Sonographic subcutaneous and visceral fat indices represent the distribution of body fat volume.

Background: A reliable method for direct measurement of both subcutaneous and visceral fat volume is the measurement of fat tissue area from tomographic pictures by CT or by MR imaging. However, these are not widely usable because of high cost and/or exposure to radiation.

Methods: We compared sonographic subcutaneous and visceral fat indices with fat distribution by serial-slice MR imaging in 17 subjects. Sonographic subcutaneous or visceral fat index is standardized thickness of subcutaneous fat tissue or the intra-abdominal depth at the level of umbilicus by height.

Results: Sonographic visceral fat index and intra-abdominal depth were significantly correlated with visceral fat volume by serial-slice MR imaging (r = 0.746, r = 0.726, respectively). Similarly, sonographic subcutaneous fat index and subcutaneous fat thickness were significantly correlated with subcutaneous fat volume by serial-slice MR imaging (r = 0.825, r = 0.816, respectively). The ratio of sonographic visceral fat index and sonographic subcutaneous fat index was closely correlated with the ratio of the visceral fat volume and the subcutaneous fat volume by single-slice MR imaging, which proves to be related to cardiovascular disease risk (r = 0.722).

Conclusion: Sonographic subcutaneous or visceral fat index could be an easily measured and inexpensive indicator for the assessment of fat distribution instead of CT or MR imaging.