A comparison of two different software packages for the analysis of body composition using computed tomography images.

Objectives: Body composition analysis from computed tomography (CT) imaging has become widespread. However, the methodology used is far from established. Two main software packages are in common usage for body composition analysis, with results used interchangeably. However, the equivalence of these has not been well established. The aim of this study was to compare the results of body composition analysis performed using the two software packages to assess their equivalence. Methods: Tri-phasic abdominal CT scans from 50 patients were analysed for a range of body composition measures at the third vertebral level using OsiriX (v7.5.1, Pixmeo, Switzerland) and SliceOmatic (v5.0, TomoVision, Montreal, Canada) software packages. Measures analysed were skeletal muscle index (SMI), fat mass (FM), fat free mass (FFM) and mean skeletal muscle Hounsfield Units (SMHU). Results: The overall mean SMI calculated using the two software packages was significantly different (SliceOmatic 51.33 vs. OsiriX 53.77, p<0.0001), and this difference remained significant for non-contrast and arterial scans. When FM and FFM were considered, again the results were significantly different (SliceOmatic 33.7kg vs. OsiriX 33.1kg, p<0.0001; SliceOmatic 52.1kg vs. OsiriX 54.2kg, p<0.0001, respectively), and this difference remained for all phases of CT. Finally, when mean SMHU was analysed, this was also significantly different (SliceOmatic 32.7 HU vs. OsiriX 33.1 HU, p=0.046). Conclusions: All four body composition measures were statistically significantly different by the software package used for analysis, however the clinical significance of these differences is doubtful. Nevertheless, the same software package should be utilised if serial measurements are being performed.