneal (IP) delivery of iopamidol to facilitate longitudinal assessments of orthotopic pancreatic tumor pHe by CEST-MRI. Following IV-infusion and IP-bolus injections, we compared the two protocols for assessing tumor pH. Time-resolved CT imaging was used to evaluate the uptake of iopamidol in the tumor, revealing that IP-bolus delivered a high amount of contrast agent 40 min postinjection, which was similar to the amounts reached with the IV-infusion protocol. As expected, both IP and IV injection protocols produced comparable measurements of tumor pHe, showing no statistically significant difference between groups (p=0.16). In addition, we showed the ability to conduct longitudinal monitoring of tumor pHe using CEST-MRI with the IP injection protocol, revealing a statistically significant increase in tumor pHe following bicarbonate administration (p < 0.001). In conclusion, this study shows the capability to measure pHe using an IP delivery of iopamidol into orthotopic pancreatic tumors, which is important to conduct longitudinal studies.
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Affiliation(s)
| | - Pietro Irrera
- Department of Cancer Physiology, H. Lee Moffitt Cancer Center and Research Institute, Tampa, FL, USA
| | - Justin Y. C. Lau
- Small Animal Imaging Laboratory, H. Lee Moffitt Cancer Center and Research Institute, Tampa, FL, USA
| | - Mikalai Budzevich
- Small Animal Imaging Laboratory, H. Lee Moffitt Cancer Center and Research Institute, Tampa, FL, USA
| | - Christopher J. Whelan
- Department of Cancer Physiology, H. Lee Moffitt Cancer Center and Research Institute, Tampa, FL, USA
- Department of Biological Sciences, University of Illinois, Chicago, IL, USA
| | | | - Epifanio Ruiz
- Small Animal Imaging Laboratory, H. Lee Moffitt Cancer Center and Research Institute, Tampa, FL, USA
| | - Arig Ibrahim-Hashim
- Department of Cancer Physiology, H. Lee Moffitt Cancer Center and Research Institute, Tampa, FL, USA
| | - Sultan Damgaci Erturk
- Department of Cancer Physiology, H. Lee Moffitt Cancer Center and Research Institute, Tampa, FL, USA
| | - Dario Livio Longo
- Institute of Biostructures and Bioimages (IBB), National Research Council of Italy (CNR), Turin, Italy
| | - Shari A. Pilon-Thomas
- Department of Immunology, H. Lee Moffitt Cancer Center and Research Institute, Tampa, FL, USA
| | - Robert J. Gillies
- Department of Cancer Physiology, H. Lee Moffitt Cancer Center and Research Institute, Tampa, FL, USA
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13
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Longo DL, Pirotta E, Gambino R, Romdhane F, Carella A, Corrado A. Tumor pH Imaging Using Chemical Exchange Saturation Transfer (CEST)-MRI. Methods Mol Biol 2023; 2614:287-311. [PMID: 36587132 DOI: 10.1007/978-1-0716-2914-7_18] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Magnetic resonance imaging (MRI) is a noninvasive imaging technique that allows for physiological and functional studies of the tumor microenvironment. Within MRI, the emerging field of chemical exchange saturation transfer (CEST) has been largely exploited for assessing a salient feature of all solid tumors, extracellular acidosis. Iopamidol-based tumor pH imaging has been demonstrated to provide accurate and high spatial resolution extracellular tumor pH maps to elucidate tumor aggressiveness and for assessing response to therapy, with a high potential for clinical translation. Here, we describe the overall setup and steps for measuring tumor extracellular pH of tumor models in mice by exploiting MRI-CEST pH imaging with a preclinical MRI scanner following the administration of iopamidol. We address issues of pH calibration curve setup, animal handling, pH-responsive contrast agent injection, acquisition protocol, and image processing for accurate quantification and visualization of tumor acidosis.
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Affiliation(s)
- Dario Livio Longo
- Institute of Biostructures and Bioimaging (IBB), Italian National Research Council (CNR), Torino, Italy.
