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Bachrata B, Strasser B, Bogner W, Schmid AI, Korinek R, Krššák M, Trattnig S, Robinson SD. Simultaneous Multiple Resonance Frequency imaging (SMURF): Fat-water imaging using multi-band principles. Magn Reson Med 2021; 85:1379-1396. [PMID: 32981114 PMCID: PMC7756227 DOI: 10.1002/mrm.28519] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2019] [Revised: 07/31/2020] [Accepted: 08/24/2020] [Indexed: 12/15/2022]
Abstract
PURPOSE To develop a fat-water imaging method that allows reliable separation of the two tissues, uses established robust reconstruction methods, and requires only one single-echo acquisition. THEORY AND METHODS The proposed method uses spectrally selective dual-band excitation in combination with CAIPIRINHA to generate separate images of fat and water simultaneously. Spatially selective excitation without cross-contamination is made possible by the use of spatial-spectral pulses. Fat and water images can either be visualized separately, or the fat images can be corrected for chemical shift displacement and, in gradient echo imaging, for chemical shift-related phase discrepancy, and recombined with water images, generating fat-water images free of chemical shift effects. Gradient echo and turbo spin echo sequences were developed based on this Simultaneous Multiple Resonance Frequency imaging (SMURF) approach and their performance was assessed at 3Tesla in imaging of the knee, breasts, and abdomen. RESULTS The proposed method generated well-separated fat and water images with minimal unaliasing artefacts or cross-excitation, evidenced by the near absence of water signal attributed to the fat image and vice versa. The separation achieved was similar to or better than that using separate acquisitions with water- and fat-saturation or Dixon methods. The recombined fat-water images provided similar image contrast to conventional images, but the chemical shift effects were eliminated. CONCLUSION Simultaneous Multiple Resonance Frequency imaging is a robust fat-water imaging technique that offers a solution to imaging of body regions with significant amounts of fat.
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Affiliation(s)
- Beata Bachrata
- High Field MR Centre, Department of Biomedical Imaging and Image‐Guided TherapyMedical University of ViennaViennaAustria,Christian Doppler Laboratory for Clinical Molecular MR ImagingViennaAustria
| | - Bernhard Strasser
- High Field MR Centre, Department of Biomedical Imaging and Image‐Guided TherapyMedical University of ViennaViennaAustria,Athinoula A. Martinos Center for Biomedical Imaging, Department of RadiologyMassachusetts General Hospital, Harvard Medical SchoolBostonMAUSA
| | - Wolfgang Bogner
- High Field MR Centre, Department of Biomedical Imaging and Image‐Guided TherapyMedical University of ViennaViennaAustria
| | - Albrecht Ingo Schmid
- High Field MR Centre, Center for Medical Physics and Biomedical EngineeringMedical University of ViennaViennaAustria
| | - Radim Korinek
- Institute of Scientific Instruments of the CASBrnoCzech Republic
| | - Martin Krššák
- High Field MR Centre, Department of Biomedical Imaging and Image‐Guided TherapyMedical University of ViennaViennaAustria,Christian Doppler Laboratory for Clinical Molecular MR ImagingViennaAustria,Department of Internal Medicine III, Division of Endocrinology and MetabolismMedical University of ViennaViennaAustria
| | - Siegfried Trattnig
- High Field MR Centre, Department of Biomedical Imaging and Image‐Guided TherapyMedical University of ViennaViennaAustria,Christian Doppler Laboratory for Clinical Molecular MR ImagingViennaAustria
| | - Simon Daniel Robinson
- High Field MR Centre, Department of Biomedical Imaging and Image‐Guided TherapyMedical University of ViennaViennaAustria,Centre of Advanced ImagingUniversity of QueenslandBrisbaneQLDAustralia,Department of NeurologyMedical University of GrazGrazAustria
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Topping GJ, Hundshammer C, Nagel L, Grashei M, Aigner M, Skinner JG, Schulte RF, Schilling F. Acquisition strategies for spatially resolved magnetic resonance detection of hyperpolarized nuclei. MAGMA (NEW YORK, N.Y.) 2020; 33:221-256. [PMID: 31811491 PMCID: PMC7109201 DOI: 10.1007/s10334-019-00807-6] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/09/2019] [Revised: 10/08/2019] [Accepted: 11/21/2019] [Indexed: 12/13/2022]
Abstract
Hyperpolarization is an emerging method in magnetic resonance imaging that allows nuclear spin polarization of gases or liquids to be temporarily enhanced by up to five or six orders of magnitude at clinically relevant field strengths and administered at high concentration to a subject at the time of measurement. This transient gain in signal has enabled the non-invasive detection and imaging of gas ventilation and diffusion in the lungs, perfusion in blood vessels and tissues, and metabolic conversion in cells, animals, and patients. The rapid development of this method is based on advances in polarizer technology, the availability of suitable probe isotopes and molecules, improved MRI hardware and pulse sequence development. Acquisition strategies for hyperpolarized nuclei are not yet standardized and are set up individually at most sites depending on the specific requirements of the probe, the object of interest, and the MRI hardware. This review provides a detailed introduction to spatially resolved detection of hyperpolarized nuclei and summarizes novel and previously established acquisition strategies for different key areas of application.
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Affiliation(s)
- Geoffrey J Topping
- Department of Nuclear Medicine, Klinikum rechts der Isar, Technical University of Munich, Munich, Germany
| | - Christian Hundshammer
- Department of Nuclear Medicine, Klinikum rechts der Isar, Technical University of Munich, Munich, Germany
| | - Luca Nagel
- Department of Nuclear Medicine, Klinikum rechts der Isar, Technical University of Munich, Munich, Germany
| | - Martin Grashei
- Department of Nuclear Medicine, Klinikum rechts der Isar, Technical University of Munich, Munich, Germany
| | - Maximilian Aigner
- Department of Nuclear Medicine, Klinikum rechts der Isar, Technical University of Munich, Munich, Germany
| | - Jason G Skinner
- Department of Nuclear Medicine, Klinikum rechts der Isar, Technical University of Munich, Munich, Germany
| | | | - Franz Schilling
- Department of Nuclear Medicine, Klinikum rechts der Isar, Technical University of Munich, Munich, Germany.
