Intermuscular adipose tissue (IMAT): association with other adipose tissue compartments and insulin sensitivity.

Purpose: To quantify intermuscular adipose tissue (IMAT) of the lower leg as well as to investigate associations with other adipose tissue (AT) compartments. The relationship between IMAT and insulin sensitivity was also examined.
Materials and Methods: Standardized quantification of IMAT was performed in a large cohort (N = 249) at increased risk for type 2 diabetes in the right calf by T1-weighted fast spin-echo imaging at 1.5T (Magnetom Sonata; Siemens Healthcare). Additionally, whole-body AT distribution was assessed. Insulin sensitivity was determined by glucose clamp.
Results: Males showed significantly more IMAT than females (2.1 +/- 1.1 cm(2) vs. 1.5 +/- 0.9 cm(2); P < 0.001). IMAT correlated well with other AT depots, especially with visceral AT (VAT; r(females) = 0.52, P < 0.0001 vs. r(males) = 0.42, P < 0.0001). Moreover, IMAT showed a negative correlation with the glucose infusion rate (GIR; r(females) = -0.43, P = 0.0002 vs. r(males) = -0.40, P = 0.0007).
Conclusion: Quantification of IMAT is possible by standard MR techniques. AT distribution of the lower leg is comparable to the visceral compartment with males having higher IMAT/VAT but lower subcutaneous AT (SCAT). IMAT seems to be involved in the pathogenesis of insulin resistance, as shown by the significant negative correlation with GIR.