1
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Thanaj M, Basty N, Whitcher B, Bell JD, Thomas EL. MRI assessment of adipose tissue fatty acid composition in the UK Biobank and its association with diet and disease. Obesity (Silver Spring) 2024; 32:1699-1708. [PMID: 39051177 DOI: 10.1002/oby.24108] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/26/2024] [Revised: 05/24/2024] [Accepted: 05/30/2024] [Indexed: 07/27/2024]
Abstract
OBJECTIVE This study aimed to assess the fatty acid (FA) composition of abdominal subcutaneous and visceral adipose tissue (ASAT and VAT, respectively) in the UK Biobank imaging cohort (N = 33,823) using magnetic resonance imaging (MRI). METHODS We measured the fractions of saturated, monounsaturated, and polyunsaturated FA (fSFA, fMUFA, and fPUFA, respectively) in ASAT and VAT from multiecho MRI scans. We selected a subcohort of participants who followed a vegan and an omnivore diet (N = 36) to validate the effect of diet on adipose tissue. In the wider imaging cohort, we examined the relationships between adipose tissue FA composition and various traits related to disease and body size. RESULTS We measured adipose tissue FA composition for over 33,000 participants, revealing higher fSFA and fPUFA and lower fMUFA in VAT (p < 0.00016). fMUFA and fPUFA were higher in ASAT and lower in VAT for women (p < 0.00016). Vegan participants exhibited lower fSFA in both ASAT and VAT (p < 0.00016). VAT fSFA and fMUFA showed significant associations with disease, as well as anthropometric variables. CONCLUSIONS This extensive analysis revealed the relationships between adipose tissue FA composition and a range of factors in a diverse population, highlighting the importance of studying body adipose tissue beyond its quantity.
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Affiliation(s)
- Marjola Thanaj
- Research Centre for Optimal Health, School of Life Sciences, University of Westminster, London, UK
| | - Nicolas Basty
- Research Centre for Optimal Health, School of Life Sciences, University of Westminster, London, UK
| | - Brandon Whitcher
- Research Centre for Optimal Health, School of Life Sciences, University of Westminster, London, UK
| | - Jimmy D Bell
- Research Centre for Optimal Health, School of Life Sciences, University of Westminster, London, UK
| | - E Louise Thomas
- Research Centre for Optimal Health, School of Life Sciences, University of Westminster, London, UK
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2
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Shih SF, Wu HH. Free-breathing MRI techniques for fat and R 2* quantification in the liver. MAGMA (NEW YORK, N.Y.) 2024:10.1007/s10334-024-01187-2. [PMID: 39039272 DOI: 10.1007/s10334-024-01187-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/22/2023] [Revised: 05/18/2024] [Accepted: 07/02/2024] [Indexed: 07/24/2024]
Abstract
OBJECTIVE To review the recent advancements in free-breathing MRI techniques for proton-density fat fraction (PDFF) and R2* quantification in the liver, and discuss the current challenges and future opportunities. MATERIALS AND METHODS This work focused on recent developments of different MRI pulse sequences, motion management strategies, and reconstruction approaches that enable free-breathing liver PDFF and R2* quantification. RESULTS Different free-breathing liver PDFF and R2* quantification techniques have been evaluated in various cohorts, including healthy volunteers and patients with liver diseases, both in adults and children. Initial results demonstrate promising performance with respect to reference measurements. These techniques have a high potential impact on providing a solution to the clinical need of accurate liver fat and iron quantification in populations with limited breath-holding capacity. DISCUSSION As these free-breathing techniques progress toward clinical translation, studies of the linearity, bias, and repeatability of free-breathing PDFF and R2* quantification in a larger cohort are important. Scan acceleration and improved motion management also hold potential for further enhancement.
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Affiliation(s)
- Shu-Fu Shih
- Department of Radiological Sciences, University of California Los Angeles, Los Angeles, CA, USA
- Department of Bioengineering, University of California Los Angeles, Los Angeles, CA, USA
| | - Holden H Wu
- Department of Radiological Sciences, University of California Los Angeles, Los Angeles, CA, USA.
- Department of Bioengineering, University of California Los Angeles, Los Angeles, CA, USA.
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3
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Shrestha U, Esparza JP, Satapathy SK, Vanatta JM, Abramson ZR, Tipirneni-Sajja A. Hepatic steatosis modeling and MRI signal simulations for comparison of single- and dual-R2* models and estimation of fat fraction at 1.5T and 3T. Comput Biol Med 2024; 174:108448. [PMID: 38626508 DOI: 10.1016/j.compbiomed.2024.108448] [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: 12/07/2023] [Revised: 03/06/2024] [Accepted: 04/07/2024] [Indexed: 04/18/2024]
Abstract
BACKGROUND AND OBJECTIVE Magnetic resonance imaging (MRI) has emerged as a noninvasive clinical tool for assessment of hepatic steatosis. Multi-spectral fat-water MRI models, incorporating single or dual transverse relaxation decay rate(s) (R2*) have been proposed for accurate fat fraction (FF) estimation. However, it is still unclear whether single- or dual-R2* model accurately mimics in vivo signal decay for precise FF estimation and the impact of signal-to-noise ratio (SNR) on each model performance. Hence, this study aims to construct virtual steatosis models and synthesize MRI signals with different SNRs to systematically evaluate the accuracy of single- and dual-R2* models for FF and R2* estimations at 1.5T and 3.0T. METHODS Realistic hepatic steatosis models encompassing clinical FF range (0-60 %) were created using morphological features of fat droplets (FDs) extracted from human liver biopsy samples. MRI signals were synthesized using Monte Carlo simulations for noise-free (SNRideal) and varying SNR conditions (5-100). Fat-water phantoms were scanned with different SNRs to validate simulation results. Fat water toolbox was used to calculate R2* and FF for both single- and dual-R2* models. The model accuracies in R2* and FF estimates were analyzed using linear regression, bias plot and heatmap analysis. RESULTS The virtual steatosis model closely mimicked in vivo fat morphology and Monte Carlo simulation produced realistic MRI signals. For SNRideal and moderate-high SNRs, water R2* (R2*W) by dual-R2* and common R2* (R2*com) by single-R2* model showed an excellent agreement with slope close to unity (0.95-1.01) and R2 > 0.98 at both 1.5T and 3.0T. In simulations, the R2*com-FF and R2*W-FF relationships exhibited slopes similar to in vivo calibrations, confirming the accuracy of our virtual models. For SNRideal, fat R2* (R2*F) was similar to R2*W and dual-R2* model showed slightly higher accuracy in FF estimation. However, in the presence of noise, dual-R2* produced higher FF bias with decreasing SNR, while leading to only marginal improvement for high SNRs and in regions dominated by fat and water. In contrast, single-R2* model was robust and produced accurate FF estimations in simulations and phantom scans with clinical SNRs. CONCLUSION Our study demonstrates the feasibility of creating virtual steatosis models and generating MRI signals that mimic in vivo morphology and signal behavior. The single-R2* model consistently produced lower FF bias for clinical SNRs across entire FF range compared to dual-R2* model, hence signifying that single-R2* model is optimal for assessing hepatic steatosis.
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Affiliation(s)
- Utsav Shrestha
- Department of Biomedical Engineering, The University of Memphis, Memphis, TN, USA; Department of Diagnostic Imaging, St. Jude Children's Research Hospital, Memphis, TN, USA
| | - Juan P Esparza
- Department of Biomedical Engineering, The University of Memphis, Memphis, TN, USA
| | - Sanjaya K Satapathy
- Department of Medicine, Division of Hepatology, Donald and Barbara Zucker School of Medicine at Hofstra, Hempstead, NY, USA; Northwell Health Center for Liver Diseases & Transplantation, North Shore University Hospital, Manhasset, NY, USA
| | - Jason M Vanatta
- Department of Surgery, University of Tennessee Health and Science Center, Memphis, TN, USA
| | - Zachary R Abramson
- Department of Diagnostic Imaging, St. Jude Children's Research Hospital, Memphis, TN, USA
| | - Aaryani Tipirneni-Sajja
- Department of Biomedical Engineering, The University of Memphis, Memphis, TN, USA; Department of Diagnostic Imaging, St. Jude Children's Research Hospital, Memphis, TN, USA.