| | - Elisa Pirotta
- Institute of Biostructures and Bioimaging (IBB), Italian National Research Council (CNR), Torino, Italy
| | - Riccardo Gambino
- Department of Molecular Biotechnology and Health Sciences, University of Torino, Torino, Italy
| | - Feriel Romdhane
- Institute of Biostructures and Bioimaging (IBB), Italian National Research Council (CNR), Torino, Italy
| | - Antonella Carella
- Institute of Biostructures and Bioimaging (IBB), Italian National Research Council (CNR), Torino, Italy
| | - Alessia Corrado
- Institute of Biostructures and Bioimaging (IBB), Italian National Research Council (CNR), Torino, Italy
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14
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Irrera P, Roberto M, Consolino L, Anemone A, Villano D, Navarro-Tableros V, Carella A, Dastrù W, Aime S, Longo DL. Effect of Esomeprazole Treatment on Extracellular Tumor pH in a Preclinical Model of Prostate Cancer by MRI-CEST Tumor pH Imaging. Metabolites 2022; 13:metabo13010048. [PMID: 36676972 PMCID: PMC9866131 DOI: 10.3390/metabo13010048] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2022] [Revised: 12/20/2022] [Accepted: 12/22/2022] [Indexed: 12/29/2022] Open
Abstract
Novel anticancer treatments target the pH regulating system that plays a major role in tumor progression by creating an acidic microenvironment, although few studies have addressed their effect on tumor acidosis. In this study, we investigated in vivo several proton pump inhibitors (PPIs) targeting NHE-1 (Amiloride and Cariporide) and V-ATPase (Esomeprazole and Lansoprazole) proton transporters in the DU145 androgen-insensitive human prostate cancer model. In cellulo results showed that DU145 are sensitive, with decreasing efficacy, to Amiloride, Esomeprazole and Lansoprazole, with marked cell toxicity both in normoxia and in hypoxia, with almost any change in pH. In vivo studies were performed upon administration of Esomeprazole to assess both the acute and chronic effects, and Iopamidol-based tumor pH imaging was performed to evaluate tumor acidosis. Although statistically significant tumor pH changes were observed a few hours after Esomeprazole administration in both the acute study and up to one week of treatment in the chronic study, longer treatment resulted in a lack of changes in tumor acidosis, which was associated to similar tumor growth curves between treated and control groups in both the subcutaneous and orthotopic models. Overall, this study highlights MRI-CEST tumor pH imaging as a valid approach to monitoring treatment response to PPIs.
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Affiliation(s)
- Pietro Irrera
- Department of Environmental Biological and Pharmaceutical Sciences and Technologies, University of Campania “Luigi Vanvitelli”, 81100 Caserta, Italy
- Institute of Biostructures and Bioimaging (IBB), National Research Council of Italy (CNR), 10126 Turin, Italy
| | - Miriam Roberto
- Department of Molecular Biotechnology and Health Sciences, University of Turin, 10126 Turin, Italy
| | - Lorena Consolino
- Department of Nanomedicines and Theranostics, Institute for Experimental Molecular Imaging, RWTH Aachen University, 52074 Aachen, Germany
| | - Annasofia Anemone
- Department of Molecular Biotechnology and Health Sciences, University of Turin, 10126 Turin, Italy
| | - Daisy Villano
- Department of Molecular Biotechnology and Health Sciences, University of Turin, 10126 Turin, Italy
| | - Victor Navarro-Tableros
- Department of Molecular Biotechnology and Health Sciences, University of Turin, 10126 Turin, Italy
| | - Antonella Carella
- Institute of Biostructures and Bioimaging (IBB), National Research Council of Italy (CNR), 10126 Turin, Italy
| | - Walter Dastrù
- Department of Molecular Biotechnology and Health Sciences, University of Turin, 10126 Turin, Italy
| | | | - Dario Livio Longo
- Institute of Biostructures and Bioimaging (IBB), National Research Council of Italy (CNR), 10126 Turin, Italy
- Correspondence:
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15
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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.
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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
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16
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Jackson LR, Masi MR, Selman BM, Sandusky GE, Zarrinmayeh H, Das SK, Maharjan S, Wang N, Zheng QH, Pollok KE, Snyder SE, Sun PZ, Hutchins GD, Butch ER, Veronesi MC. Use of multimodality imaging, histology, and treatment feasibility to characterize a transgenic Rag2-null rat model of glioblastoma. Front Oncol 2022; 12:939260. [PMID: 36483050 PMCID: PMC9722958 DOI: 10.3389/fonc.2022.939260] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2022] [Accepted: 10/20/2022] [Indexed: 11/23/2022] Open
Abstract
Many drugs that show potential in animal models of glioblastoma (GBM) fail to translate to the clinic, contributing to a paucity of new therapeutic options. In addition, animal model development often includes histologic assessment, but multiparametric/multimodality imaging is rarely included despite increasing utilization in patient cancer management. This study developed an intracranial recurrent, drug-resistant, human-derived glioblastoma tumor in Sprague-Dawley Rag2-Rag2 tm1Hera knockout rat and was characterized both histologically and using multiparametric/multimodality neuroimaging. Hybrid 18F-fluoroethyltyrosine positron emission tomography and magnetic resonance imaging, including chemical exchange saturation transfer (18F-FET PET/CEST MRI), was performed for full tumor viability determination and characterization. Histological analysis demonstrated human-like GBM features of the intracranially implanted tumor, with rapid tumor cell proliferation (Ki67 positivity: 30.5 ± 7.8%) and neovascular heterogeneity (von Willebrand factor VIII:1.8 to 5.0% positivity). Early serial MRI followed by simultaneous 18F-FET PET/CEST MRI demonstrated consistent, predictable tumor growth, with exponential tumor growth most evident between days 35 and 49 post-implantation. In a second, larger cohort of rats, 18F-FET PET/CEST MRI was performed in mature tumors (day 49 post-implantation) for biomarker determination, followed by evaluation of single and combination therapy as part of the model development and validation. The mean percentage of the injected dose per mL of 18F-FET PET correlated with the mean %CEST (r = 0.67, P < 0.05), but there was also a qualitative difference in hot spot location within the tumor, indicating complementary information regarding the tumor cell demand for amino acids and tumor intracellular mobile phase protein levels. Finally, the use of this glioblastoma animal model for therapy assessment was validated by its increased overall survival after treatment with combination therapy (temozolomide and idasanutlin) (P < 0.001). Our findings hold promise for a more accurate tumor viability determination and novel therapy assessment in vivo in a recently developed, reproducible, intracranial, PDX GBM.