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Song JE, Shin J, Lee H, Choi YS, Song HT, Kim DH. Dynamic hyperpolarized 13 C MR spectroscopic imaging using SPICE in mouse kidney at 9.4 T. NMR IN BIOMEDICINE 2020; 33:e4230. [PMID: 31856426 DOI: 10.1002/nbm.4230] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/23/2019] [Revised: 10/29/2019] [Accepted: 11/04/2019] [Indexed: 05/16/2023]
Abstract
This study aims to investigate the feasibility of dynamic hyperpolarized 13 C MR spectroscopic imaging (MRSI) using the SPectroscopic Imaging by exploiting spatiospectral CorrElation (SPICE) technique and an estimation of the spatially resolved conversion constant rate (kpl ). An acquisition scheme comprising a single training dataset and several imaging datasets was proposed considering hyperpolarized 13 C circumstances. The feasibility and advantage of the scheme were investigated in two parts: (a) consistency of spectral basis over time and (b) accuracy of the estimated kpl . The simulations and in vivo experiments support accurate kpl estimation with consistent spectral bases. The proposed method was implemented in an enzyme phantom and via in vivo experiments. In the enzyme phantom experiments, spatially resolved homogeneous kpl maps were observed. In the in vivo experiments, normal diet (ND) mice and high-fat diet (HFD) mice had kpl (s-1 ) values of medullar (ND: 0.0119 ± 0.0022, HFD: 0.0195 ± 0.0005) and cortical (ND: 0.0148 ±0.0023, HFD: 0.0224 ±0.0054) regions which were higher than vascular (ND: 0.0087 ±0.0013, HFD: 0.0132 ±0.0050) regions. In particular, the kpl value in the medullar region exhibited a significant difference between the two diet groups. In summary, the feasibility of using modified SPICE for dynamic hyperpolarized 13 C MRSI was demonstrated via simulations and in vivo experiments. The consistency of spectral bases over time and the accuracy of the estimated kpl values validate the proposed acquisition scheme, which comprises only a single training dataset. The proposed method improved the spatial resolution of dynamic hyperpolarized 13 C MRSI, which could be used for kpl estimation using high signal-to-noise ratio spectral bases.
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Affiliation(s)
- Jae Eun Song
- Department of Electrical and Electronic Engineering, Yonsei University, Seoul, South Korea
| | - Jaewook Shin
- Department of Electrical and Electronic Engineering, Yonsei University, Seoul, South Korea
| | - Hansol Lee
- Department of Electrical and Electronic Engineering, Yonsei University, Seoul, South Korea
| | - Young-Suk Choi
- Department of Radiology and Research Institute of Radiological Science, College of Medicine, Yonsei University, Seoul, South Korea
| | - Ho-Taek Song
- Department of Radiology and Research Institute of Radiological Science, College of Medicine, Yonsei University, Seoul, South Korea
| | - Dong-Hyun Kim
- Department of Electrical and Electronic Engineering, Yonsei University, Seoul, South Korea
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Peeters TH, Kobus T, Breukels V, Lenting K, Veltien A, Heerschap A, Scheenen TWJ. Imaging Hyperpolarized Pyruvate and Lactate after Blood-Brain Barrier Disruption with Focused Ultrasound. ACS Chem Neurosci 2019; 10:2591-2601. [PMID: 30873831 PMCID: PMC6523999 DOI: 10.1021/acschemneuro.9b00085] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
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Imaging of hyperpolarized 13C-labeled substrates has
emerged as an important magnetic resonance (MR) technique to study
metabolic pathways in real time in vivo. Even though
this technique has found its way to clinical trials, in vivo dynamic nuclear polarization is still mostly applied in preclinical
models. Its tremendous increase in signal-to-noise ratio (SNR) overcomes
the intrinsically low MR sensitivity of the 13C nucleus
and allows real-time metabolic imaging in small structures like the
mouse brain. However, applications in brain research are limited as
delivery of hyperpolarized compounds is restrained by the blood–brain
barrier (BBB). A local noninvasive disruption of the BBB could facilitate
delivery of hyperpolarized substrates and create opportunities to
study metabolic pathways in the brain that are generally not within
reach. In this work, we designed a setup to apply BBB disruption in
the mouse brain by MR-guided focused ultrasound (FUS) prior to MR
imaging of 13C-enriched hyperpolarized [1-13C]-pyruvate and its conversion to [1-13C]-lactate. To
overcome partial volume issues, we optimized a fast multigradient-echo
imaging method (temporal resolution of 2.4 s) with an in-plane spatial
resolution of 1.6 × 1.6 mm2, without the need of processing
large amounts of spectroscopic data. We demonstrated the feasibility
to apply 13C imaging in less than 1 h after FUS treatment
and showed a locally disrupted BBB during the time window of the whole
experiment. From detected hyperpolarized pyruvate and lactate signals
in both FUS-treated and untreated mice, we conclude that even at high
spatial resolution, signals from the blood compartment dominate in
the 13C images, leaving the interpretation of hyperpolarized
signals in the mouse brain challenging.
