Technical evaluation of in vivo abdominal fat and IMCL quantification using MRI and MRSI at 3 T.
OBJECTIVE
The objectives of this study were to develop protocols that measure abdominal fat and calf muscle lipids with magnetic resonance imaging (MRI) and magnetic resonance spectroscopy (MRS), respectively, at 3 T and to examine the correlation between these parameters and insulin sensitivity.


METHODS
Ten nondiabetic subjects [five insulin-sensitive (IS) subjects and five insulin-resistant (IR) subjects] were scanned at 3 T. Visceral adipose tissue (VAT) and subcutaneous adipose tissue (SAT) were segmented semiautomatically from abdominal imaging. Intramyocellular lipids (IMCL) in calf muscles were quantified with single-voxel MRS in both soleus and tibialis anterior muscles and with magnetic resonance spectroscopic imaging (MRSI).


RESULTS
The average coefficient of variation (CV) of VAT/(VAT+SAT) was 5.2%. The interoperator CV was 1.1% and 5.3% for SAT and VAT estimates, respectively. The CV of IMCL was 13.7% in soleus, 11.9% in tibialis anterior and 2.9% with MRSI. IMCL based on MRSI (3.8+/-1.2%) were significantly inversely correlated with glucose disposal rate, as measured by a hyperinsulinemic-euglycemic clamp. VAT volume correlated significantly with IMCL. IMCL based on MRSI for IR subjects was significantly greater than that for IS subjects (4.5+/-0.9% vs. 2.8+/-0.5%, P=.02).


CONCLUSIONS
MRI and MRS techniques provide a robust noninvasive measurement of abdominal fat and muscle IMCL, which are correlated with insulin action in humans.
Musculoskeletal Quantitative Imaging Research, Department of Radiology, University of California, San Francisco, CA 94107, USA. xiaojuan.li@radiology.ucsf.edu <xiaojuan.li@radiology.ucsf.edu>
Xiaojuan
X
Li
Jack F
JF
Youngren
Ben
B
Hyun
Giorgos K
GK
Sakkas
Kathleen
K
Mulligan
Sharmila
S
Majumdar
Umesh B
UB
Masharani
Morris
M
Schambelan
Ira D
ID
Goldfine
D050153:Abdominal Fat / Q000033:anatomy & histology*; D000328:Adult; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted; D007333:Insulin Resistance; D007866:Leg; D008055:Lipids / Q000032:analysis*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D008297:Male; D008875:Middle Aged; D018482:Muscle, Skeletal / Q000378:metabolism*
D008055:Lipids