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4
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Kuang J, Qi Y, Wu Q, Cheng G, Wu Y. Demonstration of magnetic resonance Z-spectral imaging for fatty acid characterization of bone marrow at 3 T. NMR IN BIOMEDICINE 2024; 37:e5099. [PMID: 38185878 DOI: 10.1002/nbm.5099] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/14/2023] [Revised: 12/07/2023] [Accepted: 12/08/2023] [Indexed: 01/09/2024]
Abstract
Magnetic resonance Z-spectral imaging (ZSI) has emerged as a new approach to measure fat fraction (FF). However, its feasibility for fat spectral imaging remains to be elucidated. In this study, a single-slice ZSI sequence dedicated to fat spectral imaging was designed, and its capability for fatty acid characterization was investigated on peanut oil samples, a multiple-vial fat-water phantom with varied oil volumes, and vertebral body marrow in healthy volunteers and osteoporosis patients at 3 T. The peanut oil spectrum was also recorded with a 400-MHz NMR spectrometer. A Gaussian-Lorentzian sum model was used to resolve water and six fat signals of the pure oil sample or four fat signals of the fat-water phantom or vertebral bone marrow from Z spectra. Fat peak amplitudes were normalized to the total peak amplitude of water and all fat signals. Normalized fat peak amplitudes and FF were quantified and compared among vials of the fat-water phantom or between healthy volunteers and osteoporosis patients. An unpaired student's t-test and Pearson's correlation were conducted, with p less than 0.05 considered statistically significant. The results showed that the peanut oil spectra measured with the ZSI technique were in line with respective NMR spectra, with amplitudes of the six fat signal peaks significantly correlated between the two methods (y = x + 0.001, r = 0.996, p < 0.001 under a repetition time of 1.6 s; and y = 1.026x - 0.003, r = 0.996, p < 0.001 under a repetition time of 3.1 s). Moreover, ZSI-measured FF exhibited a significant correlation with prepared oil volumes (y = 0.876x + 1.290, r = 0.996, p < 0.001). The osteoporosis patients showed significantly higher normalized fat peak amplitudes and FF in the L4 vertebral body marrow than the healthy volunteers (all p < 0.01). In summary, the designed ZSI sequence is feasible for fatty acid characterization, and has the potential to facilitate the diagnosis and evaluation of diseases associated with fat alterations at 3 T.
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Affiliation(s)
- Junfeng Kuang
- Paul C. Lauterbur Research Center for Biomedical Imaging, Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences, Shenzhen, Guangdong, China
| | - Yulong Qi
- Department of Medical Imaging, Peking University Shenzhen Hospital, Shenzhen, Guangdong, China
| | - Qiting Wu
- Paul C. Lauterbur Research Center for Biomedical Imaging, Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences, Shenzhen, Guangdong, China
| | - Guanxun Cheng
- Department of Medical Imaging, Peking University Shenzhen Hospital, Shenzhen, Guangdong, China
| | - Yin Wu
- Paul C. Lauterbur Research Center for Biomedical Imaging, Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences, Shenzhen, Guangdong, China
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5
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Trinh L, Stenkula KG, Olsson LE, Svensson J, Peterson P, Bennet L, Månsson S. Favorable fatty acid composition in adipose tissue in healthy Iraqi- compared to Swedish-born men - a pilot study using MRI assessment. Adipocyte 2022; 11:153-163. [PMID: 35291924 PMCID: PMC8928862 DOI: 10.1080/21623945.2022.2042963] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
Middle Eastern immigrants are at high-risk for insulin resistance. Fatty acid composition (FAC) plays an important role in the development of insulin resistance but has not been investigated in people of Middle Eastern ancestry. Here, the aim was to assess the FAC in visceral and subcutaneous adipose tissue (VAT and SAT) in healthy Iraqi- and Swedish-born men using a magnetic resonance imaging (MRI) method.This case-control study included 23 Iraqi- and 15 Swedish-born middle-aged men, without cardiometabolic disease. Using multi-echo MRI of the abdomen, the fractions of saturated, monounsaturated, and polyunsaturated fatty acids (fSFA, fMUFA, and fPUFA) were estimated in VAT and SAT. SAT was further analyzed in deep and superficial compartments (dSAT and sSAT). In all depots, fPUFA was significantly higher and fSFA significantly lower in Iraqi men, independently of age and BMI. In both Iraqi- and Swedish-born men, higher fPUFA and lower fMUFA were found in sSAT vs. dSAT. Among Iraqi men only, higher fPUFA and lower fMUFA were found in SAT vs. VAT.Iraqi-born men presented a more favorable abdominal FAC compared to Swedish-born men. This MRI method also revealed different FACs in different abdominal depots. Our results may reflect a beneficial FAC in Middle Eastern immigrants.
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Affiliation(s)
- Lena Trinh
- Medical Radiation Physics, Department of Translational Medicine, Lund University, Malmö, Sweden
| | - Karin G Stenkula
- Department of Experimental Medical Sciences, Lund University, Lund, Sweden
| | - Lars E Olsson
- Medical Radiation Physics, Department of Translational Medicine, Lund University, Malmö, Sweden
- Hematology, Oncology and Radiation Physics, Skåne University Hospital, Malmö, Sweden
| | - Jonas Svensson
- Medical Radiation Physics, Department of Translational Medicine, Lund University, Malmö, Sweden
- Medical Imaging and Physiology, Skåne University Hospital, Lund, Sweden
| | - Pernilla Peterson
- Medical Radiation Physics, Department of Translational Medicine, Lund University, Malmö, Sweden
- Medical Imaging and Physiology, Skåne University Hospital, Lund, Sweden
| | - Louise Bennet
- Department of Clinical Sciences, Lund University, Malmö, Sweden
- Clinical Research and Trial Centre, Lund University Hospital, Lund, Sweden
| | - Sven Månsson
- Medical Radiation Physics, Department of Translational Medicine, Lund University, Malmö, Sweden
- Hematology, Oncology and Radiation Physics, Skåne University Hospital, Malmö, Sweden
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6
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Yoshimaru D. [6. Methods of Abdominal MR Spectroscopy and Future Prospects]. Nihon Hoshasen Gijutsu Gakkai Zasshi 2022; 78:213-218. [PMID: 35185101 DOI: 10.6009/jjrt.780214] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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7
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Willis SA, Bawden SJ, Malaikah S, Sargeant JA, Stensel DJ, Aithal GP, King JA. The role of hepatic lipid composition in obesity-related metabolic disease. Liver Int 2021; 41:2819-2835. [PMID: 34547171 DOI: 10.1111/liv.15059] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/02/2021] [Revised: 09/15/2021] [Accepted: 09/17/2021] [Indexed: 12/14/2022]
Abstract
Obesity is a primary antecedent to non-alcoholic fatty liver disease whose cardinal feature is excessive hepatic lipid accumulation. Although total hepatic lipid content closely associates with hepatic and systemic metabolic dysfunction, accumulating evidence suggests that the composition of hepatic lipids may be more discriminatory. This review summarises cross-sectional human studies using liver biopsy/lipidomics and proton magnetic resonance spectroscopy to characterise hepatic lipid composition in people with obesity and related metabolic disease. A comprehensive literature search identified 26 relevant studies published up to 31st March 2021 which were included in the review. The available evidence provides a consistent picture showing that people with hepatic steatosis possess elevated saturated and/or monounsaturated hepatic lipids and a reduced proportion of polyunsaturated hepatic lipids. This altered hepatic lipid profile associates more directly with metabolic derangements, such as insulin resistance, and may be exacerbated in non-alcoholic steatohepatitis. Further evidence from lipidomic studies suggests that these deleterious changes may be related to defects in lipid desaturation and elongation, and an augmentation of the de novo lipogenic pathway. These observations are consistent with mechanistic studies implicating saturated fatty acids and associated bioactive lipid intermediates (ceramides, lysophosphatidylcholines and diacylglycerol) in the development of hepatic lipotoxicity and wider metabolic dysfunction, whilst monounsaturated fatty acids and polyunsaturated fatty acids may exhibit a protective role. Future studies are needed to prospectively determine the relevance of hepatic lipid composition for hepatic and non-hepatic morbidity and mortality; and to further evaluate the impact of therapeutic interventions such as pharmacotherapy and lifestyle interventions.
