Xiaoen Wang MD, Presenter: Nothing to Disclose

Aristidis Veves DSc, MD, Abstract Co-Author: Nothing to Disclose

Robert L. Greenman MD, PhD, Abstract Co-Author: Nothing to Disclose

Metabolic abnormalities and fatty infiltration of the muscles of the foot are both consequences of diabetic lower extremity disease. We applied proton MR (1H-MR) spectroscopy and phosphorus-31 (31P) MR imaging to gain insights into the relationship between the muscle energy metabolism and the muscular fat content in the diabetic foot.

Data were acquired at 3.0 T using a double-tuned (31P/1H) birdcage RF coil for MR of the foot. Twenty-one diabetic patients and 14 normal controls were studied. The patients with diabetes were divided into those with lower extremity neuropathy (n=7) and those without neuropathy (n=14). Single-voxel 1H spectra were acquired using the point resolved spectral selection (PRESS) technique without water suppression. A voxel (15 x12 x10 mm3) was prescribed in an area of muscle at the center of the metatarsal head region on a T2-weighted image acquired earlier.The ratio of total lipids to water was calculated from the areas of lipid and water spectral peaks. Axial inorganic phosphate (Pi) and phosphocreatine (PCr) images were simultaneously acquired through the center of the metatarsal head region using the rapid acquisition with relaxation enhancement (RARE) imaging method. Pi:PCr ratio maps were generated from the Pi and PCr images. 

The lipid:water ratio was significantly different between the normal and neuropathic group (0.21 ± 0.11 vs 1.40 ± 0.78, p<0.001), whereas no significant difference was seen between the normal and non-neuropathic groups (0.24 ± 0.15, p=0.59). There was a good correlation (r=0.78) between the lipid:water ratio and Pi:PCr ratio. The average Pi:PCr ratio was significantly different among the normal control, non-neuropathic, and neuropathic groups (0.26 ± 0.06, 0.38 ± 0.07, and 0.58 ± 0.23, respectively; p<0.001).

A relationship exists between muscular fat content and the energy metabolism in the foot muscles of diabetic patients with changes in energy metabolism preceding changes in muscular fat content. The direct measurement of phosphorus energy metabolites may be a more sensitive indicator than the fat content in foot muscle to identify diabetic patients who are at risk of developing complications.

 Measurement of the 31P energy metabolism of the muscle in the feet of diabetic patients may help clinicians to identify patients at risk for developing foot disorders.

Wang, X, Veves, A, Greenman, R, The Relationship between Muscle Energy Metabolism and Muscular Fat in the Diabetic Foot.  Radiological Society of North America 2008 Scientific Assembly and Annual Meeting, February 18 - February 20, 2008 ,Chicago IL. http://archive.rsna.org/2008/6012491.html