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Affiliation(s)
- Luke R. Jackson
- Department of Radiology and Imaging Sciences, Indiana University (IU) School of Medicine, Indianapolis, IN, United States
| | - Megan R. Masi
- Department of Radiology and Imaging Sciences, Indiana University (IU) School of Medicine, Indianapolis, IN, United States
| | - Bryce M. Selman
- Department of Pathology and Laboratory Medicine, Indiana University (IU) School of Medicine, Indianapolis, IN, United States
| | - George E. Sandusky
- Department of Pathology and Laboratory Medicine, Indiana University (IU) School of Medicine, Indianapolis, IN, United States
| | - Hamideh Zarrinmayeh
- Department of Radiology and Imaging Sciences, Indiana University (IU) School of Medicine, Indianapolis, IN, United States
| | - Sudip K. Das
- Department of Pharmaceutical Sciences, Butler University, Indianapolis, IN, United States
| | - Surendra Maharjan
- Department of Radiology and Imaging Sciences, Indiana University (IU) School of Medicine, Indianapolis, IN, United States
| | - Nian Wang
- Department of Radiology and Imaging Sciences, Indiana University (IU) School of Medicine, Indianapolis, IN, United States
| | - Qi-Huang Zheng
- Department of Radiology and Imaging Sciences, Indiana University (IU) School of Medicine, Indianapolis, IN, United States
| | - Karen E. Pollok
- Department of Pediatrics, Indiana University (IU) School of Medicine, Indianapolis, IN, United States
| | - Scott E. Snyder
- Department of Radiology and Imaging Sciences, Indiana University (IU) School of Medicine, Indianapolis, IN, United States
| | - Phillip Zhe Sun
- Department of Radiology and Imaging Sciences, Emory School of Medicine, Atlanta, GA, United States
| | - Gary D. Hutchins
- Department of Radiology and Imaging Sciences, Indiana University (IU) School of Medicine, Indianapolis, IN, United States
| | - Elizabeth R. Butch
- Department of Radiology and Imaging Sciences, Indiana University (IU) School of Medicine, Indianapolis, IN, United States
| | - Michael C. Veronesi
- Department of Radiology and Imaging Sciences, Indiana University (IU) School of Medicine, Indianapolis, IN, United States,*Correspondence: Michael C. Veronesi,
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17
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Stabinska J, Singh A, Haney NM, Li Y, Sedaghat F, Kates M, McMahon MT. Noninvasive assessment of renal dynamics and
pH
in a unilateral ureter obstruction model using
DCE MR‐CEST
urography. Magn Reson Med 2022; 89:343-355. [PMID: 36089805 PMCID: PMC9753579 DOI: 10.1002/mrm.29436] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2022] [Revised: 06/29/2022] [Accepted: 08/10/2022] [Indexed: 11/10/2022]
Abstract
PURPOSE To assess the potential of DCE MR CEST urography for assessing renal function in mice with unilateral ureter obstruction (UUO) by simultaneous pH and renal uptake/clearance measurements following injection of iopamidol. METHODS The right ureter of nine mice was obstructed via suture ligation. The animals were imaged at day 1, 2, and 3 post-obstruction on an 11.7T MRI scanner. Ninety-six sets of saturated CEST images at 4.3 and 5.5 ppm were collected. Renal pH values were obtained by calculating the signal ratio for these two frequencies and using a pH calibration curve. Renal time activity curves were measured as a percentage change in the post-injection CEST signal at 4.3 ppm relative to the average pre-injection signal. RESULTS For the healthy mice, the time activity curves of both kidneys were nearly identical and displayed rapid excretion of contrast. For the UUO mice, the dynamic CEST curves for the obstructed kidneys displayed prolonged time to peak (TTP) values and delayed contrast excretion compared with the contralateral (CL) kidneys. Renal pH maps of the healthy animals showed similar acidic values for both kidneys (pH 6.65 ± 0.04 vs 6.67 ± 0.02), whereas in the obstructed kidneys there was a significant increase in pH values compared with the CL kidneys (pH 6.67 ± 0.08 vs 6.79 ± 0.11 in CL and UUO kidneys, respectively). CONCLUSION Our findings indicate that DCE-MR-CEST urography can detect changes in renal uptake/excretion and pH homeostasis and distinguish between obstructed and unobstructed kidney as early as 1 day after UUO.
