Rollins Katie E, Javanmard-Emamghissi Hannah, Awwad Amir, Macdonald Ian A, Fearon Kenneth C H, Lobo Dileep N
Gastrointestinal Surgery, Nottingham Digestive Diseases Centre, National Institute for Health Research Biomedical Research Centre, Nottingham University Hospitals and University of Nottingham, Queen's Medical Centre, Nottingham, UK.
Sir Peter Mansfield Imaging Centre (SPMIC), University of Nottingham, University Park, Nottingham, UK.
Nutrition. 2017 Sep;41:37-44. doi: 10.1016/j.nut.2017.02.011. Epub 2017 Apr 6.
The aim of this study was to determine, from the methodologic standpoint, the effect of the presence or absence of intravenous contrast on body composition variables obtained by analysis of computed tomography (CT) images.
Triphasic abdominal (noncontrast, arterial phase, and portovenous phase contrast) CT scans from 111 patients were analyzed by two independent assessors at the third lumbar vertebral level using SliceOmatic software (version 5.0, TomoVision, Montreal, Canada). Variables included skeletal muscle index (SMI), fat and fat-free mass (FM and FFM, respectively), and mean skeletal muscle Hounsfield units (SMHU).
Mean SMHU was lowest in the noncontrast phase (29.4, standard deviation [SD] 8.9 HU), followed by arterial (32.4, SD 9.3 HU) then portovenous phases (34.9, SD 9.4 HU). The mean skeletal muscle attenuation was significantly different depending on the phase of the scan in which the images were obtained. Calculated FM was significantly lower in both arterial (28.6, SD 8.8 kg, P < 0.0001) and portovenous phase scans (28.5, SD 8.9 kg, P < 0.0001) when compared with noncontrast (29.2, SD 8.9 kg). The mean FFM was not significantly different as measured on noncontrast, arterial, or portovenous phase CT scans (48, SD 11.2; 48.1, SD 9.8; and 48.6, SD 10.2 kg, respectively). No difference was seen in SMI. Interobserver reliability was high.
The definition of myosteatosis should include a standardized phase of CT for analysis and this should be incorporated within its definition. However, as the magnitudes of the differences were relatively small, the effect of the phase of the scan on predicting outcome needs to be determined.
本研究旨在从方法学角度确定静脉造影剂的有无对通过计算机断层扫描（CT）图像分析获得的身体成分变量的影响。
两名独立评估人员使用SliceOmatic软件（5.0版，TomoVision，加拿大蒙特利尔）在第三腰椎水平对111例患者的三相腹部CT扫描（非增强、动脉期和门静脉期造影）进行分析。变量包括骨骼肌指数（SMI）、脂肪和去脂体重（分别为FM和FFM）以及平均骨骼肌亨氏单位（SMHU）。
平均SMHU在非增强期最低（29.4，标准差[SD]8.9 HU），其次是动脉期（32.4，SD 9.3 HU），然后是门静脉期（34.9，SD 9.4 HU）。根据获取图像的扫描期相不同，平均骨骼肌衰减存在显著差异。与非增强扫描（29.2，SD 8.9 kg）相比，动脉期（28.6，SD 8.8 kg，P < 0.0001）和门静脉期扫描（28.5，SD 8.9 kg，P < 0.0001）计算得出的FM均显著降低。非增强、动脉期或门静脉期CT扫描测得的平均FFM无显著差异（分别为48，SD 11.2；48.1，SD 9.8；48.6，SD 10.2 kg）。SMI未见差异。观察者间可靠性较高。
肌脂肪变性的定义应包括用于分析的标准化CT期相，且应纳入其定义中。然而，由于差异幅度相对较小，扫描期相对预测结果的影响有待确定。
