脑动静脉畸形伽玛刀治疗的影像学检查与剂量设计的相关研究

Relative Study Between Imaging Examinations and Dose Planning in Treating Brain Arteriovenous Malformations With Leksell Gamma Knife.

目的：为提高脑ＡＶＭ伽玛刀治疗剂量设计精度，作者对如何正确选择和组合影像学检查进行了研究。材料和方法：收集１９９３年１０月至１９９４年１１月在本院作伽玛刀治疗的４０例脑ＡＶＭ患者。治疗前，３３例采用血管造影＋ＣＴ定位，７例采用血管造影＋ＭＲＩ定位。观察各例畸形血管团的部位、形态、大小、影像学表现以及它与引流静脉之间的关系，比较采用不同影像学检查作剂量设计在覆盖形态、覆盖体积和确定周边剂量方面的差别。结果：单独采用血管造影定位有２１个不规则形病灶和９个长轴方向与Ｘ轴或Ｙ轴平面倾斜的卵圆形病灶的覆盖体积过大，１８个毗邻重要结构和头皮的病灶无法确定合适的周边剂量；而单独采用ＣＴ或ＭＲＩ定位分别有２５个和５个病灶因受引流静脉和正常脑组织部分容积效应等因素的影响覆盖体积小于采用血管造影＋ＣＴ或ＭＲＩ定位者，但各例均能确定合适的周边剂量。结论：对在血管造影和ＣＴ或ＭＲＩ上显示畸形血管团形态不规则、大小不一致且与引流静脉相互混杂在一起者应选择血管造影＋ＣＴ或ＭＲＩ定位，而对呈圆形、大小基本一致者则应视具体情况选择三种方法中的任何一种方法定位。

Purpose: To improve precision of dose planning in treating brain arteriovenous malformations (AVMs) with Leksell Gamma Knife, we studied how to select and combine imaging examinations.Materials and Methods: 40 brain AVMs cases treated by Gamma Knife were collected from Oct.1993 to Nov.1994 in our hospital. Before treatment, angiography combined with CT was used to locate the target in 33 cases, and angiography with MRI in 7 cases. In all cases, it was observed that the position, shape, size and other imaging appearances of nidi and the relationship between nidi and draining veins. We also compared the differences in covering shape, target volume and margin dosage between different imaging examinations. Besnlts: In only angiographic location, the target volunie were larger than their actual ones in 21 cases with irregular nidi and 9 cases with elliptic nidus which long axis was not parallel to X axis plane or Y axis plane and in 18 nidi adjacent to important structures and sclap, the margin dosage were hard to decide. In only CT and MRI location, the target volunie of 25 nidi and 5 nidi were smaller than those located by combination of angiography and CT or MRI, because of the part volume effects of draining vein and brain tissue, but suitable margin dosage can be selected in all cases. Conclusion: The combination of angiography and CT or MRI should be adopted to locate those nidi with irregular shape or different size between angiography and CT or MRI and those mixed by draining veins. But CT, MRI or angiography can be used respectively to locate those nidi with round shape and similar size in different imaging examinations.