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Affiliation(s)
- Julia Stabinska
- F.M. Kirby Research Center for Functional Brain Imaging Kennedy Krieger Institute Baltimore Maryland USA
- Russell H. Morgan Department of Radiology and Radiological Science Johns Hopkins University School of Medicine Baltimore Maryland USA
| | - Aruna Singh
- F.M. Kirby Research Center for Functional Brain Imaging Kennedy Krieger Institute Baltimore Maryland USA
- Russell H. Morgan Department of Radiology and Radiological Science Johns Hopkins University School of Medicine Baltimore Maryland USA
| | - Nora M. Haney
- James Buchanan Brady Urological Institute and Department of Urology Johns Hopkins University School of Medicine Baltimore Maryland USA
| | - Yuguo Li
- F.M. Kirby Research Center for Functional Brain Imaging Kennedy Krieger Institute Baltimore Maryland USA
- Russell H. Morgan Department of Radiology and Radiological Science Johns Hopkins University School of Medicine Baltimore Maryland USA
| | - Farzad Sedaghat
- Russell H. Morgan Department of Radiology and Radiological Science Johns Hopkins University School of Medicine Baltimore Maryland USA
| | - Max Kates
- James Buchanan Brady Urological Institute and Department of Urology Johns Hopkins University School of Medicine Baltimore Maryland USA
| | - Michael T. McMahon
- F.M. Kirby Research Center for Functional Brain Imaging Kennedy Krieger Institute Baltimore Maryland USA
- Russell H. Morgan Department of Radiology and Radiological Science Johns Hopkins University School of Medicine Baltimore Maryland USA
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18
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Jin T, Chung JJ. Average saturation efficiency filter (ASEF) for CEST imaging. Magn Reson Med 2022; 88:254-265. [PMID: 35344594 PMCID: PMC9172934 DOI: 10.1002/mrm.29211] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2021] [Revised: 01/06/2022] [Accepted: 02/08/2022] [Indexed: 12/21/2022]
Abstract
PURPOSE Endogenous CEST signal usually has low specificity due to contamination from the magnetization transfer effect and from fast exchanging labile protons with close Larmor frequencies. We propose to improve CEST signal specificity with an average saturation efficiency filter (ASEF). METHODS ASEF measures the difference between CEST signals acquired with similar average irradiation power but largely different duty cycles (DC), for example, a continuous wave or a high DC pulse train versus a low DC one. Simulation and Cr phantom studies were performed to evaluate the characteristics of ASEF for CEST. RESULTS Theoretical and simulation studies show that ASEF can suppress fast exchanging processes, with only a small loss of chemical exchange contrast for slow-to-intermediate exchange rates if the difference in DC is large. In the RF offset range of 2 to 5 ppm with an averaged saturation power of 0.8 and 1.6 microteslas, there is a mismatch of ∼0.1% to 2% in the magnetization transfer signal between saturation by continuous wave and a pulse train with DC = 15% and pulse duration of 24 ms, respectively. This mismatch can be minimized by careful selection of saturation power, pulse duration, and DC differences or by applying a small fudge factor between the 2 irradiation powers. Phantom studies of Cr confirmed that ASEF can minimize the magnetization transfer effect and reduce sensitivity to fast exchange processes. CONCLUSION ASEF can improve the specificity of slow-to-intermediate exchanging CEST signal with a relatively small loss of sensitivity.
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Affiliation(s)
- Tao Jin
- Department of Radiology, University of Pittsburgh, Pittsburgh, Pennsylvania, USA
| | - Julius Juhyun Chung
- Department of Radiology, University of Pittsburgh, Pittsburgh, Pennsylvania, USA
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19
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Chemical Exchange Saturation Transfer for Lactate-Weighted Imaging at 3 T MRI: Comprehensive In Silico, In Vitro, In Situ, and In Vivo Evaluations. Tomography 2022; 8:1277-1292. [PMID: 35645392 PMCID: PMC9149919 DOI: 10.3390/tomography8030106] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2022] [Revised: 04/29/2022] [Accepted: 05/04/2022] [Indexed: 01/22/2023] Open
Abstract
Based on in silico, in vitro, in situ, and in vivo evaluations, this study aims to establish and optimize the chemical exchange saturation transfer (CEST) imaging of lactate (Lactate-CEST—LATEST). To this end, we optimized LATEST sequences using Bloch−McConnell simulations for optimal detection of lactate with a clinical 3 T MRI scanner. The optimized sequences were used to image variable lactate concentrations in vitro (using phantom measurements), in situ (using nine human cadaveric lower leg specimens), and in vivo (using four healthy volunteers after exertional exercise) that were then statistically analyzed using the non-parametric Friedman test and Kendall Tau-b rank correlation. Within the simulated Bloch−McConnell equations framework, the magnetization transfer ratio asymmetry (MTRasym) value was quantified as 0.4% in the lactate-specific range of 0.5−1 ppm, both in vitro and in situ, and served as the imaging surrogate of the lactate level. In situ, significant differences (p < 0.001) and strong correlations (τ = 0.67) were observed between the MTRasym values and standardized intra-muscular lactate concentrations. In vivo, a temporary increase in the MTRasym values was detected after exertional exercise. In this bench-to-bedside comprehensive feasibility study, different lactate concentrations were detected using an optimized LATEST imaging protocol in vitro, in situ, and in vivo at 3 T, which prospectively paves the way towards non-invasive quantification and monitoring of lactate levels across a broad spectrum of diseases.
