Three-dimensional CT angiography (3D-CTA) for cerebral aneurysms

The accuracy, usefulness and problems of 3D-CTA in detecting aneurysms is discussed in comparison with angiography. One hundred and seven patients with subarachnoid hemorrhage in 55 patients and screening in 52 were examined by CT, angiogram and 3D-CTA. A CT system was X vigorTM (Toshiba Medical Co. 135kV, 200mA.) The slice thickness was 1.0 mm. Helical CT scan was performed using an injection of non-ionic contrast material via the antecubital vein at the rate of 3 to 2 ml/s for 90 ml, with 20 seconds scan delay. 3D-CTA was created using RealrenderTM (Toshiba Medical Co.) from zoomed image. Total number of aneurysms was 84. Eighty two out of 84 aneurysms (97.6%) were demonstrated by angiography, and these 82 aneurysms were also detected by 3D-CTA. Although 2 aneurysms were not demonstrated by angiogram, one of them was detected by 3D-CTA. It was an unruptured aneurysm and the size was about 0.8 mm in diameter confirmed by surgery. While the second one was neither detected by angiogram nor 3D-CTA. It was confirmed by surgery and its size was 0.5 mm in diameter. The sensitivity of 3D-CTA was 98.8%. The 3D-CTA gave us useful information concerning the anatomical relationship of the aneurysm, its neck and parent artery, and the surrounding branches. The problems were as follows; poor visualization of small arteries less than 1 mm and aneurysm covered with bony structures, difficulty of distinction between arteries and veins. The accurate detection of cerebral aneurysms by 3D-CTA was thought to be the same as by angiography, and 3D-CTA was useful for surgical simulation. We think it is possible to plan and perform surgery without angiography in limited cases. It is necessary to develop the hardware and the software for resolving the problems.