Technical optimization of spiral CT for depiction of renal artery stenosis: in vitro analysis.
OBJECTIVE
To determine empirically the effect of scan parameters and postprocessing techniques on depiction accuracy of renal artery stenosis with spiral computed tomographic angiography.


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.


CONCLUSIONS
Critical renal artery stenosis is best depicted with 2-mm collimation, 2-4-mm table increment, and 1-mm reconstruction interval.
Brink
J A
JA
Department of Radiology, Mallinckrodt Institute of Radiology, Washington University School of Medicine, St Louis, MO 63110.
Lim
J T
JT
Wang
G
G
Heiken
J P
JP
Deyoe
L A
LA
Vannier
M W
MW
D006801:Humans; D008961:Models, Structural; D012078:Renal Artery Obstruction / Q000000981:diagnostic imaging*; D014057:Tomography, X-Ray Computed / Q000379:methods*