Rajakumar Nagarajan1, Christian Roberts2, Cathy C. Lee3, 4, Theodore Hahn3, 4, M. Albert Thomas1
1Radiological Sciences, University of California Los Angeles, Los Angeles, CA, United States; 2Exercise and Metabolic Disease Research Laboratory, School of Nursing, University of California Los Angeles, Los Angeles, CA, United States; 3Department of Medicine, University of California Los Angeles, Los Angeles, CA, United States; 4Geriatrics, Research, Education and Clinical Center (GRECC ), VA Greater Los Angeles Healthcare System , Los Angeles, CA, United States
Type 2 diabetes (T2D) has progressed into a major cause of preventable death in recent decades, expected to reach 21 million cases in the U.S. in 2010 with an estimated additional 7 million undiagnosed. In obese individuals with insulin resistance (IR) and in patients with T2D, skeletal muscle insulin-stimulated glucose uptake is markedly blunted. Intramyocellular lipids (IMCL) in skeletal muscle can be measured non-invasively by single voxel (SV) based 1H magnetic resonance spectroscopy (MRS) or multi-voxel based magnetic resonance spectroscopic imaging (MRSI). However, SV-based MRS and conventional MRSI recording 1D MRS suffer from severe overlap of the IMCL and extramyocellular lipid (EMCL) signals hampering accurate quantitation of saturated and unsaturated portions of IMCL. Also, the total time required for SV-MRS acquisition in multiple voxels would be impractical. We have evaluated a novel four-dimensional multi-echo echo-planar spectroscopic imaging (MEEP-COSI) to record multi-voxel based 2D MRS in T2D, obese and healthy subjects. Significantly increased intramyocellular lipids (IMCL) and extramyocellular lipids (EMCL), and decreased IMCL unsaturation indices and choline were observed in this pilot study.