n. an image of the vena cava, either inferior or superior. After injecting a radiographic contrast medium in a peripheral vein, the vena cava can be imaged with X-rays (see fluoroscopy) while the contrast arrives. Alternatively, a catheter can be inserted into a vein and advanced to the vena cava, then the contrast medium is injected to image it. Noninvasive imaging with CT or MRI scan is possible, but the image quality is inferior to fluoroscopic imaging.
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