摘要
Abstract
Objective To investigate the effects on image quality of volume computed tomographic digital subtraction angiography (VCTDSA) with synchronous and asynchronous scanning.Methods Vascular model which was closely attached to bony structures was scanned by 64slice spiral CT.① Helical scanning was performed without contrast medium injection for 20 times and the tube exposure time was 2.1 s, scanning intervals differently were 1.9 s, 3.9 s, 5.9 s, 7.9 s, 9.9 s, 11.9 s, 13.9 s, 15.9 s, 17.9 s, 19.9 s, 2.9 s, 11.9 s, 6.9 s, 8.9 s, 10.9 s, 3.0 s, 4.0 s, 5.0 s, 6.0 s, 7.0 s.②After contrast medium injection, the vascular model was scanned for 10 times using the same parameters as above, but the scanning intervals differently were 9.9 s, 11.9 s,13.9 s, 15.9 s, 17.9 s, 10.9 s, 12.9 s, 11.0 s, 12.0 s, 13.0 s.The resulting images were reformatted as 3D volume rendering (3D VR) and maximum intensity projection ( MIP) images.The quality of subtraction images was then analyzed.CT values of the overall view were measured on subtracted images and the differences of tube exposure angle were recorded.Results Subtracted images quality of VCTDSA was rated grade Ⅰ with synchronous scanning for 15 times before and after contrast medium injection,while with asynchronous scanning for 15 times, 2 times were grade Ⅰ , 12 times were grade n and 1 time was grade Ⅲ.In 20 times, the average CT value of subtracted images with asynchronous scans was higher than which with synchronous scans without contrast injection.The differences of tube exposure angle with synchronous scans were obviously less than which with asynchronous scans.Conclusion The position of tube can be well matched with synchronous scanning, so the image quality of VCTD SA is improved significantly.关键词
体层摄影术/X线计算机/血管造影术/数字减影血管造影Key words
tomography/ X-ray computed / angiography/ digital subtraction angiography