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Affiliation(s)
- Scott A Willis
- National Centre for Sport and Exercise Medicine, School of Sport, Exercise and Health Sciences, Loughborough University, Loughborough, UK.,NIHR Leicester Biomedical Research Centre, University Hospitals of Leicester NHS Trust and University of Leicester, Leicester, UK
| | - Stephen J Bawden
- Sir Peter Mansfield Imaging Centre, University of Nottingham, Nottingham, UK.,NIHR Nottingham Biomedical Research Centre, Nottingham University Hospitals NHS Trust and the University of Nottingham, Leicester, UK
| | - Sundus Malaikah
- National Centre for Sport and Exercise Medicine, School of Sport, Exercise and Health Sciences, Loughborough University, Loughborough, UK.,NIHR Leicester Biomedical Research Centre, University Hospitals of Leicester NHS Trust and University of Leicester, Leicester, UK.,Faculty of Applied Medical Sciences, King Abdulaziz University, Jeddah, Saudi Arabia
| | - Jack A Sargeant
- NIHR Leicester Biomedical Research Centre, University Hospitals of Leicester NHS Trust and University of Leicester, Leicester, UK.,Diabetes Research Centre, University of Leicester, Leicester, UK
| | - David J Stensel
- National Centre for Sport and Exercise Medicine, School of Sport, Exercise and Health Sciences, Loughborough University, Loughborough, UK.,NIHR Leicester Biomedical Research Centre, University Hospitals of Leicester NHS Trust and University of Leicester, Leicester, UK
| | - Guruprasad P Aithal
- NIHR Nottingham Biomedical Research Centre, Nottingham University Hospitals NHS Trust and the University of Nottingham, Leicester, UK.,Nottingham Digestive Diseases Centre, School of Medicine, University of Nottingham, Nottingham, UK
| | - James A King
- National Centre for Sport and Exercise Medicine, School of Sport, Exercise and Health Sciences, Loughborough University, Loughborough, UK.,NIHR Leicester Biomedical Research Centre, University Hospitals of Leicester NHS Trust and University of Leicester, Leicester, UK
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8
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Shrestha U, van der Merwe M, Kumar N, Jacobs E, Satapathy SK, Morin C, Tipirneni-Sajja A. Morphological characterization of hepatic steatosis and Monte Carlo modeling of MRI signal for accurate quantification of fat fraction and relaxivity. NMR IN BIOMEDICINE 2021; 34:e4489. [PMID: 33586261 DOI: 10.1002/nbm.4489] [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: 09/26/2020] [Revised: 12/16/2020] [Accepted: 01/25/2021] [Indexed: 06/12/2023]
Abstract
Chemical-shift-based fat-water MRI signal models with single- or dual-R2 * correction have been proposed for quantification of fat fraction (FF) and assessment of hepatic steatosis. However, there is a void in our understanding of which model truly mimics the underlying biophysical mechanism of steatosis on MRI signal relaxation. The purpose of this study is to morphologically characterize and build realistic steatosis models from histology and synthesize MRI signal using Monte Carlo simulations to investigate the accuracy of single- and dual-R2 * models in quantifying FF and R2 *. Fat morphology was characterized by performing automatic segmentation on 16 mouse liver histology images and extracting the radius, nearest neighbor (NN) distance, and regional anisotropy of fat droplets. A gamma distribution function (GDF) was used to generalize extracted features, and regression analysis was performed to derive relationships between FF and GDF parameters. Virtual steatosis models were created based on derived morphological and statistical descriptors, and the MRI signal was synthesized at 1.5 T and 3 T. R2 * and FF values were calculated using single- and dual-R2 * models and compared with in vivo R2 *-FF calibrations and simulated FFs. The steatosis models generated with regional anisotropy and NN distribution closely mimicked the true in vivo fat morphology. For both R2 * models, predicted R2 * values showed positive correlation with FFs, with slopes similar to those of the in vivo calibrations (P > 0.05), and predicted FFs showed excellent agreement with true FFs (R2 > 0.99), with slopes close to unity. Our study, hence, demonstrates the proof of concept for generating steatosis models from histologic data and synthesizing MRI signal to show the expected signal relaxation under conditions of steatosis. Our results suggest that a single R2 * is sufficient to accurately estimate R2 * and FF values for lower FFs, which agrees with in vivo studies. Future work involves characterizing and building steatosis models at higher FFs and testing single- and dual-R2 * models for accurate assessment of steatosis.
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Affiliation(s)
- Utsav Shrestha
- Department of Biomedical Engineering, The University of Memphis, Memphis, Tennessee, USA
- Department of Computer Science, The University of Memphis, Memphis, Tennessee, USA
| | - Marie van der Merwe
- College of Health Sciences, The University of Memphis, Memphis, Tennessee, USA
| | - Nirman Kumar
- Department of Computer Science, The University of Memphis, Memphis, Tennessee, USA
| | - Eddie Jacobs
- Department of Electrical & Computer Engineering, The University of Memphis, Memphis, Tennessee, USA
| | - Sanjaya K Satapathy
- Department of Medicine, North Shore University Hospital/Northwell Health, Manhasset, New York, USA
| | - Cara Morin
- Department of Diagnostic Imaging, St. Jude Children's Research Hospital, Memphis, Tennessee, USA
| | - Aaryani Tipirneni-Sajja
- Department of Biomedical Engineering, The University of Memphis, Memphis, Tennessee, USA
- Department of Diagnostic Imaging, St. Jude Children's Research Hospital, Memphis, Tennessee, USA
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9
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Pirastru A, Chen Y, Pelizzari L, Baglio F, Clerici M, Haacke EM, Laganà MM. Quantitative MRI using STrategically Acquired Gradient Echo (STAGE): optimization for 1.5 T scanners and T1 relaxation map validation. Eur Radiol 2021; 31:4504-4513. [PMID: 33409790 DOI: 10.1007/s00330-020-07515-z] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2020] [Revised: 09/24/2020] [Accepted: 11/12/2020] [Indexed: 11/24/2022]
Abstract
OBJECTIVES The strategically acquired gradient echo (STAGE) protocol, developed for 3T scanners, allows one to derive quantitative maps such as T1, T2*, proton density, and quantitative susceptibility mapping in about 5 min. Our aim was to adapt the STAGE sequences for 1.5T scanners which are still commonly used in clinical practice. Furthermore, the accuracy and repeatability of the STAGE-derived T1 estimate were tested. METHODS Flip angle (FA) optimization was performed using a theoretical simulation by maximizing signal-to-noise ratio, contrast-to-noise ratio, and T1 precision. The FA choice was further refined with the ISMRM/NIST phantom and in vivo acquisitions. The accuracy of the T1 estimate was assessed by comparing STAGE-derived T1 values with T1 maps obtained with an inversion recovery sequence. T1 accuracy was investigated for both the phantom and in vivo data. Finally, one subject was acquired 10 times once a week and a group of 27 subjects was scanned once. The T1 coefficient of variation (COV) was computed to assess scan-rescan and physiological variability, respectively. RESULTS The FA1,2 = 7°,38° were identified as the optimal FA pair at 1.5T. The T1 estimate errors were below 3% and 5% for phantom and in vivo measurements, respectively. COV for different tissues ranged from 1.8 to 4.8% for physiological variability, and between 0.8 and 2% for scan-rescan repeatability. CONCLUSION The optimized STAGE protocol can provide accurate and repeatable T1 mapping along with other qualitative images and quantitative maps in about 7 min on 1.5T scanners. This study provides the groundwork to assess the role of STAGE in clinical settings. KEY POINTS • The STAGE imaging protocol was optimized for use on 1.5T field strength scanners. • A practical STAGE protocol makes it possible to derive quantitative maps (i.e., T1, T2*, PD, and QSM) in about 7 min at 1.5T. • The T1 estimate derived from the STAGE protocol showed good accuracy and repeatability.
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Affiliation(s)
- Alice Pirastru
- IRCCS, Fondazione Don Carlo Gnocchi ONLUS, Via Alfonso Capecelatro, 66, 20148, Milan, Italy
| | - Yongsheng Chen
- Department of Neurology, Wayne State University School of Medicine, 4201 St Antoine St, Detroit, MI 48201, USA
| | - Laura Pelizzari
- IRCCS, Fondazione Don Carlo Gnocchi ONLUS, Via Alfonso Capecelatro, 66, 20148, Milan, Italy
| | - Francesca Baglio
- IRCCS, Fondazione Don Carlo Gnocchi ONLUS, Via Alfonso Capecelatro, 66, 20148, Milan, Italy
| | - Mario Clerici
- IRCCS, Fondazione Don Carlo Gnocchi ONLUS, Via Alfonso Capecelatro, 66, 20148, Milan, Italy.,Department of Pathophysiology and Transplantation, University of Milan, Via Francesco Sforza, 35, Milan, 20122, Italy
| | - E Mark Haacke
- Department of Neurology, Wayne State University School of Medicine, 4201 St Antoine St, Detroit, MI 48201, USA.,The MRI Institute for Biomedical Research, 30200 Telegraph Rd, Bingham Farms, MI 48025, USA.,Magnetic Resonance Innovations Inc, 30200 Telegraph Rd, Bingham Farms, MI 48025, USA.,Department of Radiology, Wayne State University School of Medicine, 3990 John R St, Detroit, MI 48201, USA
| | - Maria Marcella Laganà
- IRCCS, Fondazione Don Carlo Gnocchi ONLUS, Via Alfonso Capecelatro, 66, 20148, Milan, Italy.