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20
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Aime S, Longo DL, Reineri F, Geninatti Crich S. New tools to investigate tumor metabolism by NMR/MRI. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2022; 338:107198. [PMID: 35339957 DOI: 10.1016/j.jmr.2022.107198] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/11/2022] [Revised: 03/09/2022] [Accepted: 03/15/2022] [Indexed: 06/14/2023]
Abstract
Changes in metabolism is an hallmark that characterizes tumour cells from healthy ones. Their detection can be highly relevant for staging the tumor and for monitoring the response to therapeutic treatments. Herein it is shown the readout of these changes can be achieved either by assessing the pH of the extracellular space in the tumour region and by monitoring real time transformations of hyperpolarized C-13 labelled substrates. Mapping pH in a MR image is possible by measuring the CEST response of an administered contrast agent such as Iopamidol that can provide accurate measurements of the heterogeneity of tumour acidosis. Direct detection of relevant enzymatic activities have been acquired by using Pyruvate and Fumarate hyperpolarized by the incorporation of a molecule of para-H2. Finally, it has been found that the tumour transformation involves an increase in the water exchange rate between the intra- and the extra-cellular compartments. A quantitative estimation of these changes can be obtained by acquiring the longitudinal relaxation times of tissue water protons at low magnetic field strength on Fast Field Cycling Relaxometers. This finding has been exploited in an application devoted to the assessment of the presence of residual tumour tissue in the margins of the resected mass in breast conservative surgery.
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Affiliation(s)
- Silvio Aime
- Department of Molecular Biotechnologies and Health Sciences, University of Torino, Via Nizza 52, 10126 Torino, Italy.
| | - Dario Livio Longo
- Institute of Biostructures and Bioimaging (IBB), National Research Council of Italy (CNR), Via Nizza 52, 10126 Torino, Italy
| | - Francesca Reineri
- Department of Molecular Biotechnologies and Health Sciences, University of Torino, Via Nizza 52, 10126 Torino, Italy
| | - Simonetta Geninatti Crich
- Department of Molecular Biotechnologies and Health Sciences, University of Torino, Via Nizza 52, 10126 Torino, Italy
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21
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Molecular Imaging of Brain Tumors and Drug Delivery Using CEST MRI: Promises and Challenges. Pharmaceutics 2022; 14:pharmaceutics14020451. [PMID: 35214183 PMCID: PMC8880023 DOI: 10.3390/pharmaceutics14020451] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2022] [Revised: 02/16/2022] [Accepted: 02/17/2022] [Indexed: 12/10/2022] Open
Abstract
Chemical exchange saturation transfer (CEST) magnetic resonance imaging (MRI) detects molecules in their natural forms in a sensitive and non-invasive manner. This makes it a robust approach to assess brain tumors and related molecular alterations using endogenous molecules, such as proteins/peptides, and drugs approved for clinical use. In this review, we will discuss the promises of CEST MRI in the identification of tumors, tumor grading, detecting molecular alterations related to isocitrate dehydrogenase (IDH) and O-6-methylguanine-DNA methyltransferase (MGMT), assessment of treatment effects, and using multiple contrasts of CEST to develop theranostic approaches for cancer treatments. Promising applications include (i) using the CEST contrast of amide protons of proteins/peptides to detect brain tumors, such as glioblastoma multiforme (GBM) and low-grade gliomas; (ii) using multiple CEST contrasts for tumor stratification, and (iii) evaluation of the efficacy of drug delivery without the need of metallic or radioactive labels. These promising applications have raised enthusiasm, however, the use of CEST MRI is not trivial. CEST contrast depends on the pulse sequences, saturation parameters, methods used to analyze the CEST spectrum (i.e., Z-spectrum), and, importantly, how to interpret changes in CEST contrast and related molecular alterations in the brain. Emerging pulse sequence designs and data analysis approaches, including those assisted with deep learning, have enhanced the capability of CEST MRI in detecting molecules in brain tumors. CEST has become a specific marker for tumor grading and has the potential for prognosis and theranostics in brain tumors. With increasing understanding of the technical aspects and associated molecular alterations detected by CEST MRI, this young field is expected to have wide clinical applications in the near future.
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22
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Kim M, Eleftheriou A, Ravotto L, Weber B, Rivlin M, Navon G, Capozza M, Anemone A, Longo DL, Aime S, Zaiss M, Herz K, Deshmane A, Lindig T, Bender B, Golay X. What do we know about dynamic glucose-enhanced (DGE) MRI and how close is it to the clinics? Horizon 2020 GLINT consortium report. MAGMA (NEW YORK, N.Y.) 2022; 35:87-104. [PMID: 35032288 PMCID: PMC8901523 DOI: 10.1007/s10334-021-00994-1] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/12/2021] [Revised: 12/20/2021] [Accepted: 12/21/2021] [Indexed: 12/27/2022]
Abstract
Cancer is one of the most devastating diseases that the world is currently facing, accounting for 10 million deaths in 2020 (WHO). In the last two decades, advanced medical imaging has played an ever more important role in the early detection of the disease, as it increases the chances of survival and the potential for full recovery. To date, dynamic glucose-enhanced (DGE) MRI using glucose-based chemical exchange saturation transfer (glucoCEST) has demonstrated the sensitivity to detect both d-glucose and glucose analogs, such as 3-oxy-methyl-d-glucose (3OMG) uptake in tumors. As one of the recent international efforts aiming at pushing the boundaries of translation of the DGE MRI technique into clinical practice, a multidisciplinary team of eight partners came together to form the “glucoCEST Imaging of Neoplastic Tumors (GLINT)” consortium, funded by the Horizon 2020 European Commission. This paper summarizes the progress made to date both by these groups and others in increasing our knowledge of the underlying mechanisms related to this technique as well as translating it into clinical practice.
