The Role of Ultrasonography in the Evaluation of Abdominal Fat: Analysis of Technical and Methodological Issues

Rationale and Objectives: Ultrasonography (US) is becoming popular for the assessment of adiposity, but no one has studied this tool in the light of its potential limitations. Our purpose was to investigate the impact of technical conditions on the evaluation of abdominal fat by US. Materials and Methods: Forty-five healthy males and 45 healthy females were consecutively enrolled in the study, randomly assigned to three groups equally distributed by sex, and examined accordingly to three technical points: fasting state (before and after meal [A]), breathing (expiration and inspiration [B]), and US equipment from different generations: 2003 and 1998 (C). Two blinded radiologists performed US in the these opposite conditions, acquiring five parameters representative of subcutaneous and visceral adiposity in two times. Student's t-test and Lin's correlation coefficient were used for statistical analysis to assess differences in the measures as well as in inter- and intra-observer agreements. Results: The maximum and the only statistically significant changes were observed for intra-abdominal fat thickness regarding fasting state and breathing (Delta% = 24.1 +/- 21.3 and Delta% = 9.2 +/- 20.4, respectively; P < .0001). Reproducibility and repeatability, especially for visceral fat, were proved more stable in the following conditions: fasting state, expiration, and newer machine (2003). Conclusion: This article provides essential information and "range of confidence" for variations that can be expected from using different conditions in the measurement of abdominal adiposity by US to be carefully addressed as well as considered by US users and by researchers involving this technique in the field of body composition.