三维动态增强磁共振血管造影用于犬颈动脉支架植入术后随访的可行性

目的分析颈动脉支架在犬三维动态增强磁共振血管造影（3DCE-MRA）图像上的信号及伪影特点，评价3DCE—MRA用于颈动脉支架术后随访的可行性。方法通过外科手术方法在6只犬的颈动脉成功建立非粥样硬化性狭窄，选用3枚镍钛合金自膨式带膜支架及3枚不锈钢（316L）球囊膨胀式支架行经皮血管腔内成形术及颈动脉支架植入术（PTA＋CAs）。于支架植入术后行颈动脉造影及3DCE-MRA。结果PTA＋CAS技术成功率为100％。造影证实2支颈动脉轻度狭窄（〈50％），1支中度狭窄（≥50o．4且〈700．4），3支重度狭窄（≥70％）。3DCE-MRA显示镍钛合金支架表现为支架腔边缘呈锯齿样细小的暗带状伪影，伪影引起的腔内假性狭窄约0-30％；不锈钢球囊膨胀式支架表现为支架腔内信号完全丢失。结论3DCE-MRA可用于评价镍钛合金支架腔内是否通畅，尚无法对狭窄程度进行分级；但对于不锈钢球囊膨胀式支架，由于伪影严重，无法评价支架腔内情况。

Feasibility of 3D MR angiography for following up of canines after carotid artery stent implantation

Objective To analyze the intraluminal signal and artifact characteristics of carotid stent of canines,and to evaluate the feasibility of following-up of carotid stent patency with 3D CE-MRA.Methods Models of non-atherosclerotic carotid stenosis were successfully established in 6 dogs with surgical operation.Percutaneous transluminal angioplasty(PTA) and carotid artery stenting(CAS) were successfully carried out in 6 dogs using 3 self-expendable covered stent made of nitinol and 3 balloon expendable stent made of steel.Carotid angiography and 3D CE-MRA were performed after PTA.Results The successful rate of PTA+CAS was 100%.Carotid artery angiography showed mild stenosis(<50%) in 2,moderate stenosis(≥50% and <70%) in 1 and severe stenosis(≥70%) in 3 carotid arteries.3D CE-MRA showed the stent made of nitinol was characterized by only minor artifact,which consisted of thin,dark,indistinct ridges that appeared to indent the stent lumen.The false stricture of luminal diameter was reduced only by 0—30%.The stent made of steel showed no signal within the stent.Conclusion 3D CE-MRA can be used to evaluate the patency of stents made of nitinol,but the grading of stenosis seems to be unrealistic.It is helpless to assess the patency of stents made of steel since serious artifact.