Görzer H, Heimberger K, Schindler E
Department of Radiology, Vienna University Hospital, Austria.
J Comput Assist Tomogr. 1994 Sep-Oct;18(5):839-41. doi: 10.1097/00004728-199409000-00031.
A new imaging modality is presented in which a digital subtraction algorithm is applied to spiral CT angiography of extra- and intracranial vessels.
Spiral CT angiography was carried out in 26 patients. When this was done for stereotactic purpose before radiosurgery, a Leksell stereotactic frame was used; in the other cases an atraumatic fixation system was applied. Spiral CT data were acquired twice--before and after contrast agent administration. Then, computerized subtraction of the density values of plain CT from the topographically corresponding enhanced CT was performed. Maximum intensity projection was used to visualize the vessels.
This method provided significant effacement of nonvascular structures and a considerably improved visualization of extracranial as well as intracranial vessels could be achieved. In some conditions, e.g., to exclude a suspected thrombotic occlusion of the basilar artery, conventional angiography could even be omitted.
Adequate visualization of extra- and intracranial vessels is possible with spiral CT angiography and digital subtraction. An important scope of this modality could be its contribution to radiosurgical planning and the follow-up after radiotherapy. In some conditions, CT subtraction angiography may possibly supersede conventional subtraction angiography.
介绍一种新的成像方式，即将数字减法算法应用于颅外和颅内血管的螺旋CT血管造影。
对26例患者进行螺旋CT血管造影。若在立体定向放射外科手术前出于立体定向目的进行此项检查，则使用Leksell立体定向框架；在其他情况下，则应用无创固定系统。在注射造影剂前后各进行一次螺旋CT数据采集。然后，对地形学上对应的增强CT的密度值与平扫CT的密度值进行计算机减法运算。采用最大密度投影来显示血管。
该方法能显著消除非血管结构，可大大改善颅外和颅内血管的显示效果。在某些情况下，例如排除疑似基底动脉血栓性闭塞时，甚至可以省略传统血管造影。
螺旋CT血管造影和数字减法能够充分显示颅外和颅内血管。这种成像方式的一个重要应用领域可能是对立体定向放射外科手术规划和放疗后的随访有所帮助。在某些情况下，CT减法血管造影可能会取代传统减法血管造影。
