CT ANGIOGRAPHY OF BRAIN USING ULTRAFAST CT : PHANTOM AND CLINICAL STUDY

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On the basic study, we evaluated the accuracy of CT angiography in small vessels using ultra-fast computed tomography. Vessel phantoms with inner diameters of 8 mm, 6 mm, and 4 mm were prepared with segments of 75%, 50%, and 25% stenosis in each vessel. The vessels were filled with contrast medium (Iopamidol 300 at 1/24 dilution, approximately 380 HU).The apparatus used was an lmatron C-150. The step volume scan mode was used with slice thickness of 1.5 mm and 3 mm. Both maximum intensity projection (MIP) images and three-dimensional (3D) images were obtained. Using the 8 mm vessel phantom, all stenotic segments were accurately visualized on CT angiography. The 50% stenotic segments were accurately estimated in all vessels. However, the 75% stenotic segments were slightly overestimated in smaller vessels, and the 25% stenotic segments were sligtly underestimated in smaller vessels.Clinical data are not yet sufficient for statistical analysis, but we found its usefulness in the evaluation of not only stenotic lesions but also associating calcified arterial walls.