SHORT-TERM FOLLOW-UP OF INFERIOR VENA-CAVAL FILTERS - COMPARISON OF IMAGING TECHNIQUES

OBJECTIVE. The aim of this prospective study was to assess the advanta ges and limitations of various imaging techniques in identifying probl ems associated with percutaneous placement of filters in the inferior vena cava. SUBJECTS AND METHODS. One hundred four vena caval filters ( 65 Filcard, 39 Cardial) were placed in 100 patients (four patients rec eived two filters). Venacavograms, duplex sonograms of the abdomen, ab dominal radiographs, perfusion scans of the lung, and impedance plethy smograms were obtained in all patients within 1-2 days and 3 months af ter filter placement. CT scans of the filter were obtained in 55 patie nts. RESULTS. In five patients, thrombosis of the inferior vena cava, with retraction of the filter struts in four patients, was noted on ve nacavograms, CT scans, duplex sonograms, and impedance plethysmograms. Perforation of the inferior vena cava was noted in 36 patients after comparison of findings on venacavograms and CT scans, with an increase in the filter span in 29 patients (apparent on duplex sonograms in on ly two patients). Four filter tiltings (>30-degrees) and 25 migrations (>5 mm) were noted on abdominal radiographs. Trapped thrombi in the f ilter were shown on venacavograms in nine cases, but on duplex sonogra ms and unenhanced CT scans in only two cases. CONCLUSION. Our study sh ows that the major complications of inferior vena caval filters can be detected by noninvasive examinations. Only venacavograms consistently show small trapped thrombi that do not extend above the filter, but t he importance of such thrombi is unknown.