Abdominal wall fat index, estimated by ultrasonography, for assessment of the ratio of visceral fat to subcutaneous fat in the abdomen.

PURPOSE: To establish a new index of regional fat distribution using ultrasonography for assessment of the ratio of the visceral fat area (V) to the subcutaneous fat area (S) (V/S ratio). SUBJECTS AND METHODS: The subjects examined were 62 patients (23 males and 39 females); 51 patients had hyperlipidemia and 11 patients had glucose intolerance. The mean body mass indices ranged from 20.3 to 42.9. The mean age of the patients was 44 +/- 13 years. The thicknesses of the preperitoneal fat layer (P) and subcutaneous fat layer (S) in the abdomen were measured by ultrasonography and the P/S ratio was calculated. The V/S ratio was obtained with radiographic computed tomography.
RESULTS: Of the various P/S ratios examined, the ratio of the maximum thickness of preperitoneal fat to the minimum thickness of subcutaneous fat was most closely correlated with the V/S ratio (r = 0.746, p < 0.0001). This ratio was termed the abdominal wall fat index (AFI). AFI was positively correlated with serum triglyceride levels and negatively correlated with high-density lipoprotein cholesterol (r = -0.312, p < 0.05), whereas the V/S ratio was correlated with triglyceride levels. AFI was positively correlated with basal insulin levels in both men and women.
CONCLUSION: These results suggest that AFI measured by ultrasonography may be a new indicator of visceral fat deposition, and may reflect metabolic disorders such as lipid metabolism and glucose metabolism disorders.