Quantification of intravenously administered contrast medium transit through the peripheral arteries: implications for CT angiography.
OBJECTIVE
To prospectively determine the range of aortopopliteal bolus transit times in patients with moderate-to-severe peripheral arterial occlusive disease (PAOD) as a guideline for developing injection strategies for computed tomographic (CT) angiography of peripheral arteries.


METHODS
The study protocol was approved by the local ethics board, and informed consent was obtained. Twenty patients with PAOD referred for CT angiography of the lower extremities were categorized into two groups, Fontaine stage IIb (group 1) and stage III or IV (group 2), and demographic information was collected. In all patients, a 16-mL test bolus was injected intravenously, and single-level dynamic acquisitions were obtained at the level of the abdominal aorta. After injection of a second 16-mL test bolus, dynamic acquisitions were obtained at the level of the knee (popliteal arteries). Aortopopliteal bolus transit times were calculated by subtracting the time to peak enhancement in the popliteal arteries from that in the aorta. Aortopopliteal transit speeds also were derived. Transit times and speeds were compared graphically between clinical stage groups. The time required for the contrast medium to enhance the entire peripheral arterial tree in patients with PAOD was estimated by using linear extrapolation.


RESULTS
Sixteen men and four women with a mean age of 69 years (range, 49-86 years) were included. Twelve patients were included in group 1, and eight patients, in group 2. Aortopopliteal bolus transit times ranged from 4 to 24 seconds (median, 8 seconds) in all subjects, which corresponded to bolus transit speeds of 177 and 29 mm/sec, respectively. Wide overlap of transit times and transit speeds was observed between clinical stage groups. The estimated time needed for the bolus to enhance the entire peripheral arterial tree was 6-39 seconds.


CONCLUSIONS
Aortopopliteal bolus transit times differ widely among patients and may be substantially delayed in all patients with PAOD. Empirical injection protocols should include an injection duration of 35 seconds or more, as well as an increased scanning delay, with table speeds of more than 30 mm/sec.
Fleischmann
Dominik
D
Department of Angiography and Interventional Radiology, Medical University of Vienna, Vienna, Austria. d.fleischmann@stanford.edu
Rubin
Geoffrey D
GD
D000368:Aged; D000369:Aged, 80 and over; D000792:Angiography / Q000379:methods*; D001157:Arterial Occlusive Diseases / Q000000981:diagnostic imaging*; D016001:Confidence Intervals; D003287:Contrast Media / Q000008:administration & dosage / Q000493:pharmacokinetics*; D005260:Female; D006801:Humans; D007275:Injections, Intravenous; D007479:Iopamidol / Q000008:administration & dosage / Q000493:pharmacokinetics*; D007866:Leg / Q000098:blood supply; D008297:Male; D008875:Middle Aged; D016491:Peripheral Vascular Diseases / Q000000981:diagnostic imaging*; D011446:Prospective Studies; D014057:Tomography, X-Ray Computed
D003287:Contrast Media; D007479:Iopamidol