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Affiliation(s)
- Tom H. Peeters
- Department of Radiology and Nuclear Medicine, Radboud university medical center, Nijmegen, The Netherlands
| | - Thiele Kobus
- Department of Radiology and Nuclear Medicine, Radboud university medical center, Nijmegen, The Netherlands
| | - Vincent Breukels
- Department of Radiology and Nuclear Medicine, Radboud university medical center, Nijmegen, The Netherlands
| | - Krissie Lenting
- Department of Biochemistry, Radboud Institute for Molecular Life Sciences, Nijmegen, The Netherlands
| | - Andor Veltien
- Department of Radiology and Nuclear Medicine, Radboud university medical center, Nijmegen, The Netherlands
| | - Arend Heerschap
- Department of Radiology and Nuclear Medicine, Radboud university medical center, Nijmegen, The Netherlands
| | - Tom W. J. Scheenen
- Department of Radiology and Nuclear Medicine, Radboud university medical center, Nijmegen, The Netherlands
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Hundshammer C, Braeuer M, Müller CA, Hansen AE, Schillmaier M, Düwel S, Feuerecker B, Glaser SJ, Haase A, Weichert W, Steiger K, Cabello J, Schilling F, Hövener JB, Kjær A, Nekolla SG, Schwaiger M. Simultaneous characterization of tumor cellularity and the Warburg effect with PET, MRI and hyperpolarized 13C-MRSI. Am J Cancer Res 2018; 8:4765-4780. [PMID: 30279736 PMCID: PMC6160766 DOI: 10.7150/thno.25162] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2018] [Accepted: 06/26/2018] [Indexed: 02/07/2023] Open
Abstract
Modern oncology aims at patient-specific therapy approaches, which triggered the development of biomedical imaging techniques to synergistically address tumor biology at the cellular and molecular level. PET/MR is a new hybrid modality that allows acquisition of high-resolution anatomic images and quantification of functional and metabolic information at the same time. Key steps of the Warburg effect-one of the hallmarks of tumors-can be measured non-invasively with this emerging technique. The aim of this study was to quantify and compare simultaneously imaged augmented glucose uptake and LDH activity in a subcutaneous breast cancer model in rats (MAT-B-III) and to study the effect of varying tumor cellularity on image-derived metabolic information. Methods: For this purpose, we established and validated a multimodal imaging workflow for a clinical PET/MR system including proton magnetic resonance (MR) imaging to acquire accurate morphologic information and diffusion-weighted imaging (DWI) to address tumor cellularity. Metabolic data were measured with dynamic [18F]FDG-PET and hyperpolarized (HP) 13C-pyruvate MR spectroscopic imaging (MRSI). We applied our workflow in a longitudinal study and analyzed the effect of growth dependent variations of cellular density on glycolytic parameters. Results: Tumors of similar cellularity with similar apparent diffusion coefficients (ADC) showed a significant positive correlation of FDG uptake and pyruvate-to-lactate exchange. Longitudinal DWI data indicated a decreasing tumor cellularity with tumor growth, while ADCs exhibited a significant inverse correlation with PET standard uptake values (SUV). Similar but not significant trends were observed with HP-13C-MRSI, but we found that partial volume effects and point spread function artifacts are major confounders for the quantification of 13C-data when the spatial resolution is limited and major blood vessels are close to the tumor. Nevertheless, analysis of longitudinal data with varying tumor cellularity further detected a positive correlation between quantitative PET and 13C-data. Conclusions: Our workflow allows the quantification of simultaneously acquired PET, MRSI and DWI data in rodents on a clinical PET/MR scanner. The correlations and findings suggest that a major portion of consumed glucose is metabolized by aerobic glycolysis in the investigated tumor model. Furthermore, we conclude that variations in cell density affect PET and 13C-data in a similar manner and correlations of longitudinal metabolic data appear to reflect both biochemical processes and tumor cellularity.
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Milshteyn E, von Morze C, Gordon JW, Zhu Z, Larson PEZ, Vigneron DB. High spatiotemporal resolution bSSFP imaging of hyperpolarized [1- 13 C]pyruvate and [1- 13 C]lactate with spectral suppression of alanine and pyruvate-hydrate. Magn Reson Med 2018; 80:1048-1060. [PMID: 29451329 PMCID: PMC5980670 DOI: 10.1002/mrm.27104] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2017] [Revised: 12/02/2017] [Accepted: 01/03/2018] [Indexed: 12/23/2022]
Abstract
Purpose The bSSFP acquisition enables high spatiotemporal resolution for hyperpolarized 13C MRI at 3T, but is limited by spectral contamination from adjacent resonances. The purpose of this study was to develop a framework for in vivo dynamic high resolution imaging of hyperpolarized [1-13C]pyruvate and [1-13C]lactate generated in vivo at 3T by simplifying the spectrum through the use of selective suppression pulses. Methods Spectral suppression pulses were incorporated into the bSSFP sequence for suppression of [1-13C]alanine and [1-13C]pyruvate-hydrate signals, leaving only the pyruvate and lactate resonances. Subsequently, the bSSFP pulse width, time-bandwidth, and repetition time were optimized for imaging these dual resonances. Results The spectral suppression reduced both the alanine and pyruvate-hydrate signals by 85.5 ± 4.9% and had no significant effect on quantitation of pyruvate to lactate conversion (liver: P = 0.400, kidney: P = 0.499). High resolution (2 × 2 mm2 and 3 × 3 mm2) sub-second 2D coronal projections and 3D 2.5 mm isotropic images were obtained in rats and tumor-bearing mice with 1.8-5 s temporal resolution, allowing for calculation of lactate-to-pyruvate ratios and k PL. Conclusion The developed framework presented here shows the capability for dynamic high resolution volumetric hyperpolarized bSSFP imaging of pyruvate-to-lactate conversion on a clinical 3T MR scanner.
