Kinh Gian Do MD,PhD, Presenter: Nothing to Disclose

Bachir Taouli MD, Abstract Co-Author: Nothing to Disclose

Mark E. Schweitzer MD, Abstract Co-Author: Nothing to Disclose

The physiologic literature differentiates essential from storage fat. As this concept is not widely recognized in the imaging literature, we investigated with 3T MRI, the effect of rapid weight loss on the different fat compartments.

Eight patients undergoing rapid, medically supervised weight loss were studied with 3T MRI before and after a liquid diet of approximately two weeks. Fat compartments were analyzed on single-slice breath-hold axial water-suppressed images (TR 200 ms, TE 2.32 ms, slice thickness 1 cm). The following measurements were made via electronic calipers at the L1 level by a single observer as windows into physiologically recognized fat compartments: abdominal diameter (including subcutaneous and visceral fat), spinal epidural fat diameter (AP+transverse diameters) and the grade of fat in the paraspinal muscle (marbling). The latter was graded according to an accepted methodology of Goutallier et al, from 0-4 (0=no fatty infiltration, 1=some fatty streaks, 2=less fat than muscle, 3=as much fat as muscle, 4=more fat than muscle).

The pre- and post-diet images for the eight patients were obtained an average of 14.1 days apart. The mean weight loss was 7.4 kg, with a standard deviation (SD) of 3.4 kg. The baseline and follow-up abdominal diameters were 31.9 cm and 30.5 cm, with a mean decrease of 13 mm (SD 7 mm) (P=0.001). The baseline and follow up epidural diameters were14 and 13 mm, with no change (P=0.09). Average paraspinal muscle marbling grades were 1.6 (range 1-2) and were unchanged between the two time points.

Rapid weight loss was concomitant with visceral and subcutaneous fat loss, with no significant loss of fat from the epidural space or within paraspinal muscles as visualized by MRI, supporting a different role for these fat compartments.

These findings suggest differing physiologic roles for different fat compartments, as shown by their variable responses to rapid weight loss.

Do, K, Taouli, B, Schweitzer, M, Effect of Weight Loss on Different Fat Compartments: Prospective Evaluation with 3T MRI.  Radiological Society of North America 2006 Scientific Assembly and Annual Meeting, November 26 - December 1, 2006 ,Chicago IL. http://archive.rsna.org/2006/4433116.html