Radiology, Vol 194, 157-163, Copyright © 1995 by Radiological Society of North America
Technical optimization of spiral CT for depiction of renal artery stenosis: in vitro analysis
JA Brink, JT Lim, G Wang, JP Heiken, LA Deyoe and MW Vannier
Department of Radiology, Mallinckrodt Institute of Radiology, Washington University School of Medicine, St Louis, MO 63110.
PURPOSE: To determine empirically the effect of scan parameters and
postprocessing techniques on depiction accuracy of renal artery stenosis
with spiral computed tomographic angiography. MATERIALS AND METHODS:
Critical (85%) and noncritical (45%) stenoses in the coronal plane were
modeled in vitro and scanned with 12 combinations of collimation (1, 2, or
3 mm), table increment (pitch = 1-2),2 and reconstruction interval (0.5 or
1.0 mm). Five test images were generated for each spiral scanning
technique: multiplanar reformation (MPR), maximum-intensity projections
(MIPs: coronal MIP [MIPcor], coronal MIP targeted to phantom vessel and
surrounding fat [target MIPcor]), transaxial imaging, and transaxial MIP.
RESULTS: With 3-mm collimation, critical stenosis was overestimated to the
point of occlusion on MIPcor images and underestimated on MPR and target
MIPcor images. A 0.5-mm reconstruction interval was marginally beneficial
for 1- and 2-mm collimation, but noise was prohibitive with 1-mm
collimation. CONCLUSION: Critical renal artery stenosis is best depicted
with 2-mm collimation, 2-4-mm table increment, and 1-mm reconstruction
interval.