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10
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Imajo K, Honda Y, Yoneda M, Saito S, Nakajima A. Magnetic resonance imaging for the assessment of pathological hepatic findings in nonalcoholic fatty liver disease. J Med Ultrason (2001) 2020; 47:535-548. [PMID: 33108553 DOI: 10.1007/s10396-020-01059-x] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2020] [Accepted: 09/25/2020] [Indexed: 02/06/2023]
Abstract
The prevalence of nonalcoholic fatty liver disease (NAFLD) is expected to increase because of the current epidemics of obesity and diabetes, and NAFLD has become a major cause of chronic liver disease worldwide. Liver fibrosis is associated with poor long-term outcomes in patients with NAFLD. Additionally, increased mortality and liver-related complications are primarily seen in patients with nonalcoholic steatohepatitis (NASH); however, nonalcoholic fatty liver (NAFL) is believed to be benign and non-progressive. Therefore, distinguishing between NASH and NAFL is clinically important. Liver biopsy is the gold standard method for the staging of liver fibrosis and distinguishing between NASH and NAFL. Unfortunately, liver biopsy is an invasive and expensive procedure. Therefore, noninvasive methods, to replace biopsy, are urgently needed for the staging of liver fibrosis and diagnosing NASH. In this review, we discuss the recent studies on magnetic resonance imaging (MRI), including magnetic resonance elastography, proton density fat fraction measurement, and multiparametric MRI (mpMRI) that can be used in the assessment of NASH components such as liver fibrosis, steatosis, and liver injury including inflammation and ballooning.
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Affiliation(s)
- Kento Imajo
- Department of Gastroenterology and Hepatology, Yokohama City University Graduate School of Medicine, Yokohama, 236-0004, Japan
| | - Yasushi Honda
- Department of Gastroenterology and Hepatology, Yokohama City University Graduate School of Medicine, Yokohama, 236-0004, Japan
| | - Masato Yoneda
- Department of Gastroenterology and Hepatology, Yokohama City University Graduate School of Medicine, Yokohama, 236-0004, Japan
| | - Satoru Saito
- Department of Gastroenterology and Hepatology, Yokohama City University Graduate School of Medicine, Yokohama, 236-0004, Japan
| | - Atsushi Nakajima
- Department of Gastroenterology and Hepatology, Yokohama City University Graduate School of Medicine, Yokohama, 236-0004, Japan.
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11
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Peterson P, Trinh L, Månsson S. Quantitative 1 H MRI and MRS of fatty acid composition. Magn Reson Med 2020; 85:49-67. [PMID: 32844500 DOI: 10.1002/mrm.28471] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2020] [Revised: 07/08/2020] [Accepted: 07/20/2020] [Indexed: 12/22/2022]
Abstract
Adipose tissue as well as other depots of fat (triglycerides) are increasingly being recognized as active contributors to the human function and metabolism. In addition to the fat concentration, also the fatty acid chemical composition (FAC) of the triglyceride molecules may play an important part in diseases such as obesity, insulin resistance, hepatic steatosis, osteoporosis, and cancer. MR spectroscopy and chemical-shift-encoded imaging (CSE-MRI) are established methods for non-invasive quantification of fat concentration in tissue. More recently, similar techniques have been developed for assessment also of the FAC in terms of the number of double bonds, the fraction of saturated, monounsaturated, and polyunsaturated fatty acids, or semi-quantitative unsaturation indices. The number of papers focusing on especially CSE-MRI-based techniques has steadily increased during the past few years, introducing a range of acquisition protocols and reconstruction algorithms. However, a number of potential sources of bias have also been identified. Furthermore, the measures used to characterize the FAC using both MRI and MRS differ, making comparisons between different techniques difficult. The aim of this paper is to review MRS- and MRI-based methods for in vivo quantification of the FAC. We describe the chemical composition of triglycerides and discuss various potential FAC measures. Furthermore, we review acquisition and reconstruction methodology and finally, some existing and potential applications are summarized. We conclude that both MRI and MRS provide feasible non-invasive alternatives to the gold standard gas chromatography for in vivo measurements of the FAC. Although both are associated with gas chromatography, future studies are warranted.
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Affiliation(s)
- Pernilla Peterson
- Medical Radiation Physics, Malmö, Department of Translational Medicine, Lund University, Skåne University Hospital, Malmö, Sweden.,Medical Imaging and Physiology, Skåne University Hospital, Lund, Sweden
| | - Lena Trinh
- Medical Radiation Physics, Malmö, Department of Translational Medicine, Lund University, Skåne University Hospital, Malmö, Sweden
| | - Sven Månsson
- Medical Radiation Physics, Malmö, Department of Translational Medicine, Lund University, Skåne University Hospital, Malmö, Sweden
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Trinh L, Peterson P, Leander P, Brorson H, Månsson S. In vivo comparison of MRI‐based and MRS‐based quantification of adipose tissue fatty acid composition against gas chromatography. Magn Reson Med 2020; 84:2484-2494. [DOI: 10.1002/mrm.28300] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2020] [Revised: 03/19/2020] [Accepted: 04/03/2020] [Indexed: 12/19/2022]
Affiliation(s)
- Lena Trinh
- Medical Radiation Physics Department of Translational Medicine Lund University Skåne University Hospital Malmö Sweden
| | - Pernilla Peterson
- Medical Radiation Physics Department of Translational Medicine Lund University Skåne University Hospital Malmö Sweden
- Medical Imaging and Physiology Skåne University Hospital Lund Sweden
| | - Peter Leander
- Diagnostic Radiology Department of Translational Medicine Lund University Skåne University Hospital Malmö Sweden
| | - Håkan Brorson
- Department of Clinical Sciences Lund University Malmö Sweden
- Department of Plastic and Reconstructive Surgery Skåne University Hospital Malmö Sweden
| | - Sven Månsson
- Medical Radiation Physics Department of Translational Medicine Lund University Skåne University Hospital Malmö Sweden
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13
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Analysis of muscle, hip, and subcutaneous fat in osteoporosis patients with varying degrees of fracture risk using 3T Chemical Shift Encoded MRI. Bone Rep 2020; 12:100259. [PMID: 32322608 PMCID: PMC7163287 DOI: 10.1016/j.bonr.2020.100259] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/09/2020] [Accepted: 03/18/2020] [Indexed: 02/08/2023] Open
Abstract
Osteoporosis (OP) is a major disease that affects 200 million people worldwide. Fatty acid metabolism plays an important role in bone health and plays an important role in bone quality and remodeling. Increased bone marrow fat quantity has been shown to be associated with a decrease in bone mineral density (BMD), which is used to predict fracture risk. Chemical-Shift Encoded magnetic resonance imaging (CSE-MRI) allows noninvasive and quantitative assessment of adipose tissues (AT). The aim of our study was to assess hip or proximal femoral bone marrow adipose tissue (BMAT), thigh muscle (MUS), and subcutaneous adipose tissue (SAT) in 128 OP subjects matched for age, BMD, weight and height with different degrees of fracture risk assessed through the FRAX score (low, moderate and high). Our results showed an increase in BMAT and in MUS in high compared to low fracture risk patients. We also assessed the relationship between fracture risk as assessed by FRAX and AT quantities. Overall, the results of this study suggest that assessment of adipose tissue via 3T CSE-MRI provides insight into the pathophysiology fracture risk by showing differences in the bone marrow and muscle fat content in subjects with similarly osteoporotic BMD as assessed by DXA, but with varying degrees of fracture risk as assessed by FRAX.
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14
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Bas J, Ogier AC, Le Troter A, Delmont E, Leporq B, Pini L, Guye M, Parlanti A, Lefebvre MN, Bendahan D, Attarian S. Fat fraction distribution in lower limb muscles of patients with CMT1A: A quantitative MRI study. Neurology 2020; 94:e1480-e1487. [PMID: 31980579 DOI: 10.1212/wnl.0000000000009013] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2019] [Accepted: 10/10/2019] [Indexed: 11/15/2022] Open
Abstract
OBJECTIVE To quantitatively describe the MRI fat infiltration pattern of muscle degeneration in Charcot-Marie-Tooth (CMT) type 1A (CMT1A) disease and to look for correlations with clinical variables. METHODS MRI fat fraction was assessed in lower-limb musculature of patients with CMT1A and healthy controls. More particularly, 14 muscle compartments were selected at leg and thigh levels and for proximal, distal, and medial slices. Muscle fat infiltration profile was determined quantitatively in each muscle compartment and along the entire volume of acquisition to determine a length-dependent gradient of fat infiltration. Clinical impairment was evaluated with muscle strength measurements and CMT Examination Scores (CMTESs). RESULTS A total of 16 patients with CMT1A were enrolled and compared to 11 healthy controls. Patients with CMT1A showed a larger muscle fat fraction at leg and thigh levels with a proximal-to-distal gradient. At the leg level, the largest fat infiltration was quantified in the anterior and lateral compartments. CMTES was correlated with fat fraction, especially in the anterior compartment of leg muscles. Strength of plantar flexion was also correlated with fat fraction of the posterior compartments of leg muscles. CONCLUSION On the basis of quantitative MRI measurements combined with a dedicated segmentation method, muscle fat infiltration quantified in patients with CMT1A disclosed a length-dependent peroneal-type pattern of fat infiltration and was correlated to main clinical variables. Quantification of fat fraction at different levels of the leg anterior compartment might be of interest in future clinical trials.
