ObjectiveTo discusses the MSCT multiplanar reconstruction manifestation (MPR) of localized fat collection adjaction to subdiaphragmatic inferior vena cava (IVCfat).MethodsThe thoracic and abdominal MSCT scan data of 8246 patients were browsed,45 patients with presumed IVCfat on axial CT scans were further studied prospectively with MSCT MPR.The predisposing position of IVCfat and its relationship with IVC were observed.It was divided into two kinds of intraluminal type and extraluminal type according to the angle of IVCfat with respect of the wall of IVC.The other 50 patients without IVCfat were randomly selected as the control group.The sagittal inclination angle (SIA) and diameter ratio (DR) between supra- and sub-diaphragmatic IVC between the two groups were compared by using t test.Results The detection rate was 0.55％ (45/8246).Of which hepatic vein lacuna 8 patients,subdiaphragmatic gap medial to IVC 28 patients and IVC groove 9 patients.The shape of IVCfat showed mainly for the round,oval and crescents on axial CT scans,of 15 patients intraluminal type,4 showed target signs .The shape of IVCfat showed mainly for half-moon at MPR.The SIA and DR at IVCfat group were 21.62° ± 8.42°and 2.01 ±0.84 respectively,at control group were 16.75° ±7.82°(t =1.594,P ＞0.05) and 1.31 ±0.28(t =2.341,P ＜ 0.05 ) respectively.ConclusionThe round,oval or half of limited fat density shadow adjaction to subdiaphragmatic inferior vena cava which similar to in the lumen is the characteristic performance of IVCfat,it may be an anatomical variation.