[Effects of Different Respiratory Phases on Radiation Dose and Abdominal Fat Area Measurements in Abdominal CT].

PURPOSE: To investigate the effects of different respiratory phases on radiation dose and abdominal fat area measurements in abdominal computed tomography (CT).

METHODS

Thirty-three patients who underwent abdominal CT examinations in both inspiratory and expiratory phases within one year were retrospectively analyzed. Scan length, CT dose index volume (CTDIvol), dose-length product (DLP), maximum abdominal thickness, visceral fat area (VFA), and subcutaneous fat area (SFA) were evaluated. Differences between inspiration and expiration were assessed using the Wilcoxon signed-rank test. Linear regression analysis was performed to evaluate the relationship between fat areas measured in the two phases.

RESULTS

Maximum abdominal thickness, VFA, and CTDIvol showed a slight but significant increase during inspiration (p<0.05). In contrast, DLP was significantly lower during inspiration (p<0.05). No significant difference was observed in SFA. Regression analysis showed that VFA increased during inspiration, whereas SFA did not change significantly.

CONCLUSION

Differences in respiratory phases during abdominal CT affect VFA measurements and DLP. VFA was significantly higher during inspiration, whereas SFA was minimally affected. Although CTDIvol increased during inspiration, the overall radiation dose, as reflected by DLP, decreased due to the shorter scan length. Standardization of the respiratory phase is essential for accurate assessment of visceral fat area in abdominal CT.