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Affiliation(s)
- Joachim Bas
- From the Reference Center for Neuromuscular Diseases and ALS (J.B., E.D., A.P., S.A.) and CIC-CPCET (M.-N.L.), La Timone University Hospital, Aix-Marseille University; Aix-Marseille University (A.C.O., A.L.T., L.P., M.G., D.B.), CNRS, Center for Magnetic Resonance in Biology and Medicine; Aix-Marseille University (E.D.), UMR 7286, Medicine Faculty; Aix-Marseille University (S.A.), Inserm, GMGF; Aix Marseille University (A.C.O.), Université de Toulon, CNRS, LIS, Marseille; Université de Lyon (B.L.); and CREATIS CNRS UMR 5220 (B.L.), Inserm U1206, INSA-Lyon, UCBL Lyon 1, France
| | - Augustin C Ogier
- From the Reference Center for Neuromuscular Diseases and ALS (J.B., E.D., A.P., S.A.) and CIC-CPCET (M.-N.L.), La Timone University Hospital, Aix-Marseille University; Aix-Marseille University (A.C.O., A.L.T., L.P., M.G., D.B.), CNRS, Center for Magnetic Resonance in Biology and Medicine; Aix-Marseille University (E.D.), UMR 7286, Medicine Faculty; Aix-Marseille University (S.A.), Inserm, GMGF; Aix Marseille University (A.C.O.), Université de Toulon, CNRS, LIS, Marseille; Université de Lyon (B.L.); and CREATIS CNRS UMR 5220 (B.L.), Inserm U1206, INSA-Lyon, UCBL Lyon 1, France
| | - Arnaud Le Troter
- From the Reference Center for Neuromuscular Diseases and ALS (J.B., E.D., A.P., S.A.) and CIC-CPCET (M.-N.L.), La Timone University Hospital, Aix-Marseille University; Aix-Marseille University (A.C.O., A.L.T., L.P., M.G., D.B.), CNRS, Center for Magnetic Resonance in Biology and Medicine; Aix-Marseille University (E.D.), UMR 7286, Medicine Faculty; Aix-Marseille University (S.A.), Inserm, GMGF; Aix Marseille University (A.C.O.), Université de Toulon, CNRS, LIS, Marseille; Université de Lyon (B.L.); and CREATIS CNRS UMR 5220 (B.L.), Inserm U1206, INSA-Lyon, UCBL Lyon 1, France
| | - Emilien Delmont
- From the Reference Center for Neuromuscular Diseases and ALS (J.B., E.D., A.P., S.A.) and CIC-CPCET (M.-N.L.), La Timone University Hospital, Aix-Marseille University; Aix-Marseille University (A.C.O., A.L.T., L.P., M.G., D.B.), CNRS, Center for Magnetic Resonance in Biology and Medicine; Aix-Marseille University (E.D.), UMR 7286, Medicine Faculty; Aix-Marseille University (S.A.), Inserm, GMGF; Aix Marseille University (A.C.O.), Université de Toulon, CNRS, LIS, Marseille; Université de Lyon (B.L.); and CREATIS CNRS UMR 5220 (B.L.), Inserm U1206, INSA-Lyon, UCBL Lyon 1, France
| | - Benjamin Leporq
- From the Reference Center for Neuromuscular Diseases and ALS (J.B., E.D., A.P., S.A.) and CIC-CPCET (M.-N.L.), La Timone University Hospital, Aix-Marseille University; Aix-Marseille University (A.C.O., A.L.T., L.P., M.G., D.B.), CNRS, Center for Magnetic Resonance in Biology and Medicine; Aix-Marseille University (E.D.), UMR 7286, Medicine Faculty; Aix-Marseille University (S.A.), Inserm, GMGF; Aix Marseille University (A.C.O.), Université de Toulon, CNRS, LIS, Marseille; Université de Lyon (B.L.); and CREATIS CNRS UMR 5220 (B.L.), Inserm U1206, INSA-Lyon, UCBL Lyon 1, France
| | - Lauriane Pini
- From the Reference Center for Neuromuscular Diseases and ALS (J.B., E.D., A.P., S.A.) and CIC-CPCET (M.-N.L.), La Timone University Hospital, Aix-Marseille University; Aix-Marseille University (A.C.O., A.L.T., L.P., M.G., D.B.), CNRS, Center for Magnetic Resonance in Biology and Medicine; Aix-Marseille University (E.D.), UMR 7286, Medicine Faculty; Aix-Marseille University (S.A.), Inserm, GMGF; Aix Marseille University (A.C.O.), Université de Toulon, CNRS, LIS, Marseille; Université de Lyon (B.L.); and CREATIS CNRS UMR 5220 (B.L.), Inserm U1206, INSA-Lyon, UCBL Lyon 1, France
| | - Maxime Guye
- From the Reference Center for Neuromuscular Diseases and ALS (J.B., E.D., A.P., S.A.) and CIC-CPCET (M.-N.L.), La Timone University Hospital, Aix-Marseille University; Aix-Marseille University (A.C.O., A.L.T., L.P., M.G., D.B.), CNRS, Center for Magnetic Resonance in Biology and Medicine; Aix-Marseille University (E.D.), UMR 7286, Medicine Faculty; Aix-Marseille University (S.A.), Inserm, GMGF; Aix Marseille University (A.C.O.), Université de Toulon, CNRS, LIS, Marseille; Université de Lyon (B.L.); and CREATIS CNRS UMR 5220 (B.L.), Inserm U1206, INSA-Lyon, UCBL Lyon 1, France
| | - Amandine Parlanti
- From the Reference Center for Neuromuscular Diseases and ALS (J.B., E.D., A.P., S.A.) and CIC-CPCET (M.-N.L.), La Timone University Hospital, Aix-Marseille University; Aix-Marseille University (A.C.O., A.L.T., L.P., M.G., D.B.), CNRS, Center for Magnetic Resonance in Biology and Medicine; Aix-Marseille University (E.D.), UMR 7286, Medicine Faculty; Aix-Marseille University (S.A.), Inserm, GMGF; Aix Marseille University (A.C.O.), Université de Toulon, CNRS, LIS, Marseille; Université de Lyon (B.L.); and CREATIS CNRS UMR 5220 (B.L.), Inserm U1206, INSA-Lyon, UCBL Lyon 1, France
| | - Marie-Noëlle Lefebvre
- From the Reference Center for Neuromuscular Diseases and ALS (J.B., E.D., A.P., S.A.) and CIC-CPCET (M.-N.L.), La Timone University Hospital, Aix-Marseille University; Aix-Marseille University (A.C.O., A.L.T., L.P., M.G., D.B.), CNRS, Center for Magnetic Resonance in Biology and Medicine; Aix-Marseille University (E.D.), UMR 7286, Medicine Faculty; Aix-Marseille University (S.A.), Inserm, GMGF; Aix Marseille University (A.C.O.), Université de Toulon, CNRS, LIS, Marseille; Université de Lyon (B.L.); and CREATIS CNRS UMR 5220 (B.L.), Inserm U1206, INSA-Lyon, UCBL Lyon 1, France
| | - David Bendahan
- From the Reference Center for Neuromuscular Diseases and ALS (J.B., E.D., A.P., S.A.) and CIC-CPCET (M.-N.L.), La Timone University Hospital, Aix-Marseille University; Aix-Marseille University (A.C.O., A.L.T., L.P., M.G., D.B.), CNRS, Center for Magnetic Resonance in Biology and Medicine; Aix-Marseille University (E.D.), UMR 7286, Medicine Faculty; Aix-Marseille University (S.A.), Inserm, GMGF; Aix Marseille University (A.C.O.), Université de Toulon, CNRS, LIS, Marseille; Université de Lyon (B.L.); and CREATIS CNRS UMR 5220 (B.L.), Inserm U1206, INSA-Lyon, UCBL Lyon 1, France
| | - Shahram Attarian
- From the Reference Center for Neuromuscular Diseases and ALS (J.B., E.D., A.P., S.A.) and CIC-CPCET (M.-N.L.), La Timone University Hospital, Aix-Marseille University; Aix-Marseille University (A.C.O., A.L.T., L.P., M.G., D.B.), CNRS, Center for Magnetic Resonance in Biology and Medicine; Aix-Marseille University (E.D.), UMR 7286, Medicine Faculty; Aix-Marseille University (S.A.), Inserm, GMGF; Aix Marseille University (A.C.O.), Université de Toulon, CNRS, LIS, Marseille; Université de Lyon (B.L.); and CREATIS CNRS UMR 5220 (B.L.), Inserm U1206, INSA-Lyon, UCBL Lyon 1, France.
