Radiology, Vol 194, 83-90, Copyright © 1995 by Radiological Society of North America
Helical CT during arterial portography: optimization of contrast enhancement and scanning parameters
PC Freeny, HV Nghiem and TC Winter
Department of Radiology SB-05, University of Washington School of Medicine, Seattle 98195.
PURPOSE: To determine the optimal scanning parameters for helical computed
tomography during arterial portography (CTAP) of the liver. MATERIALS AND
METHODS: Single- and double-helix CTAP were performed in 11 and 20 adult
patients, respectively, with 200 mL of contrast material (300 mg of iodine
per milliliter) injected at a rate of 3 mL/sec via the superior mesenteric
artery. Scanning delays were adjusted for single-helix CTAP so the last
scan was obtained at 66 seconds. Delays were adjusted for double-helix CTAP
so the last scan during the first helix (CTAP-1) was obtained 10 seconds
before the end of the injection at 56 seconds and the first scan during the
second helix (CTAP-2) was obtained at the end of the injection at 66
seconds. RESULTS: Single-helix CTAP scans were of poor quality owing to
multiple perfusion abnormalities. Lesion detection for double-helix CTAP-1
was 93.2% and was 100% for CTAP-2, and CTAP-2 scans had significantly fewer
perfusion abnormalities. CONCLUSION: A scanning delay of 60-66 seconds
appears to be optimal. The CTAP-1 scans showed no useful information and
need not be acquired.
