Abdominal computed tomography and the placement of inferior vena caval filters

Standard cavography is performed with iodinated contrast material with plain film or digital subtraction technique. However, preplacement imaging may change final inferior vena cava filter (IVC) placement in 11 to 26% of patients. This study will examine the use and reliability of incidental spiral computed abdominal tomography (CAT) scans for the placement of IVC filters.

Over a 25-month period, CAT scan data were prospectively collected on patients at high risk for pulmonary embolism (PE) or with PE that required an IVC filter. CAT scans were then evaluated specifically for vena cava anatomy and relationship to renal veins and lumbar spine. IVC filters were then placed before cavography under fluoroscopy (performed only to confirm accurate placement) based on the static relationship of the renal veins/IVC and spine.

One hundred twenty-two patients had IVC filters placed. In the last 78 eligible patients, CAT scan placement was verified with post deployment cavography. IVC filters were deployed an average of 3.25 mm below the lowest renal vein with no veins misidentified. No strut malposition was noted on post deployment cavography. 12.1% had findings by CAT scan that altered some aspect of IVC filter placement.

Admission or same hospital stay spiral CAT scan can provide enough anatomic detail to safely guide placement of an IVC filter. IVC filters can be deployed at bedside without contrast cavography if the preplacement CAT scan is adequate.