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Hu HH, Branca RT, Hernando D, Karampinos DC, Machann J, McKenzie CA, Wu HH, Yokoo T, Velan SS. Magnetic resonance imaging of obesity and metabolic disorders: Summary from the 2019 ISMRM Workshop. Magn Reson Med 2019; 83:1565-1576. [PMID: 31782551 DOI: 10.1002/mrm.28103] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2019] [Revised: 11/04/2019] [Accepted: 11/11/2019] [Indexed: 02/06/2023]
Abstract
More than 100 attendees from Australia, Austria, Belgium, Canada, China, Germany, Hong Kong, Indonesia, Japan, Malaysia, the Netherlands, the Philippines, Republic of Korea, Singapore, Sweden, Switzerland, the United Kingdom, and the United States convened in Singapore for the 2019 ISMRM-sponsored workshop on MRI of Obesity and Metabolic Disorders. The scientific program brought together a multidisciplinary group of researchers, trainees, and clinicians and included sessions in diabetes and insulin resistance; an update on recent advances in water-fat MRI acquisition and reconstruction methods; with applications in skeletal muscle, bone marrow, and adipose tissue quantification; a summary of recent findings in brown adipose tissue; new developments in imaging fat in the fetus, placenta, and neonates; the utility of liver elastography in obesity studies; and the emerging role of radiomics in population-based "big data" studies. The workshop featured keynote presentations on nutrition, epidemiology, genetics, and exercise physiology. Forty-four proffered scientific abstracts were also presented, covering the topics of brown adipose tissue, quantitative liver analysis from multiparametric data, disease prevalence and population health, technical and methodological developments in data acquisition and reconstruction, newfound applications of machine learning and neural networks, standardization of proton density fat fraction measurements, and X-nuclei applications. The purpose of this article is to summarize the scientific highlights from the workshop and identify future directions of work.
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Affiliation(s)
- Houchun H Hu
- Department of Radiology, Nationwide Children's Hospital, Columbus, Ohio
| | - Rosa Tamara Branca
- Department of Physics and Astronomy, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
| | - Diego Hernando
- Department of Radiology, University of Wisconsin-Madison, Madison, Wisconsin.,Department of Medical Physics, University of Wisconsin-Madison, Madison, Wisconsin
| | - Dimitrios C Karampinos
- Department of Diagnostic and Interventional Radiology, School of Medicine, Technical University of Munich, Munich, Germany
| | - Jürgen Machann
- Institute for Diabetes Research and Metabolic Diseases, Helmholtz Center Munich at the University of Tübingen, Tübingen, Germany.,German Center for Diabetes Research, Tübingen, Germany.,Section on Experimental Radiology, Department of Diagnostic and Interventional Radiology, University Hospital Tübingen, Tübingen, Germany
| | - Charles A McKenzie
- Department of Medical Biophysics, University of Western Ontario, London, Ontario, Canada
| | - Holden H Wu
- Department of Radiological Sciences, University of California Los Angeles, Los Angeles, California
| | - Takeshi Yokoo
- Department of Radiology, University of Texas Southwestern Medical Center, Dallas, Texas
| | - S Sendhil Velan
- Singapore Institute for Clinical Sciences, Agency for Science Technology and Research, Singapore.,Singapore BioImaging Consortium, Agency for Science Technology and Research, Singapore
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Besutti G, Valenti L, Ligabue G, Bassi MC, Pattacini P, Guaraldi G, Giorgi Rossi P. Accuracy of imaging methods for steatohepatitis diagnosis in non-alcoholic fatty liver disease patients: A systematic review. Liver Int 2019; 39:1521-1534. [PMID: 30972903 DOI: 10.1111/liv.14118] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/31/2019] [Revised: 03/29/2019] [Accepted: 04/04/2019] [Indexed: 02/13/2023]
Abstract
BACKGROUND & AIMS Non-invasive tests to diagnose non-alcoholic steatohepatitis (NASH) are urgently needed. This systematic review aims to evaluate imaging accuracy in diagnosing NASH among non-alcoholic fatty liver disease (NAFLD) patients, using liver biopsy as reference. METHODS Eligible studies were systematic reviews and cross-sectional/cohort studies of NAFLD patients comparing imaging with histology, considering accuracy and/or associations. MEDLINE, Scopus, EMBASE and Cochrane Library databases were searched up to April 2018. Studies were screened on title/abstract, then assessed for eligibility on full-text. Data were extracted using a predesigned form. Risk of bias was assessed using Quality Assessment of Diagnostic Accuracy Studies-2 tool. RESULTS Of the 641 studies screened, 61 were included in scoping review, 30 of which (with accuracy results) in data synthesis. Imaging techniques included: elastography (transient elastography-TE, acoustic radiation force impulse-ARFI, magnetic resonance elastography-MRE), ultrasound (US), magnetic resonance (MR), computed tomography and scintigraphy. Histological NASH definition was heterogeneous. In 28/30 studies, no prespecified threshold was used (high risk of bias). AUROCs were up to 0.82 for TE, 0.90 for ARFI, 0.93 for MRE and 0.82 for US scores. MR techniques with higher accuracy were spectroscopy (AUROC = 1 for alanine), susceptibility-weighted imaging (AUROC = 0.91), multiparametric MR (AUROC = 0.80), optical analysis (AUROC = 0.83), gadoxetic acid-enhanced MR (AUROCs = 0.85) and superparamagnetic iron oxide-enhanced MR (AUROC = 0.87). Results derived mostly from single studies without independent prospective validation. CONCLUSIONS There is currently insufficient evidence to support the use of imaging to diagnose NASH. More studies are needed on US and MR elastography and non-elastographic techniques, to date the most promising methods.
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Affiliation(s)
- Giulia Besutti
- Clinical and Experimental Medicine PhD Program, University of Modena and Reggio Emilia, Modena, Italy.,Radiology Unit, Azienda Unità Sanitaria Locale-IRCCS of Reggio Emilia, Reggio Emilia, Italy
| | - Luca Valenti
- Department of Pathophysiology and Transplantation, Università degli Studi di Milano, Milan, Italy.,Translational Medicine, Department of Transfusion Medicine and Hematology, Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, Milan, Italy
| | - Guido Ligabue
- Radiology Unit, University of Modena and Reggio Emilia, Modena, Italy
| | - Maria Chiara Bassi
- Medical Library, Azienda Unità Sanitaria Locale-IRCCS of Reggio Emilia, Reggio Emilia, Italy
| | - Pierpaolo Pattacini
- Radiology Unit, Azienda Unità Sanitaria Locale-IRCCS of Reggio Emilia, Reggio Emilia, Italy
| | - Giovanni Guaraldi
- Modena HIV Metabolic Clinic, University of Modena and Reggio Emilia, Modena, Italy
| | - Paolo Giorgi Rossi
- Epidemiology Unit, Azienda Unità Sanitaria Locale-IRCCS of Reggio Emilia, Reggio Emilia, Italy
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Measurement of liver iron by magnetic resonance imaging in the UK Biobank population. PLoS One 2018; 13:e0209340. [PMID: 30576354 PMCID: PMC6303057 DOI: 10.1371/journal.pone.0209340] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2018] [Accepted: 12/04/2018] [Indexed: 01/07/2023] Open
Abstract
The burden of liver disease continues to increase in the UK, with liver cirrhosis reported to be the third most common cause of premature death. Iron overload, a condition that impacts liver health, was traditionally associated with genetic disorders such as hereditary haemochromatosis, however, it is now increasingly associated with obesity, type-2 diabetes and non-alcoholic fatty liver disease. The aim of this study was to assess the prevalence of elevated levels of liver iron within the UK Biobank imaging study in a cohort of 9108 individuals. Magnetic resonance imaging (MRI) was undertaken at the UK Biobank imaging centre, acquiring a multi-echo spoiled gradient-echo single-breath-hold MRI sequence from the liver. All images were analysed for liver iron and fat (expressed as proton density fat fraction or PDFF) content using LiverMultiScan. Liver iron was measured in 97.3% of the cohort. The mean liver iron content was 1.32 ± 0.32 mg/g while the median was 1.25 mg/g (min: 0.85 max: 6.44 mg/g). Overall 4.82% of the population were defined as having elevated liver iron, above commonly accepted 1.8 mg/g threshold based on biochemical iron measurements in liver specimens obtained by biopsy. Further analysis using univariate models showed elevated liver iron to be related to male sex (p<10−16, r2 = 0.008), increasing age (p<10−16, r2 = 0.013), and red meat intake (p<10−16, r2 = 0.008). Elevated liver fat (>5.6% PDFF) was associated with a slight increase in prevalence of elevated liver iron (4.4% vs 6.3%, p = 0.0007). This study shows that population studies including measurement of liver iron concentration are feasible, which may in future be used to better inform patient stratification and treatment.
