Abstract
Appropriate placement of an inferior vena cava (IVC) filter necessitates imaging of
the renal veins because when an IVC filter is deployed its tip should be at or below
the inferior aspect of the inferiormost renal vein. Traditionally, imaging during
placement of IVC filters has been with conventional cavography and fluoroscopy. Recently,
intravascular ultrasound has been used for the same purpose but with additional expense.
Morbidly obese patients often exceed the weight limit of fluoroscopy tables. In addition,
short obese patients are at risk of falling from narrow fluoroscopy tables. For such
patients, computed tomography (CT) guidance is a viable alternative to conventional
fluoroscopic guidance.
IVC placement was performed in the CT suite for two obese patients who exceeded the
weight limits of the available fluoroscopy tables. In one case, a Vena-Tech filter
(Braun Medical, Melsungen, Germany) was placed using CT fluoroscopy. In the second
case, a Recovery (Bard, Murray Hill, NJ) filter was placed using intermittent limited
z-axis scanning.
In the first case, the filter was placed below the level of the renal veins and above
the confluence of the iliac veins, which is acceptable placement. In the second case,
with refinement of technique, the filter tip was placed less than 1 cm below the inferiormost
renal vein, which is considered optimal placement.
CT of the IVC precisely images the renal veins and can characterize their number and
their confluence with the IVC. CT guidance is a viable alternative to fluoroscopic
guidance for the placement of IVC filters in morbidly obese patients.
Keywords
inferior vena cava - computed tomography - filterplacementguidance - deep vein thrombosis
- obesity
