Comparison of anthropometric, area- and volume-based assessment of abdominal subcutaneous and visceral adipose tissue volumes using multi-detector computed tomography.

PURPOSE: Cross-sectional imaging may enable accurate localization and quantification of subcutaneous and visceral adipose tissue. The reproducibility of multi-detector computed tomography (MDCT)-based volumetric quantification of abdominal adipose tissue and the ability to depict age- and gender-related characteristics of adipose tissue deposition have not been reported. METHODS: We evaluated a random subset of 100 Caucasian subjects (age range: 37-83 years; 49% women) of the Framingham Heart Study offspring cohort who underwent MDCT scanning. Two readers measured subcutaneous and visceral adipose tissue volumes (SAV and VAV; cm(3)) and areas (SAA and VAA; cm(2)) as well as abdominal sagital diameter (SD) and waist circumference (WC). RESULTS: Inter-reader reproducibility was excellent (relative difference: -0.34+/-0.52% for SAV and 0.59+/-0.93% for VAV, intra-class correlation (ICC)=0.99 each). The mean SAA/VAA ratio was significantly different from the mean SAV/VAV ratio (2.0+/-1.2 vs 1.7+/-0.9; P<0.001). The ratio of SAV/VAV was only weakly inversely associated with SD (ICC=-0.32, P=0.01) and not significantly associated with WC (ICC=-0.14, P=0.14) or body mass index (ICC=-0.17, P=0.09). The mean SAV/VAV ratio was significantly different between participants <60 vs >60 years (1.9+/-1.0 vs 1.5+/-0.7; P<0.001) and between men and women (1.2+/-0.5 vs 2.2+/-0.9; P<0.001). CONCLUSION: This study demonstrates that MDCT-based volumetric quantification of abdominal adipose tissue is highly reproducible. In addition, our results suggest that volumetric measurements can depict age- and gender-related differences of visceral and subcutaneous abdominal adipose tissue deposition. Further research is warranted to assess whether volumetric measurements may substantially improve the predictive value of obesity measures for insulin resistance, type 2 diabetes mellitus and other diseases.

Noninvasive imaging of the coronary arteries.

A reliable noninvasive imaging method for significant coronary artery stenosis would have enormous implications related to cost of diagnosis and enhanced patient safety. Cardiac motion and calcified plaques, in the past, rendered a substantial number of computed tomographic (CT) images of the coronary arteries uninterpretation. The accuracy of multidetector CT for the detection of coronary stenosis appears to have progressively improved as the imaging equipment increased from 4-slice and 16-slice to 64-slice CT. With 64-slice CT, scanning of the entire coronary artery tree is possible in 10 to 13 s. Pooled data of results of a few investigations with 64-slice CT showed that the proportion of unevaluable segments is only 4%. The sensitivity of 64-slice CT for the detection of significant (>50% or = or >50%) coronary stenosis in a patient, based on pooled data, was 97% and specificity was 91%. Regarding detection of significant stenosis in any segment, the sensitivity, based on pooled data, was 91% with 64-slice CT and specificity was 96%. In a limited number of patients, sensitivity for detection of significant stenoses in proximal segments was 100%, in mid segments it was 94%, and in distal segments sensitivity it was 80%. Multi-detector CT provides the opportunity to quantify non-calcified coronary artery plaques, which may potentially be a strong predictor of cardiac events. It was also shown to be useful for the detection of stenosis in coronary artery bypass grafts.