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Martel D, Leporq B, Saxena A, Belmont HM, Turyan G, Honig S, Regatte RR, Chang G. 3T chemical shift-encoded MRI: Detection of altered proximal femur marrow adipose tissue composition in glucocorticoid users and validation with magnetic resonance spectroscopy. J Magn Reson Imaging 2018; 50:490-496. [PMID: 30548522 DOI: 10.1002/jmri.26586] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2018] [Revised: 11/07/2018] [Accepted: 11/08/2018] [Indexed: 12/30/2022] Open
Abstract
BACKGROUND Osteoporosis (OP) results in weak bone and can ultimately lead to fracture. Drugs such as glucocorticoids can also induce OP (glucocorticoid-induced osteoporosis [GIO]). Bone marrow adipose tissue composition and quantity may play a role in OP pathophysiology, but has not been thoroughly studied in GIO compared to primary OP. PURPOSE/HYPOTHESIS Chemical shift-encoded (CSE) MRI allows detection of subregional differences in bone marrow adipose tissue composition and quantity in the proximal femur of GIO compared to OP subjects and has high agreement with the reference standard of magnetic resonance spectroscopy (MRS). STUDY TYPE Prospective. SUBJECTS In all, 18 OP and 13 GIO subjects. FIELDS STRENGTH 3T. SEQUENCE Multiple gradient-echo, stimulated echo acquisition mode (STEAM). ASSESSMENT Subjects underwent CSE-MRI in the proximal femurs, and for each parametric map regions of interest (ROIs) were assessed in the femoral head (fHEAD), femoral neck (fNECK), Ward's triangle (fTRIANGLE), and the greater trochanter (GTROCH). In addition, we compared CSE-MRI against the reference standard of MRS performed in the femoral neck and Ward's triangle. STATISTICAL TESTS Differences between OP/GIO were investigated using the Mann-Whitney nonparametric test. Bland-Altman methodology was used to assess measurement agreement between CSE-MRI and MRS. RESULTS GIO compared with OP subjects demonstrated: decreased monounsaturated fat fraction (MUFA) (-2.1%, P < 0.05) in fHEAD; decreased MUFA (-3.8%, P < 0.05), increased saturated fat fraction (SFA) (5.5%, P < 0.05), and decreased T 2 * (-3.8 msec, P < 0.05) in fNECK; decreased proton density fat fraction (PDFF) (-15.1%, P < 0.05), MUFA (-9.8%, P < 0.05), polyunsaturated fat fraction (PUFA) (-1.8%, P < 0.01), increased SFA (11.6%, P < 0.05), and decreased T 2 * (-5.4 msec, P < 0.05) in fTRIANGLE; and decreased T 2 * (-1.5 msec, P < 0.05) in GTROCH. There was high measurement agreement between MRI and MRS using the Bland-Altman test. DATA CONCLUSION 3T CSE-MRI may allow reliable assessment of subregional bone marrow adipose tissue (bMAT) quantity and composition in the proximal femur in a clinically reasonable scan time. Glucocorticoids may alter the lipid profile of bMAT and potentially result in reduced bone quality. LEVEL OF EVIDENCE 2 Technical Efficacy: Stage 2 J. Magn. Reson. Imaging 2019;50:490-496.
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Affiliation(s)
- Dimitri Martel
- New York Langone Health, Department of Radiology, New York University School of Medicine, New York, New York, USA
| | - Benjamin Leporq
- Université de Lyon, CREATIS CNRS UMR 5220, Inserm U1206, INSA-Lyon, UCBL Lyon 1, Lyon, France
| | - Amit Saxena
- New York Langone Health, Division of Rheumatology, Hospital for Joint Diseases, New York, New York, USA
| | - H Michael Belmont
- New York Langone Health, Division of Rheumatology, Hospital for Joint Diseases, New York, New York, USA
| | - Gabrielle Turyan
- New York Langone Health, Osteoporosis Center, Hospital for Joint Diseases, New York, New York, USA
| | - Stephen Honig
- New York Langone Health, Osteoporosis Center, Hospital for Joint Diseases, New York, New York, USA
| | - Ravinder R Regatte
- New York Langone Health, Department of Radiology, New York University School of Medicine, New York, New York, USA
| | - Gregory Chang
- New York Langone Health, Department of Radiology, New York University School of Medicine, New York, New York, USA
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Schneider M, Janas G, Lugauer F, Hoppe E, Nickel D, Dale BM, Kiefer B, Maier A, Bashir MR. Accurate fatty acid composition estimation of adipose tissue in the abdomen based on bipolar multi‐echo MRI. Magn Reson Med 2018; 81:2330-2346. [DOI: 10.1002/mrm.27557] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2018] [Revised: 08/18/2018] [Accepted: 09/11/2018] [Indexed: 12/13/2022]
Affiliation(s)
- Manuel Schneider
- Pattern Recognition Lab, Department of Computer Science Friedrich‐Alexander‐Universität Erlangen‐Nürnberg Erlangen Germany
| | - Gemini Janas
- Radiology Duke University Medical Center Durham North Carolina
- Center for Advanced Magnetic Resonance Development Duke University Medical Center Durham North Carolina
| | - Felix Lugauer
- Pattern Recognition Lab, Department of Computer Science Friedrich‐Alexander‐Universität Erlangen‐Nürnberg Erlangen Germany
| | - Elisabeth Hoppe
- Pattern Recognition Lab, Department of Computer Science Friedrich‐Alexander‐Universität Erlangen‐Nürnberg Erlangen Germany
| | - Dominik Nickel
- MR Applications Predevelopment Siemens Healthcare GmbH Erlangen Germany
| | - Brian M. Dale
- MR R&D Collaborations Siemens Healthineers Cary North Carolina
| | - Berthold Kiefer
- MR Applications Predevelopment Siemens Healthcare GmbH Erlangen Germany
| | - Andreas Maier
- Pattern Recognition Lab, Department of Computer Science Friedrich‐Alexander‐Universität Erlangen‐Nürnberg Erlangen Germany
| | - Mustafa R. Bashir
- Radiology Duke University Medical Center Durham North Carolina
- Center for Advanced Magnetic Resonance Development Duke University Medical Center Durham North Carolina
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Van Reeth E, Lefebvre PM, Ratiney H, Lambert SA, Tesch M, Brusseau E, Grenier D, Beuf O, Glaser SJ, Sugny D, Tse-Ve-Koon K. Constant gradient elastography with optimal control RF pulses. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2018; 294:153-161. [PMID: 30053754 DOI: 10.1016/j.jmr.2018.07.013] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/24/2018] [Revised: 07/16/2018] [Accepted: 07/17/2018] [Indexed: 06/08/2023]
Abstract
This article presents a new motion encoding strategy to perform magnetic resonance elastography (MRE). Instead of using standard motion encoding gradients, a tailored RF pulse is designed to simultaneously perform selective excitation and motion encoding in presence of a constant gradient. The RF pulse is designed with a numerical optimal control algorithm, in order to obtain a magnetization phase distribution that depends on the displacement characteristics inside each voxel. As a consequence, no post-excitation encoding gradients are required. This offers numerous advantages, such as reducing eddy current artifacts, and relaxing the constraint on the gradients maximum switch rate. It also allows to perform MRE with ultra-short TE acquisition schemes, which limits T2 decay and optimizes signal-to-noise ratio. The pulse design strategy is developed and analytically analyzed to clarify the encoding mechanism. Finally, simulations, phantom and ex vivo experiments show that phase-to-noise ratios are improved when compared to standard MRE encoding strategies.
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Affiliation(s)
- Eric Van Reeth
- CREATIS, CNRS UMR5220, INSERM U1206, Université Lyon 1, INSA Lyon, Université Jean Monnet Saint-Etienne, France.
