title: Can Pre-Retrieval Computed Tomography Predict the Difficult Removal of an Implementing an Inferior Vena Cava Filter?
abstract: OBJECTIVE
  Implementing an inferior vena cava (IVC) filter is a relatively safe procedure but potential negative long-term effects. The complications for filter retrieval have been noted. We examined filter characteristics on pre-retrieval computed tomography (CT) that were associated with complicated retrieval (CR) of IVC filters.
  
  
  METHODS
  A retrospective review of IVC filter retrievals between January 2008 and June 2014 was performed to identify patients who had undergone a pre-retrieval CT for IVC filter retrieval. CR was defined as the use of nonstandard techniques, procedural time over 30 min, filter fractures, filter tip incorporation into the IVC wall, and retrieval failure. Pre-retrieval CT images were evaluated for tilt angle in the mediolateral and anteroposterior directions, tip embedding into the IVC wall, degree of filter strut perforation, and distance of the filter tip from the nearest renal vein.
  
  
  RESULTS
  Of seventy-six patients, twenty-four patients (31.6%) with CRs and 56 patients (73.7%) with non-CR were evaluated for pre-retrieval CT. For IVC filter retrieval with a dwelling time of over 45 days, a tilt of over 15 degrees, the appearance of tip embedding and grade 2 perforation were associated with CR on multivariate analysis. However, for IVC filter retrievals with a dwelling time of less than 45 days, there were no factors associated with CR.
  
  
  CONCLUSIONS
  Pre-retrieval CTs may be more effective for IVC filters with a dwelling time of over 45 days. Therefore, a pre-retrieval CT may be helpful in predicting CR of IVC filters with long dwelling times.
authors.affiliation: Departments of Surgery, College of Medicine, Inha University, Incheon, Korea.
authors.forename: Shinho
authors.initials: S
authors.lastname: Hong
authors.affiliation: Departments of Surgery, College of Medicine, Inha University, Incheon, Korea.
authors.forename: Keun-Myoung
authors.initials: KM
authors.lastname: Park
authors.affiliation: Radiology, College of Medicine, Inha University, Incheon, Korea.
authors.forename: Yong Sun
authors.initials: YS
authors.lastname: Jeon
authors.affiliation: Radiology, College of Medicine, Inha University, Incheon, Korea.
authors.forename: Soon Gu
authors.initials: SG
authors.lastname: Cho
authors.affiliation: Departments of Surgery, College of Medicine, Inha University, Incheon, Korea.
authors.forename: Kee Chun
authors.initials: KC
authors.lastname: Hong
authors.affiliation: Departments of Surgery, College of Medicine, Inha University, Incheon, Korea.
authors.forename: Woo Young
authors.initials: WY
authors.lastname: Shin
authors.affiliation: Departments of Surgery, College of Medicine, Inha University, Incheon, Korea.
authors.forename: Yun-Mee
authors.initials: YM
authors.lastname: Choe
keywords: Device removal; Vena cava filters; Venous thrombosis