IN-VITRO STUDIES TO DETERMINE THE DEGREE OF STENOSIS USING SPIRAL-CT ANGIOGRAPHY

Purpose: Aim of the study was to evaluate the influence of different s piral-CT parameters for the visualisation of vascular stenoses, especi ally of the renal arteries, Material and methods: Models with a densit y equivalent to that of fat, filled with diluted contrast agent, and a n inner lumen of 4, 6, 8 mm were scanned in x-, y- and z-direction. Da ta were acquired in up to 24 second long spiral-CT scans using differe nt spiral-CT parameters (collimation, table speed, reconstruction algo rithm, tube current). Detection of the degree of stenosis was achieved by assessment of the axial images and 3D reconstructions. Results: Th e best correlation between real and measured degree of stenosis was se en by using a small collimation, a low table increment and assessment of the axial images reconstructed in standard algorithm. The stenosis degrees of models directed in x- and y-direction were overestimated an d those in z-direction were underestimated depending on the spiral-CT parameters. Conclusion: For optimal imaging of renal artery stenoses, collimation of 2 mm (pitch=1-2) and a reconstruction interval of 1 mm is recommended.