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Affiliation(s)
- Mina Kim
- Department of Brain Repair and Rehabilitation, UCL Queen Square Institute of Neurology, Faculty of Brain Sciences, University College London, London, UK.,Centre for Medical Image Computing, Department of Computer Science, University College London, London, UK
| | - Afroditi Eleftheriou
- Institute of Pharmacology and Toxicology, University of Zurich, Zurich, Switzerland
| | - Luca Ravotto
- Institute of Pharmacology and Toxicology, University of Zurich, Zurich, Switzerland
| | - Bruno Weber
- Institute of Pharmacology and Toxicology, University of Zurich, Zurich, Switzerland.,Neuroscience Center Zurich, Zurich, Switzerland
| | - Michal Rivlin
- School of Chemistry, Faculty of Exact Sciences, Tel Aviv University, Tel Aviv, Israel
| | - Gil Navon
- School of Chemistry, Faculty of Exact Sciences, Tel Aviv University, Tel Aviv, Israel
| | - Martina Capozza
- Molecular Imaging Center, Department of Molecular Biotechnology and Health Sciences, University of Torino, Torino, Italy
| | - Annasofia Anemone
- Molecular Imaging Center, Department of Molecular Biotechnology and Health Sciences, University of Torino, Torino, Italy
| | - Dario Livio Longo
- Institute of Biostructures and Bioimaging (IBB), National Research Council of Italy (CNR), Torino, Italy
| | - Silvio Aime
- Molecular Imaging Center, Department of Molecular Biotechnology and Health Sciences, University of Torino, Torino, Italy
| | - Moritz Zaiss
- Magnetic Resonance Center, Max Planck Institute for Biological Cybernetics, Tübingen, Germany.,Neuroradiology, University Clinic Erlangen, Friedrich-Alexander Universität Erlangen-Nürnberg (FAU), Erlangen, Germany
| | - Kai Herz
- Magnetic Resonance Center, Max Planck Institute for Biological Cybernetics, Tübingen, Germany.,Department of Biomedical Magnetic Resonance, University of Tübingen, Tübingen, Germany
| | - Anagha Deshmane
- Magnetic Resonance Center, Max Planck Institute for Biological Cybernetics, Tübingen, Germany.,Department of Biomedical Magnetic Resonance, University of Tübingen, Tübingen, Germany
| | - Tobias Lindig
- Magnetic Resonance Center, Max Planck Institute for Biological Cybernetics, Tübingen, Germany.,Department of Diagnostic and Interventional Neuroradiology, University Hospital Tübingen, Tübingen, Germany
| | - Benjamin Bender
- Department of Diagnostic and Interventional Neuroradiology, University Hospital Tübingen, Tübingen, Germany
| | - Xavier Golay
- Department of Brain Repair and Rehabilitation, UCL Queen Square Institute of Neurology, Faculty of Brain Sciences, University College London, London, UK.
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23
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Computationally designed dual-color MRI reporters for noninvasive imaging of transgene expression. Nat Biotechnol 2022; 40:1143-1149. [PMID: 35102291 DOI: 10.1038/s41587-021-01162-5] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2020] [Accepted: 11/12/2021] [Indexed: 12/13/2022]
Abstract
Imaging of gene-expression patterns in live animals is difficult to achieve with fluorescent proteins because tissues are opaque to visible light. Imaging of transgene expression with magnetic resonance imaging (MRI), which penetrates to deep tissues, has been limited by single reporter visualization capabilities. Moreover, the low-throughput capacity of MRI limits large-scale mutagenesis strategies to improve existing reporters. Here we develop an MRI system, called GeneREFORM, comprising orthogonal reporters for two-color imaging of transgene expression in deep tissues. Starting from two promiscuous deoxyribonucleoside kinases, we computationally designed highly active, orthogonal enzymes ('reporter genes') that specifically phosphorylate two MRI-detectable synthetic deoxyribonucleosides ('reporter probes'). Systemically administered reporter probes exclusively accumulate in cells expressing the designed reporter genes, and their distribution is displayed as pseudo-colored MRI maps based on dynamic proton exchange for noninvasive visualization of transgene expression. We envision that future extensions of GeneREFORM will pave the way to multiplexed deep-tissue mapping of gene expression in live animals.
