Abstract:
HTML
Purpose: Body fat assessment in vivo may be performed with CT. The accuracy of conventional techniques including skin-fold calipers has been questioned. Single slice measurements on CT has also been performed at specific anatomic levels. The purpose of this study was to develop an algorithm to automatically identify all fat pixels in the abdomen and pelvis and to quantify the volumetric visceral and subcutaneous fat. These measures were compared to conventional single slice methodology.
Methods and Materials: All voxels having HU values between -190 and -30 were considered fat. The body contour was extracted from CT images. Radii at a fixed angle increment were made from the body center point to the body contour point. Along each radius, the density profile was analyzed to determine the start and the end points of the subcutaneous fat. Smoothing was performed to avoid sub-optimal extraction of the internal contour. Subcutaneous and visceral fat were automatically segmented on 238 CT slices in 5 patients within the abdomen and pelvis. Volumetric visceral fat to total fat ratio and visceral fat to subcutaneous fat ratio were calculated and compared on average as well as with single slice data at the L4 vertebral body level and the L5 vertebral body level.
Results: The algorithm was able to perform segmentation in all cases. The volumetric average ratio of visceral fat to total fat per patient ranged from 10 to 43% and the volumetric average ratio of visceral fat to subcutaneous fat ranged from 11 to 75%. The difference in the single slice ratio of visceral to total fat between the L4 and L5 level ranged from 0 to 6% and from 0 to 17% for the visceral to subcutaneus ratio. Similarly, the difference between the volumetric visceral to total fat and single slice L4/L5 ratio ranged from 1 to 5%, however the difference between volumetric visceral to subcutaneous fat and single slice L4/L5 level ratio ranged from 1 to 16%.
Conclusion: Compartmental fat, including visceral and subcutaneous fat, may be automatically segmented on contiguous CT slices. By summation, total compartmental fat may be calculated for the entire abdomen and pelvis. Single slice ratios of visceral and subcutaneous fat approximate total fat ratios but there are differences up to 17%.
Questions about this event email: zhaob@mskcc.org
Zhao DSc, B,
Quantification of Body Fat Distribution in the Abdomen and Pelvis on CT with Automated Fat Segmentation. Radiological Society of North America 2003 Scientific Assembly and Annual Meeting, November 30 - December 5, 2003 ,Chicago IL.
http://archive.rsna.org/2003/3108487.html
