IVC filters are intended to prevent the passage of thrombus from the deep veins in the legs to the pulmonary arteries. Accepted indications for IVC filter placement include the presence of acute venous thromboembolism with inability to administer anticoagulation medication or failure of anticoagulation. However, IVC filters are not free of complications, which may occur during implantation/retrieval of the filter and while the filter is retained in the body.
Complications of retained filters include filter migration or embolization (3% to 69%), strut fracture and penetration (9% to 24%), IVC thrombosis (6% to 30%), lower extremity edema, post-thrombotic syndrome (5% to 70%), deep vein thrombosis (0% to 20%), and recurrent pulmonary embolism (3% to 7%). To mitigate the above-mentioned complications, confirmation of proper IVC filter deployment and surveillance is required. Unfortunately, IVC thrombosis can be asymptomatic and only discovered when imaging is performed. Computed tomography angiography (CTA) or conventional angiography is usually performed in the assessment of intrafilter thrombosis. At UW Health the correct placement of the filter and the presence of trapped thrombus is assessed routinely by CTA.
We will perform parameter optimization for improved lumen visualization and reliable detection of thrombi using a state-of-the-art MR method, ultrashort echo time (UTE) technique, developed by researchers at UW-Madison. The sequence will be optimized using different flip angles, spatial resolutions and RF pulses to minimize artifacts induced by the IVC filter and maximize the contrast between the IVC vessel lumen, the IVC filter and trapped thrombus.