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Affiliation(s)
- Eugene Milshteyn
- Department of Radiology and Biomedical Imaging, University of California, San Francisco, California, USA
- UC Berkeley-UCSF Graduate Program in Bioengineering, University of California, San Francisco and University of California, Berkeley, California, USA
| | - Cornelius von Morze
- Department of Radiology and Biomedical Imaging, University of California, San Francisco, California, USA
| | - Jeremy W. Gordon
- Department of Radiology and Biomedical Imaging, University of California, San Francisco, California, USA
| | - Zihan Zhu
- Department of Radiology and Biomedical Imaging, University of California, San Francisco, California, USA
- UC Berkeley-UCSF Graduate Program in Bioengineering, University of California, San Francisco and University of California, Berkeley, California, USA
| | - Peder E. Z. Larson
- Department of Radiology and Biomedical Imaging, University of California, San Francisco, California, USA
- UC Berkeley-UCSF Graduate Program in Bioengineering, University of California, San Francisco and University of California, Berkeley, California, USA
| | - Daniel B. Vigneron
- Department of Radiology and Biomedical Imaging, University of California, San Francisco, California, USA
- UC Berkeley-UCSF Graduate Program in Bioengineering, University of California, San Francisco and University of California, Berkeley, California, USA
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7
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Lau JYC, Geraghty BJ, Chen AP, Cunningham CH. Improved tolerance to off-resonance in spectral-spatial EPI of hyperpolarized [1- 13 C]pyruvate and metabolites. Magn Reson Med 2018; 80:925-934. [PMID: 29380423 DOI: 10.1002/mrm.27086] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2017] [Revised: 11/28/2017] [Accepted: 12/24/2017] [Indexed: 12/16/2022]
Affiliation(s)
- Justin Y C Lau
- Physical Sciences, Sunnybrook Research Institute, Toronto, Ontario, Canada.,Medical Biophysics, University of Toronto, Toronto, Ontario, Canada
| | - Benjamin J Geraghty
- Physical Sciences, Sunnybrook Research Institute, Toronto, Ontario, Canada.,Medical Biophysics, University of Toronto, Toronto, Ontario, Canada
| | | | - Charles H Cunningham
- Physical Sciences, Sunnybrook Research Institute, Toronto, Ontario, Canada.,Medical Biophysics, University of Toronto, Toronto, Ontario, Canada
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8
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Milshteyn E, von Morze C, Reed GD, Shang H, Shin PJ, Zhu Z, Chen HY, Bok R, Goga A, Kurhanewicz J, Larson PEZ, Vigneron DB. Development of high resolution 3D hyperpolarized carbon-13 MR molecular imaging techniques. Magn Reson Imaging 2017; 38:152-162. [PMID: 28077268 PMCID: PMC5360530 DOI: 10.1016/j.mri.2017.01.003] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2016] [Revised: 01/05/2017] [Accepted: 01/06/2017] [Indexed: 01/08/2023]
Abstract
The goal of this project was to develop and apply techniques for T2 mapping and 3D high resolution (1.5mm isotropic; 0.003cm3) 13C imaging of hyperpolarized (HP) probes [1-13C]lactate, [1-13C]pyruvate, [2-13C]pyruvate, and [13C,15N2]urea in vivo. A specialized 2D bSSFP sequence was implemented on a clinical 3T scanner and used to obtain the first high resolution T2 maps of these different hyperpolarized compounds in both rats and tumor-bearing mice. These maps were first used to optimize timings for highest SNR for single time-point 3D bSSFP acquisitions with a 1.5mm isotropic spatial resolution of normal rats. This 3D acquisition approach was extended to serial dynamic imaging with 2-fold compressed sensing acceleration without changing spatial resolution. The T2 mapping experiments yielded measurements of T2 values of >1s for all compounds within rat kidneys/vasculature and TRAMP tumors, except for [2-13C]pyruvate which was ~730ms and ~320ms, respectively. The high resolution 3D imaging enabled visualization the biodistribution of [1-13C]lactate, [1-13C]pyruvate, and [2-13C]pyruvate within different kidney compartments as well as in the vasculature. While the mouse anatomy is smaller, the resolution was also sufficient to image the distribution of all compounds within kidney, vasculature, and tumor. The development of the specialized 3D sequence with compressed sensing provided improved structural and functional assessments at a high (0.003cm3) spatial and 2s temporal resolution in vivo utilizing HP 13C substrates by exploiting their long T2 values. This 1.5mm isotropic resolution is comparable to 1H imaging and application of this approach could be extended to future studies of uptake, metabolism, and perfusion in cancer and other disease models and may ultimately be of value for clinical imaging.
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Affiliation(s)
- Eugene Milshteyn
- Department of Radiology and Biomedical Imaging, University of California, San Francisco, CA, USA; UC Berkeley-UCSF Graduate Program in Bioengineering, University of California, San Francisco and University of California, Berkeley, CA, USA
| | - Cornelius von Morze
- Department of Radiology and Biomedical Imaging, University of California, San Francisco, CA, USA
| | | | - Hong Shang
- Department of Radiology and Biomedical Imaging, University of California, San Francisco, CA, USA; UC Berkeley-UCSF Graduate Program in Bioengineering, University of California, San Francisco and University of California, Berkeley, CA, USA
| | - Peter J Shin
- Department of Radiology and Biomedical Imaging, University of California, San Francisco, CA, USA
| | - Zihan Zhu
- Department of Radiology and Biomedical Imaging, University of California, San Francisco, CA, USA; UC Berkeley-UCSF Graduate Program in Bioengineering, University of California, San Francisco and University of California, Berkeley, CA, USA
| | - Hsin-Yu Chen
- Department of Radiology and Biomedical Imaging, University of California, San Francisco, CA, USA; UC Berkeley-UCSF Graduate Program in Bioengineering, University of California, San Francisco and University of California, Berkeley, CA, USA
| | - Robert Bok
- Department of Radiology and Biomedical Imaging, University of California, San Francisco, CA, USA
| | - Andrei Goga
- Department of Cell and Tissue Biology, University of California, San Francisco, CA, USA
| | - John Kurhanewicz
- Department of Radiology and Biomedical Imaging, University of California, San Francisco, CA, USA; UC Berkeley-UCSF Graduate Program in Bioengineering, University of California, San Francisco and University of California, Berkeley, CA, USA
| | - Peder E Z Larson
- Department of Radiology and Biomedical Imaging, University of California, San Francisco, CA, USA; UC Berkeley-UCSF Graduate Program in Bioengineering, University of California, San Francisco and University of California, Berkeley, CA, USA
| | - Daniel B Vigneron
- Department of Radiology and Biomedical Imaging, University of California, San Francisco, CA, USA; UC Berkeley-UCSF Graduate Program in Bioengineering, University of California, San Francisco and University of California, Berkeley, CA, USA.
