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Honecker J, Prokopchuk O, Seeliger C, Hauner H, Junker D, Karampinos DC, Ruschke S. Feasibility of omega-3 fatty acid fraction mapping using chemical shift encoding-based imaging at 3 T. NMR IN BIOMEDICINE 2024:e5181. [PMID: 38830747 DOI: 10.1002/nbm.5181] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/12/2023] [Revised: 04/21/2024] [Accepted: 05/06/2024] [Indexed: 06/05/2024]
Abstract
PURPOSE The aim of this work is to develop an ω-3 fatty acid fraction mapping method at 3 T based on a chemical shift encoding model, to assess its performance in a phantom and in vitro study, and to further demonstrate its feasibility in vivo. METHODS A signal model was heuristically derived based on spectral appearance and theoretical considerations of the corresponding molecular structures to differentiate between ω-3 and non-ω-3 fatty acid substituents in triacylglycerols in addition to the number of double bonds (ndb), the number of methylene-interrupted double bonds (nmidb), and the mean fatty acid chain length (CL). First, the signal model was validated using single-voxel spectroscopy and a time-interleaved multi-echo gradient-echo (TIMGRE) sequence in gas chromatography-mass spectrometry (GC-MS)-calibrated oil phantoms. Second, the TIMGRE-based method was validated in vitro in 21 adipose tissue samples with corresponding GC-MS measurements. Third, an in vivo feasibility study was performed for the TIMGRE-based method in the gluteal region of two healthy volunteers. Phantom and in vitro data was analyzed using a Bland-Altman analysis. RESULTS Compared with GC-MS, MRS showed in the phantom study significant correlations in estimating the ω-3 fraction (p < 0.001), ndb (p < 0.001), nmidb (p < 0.001), and CL (p = 0.001); MRI showed in the phantom study significant correlations (all p < 0.001) for the ω-3 fraction, ndb, and nmidb, but no correlation for CL. Also in the in vitro study, significant correlations (all p < 0.001) between MRI and GC-MS were observed for the ω-3 fraction, ndb, and nmidb, but not for CL. An exemplary ROI measurement in vivo in the gluteal subcutaneous adipose tissue yielded (mean ± standard deviation) 0.8% ± 1.9% ω-3 fraction. CONCLUSION The present study demonstrated strong correlations between gradient-echo imaging-based ω-3 fatty acid fraction mapping and GC-MS in the phantom and in vitro study. Furthermore, feasibility was demonstrated for characterizing adipose tissue in vivo.
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Affiliation(s)
- Julius Honecker
- Else Kröner Fresenius Center for Nutritional Medicine, ZIEL-Institute for Food and Health, Technical University of Munich, Freising, Germany
| | - Olga Prokopchuk
- Department of Surgery, Klinikum rechts der Isar, School of Medicine and Health, Technical University of Munich, Munich, Germany
| | - Claudine Seeliger
- Else Kröner Fresenius Center for Nutritional Medicine, ZIEL-Institute for Food and Health, Technical University of Munich, Freising, Germany
| | - Hans Hauner
- Else Kröner Fresenius Center for Nutritional Medicine, ZIEL-Institute for Food and Health, Technical University of Munich, Freising, Germany
- Institute of Nutritional Medicine, School of Medicine and Health, Technical University of Munich, Munich, Germany
| | - Daniela Junker
- Department of Diagnostic and Interventional Radiology, Klinikum rechts der Isar, School of Medicine and Health, Technical University of Munich, Munich, Germany
| | - Dimitrios C Karampinos
- Department of Diagnostic and Interventional Radiology, Klinikum rechts der Isar, School of Medicine and Health, Technical University of Munich, Munich, Germany
| | - Stefan Ruschke
- Department of Diagnostic and Interventional Radiology, Klinikum rechts der Isar, School of Medicine and Health, Technical University of Munich, Munich, Germany
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Lin D, Zhou J, Cao Y, Wang Z, Hsu YC, Zheng F, Li H, Sun S, Ren H, Deng L, Chen F, Wang M. Echo time optimization for in-vivo measurement of unsaturated lipid resonances using J-difference-edited MRS. Magn Reson Med 2023; 90:2217-2232. [PMID: 37496253 DOI: 10.1002/mrm.29807] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2023] [Revised: 07/01/2023] [Accepted: 07/06/2023] [Indexed: 07/28/2023]
