The Simon Nitinol Filter: Evaluation by MR and Ultrasound

• Published in: Angiology 1992-07, Vol.43 (7), p.541-548
• Main Authors: Kim, Ducksoo, Edelman, Robert R., Margolin, Chaim J., Porter, David H., McArdle, Colin R., Schlam, Bertrand W., Gianturco, Laurie E., Siegel, Jeffrey B., Simon, Morris
• Format: Article
• Language: English
• Subjects: Adult; Aged; Aged, 80 and over; Alloys; Biological and medical sciences; Evaluation Studies as Topic; Female; Humans; Magnetic Resonance Imaging; Male; Medical sciences; Middle Aged; Prospective Studies; Surgery (general aspects). Transplantations, organ and tissue grafts. Graft diseases; Thrombosis - diagnosis; Thrombosis - diagnostic imaging; Ultrasonography; Vascular Patency; Vascular surgery: aorta, extremities, vena cava. Surgery of the lymphatic vessels; Vena Cava Filters; Vena Cava, Inferior - diagnostic imaging; Vena Cava, Inferior - pathology
• ISSN: 0003-3197; 1940-1574
• DOI: 10.1177/000331979204300701

In this prospective blinded study of inferior vena caval (IVC) patency, 18 patients underwent 25 duplex ultrasound (US) and magnetic resonance (MR) angiography examinations over an eight-month period following Simon nitinol filter placement. Clinical examination for lower extremity venous stasis and plain abdominal radiography were also performed. Twenty-three of 24 MR ex aminations and 11 of 24 US examinations were judged technically adequate by the blinded observers. One technically adequate US exam was false positive for intraluminal caval thrombus. Thirteen technically inadequate US examinations missed 3 complete caval occlusions and 2 partial occlusions. MR identified all patients with complete or partial caval occlusion. The authors conclude that duplex US reliably confirms IVC patency only when strict criteria for technical adequacy and interpretation are met (good visualization of filter and IVC above and below filter). MR, although expensive, more reliably identifies nonoccluding intraluminal thrombus and caval occlu sion. It should be the noninvasive study of choice in symptomatic patients with venous stasis and patients with recurrent pulmonary emboli.