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Abstract
The technique of induced metabolic bioluminescence imaging (imBI) has been developed to obtain a "snapshot" of the momentary metabolic status of biological tissues. Using cryosections of snap-frozen tissue specimens, imBI combines highly specific and sensitive in situ detection of metabolites with a spatial resolution on a microscopic level and with metabolic imaging in relation to tissue histology. Here, we present the application of imBI in human colorectal cancer. Comparing the metabolic information of one biopsy with that of 2 or 3 biopsies per individual cancer, the classification into high versus low lactate tumors, reflecting different glycolytic activities, based on a single biopsy was in agreement with the result from multiple biopsies in 83 % of all cases. We further demonstrate that the metabolic status of tumor tissue can be preserved at least over 10 years by storage in liquid nitrogen, but not by storage at -80 °C. This means that tissue banking with long-term preservation of the metabolic status is possible at -180 °C, which may be relevant for studies on long-term survival of cancer patients. As with other tumor entities, tissue lactate concentration was shown to be correlated with tumor development and progression in colorectal cancer. At first-time diagnosis, lactate values were low in rectal normal tissue and adenomas, were significantly elevated to intermediate levels in non-metastatic adenocarcinomas, and were very high in carcinomas with distant metastasis. There was an inverse behavior of tissue glucose concentration under corresponding conditions. The expression level of monocarboxylate transporter-4 (MCT4) was positively correlated with the tumor lactate concentration and may thus contribute to high lactate tumors being associated with a high degree of malignancy.
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Gordon JW, Vigneron DB, Larson PEZ. Development of a symmetric echo planar imaging framework for clinical translation of rapid dynamic hyperpolarized 13 C imaging. Magn Reson Med 2016; 77:826-832. [PMID: 26898849 DOI: 10.1002/mrm.26123] [Citation(s) in RCA: 52] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2015] [Revised: 11/25/2015] [Accepted: 12/19/2015] [Indexed: 01/24/2023]
Abstract
PURPOSE To develop symmetric echo planar imaging (EPI) and a reference scan framework for hyperpolarized 13 C metabolic imaging. METHODS Symmetric, ramp-sampled EPI with partial Fourier reconstruction was implemented on a 3T scanner. The framework for acquiring a reference scan on the 1 H channel and applied to 13 C data was described and validated in both phantoms and in vivo metabolism of [1-13 C]pyruvate. RESULTS Ramp-sampled, symmetric EPI provided a substantial increase in the signal-to-noise ratio of the phantom experiments. The reference scan acquired on the 1 H channel yielded 13 C phantom images that varied in mean signal intensity <2%, compared with 13 C images reconstructed with a reference scan directly measured on the 13 C channel. The structural similarity index and dynamic time course from in vivo 13 C data further support the application of a 1 H reference scan to 13 C data to mitigate Nyquist ghost artifacts. CONCLUSION Ramp-sampled, symmetric EPI with spectral-spatial excitation of a single metabolite provides a fast, robust, and clinically efficacious approach to acquire hyperpolarized 13 C dynamic molecular imaging data. The gains of this efficient sampling, combined with partial Fourier methods, enables large matrix sizes required for human studies. Magn Reson Med 77:826-832, 2017. © 2016 International Society for Magnetic Resonance in Medicine.
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Affiliation(s)
- Jeremy W Gordon
- Department of Radiology & Biomedical Imaging, University of California, San Francisco, California, USA
| | - Daniel B Vigneron
- Department of Radiology & Biomedical Imaging, University of California, San Francisco, California, USA
| | - Peder E Z Larson
- Department of Radiology & Biomedical Imaging, University of California, San Francisco, California, USA
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11
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Fan TWM, Lane AN. Applications of NMR spectroscopy to systems biochemistry. PROGRESS IN NUCLEAR MAGNETIC RESONANCE SPECTROSCOPY 2016; 92-93:18-53. [PMID: 26952191 PMCID: PMC4850081 DOI: 10.1016/j.pnmrs.2016.01.005] [Citation(s) in RCA: 123] [Impact Index Per Article: 15.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/14/2015] [Revised: 01/26/2016] [Accepted: 01/28/2016] [Indexed: 05/05/2023]
Abstract
The past decades of advancements in NMR have made it a very powerful tool for metabolic research. Despite its limitations in sensitivity relative to mass spectrometric techniques, NMR has a number of unparalleled advantages for metabolic studies, most notably the rigor and versatility in structure elucidation, isotope-filtered selection of molecules, and analysis of positional isotopomer distributions in complex mixtures afforded by multinuclear and multidimensional experiments. In addition, NMR has the capacity for spatially selective in vivo imaging and dynamical analysis of metabolism in tissues of living organisms. In conjunction with the use of stable isotope tracers, NMR is a method of choice for exploring the dynamics and compartmentation of metabolic pathways and networks, for which our current understanding is grossly insufficient. In this review, we describe how various direct and isotope-edited 1D and 2D NMR methods can be employed to profile metabolites and their isotopomer distributions by stable isotope-resolved metabolomic (SIRM) analysis. We also highlight the importance of sample preparation methods including rapid cryoquenching, efficient extraction, and chemoselective derivatization to facilitate robust and reproducible NMR-based metabolomic analysis. We further illustrate how NMR has been applied in vitro, ex vivo, or in vivo in various stable isotope tracer-based metabolic studies, to gain systematic and novel metabolic insights in different biological systems, including human subjects. The pathway and network knowledge generated from NMR- and MS-based tracing of isotopically enriched substrates will be invaluable for directing functional analysis of other 'omics data to achieve understanding of regulation of biochemical systems, as demonstrated in a case study. Future developments in NMR technologies and reagents to enhance both detection sensitivity and resolution should further empower NMR in systems biochemical research.
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Affiliation(s)
- Teresa W-M Fan
- Department of Toxicology and Cancer Biology, University of Kentucky, 789 S. Limestone St., Lexington, KY 40536, United States.
| | - Andrew N Lane
- Department of Toxicology and Cancer Biology, University of Kentucky, 789 S. Limestone St., Lexington, KY 40536, United States.
