Brothers M F, Fox A J, Lee D H, Pelz D M, Deveikis J P
Department of Diagnostic Radiology, University Hospital, University of Western Ontario, London, Canada.
AJNR Am J Neuroradiol. 1990 Jan-Feb;11(1):149-61.
We examined the safety and utility of high-field MR in patients who had surgery for cerebral aneurysms of the vertebrobasilar system. Eighteen posterior (and three coincidental anterior) circulation aneurysms were treated. Twenty-one MR scans were obtained at a mean postoperative interval of 7.2 days. The mean size of the preoperative vertebrobasilar aneurysm was 2.2 cm; six were giant (greater than 2.5 cm) and eight were large (greater than 1.5, less than or equal to 2.5 cm). In 17 patients, Sugita nonmagnetic clips were used. In one other, a Drake tourniquet was used. No ill effects occurred from scanning with a high-field imaging unit at 1.5 T. The MR clip artifact was much less obtrusive than that on CT. In 11 cases, the aneurysm could be partially imaged postoperatively, mainly in very large aneurysms or in those treated by clipping the parent vessel. Of these, two revealed residual lumina on MR and nine looked completely thrombosed. Postoperative angiography showed that in four of the thrombosed-appearing aneurysms a residual lumen with a mean diameter of 1.0 cm had been missed. In the patient imaged after application of a Drake tourniquet, no artifact was seen, and a good assessment of progressive partial thrombosis was obtained. Evolution of the signal intensity of new aneurysm thrombus, in those minimally or not obscured by artifact, coincides with patterns previously described for hemoglobin in intracerebral hematomas. The earliest hyperintensity could be seen in either the periphery or the center of the new thrombus. All 15 patients examined with new postoperative deficits showed appropriate lesions, mainly small brainstem ischemic foci. Postoperative CT (performed in all but four of these patients) missed over 80% of these lesions, mainly owing to artifact from clip or bone. We conclude that MR is better than CT in the postoperative assessment of aneurysm patients, particularly in demonstrating small zones of ischemia. High-field MR scanning is safe if nonmagnetic surgical clips are used. MR is not accurate in assessing residual lumina.
我们研究了高场强磁共振成像（MR）在接受椎基底动脉系统脑动脉瘤手术患者中的安全性和实用性。共治疗了18例后循环（另有3例合并前循环）动脉瘤。术后平均7.2天进行了21次MR扫描。术前椎基底动脉瘤的平均大小为2.2 cm；其中6例为巨大动脉瘤（直径大于2.5 cm），8例为大型动脉瘤（直径大于1.5 cm且小于或等于2.5 cm）。17例患者使用了杉田非磁性夹，另1例使用了德雷克止血带。使用1.5 T高场成像设备进行扫描未出现不良影响。MR上的夹子伪影比CT上的要轻得多。11例患者术后动脉瘤可部分显影，主要见于非常大的动脉瘤或通过夹闭载瘤血管治疗的动脉瘤。其中，2例MR显示有残余管腔，9例看起来完全血栓形成。术后血管造影显示，在4例看似血栓形成的动脉瘤中，遗漏了平均直径为1.0 cm的残余管腔。在应用德雷克止血带后成像的患者中，未见到伪影，且对逐渐形成的部分血栓形成情况评估良好。在那些极少或无伪影干扰的动脉瘤新血栓中，其信号强度的演变与先前描述的脑内血肿中血红蛋白的变化模式一致。最早的高信号可出现在新血栓的周边或中心。所有15例术后出现新的神经功能缺损的患者均显示有相应病变，主要为小脑干缺血灶。术后CT（除4例患者外均进行了此项检查）遗漏了80%以上的这些病变，主要是由于夹子或骨质造成的伪影。我们得出结论，在动脉瘤患者的术后评估中，MR优于CT，尤其是在显示小的缺血区域方面。如果使用非磁性手术夹，高场强MR扫描是安全的。MR在评估残余管腔方面不准确。
