描述下腔静脉滤器置入后的CT表现，探讨CT评估下腔静脉滤器置入后状态及相关并发症的价值。

收集2011年1月—2016年5月置入下腔静脉滤器的患者31例，均行腹部CT平扫加增强扫描并行三维重组。在CT图像上评估下腔静脉滤器的位置、形态及并发症情况。

(1)CT及三维重组图可清晰显示下腔静脉滤器并确定其类型。31例中Ease型（包括可回收的Opt型）12例，表现为六菱形，6个支脚在上下端汇合形成对称性双层网篮，其中Opt Ease型滤器下端见回收钩；Vena Tech型7例,表现为6~8个放射状支脚连接成圆锥状，周围为垂直支撑杆；Günther Tulip型6例，呈倒置"郁金香"状，顶端为挂钩，下方4个支脚；Simon Nitinol型4例，表现为叠伞状，由8个部分重叠的环组成上方的"伞"，6个背离的支撑脚组成下方的"伞"；Tempofilter II型临时性可回收滤器2例，表现为长柄伞状，下方为8个脚形成锥状网篮，长回收柄与之相连，位于颈内静脉至下腔静脉行程内。(2)滤器位于双肾静脉以下者28例，属常规放置位置；位于双肾静脉以上者3例，均为双肾静脉以上的下腔静脉内血栓形成后再置入滤器。(3)滤器内及以上的腔静脉见明显血栓10例，其中1例下腔静脉狭窄；滤器内未见明确血栓21例。(4)31例滤器均未见主体或支脚断裂。1例明显移位至肝段下腔静脉并穿透至肝实质；另30例按滤器脚穿透腔静脉壁的程度分为四级，0级7例，1级13例，2级3例，3级7例（穿透至主动脉壁及腰椎3例，穿透至右侧腰大肌及回肠1例，穿透至主动脉壁、腰椎前缘、右侧膈肌脚各1例）。滤器轴向明显偏斜7例，表现为滤器纵轴与下腔静脉纵轴间夹角超过15°，以冠状位和矢状位重组显示为佳。

CT能清楚显示下腔静脉滤器的形态、位置及相关并发症情况，可为临床回收滤器和处理并发症提供参考。

To discuss the CT findings after inferior vena cava(IVC) filter placement, and their value in evaluating the status of IVC filters after placement and related complications.

Pertinent data of 31 cases with IVC filter placement who underwent abdominal CT plain scan, contrast-enhanced scan and 3D reconstruction from January 2011 to May 2016 was collected for this study. The location, morphology and complications of IVC filters were evaluated on CT images.

(1) CT and 3D reconstruction images can clearly display the IVC filter and determine its type. Among the 31 cases, 12 cases of Ease type (including the retrievable Opt type) showed six-diamond shape, and 6 struts converging at the upper and lower apex of the filter formed the symmetric double baskets, with a retrieval hook in the bottom of OptEase filter; 7 cases of Vena Tech showed a cone shape formed by 6~8radial prongs, with vertical stabilizing struts around; 6 cases of Günther Tulip presented as inverted "tulip" shape, with a hook at the top and 4 struts below; 4 cases of Simon Nitinol presented as overlapping "umbrellas" , with 8 partially overlapping loops forming the top "umbrella" , and 6 diverging legs forming the lower "umbrella" ; 2 cases of temporary retrivable filter Tempofilter II showed long-arm "umbrella" shape, with 8 struts forming the cone-shaped basket, connected with long retrieval handle located in the course from internal jugular vein to inferior vena cava. (2) In 28 cases the filters were located in the infrarenal IVC, which was the conventional position, while 3 cases were in the suprarenal IVC, all of which formed suprarenal IVC thrombus before filter placement. (3) 10 cases showed obvious thrombus in the filters and above IVC, 1 of which also showed IVC stenosis, while no thrombus was found in the remaining 21 cases. (4) None of the 31 cases showed rupture of the main body or struts of IVC filters. 1filter migrated to the hepatic IVC and penetrated to liver parenchyma; the other 30 cases were classified into four grades according to IVC filter strut interactions with IVC wall. There were 7 cases classified as Grade 0, 13 cases as Grade 1, 3 cases as Grade 2, and 7 cases as Grade 3 (3 cases penetrating to the aortic wall and lumbar vertebrae, 1 case to the right psoas major and ileum, and 1 each to the aortic wall, anterior lumbar, and right diaphragmatic crura). The filters were significantly tilted in 7 cases, with the angle between the central longitudinal axis of the filter and the IVC being more than 15°, which showed the best result with coronal and sagittal reconstruction.

CT can clearly show the shapes, location and complications of IVC filters, which can provide a good way for retrieval of filters and treatment of complications.