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Ko H, Gong G, Jeong G, Choi I, Seo H, Lee Y. Hyperpolarization: Sensitivity Boost in Magnetic Resonance Spectroscopy and Imaging. JOURNAL OF THE KOREAN MAGNETIC RESONANCE SOCIETY 2015. [DOI: 10.6564/jkmrs.2015.19.3.124] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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Shin PJ, Larson PE, Uecker M, Reed GD, Kerr AB, Tropp J, Ohliger MA, Nelson SJ, Pauly JM, Lustig M, Vigneron DB. Chemical shift separation with controlled aliasing for hyperpolarized (13) C metabolic imaging. Magn Reson Med 2015; 74:978-89. [PMID: 25298086 PMCID: PMC4390401 DOI: 10.1002/mrm.25473] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2014] [Revised: 08/15/2014] [Accepted: 09/05/2014] [Indexed: 12/21/2022]
Abstract
PURPOSE A chemical shift separation technique for hyperpolarized (13) C metabolic imaging with high spatial and temporal resolution was developed. Specifically, a fast three-dimensional pulse sequence and a reconstruction method were implemented to acquire signals from multiple (13) C species simultaneously with subsequent separation into individual images. THEORY AND METHODS A stack of flyback echo-planar imaging readouts and a set of multiband excitation radiofrequency pulses were designed to spatially modulate aliasing patterns of the acquired metabolite images, which translated the chemical shift separation problem into parallel imaging reconstruction problem. An eight-channel coil array was used for data acquisition and a parallel imaging method based on nonlinear inversion was developed to separate the aliased images. RESULTS Simultaneous acquisitions of pyruvate and lactate in a phantom study and in vivo rat experiments were performed. The results demonstrated successful separation of the metabolite distributions into individual images having high spatial resolution. CONCLUSION This method demonstrated the ability to provide accelerated metabolite imaging in hyperpolarized (13) C MR using multichannel coils, tailored readout, and specialized RF pulses.
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Affiliation(s)
- Peter J. Shin
- Department of Radiology and Biomedical Imaging, University of California at San Francisco, San Francisco, California, USA
- The UC Berkeley - UCSF Graduate Program in Bioengineering, California, USA
| | - Peder E.Z. Larson
- Department of Radiology and Biomedical Imaging, University of California at San Francisco, San Francisco, California, USA
- The UC Berkeley - UCSF Graduate Program in Bioengineering, California, USA
| | - Martin Uecker
- Department of Electrical Engineering and Computer Sciences, University of California at Berkeley, Berkeley, California, USA
| | - Galen D. Reed
- Department of Radiology and Biomedical Imaging, University of California at San Francisco, San Francisco, California, USA
- The UC Berkeley - UCSF Graduate Program in Bioengineering, California, USA
| | - Adam B. Kerr
- Magnetic Resonance Systems Research Laboratory, Department of Electrical Engineering, Stanford University, Stanford, California, USA
| | - James Tropp
- General Electric Healthcare, Fremont, California, USA
| | - Michael A. Ohliger
- Department of Radiology and Biomedical Imaging, University of California at San Francisco, San Francisco, California, USA
| | - Sarah J. Nelson
- Department of Radiology and Biomedical Imaging, University of California at San Francisco, San Francisco, California, USA
- The UC Berkeley - UCSF Graduate Program in Bioengineering, California, USA
| | - John M. Pauly
- Magnetic Resonance Systems Research Laboratory, Department of Electrical Engineering, Stanford University, Stanford, California, USA
| | - Michael Lustig
- The UC Berkeley - UCSF Graduate Program in Bioengineering, California, USA
- Department of Electrical Engineering and Computer Sciences, University of California at Berkeley, Berkeley, California, USA
| | - Daniel B. Vigneron
- Department of Radiology and Biomedical Imaging, University of California at San Francisco, San Francisco, California, USA
- The UC Berkeley - UCSF Graduate Program in Bioengineering, California, USA
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von Morze C, Carvajal L, Reed GD, Swisher CL, Tropp J, Vigneron DB. Directly detected (55)Mn MRI: application to phantoms for human hyperpolarized (13)C MRI development. Magn Reson Imaging 2014; 32:1165-70. [PMID: 25179135 PMCID: PMC4254142 DOI: 10.1016/j.mri.2014.08.030] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2014] [Revised: 08/12/2014] [Accepted: 08/21/2014] [Indexed: 11/18/2022]
Abstract
In this work we demonstrate for the first time directly detected manganese-55 ((55)Mn) magnetic resonance imaging (MRI) using a clinical 3T MRI scanner designed for human hyperpolarized (13)C clinical studies with no additional hardware modifications. Due to the similar frequency of the (55)Mn and (13)C resonances, the use of aqueous permanganate for large, signal-dense, and cost-effective "(13)C" MRI phantoms was investigated, addressing the clear need for new phantoms for these studies. Due to 100% natural abundance, higher intrinsic sensitivity, and favorable relaxation properties, (55)Mn MRI of aqueous permanganate demonstrates dramatically increased sensitivity over typical (13)C phantom MRI, at greatly reduced cost as compared with large (13)C-enriched phantoms. A large sensitivity advantage (22-fold) was demonstrated. A cylindrical phantom (d=8 cm) containing concentrated aqueous sodium permanganate (2.7 M) was scanned rapidly by (55)Mn MRI in a human head coil tuned for (13)C, using a balanced steady state free precession acquisition. The requisite penetration of radiofrequency magnetic fields into concentrated permanganate was investigated by experiments and high frequency electromagnetic simulations, and found to be sufficient for (55)Mn MRI with reasonably sized phantoms. A sub-second slice-selective acquisition yielded mean image signal-to-noise ratio of ~60 at 0.5 cm(3) spatial resolution, distributed with minimum central signal ~40% of the maximum edge signal. We anticipate that permanganate phantoms will be very useful for testing HP (13)C coils and methods designed for human studies.
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Affiliation(s)
- Cornelius von Morze
- Department of Radiology and Biomedical Imaging, University of California, San Francisco, CA.
