Magnification spot radiographs (MSR)improve the detection of inferior vena cava (IVC) filter fractures, according to a study by researchers at the Perelman School of Medicine at the University of Pennsylvania in Philadelphia.
As a result, authors of the study, appearing in the January 2020 Journal of Vascular and Interventional Radiology, recommend MSR for routine treatment planning before filter removal.
Filter fractures can be lethal if fragments migrate to the heart and cause cardiac perforation. Because removal of a fractured filter may differ from that of an intact one, patients must be evaluated with pre-procedure imaging.
The retrospective study by interventional radiologists was conducted to compare the accuracy of MSR with computed tomography (CT) in evaluating IVC filter fractures prior to filter removal. MSR using fluoroscopy is routinely acquired at the Hospital of the University of Pennsylvania, where interventional radiologists believe their increased spatial resolution facilitates better assessment of IVC filters than does CT.
The patient cohort consisted of 96 patients requiring complex IVC filter removals between October 2015 through April 2017. Six types of filters had been implanted, and 28% of the 96 filters had fractured. Two interventional radiologists independently reviewed CT and MSR images, classifying each as negative or positive for at least one filter fracture.
The MSR images were more accurate than CT imaging for the assessment of filter fractures, reported lead author Vlasios S. Sotirchos, MD, and colleagues. Accuracy of the former was 98% for both readers compared to 89% (reader 1) and 68% (reader 2) for CT. The sensitivity of MSR was 93% for both radiologists, compared to 63% (reader 1) and 33% (reader 2) for CT. Specificity for MSR was comparable to CT for reader 1, at 100% and 99%, respectively, but was superior for reader 2, with a specificity of 99% for MSR compared to 81% for CT.
The retrospective nature of the study prevented assessment of changes in treatment planning, according to the researchers.
“Magnification spot radiographs acquired before attempting IVC filter removal improves detection of filter fractures and agreement among interventional radiologists. Therefore, these should be performed routinely to allow for optimal treatment planning,” they concluded.
Magnification Spot Radiographs Improve IVC Filter Fracture Assessment. Appl Radiol.