Zhongwei Qiao^1,2, Peng Cao^1,2, Iris Y. Zhou^1,2, Shujuan Fan^1,2, Matthew M. Cheung^1,2, Jevin W. Zhang^1,2, and Ed X. Wu^1,2
1Laboratory of Biomedical Imaging and Signal Processing, The University of Hong Kong, Hong Kong SAR, China, ²Department of Electrical and Electronic Engineering, The University of Hong Kong, Hong Kong SAR, China

The relationship between accumulation of intramyocellular lipid (IMCL) in skeletal muscle and insulin resistance is not well understood at present time. IMCL storage in skeletal muscles depends on lipid oxidative capacity and fatty acid flux rate. With dynamic 1H-MRS and creatine as the internal reference, a muscle type dependent IMCL storage at resting state was observed and quantified in this study. Such functional IMCL storage quantified by dynamic 1H-MRS could be used as an indicator for studying and probing the dynamic balance between IMCL synthesis and utilization during lipid metabolism in both animal models and humans in vivo.

Ladislav Valkovic^1,2, Marek Chmelik¹, Ivica Just Kukurova¹, Martin Krššák³, Stephan Gruber¹, Ivan Frollo², Siegfried Trattnig¹, and Wolfgang Bogner^1
1MR Centre of Excellence, Department of Radiology, Medical University of Vienna, Vienna, Austria, ²Department of Imaging Methods, Institute of Measurement Science, Slovak Academy of Sciences, Bratislava, Slovakia, ³Department of Internal Medicine III, Medical University of Vienna, Vienna, Austria

The aim of this study was to compare precision of magnetization transfer (MT) experiments at 3T&7T and to analyze the potential time resolution of MT at 7T. Calf muscles of six healthy subjects were consecutively measured on two MR scanners (3T&7T). The MT protocol was split to four parts (each 10min 36sec) to compare the variability of repeated measurements and to test time resolved MT experiments. No MT experiments of the skeletal muscle have been performed as yet at 7T. We were able to show that the time-resolved MT in the muscle with ~10min temporal resolution is feasible at 7T.

Suresh Anand Sadananthan^1,2, Eric Khoo Yin Hao³, Melvin K-S Leow^1,4, ChinMeng Khoo³, Lee Yung Seng^1,5, Peter Gluckman¹, Tai E Shyong^1,3, and S. Sendhil Velan^1,6
1Singapore Institute for Clinical Sciences, A*STAR, Singapore, ²Dept. of Obstetrics & Gynaecology, National University of Singapore, Singapore, ³Dept. of Medicine, National University of Singapore, ⁴Dept. of Endocrinology, Tan Tock Seng Hospital, ⁵Dept. of Pediatrics, National University of Singapore,⁶Singapore Bioimaging Consortium, A*STAR, Singapore

Fatty acid composition in individuals with insulin resistance and metabolic syndrome is typically characterized by high levels of saturated fatty acids and low levels of polyunsaturated fatty acids. Recently, the degree of IMCL unsaturation was shown to significantly decrease with BMI in overweight and obese Caucasian men. However, the saturated and unsaturated components within these lipid pools have not been thoroughly investigated after a weight loss intervention. In this study, we employed a 2D localized correlated spectroscopy (L-COSY) technique to estimate the degree of unsaturation within IMCL and EMCL in overweight Chinese subjects after a weight loss intervention.

Prodromos Parasoglou¹, Ding Xia¹, Gregory Chang¹, and Ravinder R Regatte^1
1Center of Biomedical Imaging, NYU Langone Medical Center, New York, New York, United States

Imaging of a single 31P metabolite has shown great potential for the study of muscular diseases with much higher spatial and temporal resolution compared to chemical shift imaging methods. In this work, we compare the benefits and challenges of imaging phosphocreatine in the human calf muscle at 3T and 7T using two geometrically identical double-tuned (1H/31P) quadrature coils. Imaging at 7T showed a 2.8 fold increase in SNR compared to 3T. This allowed imaging of PCr at 7T with double the resolution compared to 3T. Increased blurring was observed at 7T that can be compensated by modifying the acquisition parameters.

Alexander Valentinitsch¹, Dimitrios C. Karampinos¹, Hamza Alizai¹, Karupppasamy Subburaj¹, Thomas M. Link¹, and Sharmila Majumdar^1
1Department of Radiology and Biomedical Imaging, University of California San Francisco, San Francisco, CA, United States

To introduce and validate a fully automated unsupervised multi-parametric segmentation method of the subcutaneous adipose tissue and muscle region to determine intermuscular adipose tissue (IMAT) and subcutaneous adipose tissue (SAT) volumes based on the images from a quantitative chemical shift-based water/fat separation approach.