| | - Lucas Carvajal
- Department of Radiology and Biomedical Imaging, University of California, San Francisco, CA
| | - Galen D Reed
- Department of Radiology and Biomedical Imaging, University of California, San Francisco, CA; UC Berkeley-UCSF Graduate Program in Bioengineering, University of California, San Francisco and University of California, Berkeley, CA
| | - Christine Leon Swisher
- Department of Radiology and Biomedical Imaging, University of California, San Francisco, CA; UC Berkeley-UCSF Graduate Program in Bioengineering, University of California, San Francisco and University of California, Berkeley, CA
| | | | - Daniel B Vigneron
- Department of Radiology and Biomedical Imaging, University of California, San Francisco, CA; UC Berkeley-UCSF Graduate Program in Bioengineering, University of California, San Francisco and University of California, Berkeley, CA
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15
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Pagès G, Tan YL, Kuchel PW. Hyperpolarized [1,(13)C]pyruvate in lysed human erythrocytes: effects of co-substrate supply on reaction time courses. NMR IN BIOMEDICINE 2014; 27:1203-1210. [PMID: 25111006 DOI: 10.1002/nbm.3176] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/29/2014] [Revised: 06/12/2014] [Accepted: 07/10/2014] [Indexed: 06/03/2023]
Abstract
Hyperpolarized [1,(13)C]pyruvate was injected rapidly into haemolysates in which hydrolysis of nicotinamide adenine dinucleotide (phosphate) (NAD(P))/NAD(P)H had been inhibited with nicotinamide. Haemolysates provide a stable glycolytic system in which membrane permeability is not a flux-controlling step, and they enable the concentration of NADH to be adjusted experimentally while keeping the rest of the sample with the same composition as that of the cytoplasm of the cell (albeit diluted twofold at the time of injection of the [1,(13)C]pyruvate). We showed that the maximum amplitude of the (13)C NMR signal from the [1,(13)C]L-lactate, produced from [1,(13)C]pyruvate, and the time at which it occurred was dependent on NADH concentration, as predicted by enzyme-kinetic analysis. The main feature of such curves was dictated by the immediacy of the supply of the co-substrate of lactate dehydrogenase (LDH, EC 1.1.1.27), and we posit that this also pertains in vivo in various tissues including neoplasms. By constructing an appropriate mathematical model and by using a Markov-chain Monte Carlo approach, we fitted experimental data to estimate LDH and NADH concentrations. Experiments carried out with only endogenous NADH present enabled the estimation of its effective concentration in human RBCs; the ability to make this estimate is a special feature of the rapid-dissolution dynamic nuclear polarization method. We found an endogenous NADH concentration in human RBCs two to four times higher than previously reported.
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Affiliation(s)
- Guilhem Pagès
- Singapore Bioimaging Consortium, A*STAR, Singapore, 138667
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Conti M. New prospects for PET in prostate cancer imaging: a physicist's viewpoint. EJNMMI Phys 2014; 1:11. [PMID: 26501453 PMCID: PMC6890878 DOI: 10.1186/2197-7364-1-11] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2014] [Accepted: 07/31/2014] [Indexed: 11/12/2022] Open
Abstract
Prostate cancer is one of the most common forms of cancer among men. Early diagnosis, correct staging, accurate detection of metastasis, and monitoring of the therapy are the key tasks that could greatly benefit from medical imaging. After a review of the main developments in the field of positron emission tomography (PET) tracers for prostate cancer, the impact of improved PET instrumentation with good spatial resolution and high sensitivity is discussed, together with the latest development in PET technology: lutetium oxy-ortho-silicate (LSO) and lutetium-yttrium oxy-ortho-silicate (LYSO) scintillators, resolution recovery, and time-of-flight reconstruction. New directions and multiple approaches in PET instrumentation for prostate cancer are presented and discussed. In particular, improved hardware and noise suppressing reconstruction algorithms allow for higher detectability of small lesions and better spatial resolution in PET/computerized tomography (CT) and PET/magnetic resonance (MR). This can be beneficial for guiding biopsy and surgery and for accurate therapy monitoring.
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Affiliation(s)
- Maurizio Conti
- Siemens Healthcare Molecular Imaging, 810 Innovation Drive, Knoxville, TN, 37932, USA.
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Walenta S, Voelxen NF, Sattler UGA, Mueller-Klieser W. Localizing and Quantifying Metabolites In Situ with Luminometry: Induced Metabolic Bioluminescence Imaging (imBI). ACTA ACUST UNITED AC 2014. [DOI: 10.1007/978-1-4939-1059-5_9] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/16/2023]
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18
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Schmidt R, Laustsen C, Dumez JN, Kettunen MI, Serrao EM, Marco-Rius I, Brindle KM, Ardenkjaer-Larsen JH, Frydman L. In vivo single-shot 13C spectroscopic imaging of hyperpolarized metabolites by spatiotemporal encoding. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2014; 240:8-15. [PMID: 24486720 PMCID: PMC5040493 DOI: 10.1016/j.jmr.2013.12.013] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/12/2013] [Revised: 11/17/2013] [Accepted: 12/18/2013] [Indexed: 05/08/2023]
Abstract
Hyperpolarized metabolic imaging is a growing field that has provided a new tool for analyzing metabolism, particularly in cancer. Given the short life times of the hyperpolarized signal, fast and effective spectroscopic imaging methods compatible with dynamic metabolic characterizations are necessary. Several approaches have been customized for hyperpolarized (13)C MRI, including CSI with a center-out k-space encoding, EPSI, and spectrally selective pulses in combination with spiral EPI acquisitions. Recent studies have described the potential of single-shot alternatives based on spatiotemporal encoding (SPEN) principles, to derive chemical-shift images within a sub-second period. By contrast to EPSI, SPEN does not require oscillating acquisition gradients to deliver chemical-shift information: its signal encodes both spatial as well as chemical shift information, at no extra cost in experimental complexity. SPEN MRI sequences with slice-selection and arbitrary excitation pulses can also be devised, endowing SPEN with the potential to deliver single-shot multi-slice chemical shift images, with a temporal resolution required for hyperpolarized dynamic metabolic imaging. The present work demonstrates this with initial in vivo results obtained from SPEN-based imaging of pyruvate and its metabolic products, after injection of hyperpolarized [1-(13)C]pyruvate. Multi-slice chemical-shift images of healthy rats were obtained at 4.7T in the region of the kidney, and 4D (2D spatial, 1D spectral, 1D temporal) data sets were obtained at 7T from a murine lymphoma tumor model.