Abstract
PURPOSE Measuring lipid composition provides more information than just total lipid content. Hence, the non-invasive measurement of unsaturated lipid protons with both high efficiency and precision is of pressing need. This study was to optimize echo time (TE) for the best resolving of J-difference editing of unsaturated lipid resonances. METHODS The TE dependence of J-difference-edited (JDE) MRS was verified in the density-matrix simulation, soybean oil phantom, in-vivo experiments of white adipose tissue (WAT), and skeletal muscles using single-voxel MEGA-PRESS sequence at 3T. The peak SNRs and Cramér-Rao lower bounds (CRLBs) acquired at the proposed TE of 45 ms and previously published TE of 70 ms were compared (eight pairs) in WAT, extramyocelluar lipids (EMCLs), and intramyocellular lipids (IMCLs). The lipid composition in skeletal muscles was compared between healthy males (n = 7) and females (n = 7). RESULTS The optimal TE was suggested as 45 ms. Compared to 70 ms, the mean signal gains at TE of 45 ms were 151% in WAT, 168% in EMCL, 204% in IMCL for allylic resonance, and 52% in EMCL for diallylic resonance. CRLBs were significantly reduced at TE of 45 ms in WAT, EMCL, IMCL for allylic resonance and in EMCL for diallylic resonance. With TE of 45 ms, significant gender differences were found in the lipid composition in EMCL pools, while no difference in IMCL pools. CONCLUSION The JDE-MRS protocol with TE of 45 ms allows improved quantification of unsaturated lipid resonances in vivo and future lipid metabolism investigations.
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Affiliation(s)
- Dingyi Lin
- College of Biomedical Engineering and Instrument Science, Zhejiang University, Hangzhou, Zhejiang, China
| | - Jiaqiang Zhou
- School of Medicine, Sir Run Run Shaw Hospital, Department of Endocrinology, Zhejiang University, Hangzhou, Zhejiang, China
| | - Yang Cao
- College of Biomedical Engineering and Instrument Science, Zhejiang University, Hangzhou, Zhejiang, China
| | - Ziyan Wang
- College of Biomedical Engineering and Instrument Science, Zhejiang University, Hangzhou, Zhejiang, China
| | - Yi-Cheng Hsu
- MR Collaboration, Siemens Healthineers Itd, Shanghai, China
| | - Fenping Zheng
- School of Medicine, Sir Run Run Shaw Hospital, Department of Endocrinology, Zhejiang University, Hangzhou, Zhejiang, China
| | - Hong Li
- School of Medicine, Sir Run Run Shaw Hospital, Department of Endocrinology, Zhejiang University, Hangzhou, Zhejiang, China
| | - Shuiya Sun
- School of Medicine, Sir Run Run Shaw Hospital, Department of Endocrinology, Zhejiang University, Hangzhou, Zhejiang, China
| | - Hong Ren
- School of Medicine, Department of Radiology, Sir Run Run Shaw Hospital, Zhejiang University, Hangzhou, Zhejiang, China
| | - Liping Deng
- School of Medicine, Department of Radiology, Sir Run Run Shaw Hospital, Zhejiang University, Hangzhou, Zhejiang, China
| | - Feng Chen
- School of Medicine, the First Affiliated Hospital, Department of Radiology, Zhejiang University, Hangzhou, Zhejiang, China
| | - Min Wang
- College of Biomedical Engineering and Instrument Science, Zhejiang University, Hangzhou, Zhejiang, China
- School of Medicine, Sir Run Run Shaw Hospital, Department of Endocrinology, Zhejiang University, Hangzhou, Zhejiang, China
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Fat unsaturation measures in tibial, subcutaneous and breast adipose tissue using short and long TE MRS at 3 T. Magn Reson Imaging 2021; 86:61-69. [PMID: 34808305 DOI: 10.1016/j.mri.2021.11.007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2021] [Revised: 09/30/2021] [Accepted: 11/15/2021] [Indexed: 11/22/2022]
Abstract