Xiang He¹, Serter Gumus¹, Ayaz Aghayev¹, Dmitriy A Yablonskiy², and Kyongtae Ty Bae^1
1Department of Radiology, University of Pittsburgh, Pittsburgh, PA, United States, ²Mallinckrodt Institute of Radiology, Washington University in St Louis, St Louis, Missouri, United States

In this study, MR qBOLD (quantitative BOLD) based approach has been utilized for the first time to provide regional, in-vivo quantification of the human skeletal muscle oxygen metabolism, i.e., oxygen extraction fraction (OEF). Our results in healthy human subjects demonstrate that the MSK qBOLD approach is capable of evaluating regional muscle OEF in baseline state, and oxygen metabolism changes after intensive exercise. The validness of the MSK qBOLD model has been further tested in the leg rotation study, which demonstrated the random orientation for qBOLD sensitive muscle vasculature (venules and small veins).

James Alastair Meakin^1,2, Mark William Little^3,4, Thomas William Okell¹, Suzie Anthony³, Raman Uberoi³, and Peter Jezzard^1
1FMRIB Centre, University of Oxford, Oxford, United Kingdom, ²Gray Institute for Radiation Oncology and Biology, University of Oxford, Oxford, United Kingdom, ³Department of Radiology, John Radcliffe Hospital, Oxford, United Kingdom, ⁴Nuffield Department of Surgical Sciences, University of Oxford, Oxford, United Kingdom

There is a need for accurate assessment of perfusion to lower limb skeletal muscle in patients with peripheral arterial disease to aid diagnosis and management. We have developed a Velocity Selective ASL (VSASL) sequence to provide quantitative measures of resting perfusion in calf skeletal muscle, without the transit delay errors associated with Continuous ASL. In this study, we optimised the acquisition and demonstrated the feasibility of VSASL for quantifying skeletal muscle perfusion at rest in five healthy volunteers.

Jie Zheng¹, Xiaodong Zhang², Hongyu An², Andrew Coggan¹, Adil Bashir¹, Linda Peterson¹, and Robert J Gropler^1
1Washington University, Saint Louis, Missouri, United States, ²University of North Carolina, United States

A new non-contrast MRI oximetry method was presented to quantify absolute skeletal muscle O2 uptake. The feasibility of the method was evaluated in 7 normal volunteers, at rest and during an continuous isometric exercise. Two-fold increase in leg perfusion and significant decrease in oxygen extraction in skeletal muscle were observed with no apparent change in oxygen consumption, due to moderate exercise.

Guillaume Duhamel¹, Marc Jubeau^1,2, Michaël Sdika¹, Yann Le Fur¹, Sylviane Confort-Gouny¹, Christophe Vilmen¹, Alexandre Vignaud³, Patrick J. Cozzone¹, Julien Gondin¹, and David Bendahan^1
1CRMBM, UMR 6612, CNRS, Aix-Marseille University, Marseille, France, ²Laboratoire "Motricité, Interactions, Performance" - EA 4334, Nantes, France,³SIEMENS Healthcare, Saint Denis, France

Transverse relaxation time is a relevant parameter used to distinguish activated from non activated muscles as a result of exercise. Widely used CPMG-based sequences suffered from long acquisition time and B1 inhomogeneities sensitivity, especially at high field. We propose a very simple multislice approach based on segmented echo-planar imaging to rapidly and accurately measure muscle T2 values at 3T. The proposed technique was first validated on a phantom study and then applied for in vivo T2 measurements in exercising muscle.

William Rooney¹, Sean Forbes², James Pollaro¹, Dah-Jyuu Wang³, Soren de Vos², William Triplett⁴, James Meyer³, Rachel Willcocks⁴, Barry Byrne⁵, Richard Finkel⁶, Barry Russman⁷, Lee Sweeney⁸, Glenn Walter⁴, and Krista Vandenborne^2
1Advanced Imaging Research Center, Oregon Health & Science University, Portland, OR, United States, ²Department of Physical Therapy, University of Florida, Gainesville, FL, United States, ³Department of Radiology, Children's Hospital of Philadelphia, Philadelphia, PA, United States, ⁴Department of Physiology and Functional Genomics, University of Florida, Gainesville, FL, United States, ⁵Pediatrics, University of Florida, Gainesville, FL, United States,⁶Neurology, Children's Hospital of Philadelphia, Philadelphia, PA, United States, ⁷Shriners Hospital, Portland, OR, United States, ⁸Department of Physiology, University of Pennsylvania, Philadelphia, PA, United States

The purpose of the study was 1) to investigate the influence of muscle lipid content on MRI determined qT₂ values, and 2) to independently assess the behavior of MRS determined ¹H₂O qT₂ values in DMD as a function of muscle lipid content. 3T MRI data were acquired from 30 DMD boys and 8 healthy controls at three institutions. Non-fat suppressed MRI determined qT₂ values of the soleus increase quadratically with muscle lipid content. Soleus ¹H₂O T₂ values are elevated in DMD before lipid content is significantly increased, which may reflect a combination of inflammation, increased sarcolemmal water permeability, and myofiber degeneration. Lipid content increases with DMD progression and we find a significant negative association between soleus ¹H₂O T₂ and lipid fraction in DMD, perhaps associated with fibrosis.