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Affiliation(s)
- Rita Schmidt
- Department of Chemical Physics, Weizmann Institute of Science, Rehovot, Israel
| | - Christoffer Laustsen
- MR Research Centre, Aarhus University, Denmark; Danish Research Centre for Magnetic Resonance, Hvidovre Hospital, Denmark
| | - Jean-Nicolas Dumez
- Department of Chemical Physics, Weizmann Institute of Science, Rehovot, Israel
| | - Mikko I Kettunen
- Department of Biochemistry, University of Cambridge, Cambridge, United Kingdom; Cancer Research UK Cambridge Institute, Li Ka Shing Centre, Cambridge, United Kingdom
| | - Eva M Serrao
- Department of Biochemistry, University of Cambridge, Cambridge, United Kingdom; Cancer Research UK Cambridge Institute, Li Ka Shing Centre, Cambridge, United Kingdom
| | - Irene Marco-Rius
- Department of Biochemistry, University of Cambridge, Cambridge, United Kingdom; Cancer Research UK Cambridge Institute, Li Ka Shing Centre, Cambridge, United Kingdom
| | - Kevin M Brindle
- Department of Biochemistry, University of Cambridge, Cambridge, United Kingdom; Cancer Research UK Cambridge Institute, Li Ka Shing Centre, Cambridge, United Kingdom
| | | | - Lucio Frydman
- Department of Chemical Physics, Weizmann Institute of Science, Rehovot, Israel.
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Ramirez MS, Lee J, Walker CM, Sandulache VC, Hennel F, Lai SY, Bankson JA. Radial spectroscopic MRI of hyperpolarized [1-(13) C] pyruvate at 7 tesla. Magn Reson Med 2013; 72:986-95. [PMID: 24186845 DOI: 10.1002/mrm.25004] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2013] [Revised: 09/25/2013] [Accepted: 09/27/2013] [Indexed: 01/24/2023]
Abstract
PURPOSE The transient and nonrenewable signal from hyperpolarized metabolites necessitates extensive sequence optimization for encoding spatial, spectral, and dynamic information. In this work, we evaluate the utility of radial single-timepoint and cumulative spectroscopic MRI of hyperpolarized [1-(13) C] pyruvate and its metabolic products at 7 Tesla (T). METHODS Simulations of radial echo planar spectroscopic imaging (EPSI) and multiband frequency encoding (MBFE) acquisitions were performed to confirm feasibility and evaluate performance for HP (13) C imaging. Corresponding sequences were implemented on a 7T small-animal MRI system, tested in phantom, and demonstrated in a murine model of anaplastic thyroid cancer. RESULTS MBFE provides excellent spectral separation but is susceptible to blurring and T2 * signal loss inherent to using low readout gradients. The higher readout gradients and more flexible spectral encoding for EPSI result in good spatial resolution and spectral separation. Radial acquisition throughout HP signal evolution offers the flexibility for reconstructing spatial maps of mean metabolite distribution and global dynamic time courses of multiple metabolites. CONCLUSION Radial EPSI and MBFE acquisitions are well-suited for hyperpolarized (13) C MRI over short and long durations. Advantages to this approach include robustness to nonstationary magnetization, insensitivity to precise acquisition timing, and versatility for reconstructing dynamically acquired spectroscopic data.
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Affiliation(s)
- Marc S Ramirez
- The Department of Imaging Physics, The University of Texas M.D. Anderson Cancer Center, Houston, Texas, USA
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20
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Pagès G, Kuchel PW. Mathematical Modeling and Data Analysis of NMR Experiments using Hyperpolarized (13)C Metabolites. MAGNETIC RESONANCE INSIGHTS 2013; 6:13-21. [PMID: 25114541 PMCID: PMC4089703 DOI: 10.4137/mri.s11084] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/05/2022]
Abstract
Rapid-dissolution dynamic nuclear polarization (DNP) has made significant impact in the characterization and understanding of metabolism that occurs on the sub-minute timescale in several diseases. While significant efforts have been made in developing applications, and in designing rapid-imaging radiofrequency (RF) and magnetic field gradient pulse sequences, very few groups have worked on implementing realistic mathematical/kinetic/relaxation models to fit the emergent data. The critical aspects to consider when modeling DNP experiments depend on both nuclear magnetic resonance (NMR) and (bio)chemical kinetics. The former constraints are due to the relaxation of the NMR signal and the application of ‘read’ RF pulses, while the kinetic constraints include the total amount of each molecular species present. We describe the model-design strategy we have used to fit and interpret our DNP results. To our knowledge, this is the first report on a systematic analysis of DNP data.
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Affiliation(s)
- Guilhem Pagès
- Singapore BioImaging Consortium, A STAR, Helios, Singapore
| | - Philip W Kuchel
- School of Molecular Bioscience, The University of Sydney, Sydney, Australia
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Larson PEZ, Kerr AB, Swisher CL, Pauly JM, Vigneron DB. A rapid method for direct detection of metabolic conversion and magnetization exchange with application to hyperpolarized substrates. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2012; 225:71-80. [PMID: 23143011 PMCID: PMC3531583 DOI: 10.1016/j.jmr.2012.09.014] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/20/2012] [Revised: 09/26/2012] [Accepted: 09/28/2012] [Indexed: 05/27/2023]
Abstract
In this work, we present a new MR spectroscopy approach for directly observing nuclear spins that undergo exchange, metabolic conversion, or, generally, any frequency shift during a mixing time. Unlike conventional approaches to observe these processes, such as exchange spectroscopy (EXSY), this rapid approach requires only a single encoding step and thus is readily applicable to hyperpolarized MR in which the magnetization is not replenished after T(1) decay and RF excitations. This method is based on stimulated-echoes and uses phase-sensitive detection in conjunction with precisely chosen echo times in order to separate spins generated during the mixing time from those present prior to mixing. We are calling the method Metabolic Activity Decomposition Stimulated-echo Acquisition Mode or MAD-STEAM. We have validated this approach as well as applied it in vivo to normal mice and a transgenic prostate cancer mouse model for observing pyruvate-lactate conversion, which has been shown to be elevated in numerous tumor types. In this application, it provides an improved measure of cellular metabolism by separating [1-(13)C]-lactate produced in tissue by metabolic conversion from [1-(13)C]-lactate that has flowed into the tissue or is in the blood. Generally, MAD-STEAM can be applied to any system in which spins undergo a frequency shift.
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Affiliation(s)
- Peder E Z Larson
- Department of Radiology and Biomedical Imaging, University of California - San Francisco, 1700 4th St, San Francisco, CA 94158, USA.
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