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24
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Lombardi AF, Wong JH, High R, Ma Y, Jerban S, Tang Q, Du J, Frost P, Pagel MD, Chang EY. AcidoCEST MRI Evaluates the Bone Microenvironment in Multiple Myeloma. Mol Imaging Biol 2021; 23:865-873. [PMID: 33939066 PMCID: PMC8563482 DOI: 10.1007/s11307-021-01611-2] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2021] [Revised: 04/14/2021] [Accepted: 04/26/2021] [Indexed: 01/29/2023]
Abstract
PURPOSE Multiple myeloma (MM) is an incurable disease of malignant plasma cells in the bone marrow (BM). Adaptive responses to hypoxia may be an essential element in MM progression and drug resistance. This metabolic adaptation involves a decrease in extracellular pH (pHe), and it depends on the upregulation of glucose transporters (GLUTs) that is common in hypoxia and in cancer cells. CEST MRI is an imaging technique that assesses pHe indirectly by the exchange rate of magnetic saturation transfer between labile protons on a solute and water. Thus, this study aimed to determine the feasibility of acidoCEST MRI for pHe measurement using an orthotopic mouse model of MM compared with GLUT1 immunofluorescence staining as a reference. PROCEDURES Orthotopic BM engrafted MM xenografts were established in NSG/NOD mice using the human RPMI8226 myeloma cell line. AcidoCEST MRI was performed approximately 6 weeks after intravenous challenge, before and after intravenous administration of iopamidol. BM pHe values were generated via fitting the CEST spectrum with the Bloch-McConnell equations. Samples were decalcified, sectioned, and immunostained for GLUT1 expression. Pearson's correlation was used to assess the relationship between pHe and [H3O+] versus GLUT1 expression. RESULTS Ten mice underwent acidoCEST MRI followed by immunofluorescent histologic analysis. A strong negative correlation was seen between pHe versus GLUT1 expression (r = - 0.75, p < 0.001). After transformation of pH to [H3O+], a strong positive correlation between [H3O+] and GLUT1 expression was observed (r = 0.8, p < 0.001). CONCLUSIONS AcidoCEST MRI can measure the extracellular pH of bone marrow affected by multiple myeloma. In this MM orthotopic mouse model, pHe measured by acidoCEST MRI showed strong correlations with the metabolic phenotype of BM tumor assessed by immunofluorescent histological assessment of GLUT1 overexpression.
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Affiliation(s)
- Alecio F Lombardi
- Research Service, VA San Diego Healthcare System, 3350 La Jolla Village Drive, CA, 92161, San Diego, USA
- Department of Radiology, University of California, San Diego, CA, USA
| | - Jonathan H Wong
- Research Service, VA San Diego Healthcare System, 3350 La Jolla Village Drive, CA, 92161, San Diego, USA
- Department of Radiology, University of California, San Diego, CA, USA
| | - Rachel High
- Research Service, VA San Diego Healthcare System, 3350 La Jolla Village Drive, CA, 92161, San Diego, USA
- Department of Radiology, University of California, San Diego, CA, USA
| | - Yajun Ma
- Research Service, VA San Diego Healthcare System, 3350 La Jolla Village Drive, CA, 92161, San Diego, USA
- Department of Radiology, University of California, San Diego, CA, USA
| | - Saeed Jerban
- Research Service, VA San Diego Healthcare System, 3350 La Jolla Village Drive, CA, 92161, San Diego, USA
- Department of Radiology, University of California, San Diego, CA, USA
| | - Qingbo Tang
- Research Service, VA San Diego Healthcare System, 3350 La Jolla Village Drive, CA, 92161, San Diego, USA
- Department of Radiology, University of California, San Diego, CA, USA
| | - Jiang Du
- Research Service, VA San Diego Healthcare System, 3350 La Jolla Village Drive, CA, 92161, San Diego, USA
- Department of Radiology, University of California, San Diego, CA, USA
| | - Patrick Frost
- Research Service, Greater Los Angeles Veteran Administration Healthcare System, Los Angeles, CA, USA
- Department of Medicine, University of California, Los Angeles, CA, USA
| | - Mark D Pagel
- Department of Cancer Systems Imaging, University of Texas MD Anderson Cancer Center, Houston, TX, USA
| | - Eric Y Chang
- Research Service, VA San Diego Healthcare System, 3350 La Jolla Village Drive, CA, 92161, San Diego, USA.
- Department of Radiology, University of California, San Diego, CA, USA.
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25
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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.
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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
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26
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Romdhane F, Villano D, Irrera P, Consolino L, Longo DL. Evaluation of a similarity anisotropic diffusion denoising approach for improving in vivo CEST-MRI tumor pH imaging. Magn Reson Med 2021; 85:3479-3496. [PMID: 33496986 DOI: 10.1002/mrm.28676] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2020] [Revised: 12/18/2020] [Accepted: 12/18/2020] [Indexed: 12/16/2022]
Abstract
PURPOSE Chemical exchange saturation transfer MRI provides new approaches for investigating tumor microenvironment, including tumor acidosis that plays a key role in tumor progression and resistance to therapy. Following iopamidol injection, the detection of the contrast agent inside the tumor tissue allows measurements of tumor extracellular pH. However, accurate tumor pH quantifications are hampered by the low contrast efficiency of the CEST technique and by the low SNR of the acquired CEST images, hence in a reduced detectability of the injected agent. This work aims to investigate a novel denoising method for improving both tumor pH quantification and accuracy of CEST-MRI pH imaging. METHODS An hybrid denoising approach was investigated for CEST-MRI pH imaging based on the combination of the nonlocal mean filter and the anisotropic diffusion tensor method. The denoising approach was tested in simulated and in vitro data and compared with previously reported methods for CEST imaging and with established denoising approaches. Finally, it was validated with in vivo data to improve the accuracy of tumor pH maps. RESULTS The proposed method outperforms current denoising methods in CEST contrast quantification and detection of the administered contrast agent at several increasing noise levels with simulated data. In addition, it achieved a better pH quantification in in vitro data and demonstrated a marked improvement in contrast detection and a substantial improvement in tumor pH accuracy in in vivo data. CONCLUSION The proposed approach effectively reduces the noise in CEST images and increases the sensitivity detection in CEST-MRI pH imaging.