| | - Pauline M Lefebvre
- CREATIS, CNRS UMR5220, INSERM U1206, Université Lyon 1, INSA Lyon, Université Jean Monnet Saint-Etienne, France
| | - Hélène Ratiney
- CREATIS, CNRS UMR5220, INSERM U1206, Université Lyon 1, INSA Lyon, Université Jean Monnet Saint-Etienne, France
| | - Simon A Lambert
- CREATIS, CNRS UMR5220, INSERM U1206, Université Lyon 1, INSA Lyon, Université Jean Monnet Saint-Etienne, France
| | - Michael Tesch
- Department of Chemistry, Technische Universität München, Germany
| | - Elisabeth Brusseau
- CREATIS, CNRS UMR5220, INSERM U1206, Université Lyon 1, INSA Lyon, Université Jean Monnet Saint-Etienne, France
| | - Denis Grenier
- CREATIS, CNRS UMR5220, INSERM U1206, Université Lyon 1, INSA Lyon, Université Jean Monnet Saint-Etienne, France
| | - Olivier Beuf
- CREATIS, CNRS UMR5220, INSERM U1206, Université Lyon 1, INSA Lyon, Université Jean Monnet Saint-Etienne, France
| | - Steffen J Glaser
- Department of Chemistry, Technische Universität München, Germany
| | - Dominique Sugny
- ICB, CNRS UMR6303, Université de Bourgogne, France; Institute for Advanced Study, Technische Universität München, Lichtenbergstrasse 2a, D-85748 Garching, Germany
| | - Kevin Tse-Ve-Koon
- CREATIS, CNRS UMR5220, INSERM U1206, Université Lyon 1, INSA Lyon, Université Jean Monnet Saint-Etienne, France
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21
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Nemeth A, Segrestin B, Leporq B, Coum A, Gambarota G, Seyssel K, Laville M, Beuf O, Ratiney H. Comparison of MRI-derived vs. traditional estimations of fatty acid composition from MR spectroscopy signals. NMR IN BIOMEDICINE 2018; 31:e3991. [PMID: 30040156 DOI: 10.1002/nbm.3991] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/21/2017] [Revised: 05/29/2018] [Accepted: 06/07/2018] [Indexed: 06/08/2023]
Abstract
INTRODUCTION The composition of fatty acids in the body is gaining increasing interest, and can be followed up noninvasively by quantitative magnetic resonance spectroscopy (MRS). However, current MRS quantification methods have been shown to provide different quantitative results in terms of lipid signals, with possible varying outcomes for a given biological examination. Quantitative magnetic resonance imaging using multigradient echo sequence (MGE-MRI) has recently been added to MRS approaches. In contrast, these methods fit the undersampled magnetic resonance temporal signal with a simplified model function (expressing the triglyceride [TG] spectrum with only three TG parameters), specific implementations and prior knowledge. In this study, an adaptation of an MGE-MRI method to MRS lipid quantification is proposed. METHODS Several versions of the method - with time data fully or undersampled, including or excluding the spectral peak T2 knowledge in the fitting - were compared theoretically and on Monte Carlo studies with a time-domain, peak-fitting approach. Robustness, repeatability and accuracy were also inspected on in vitro oil acquisitions and test-retest in vivo subcutaneous adipose tissue acquisitions, adding results from the reference LCModel method. RESULTS On simulations, the proposed method provided TG parameter estimates with the smallest variability, but with a possible bias, which was mitigated by fitting on undersampled data and considering peak T2 values. For in vitro measurements, estimates for all approaches were correlated with theoretical values and the best concordance was found for the usual MRS method (LCModel and peak fitting). Limited in vivo test-retest variability was found (4.1% for PUFAindx, 0.6% for MUFAindx and 3.6% for SFAindx), as for LCModel (7.6% for PUFAindx, 7.8% for MUFAindx and 3.0% for SFAindx). CONCLUSION This study shows that fitting the three TG parameters directly on MRS data is one valuable solution to circumvent the poor conditioning of the MRS quantification problem.
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Affiliation(s)
- Angeline Nemeth
- Université Lyon, INSA-Lyon, Université Claude Bernard Lyon 1, UJM-Saint Etienne, CNRS, Inserm, CREATIS UMR 5220, U1206, Lyon, France
| | - Bérénice Segrestin
- Centre de Recherche en Nutrition Humaine Rhône-Alpes (CRNH-RA), Centre Hospitalier Lyon Sud, Pierre-Bénite, Lyon, France
| | - Benjamin Leporq
- Université Lyon, INSA-Lyon, Université Claude Bernard Lyon 1, UJM-Saint Etienne, CNRS, Inserm, CREATIS UMR 5220, U1206, Lyon, France
| | - Amandine Coum
- INSERM, UMR 1099, Rennes, France
- Université Rennes 1, LTSI, Rennes, France
| | - Giulio Gambarota
- INSERM, UMR 1099, Rennes, France
- Université Rennes 1, LTSI, Rennes, France
| | - Kevin Seyssel
- Department of Physiology, Faculty of Biology and Medicine, University of Lausanne, Lausanne, Switzerland
| | - Martine Laville
- Centre de Recherche en Nutrition Humaine Rhône-Alpes (CRNH-RA), Centre Hospitalier Lyon Sud, Pierre-Bénite, Lyon, France
| | - Olivier Beuf
- Université Lyon, INSA-Lyon, Université Claude Bernard Lyon 1, UJM-Saint Etienne, CNRS, Inserm, CREATIS UMR 5220, U1206, Lyon, France
| | - Hélène Ratiney
- Université Lyon, INSA-Lyon, Université Claude Bernard Lyon 1, UJM-Saint Etienne, CNRS, Inserm, CREATIS UMR 5220, U1206, Lyon, France
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22
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Abstract
PURPOSE OF REVIEW Abdominal obesity, especially the increase of visceral adipose tissue (VAT), is closely associated with increased mortality related to cardiovascular disease, diabetes, and fatty liver disease. This review provides an overview of the recent advances for abdominal obesity measurement. RECENT FINDINGS Compared to simple waist circumference, emerging three-dimensional (3D) body-scanning techniques also measure abdominal volume and shape. Abdominal dimension measures have been implemented in bioelectrical impedance analysis to improve accuracy when estimating VAT. Geometrical models have been applied in ultrasound to convert depth measurement into VAT area. Only computed tomography (CT) and MRI can provide direct measures of VAT. Recent advances in imaging allow for evaluating functional aspects of abdominal fat such as brown adipose tissue and fatty acid composition. SUMMARY Waist circumference is a simple, inexpensive method to measure abdominal obesity. CT and MRI are reference methods for measuring VAT. Further studies are needed to establish the accuracy for dual-energy X-ray absorptiometry in estimating longitudinal changes of VAT. Further studies are needed to establish whether bioelectrical impedance analysis, ultrasound, or 3D body scanning is consistently superior to waist circumference in estimating VAT in different populations.
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Affiliation(s)
- Hongjuan Fang
- Department of Endocrinology, Capital Medical University, Beijing Tiantan Hospital, Beijing, China
- Division of Pediatric Gastroenterology, Hepatology and Nutrition, Department of Pediatrics, Columbia University, New York, New York, USA
| | - Elizabeth Berg
- Division of Pediatric Gastroenterology, Hepatology and Nutrition, Department of Pediatrics, Columbia University, New York, New York, USA
| | - Xiaoguang Cheng
- Department of Radiology, Beijing Jishuitan Hospital, Beijing, China
| | - Wei Shen
- Division of Pediatric Gastroenterology, Hepatology and Nutrition, Department of Pediatrics, Columbia University, New York, New York, USA
- Institute of Human Nutrition, Columbia University, New York, New York, USA
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23
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Simchick G, Yin A, Yin H, Zhao Q. Fat spectral modeling on triglyceride composition quantification using chemical shift encoded magnetic resonance imaging. Magn Reson Imaging 2018; 52:84-93. [PMID: 29928937 DOI: 10.1016/j.mri.2018.06.012] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2018] [Revised: 06/14/2018] [Accepted: 06/17/2018] [Indexed: 12/12/2022]
Abstract
PURPOSE To explore, at a high field strength of 7T, the performance of various fat spectral models on the quantification of triglyceride composition and proton density fat fraction (PDFF) using chemical-shift encoded MRI (CSE-MRI). METHODS MR data was acquired from CSE-MRI experiments for various fatty materials, including oil and butter samples and in vivo brown and white adipose mouse tissues. Triglyceride composition and PDFF were estimated using various a priori 6- or 9-peak fat spectral models. To serve as references, NMR spectroscopy experiments were conducted to obtain material specific fat spectral models and triglyceride composition estimates for the same fatty materials. Results obtained using the spectroscopy derived material specific models were compared to results obtained using various published fat spectral models. RESULTS Using a 6-peak fat spectral model to quantify triglyceride composition may lead to large biases at high field strengths. When using a 9-peak model, triglyceride composition estimations vary greatly depending on the relative amplitudes of the chosen a priori spectral model, while PDFF estimations show small variations across spectral models. Material specific spectroscopy derived spectral models produce estimations that better correlate with NMR spectroscopy estimations in comparison to those obtained using non-material specific models. CONCLUSION At a high field strength of 7T, a material specific 9-peak fat spectral model, opposed to a widely accepted or generic human liver model, is necessary to accurately quantify triglyceride composition when using CSE-MRI estimation methods that assume the spectral model to be known as a priori information. CSE-MRI allows for the quantification of the spatial distribution of triglyceride composition for certain in vivo applications. Additionally, PDFF quantification is shown to be independent of the chosen a priori spectral model, which agrees with previously reported results obtained at lower field strengths (e.g. 3T).
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Affiliation(s)
- Gregory Simchick
- Physics and Astronomy, University of Georgia, Athens, GA, United States; Bio-Imaging Research Center, University of Georgia, Athens, GA, United States
| | - Amelia Yin
- Biochemistry and Molecular Biology, University of Georgia, Athens, GA, United States; Center for Molecular Medicine, University of Georgia, Athens, GA, United States
| | - Hang Yin
- Biochemistry and Molecular Biology, University of Georgia, Athens, GA, United States; Center for Molecular Medicine, University of Georgia, Athens, GA, United States
| | - Qun Zhao
- Physics and Astronomy, University of Georgia, Athens, GA, United States; Bio-Imaging Research Center, University of Georgia, Athens, GA, United States.
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