Purpose: The aim of this study is to determine the optimal scan parameters
for the evaluation of experimental vascular stenoses with a multislice-heli
cal CT. Material and Methods: A vascular phantom consisting of four tubes w
ith an inner diameter of 8 mm and with experimental stenoses of 50%, 75% an
d 90% was scanned in different tube orientations using a multislice-CT scan
ner (LightSpeed QX/i, GE, Milwaukee, USA). Examinations were performed with
increasing collimations (1.25-5mm), tube currents (100-300mA) and two diff
erent table speeds (0.75 HQ mode and 1.5 HS mode). Results: The most exact
measurements were obtained in tubes angulated parallel to the scan directio
n with a collimation of 2.5 mm in the HQ mode (7.5 mm/rot.). An almost equi
valent accuracy was obtained in the HS mode (15 mm/rot.) with a collimation
of 2.5 mm when higher tube currents (300 mA) were employed. The degree of
stenoses was overestimated when the tube was angulated perpendicular to the
z-axis. Conclusion: Multislice-CT provides a good detection rate of vascul
ar stenoses especially at 0 degrees and also at 45 degrees angulation in th
e HQ mode. The use of the HS mode with higher tube currents allows scanning
of longer distances with almost identical accuracy.