MRI of fat distribution in a mouse model of lysosomal acid lipase deficiency

OBJECTIVE. We assessed the use of MRI in the evaluation of abdominal fat distribution in a lysosomal acid lipase (LAL)-deficient mouse model. MATERIALS AND METHODS. LAL-deficient mice are born with a normal fat distribution but over time deplete the fat stores in the subcutaneous and retroperitoneal tissues and accumulate fat in the liver, spleen, and bowel. Four MRI studies of LAL-deficient mice and control mice were obtained with 3-T T1-weighted spin-echo images and volume segmentation processing to create parameters for the study of fat distribution: intraabdominal adipose tissue-subcutaneous adipose tissue (IAT/SAT) ratio, liver volume, reproductive fat, and retroperitoneal fat. MRI adiposity parameters in LAL-deficient mice were compared with those in control mice. Adiposity volumes calculated on MRI were compared with those calculated at autopsy. RESULTS. Statistically significant differences were found between LAL-deficient and control mice for IAT/SAT ratio (p = 0.0336), liver volume (p = 0.0336), and reproductive fat (p = 0.0336), and a statistically significant trend was found for retroperitoneal fat (p = 0.0514). No statistically significant difference was found between adiposity volumes calculated on MRI and adiposity volumes found at autopsy (all p > 0.2). CONCLUSION. Use of an in vivo model showed MRI techniques to be accurate in predicting visceral adiposity. LAL-deficient mice provided a unique model showing a pattern of adipose distribution that is markedly different from that in control mice, and MRI may provide a means of evaluating therapeutic interventions sequentially.