Fat unsaturation and poly-unsaturation measures can be obtained in vivo with magnetic resonance spectroscopy (MRS) through the olefinic (≈5.4 ppm) and diallylic (≈2.8 ppm) resonances, respectively. Long echo time (TE) MRS sequences have been previously optimized for olefinic/methylene (≈1.3 ppm) or olefinic/methyl (≈0.9 ppm) measures. The objectives of this work, using a Point RESolved Spectroscopy (PRESS) sequence, are to: 1) Investigate olefinic, methyl and methylene resonance decay in subcutaneous, tibial, and breast adipose tissue to determine if a direct comparison of unsaturation measures can be made without correction for T2 losses. 2) Assess intra-individual fat unsaturation and poly-unsaturation measures in the three adipose tissues. 3) Estimate correction factors for olefinic to methylene ratios to compensate for J-coupling and T2 relaxation losses that take place when increasing PRESS TE from 40 ms to 200 ms (previously optimized long-TE). 4) Investigate the utility of an inversion recovery for resolving the olefinic resonance from water in adipose tissue. PRESS spectra were acquired from the three adipose regions (breast in female only) in healthy volunteers at 3 T. It was found that olefinic and methyl signal decays faster in breast tissue compared to in tibial bone marrow. Poly-unsaturation measures (diallylic/methylene) differ for tibial bone marrow compared to subcutaneous and breast adipose tissue, with average values of 1.7 ± 0.4, 2.2 ± 0.4, and 2.3 ± 0.8%, respectively. PRESS (TE = 40 ms) with an inversion recovery resolves the olefinic and water resonances in breast tissue with a signal to noise ratio approximately six times greater than that using PRESS with a TE of 200 ms. Stimulated Echo Acquisition Mode (STEAM) with a TE of 20 ms (mixing time of 20 ms) was also combined with IR to resolve the olefinic resonance from that of water is spinal bone marrow.
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Fallone CJ, Tessier AG, Field CJ, Yahya A. Resolving the omega-3 methyl resonance with long echo time magnetic resonance spectroscopy in mouse adipose tissue at 9.4 T. NMR IN BIOMEDICINE 2021; 34:e4455. [PMID: 33269481 DOI: 10.1002/nbm.4455] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/14/2020] [Revised: 10/27/2020] [Accepted: 11/11/2020] [Indexed: 06/12/2023]
Abstract
Tissue omega-3 (ω-3) content is biologically important to disease; however, its quantification with magnetic resonance spectroscopy in vivo is challenging due to its low concentration. In addition, the ω-3 methyl resonance (≈ 0.98 ppm) overlaps that of the non-ω-3 (≈ 0.90 ppm), even at 9.4 T. We demonstrate that a Point-RESolved Spectroscopy (PRESS) sequence with an echo time (TE) of 109 ms resolves the ω-3 and non-ω-3 methyl peaks at 9.4 T. Sequence efficacy was verified on five oils with differing ω-3 fat content; the ω-3 content obtained correlated with that measured using 16.5 T NMR (R2 = 0.97). The PRESS sequence was also applied to measure ω-3 content in visceral adipose tissue of three different groups (all n = 3) of mice, each of which were fed a different 20% w/w fat diet. The fat portion of the diet consisted of low (1.4%), medium (9.0%) or high (16.4%) ω-3 fat. The sequence was also applied to a control mouse fed a standard chow diet (5.6% w/w fat, which was 5.9% ω-3). Gas chromatography (GC) analysis of excised tissue was performed for each mouse. The ω-3 fat content obtained with the PRESS sequence correlated with the GC measures (R2 = 0.96). Apparent T2 times of methyl protons were assessed by obtaining spectra from the oils and another group of four mice (fed the high ω-3 diet) with TE values of 109 and 399 ms. Peak areas were fit to a mono-exponentially decaying function and the apparent T2 values of the ω-3 and non-ω-3 methyl protons were 906 ± 148 and 398 ± 78 ms, respectively, in the oils. In mice, the values were 410 ± 68 and 283 ± 57 ms for ω-3 and non-ω-3 fats, respectively.
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Affiliation(s)
- Clara J Fallone
- Department of Oncology, University of Alberta, Edmonton, Alberta, Canada
| | - Anthony G Tessier
- Department of Oncology, University of Alberta, Edmonton, Alberta, Canada
- Department of Medical Physics, Cross Cancer Institute, Edmonton, Alberta, Canada
| | - Catherine J Field
- Department of Agricultural, Food, and Nutritional Science, University of Alberta, Edmonton, Alberta, Canada
| | - Atiyah Yahya
- Department of Oncology, University of Alberta, Edmonton, Alberta, Canada
- Department of Medical Physics, Cross Cancer Institute, Edmonton, Alberta, Canada
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