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Affiliation(s)
- Feriel Romdhane
- Molecular Imaging Center, Department of Molecular Biotechnology and Health Sciences, University of Torino, Torino, Italy.,National Engineering School of Tunis, University al Manar, Tunis, Tunisia
| | - Daisy Villano
- Molecular Imaging Center, Department of Molecular Biotechnology and Health Sciences, University of Torino, Torino, Italy
| | - Pietro Irrera
- University of Campania "Luigi Vanvitelli,", Caserta, Italy.,Institute of Biostructures and Bioimaging (IBB), Italian National Research Council (CNR), Torino, Italy
| | - Lorena Consolino
- Molecular Imaging Center, Department of Molecular Biotechnology and Health Sciences, University of Torino, Torino, Italy
| | - Dario Livio Longo
- Institute of Biostructures and Bioimaging (IBB), Italian National Research Council (CNR), Torino, Italy
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27
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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.
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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.
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28
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Villano D, Romdhane F, Irrera P, Consolino L, Anemone A, Zaiss M, Dastrù W, Longo DL. A fast multislice sequence for 3D MRI-CEST pH imaging. Magn Reson Med 2020; 85:1335-1349. [PMID: 33031591 PMCID: PMC7756816 DOI: 10.1002/mrm.28516] [Citation(s) in RCA: 28] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2020] [Revised: 07/30/2020] [Accepted: 08/22/2020] [Indexed: 12/13/2022]
Abstract
Purpose Chemical exchange saturation transfer MRI can provide accurate pH images, but the slow scan time (due to long saturation periods and multiple offsets sampling) reduce both the volume coverage and spatial resolution capability, hence the possibility to interrogate the heterogeneity in tumors and organs. To overcome these limitations, we propose a fast multislice CEST‐MRI sequence with high pH accuracy and spatial resolution. Methods The sequence first uses a long saturation pulse to induce the steady‐state CEST contrast and a second short saturation pulse repeated after each image acquisition to compensate for signal losses based on an uneven irradiation scheme combined with a single‐shot rapid acquisition with refocusing echoes readout. Sequence sensitivity and accuracy in measuring pH was optimized by simulation and assessed by in vitro studies in pH‐varying phantoms. In vivo validation was performed in two applications by acquiring multislice pH images covering the whole tumors and kidneys after iopamidol injection. Results Simulated and in vivo data showed comparable contrast efficiency and pH responsiveness by reducing saturation time. The experimental data from a homogeneous, pH‐varying, iopamidol‐containing phantom show that the sequence produced a uniform CEST contrast across slices and accurate values across slices in less than 10 minutes. In vivo measurements allowed us to quantify the 3D pH gradients of tumors and kidneys, with pH ranges comparable with the literature. Conclusion The proposed fast multislice CEST‐MRI sequence allows volumetric acquisitions with good pH sensitivity, accuracy, and spatial resolution for several in vivo pH imaging applications.
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Affiliation(s)
- Daisy Villano
- Molecular Imaging Center, Department of Molecular Biotechnology and Health Sciences, University of Torino, Torino, Italy
| | - Feriel Romdhane
- Molecular Imaging Center, Department of Molecular Biotechnology and Health Sciences, University of Torino, Torino, Italy.,National Engineering School of Tunis (ENIT), University al Manar, Tunis, Tunisia
| | - Pietro Irrera
- Molecular Imaging Center, Department of Molecular Biotechnology and Health Sciences, University of Torino, Torino, Italy.,Institute of Biostructures and Bioimaging, University of Campania "Luigi Vanvitelli," Italian National Research Council, Napoli, Italy
| | - Lorena Consolino
- Molecular Imaging Center, Department of Molecular Biotechnology and Health Sciences, University of Torino, Torino, Italy
| | - Annasofia Anemone
- Molecular Imaging Center, Department of Molecular Biotechnology and Health Sciences, University of Torino, Torino, Italy
| | - Moritz Zaiss
- Department of Neuroradiology, Friedrich-Alexander Universität Erlangen-Nürnberg, University Hospital Erlangen, Erlangen, Germany
| | - Walter Dastrù
- Molecular Imaging Center, Department of Molecular Biotechnology and Health Sciences, University of Torino, Torino, Italy
| | - Dario Livio Longo
- Institute of Biostructures and Bioimaging, Italian National Research Council, Torino, Italy
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