Adams W M, Laitt R D, Jackson A
Department of Neuroradiology, Central Manchester Healthcare Trust, University of Manchester, UK.
AJNR Am J Neuroradiol. 2000 Oct;21(9):1618-28.
With developments in coil technology, intracranial aneurysms are being treated increasingly by the endovascular route. Endovascular treatment of aneurysms requires an accurate depiction of the aneurysm neck and its relation to parent and branch vessels preoperatively. Our goal was to estimate the clinical efficacy of MR angiography (MRA) in the pretreatment assessment of ruptured and unruptured intracranial aneurysms. We compared MRA source data (axial acquired partitions), multiplanar reconstruction (MPR) of these data, as well as maximum intensity projection (MIP) and 3D-isosurface images with intraarterial digital subtraction angiography (IA-DSA).
The study was performed in 29 patients with 42 intracerebral aneurysms. The MRA data were examined in four different forms--as axial source data, MPR images of the source data, and MIP and 3D isosurface--rendered images. A composite standard of reference for each aneurysm was then constructed using this information together with the IA-DSA findings by looking at aneurysm detection rate, aneurysm morphology, neck interpretation, and branch vessel relationship to the aneurysm. All techniques, including conventional IA-DSA, were then scored independently on a five-point scale from 1 (non diagnostic) to 5 (excellent correlation with the standard of reference) for each of the aneurysm components as compared with the composite picture. An overall score for each technique was also obtained.
Of the 42 aneurysms examined, 34 were small (<10 mm), six were large (10-25 mm), and two were giant (>25 mm). Three aneurysms were not detected with MRA. These were smaller than 3 mm and either in an anatomically difficult location (middle cerebral artery bifurcation) or obscured by adjacent hematoma. Two large aneurysms were depicted as undersized by IA-DSA owing to the presence of intramural thrombus shown by MRA axial source data. IA-DSA received the highest scores overall and in three of the four subgroups. Three-dimensional isosurface reconstructions scored higher than did IA-DSA for depiction of the aneurysm neck, although this difference was not significant. The MPR and 3D-isosurface images were comparable to those of IA-DSA in all categories. MPR images were particularly useful for defining branch vessels and the aneurysm neck. MIP images scored poorly in all subgroups (P < .005) compared with IA-DSA findings, except for in aneurysm detection. Source data images were significantly inferior to those of IA-DSA in all categories (P < .005).
MRA is currently inferior to IA-DSA in pretreatment assessment of intracranial aneurysms, and can miss small lesions (<3 mm). It can, however, provide complementary information to IA-DSA, particularly in anatomically complex areas or in the presence of intramural thrombus. If MRA is used in aneurysm assessment, a meticulous technique with reference to both axial source data and MPR is mandatory. The axial source data should not be interpreted in isolation. Three-dimensional isosurface images are comparable to those of IA-DSA and are more reliable than are MIP images, which should be interpreted with caution.
随着线圈技术的发展，颅内动脉瘤越来越多地通过血管内途径进行治疗。动脉瘤的血管内治疗需要在术前准确描绘动脉瘤颈部及其与载瘤动脉和分支血管的关系。我们的目标是评估磁共振血管造影（MRA）在破裂和未破裂颅内动脉瘤术前评估中的临床疗效。我们将MRA源数据（轴向采集分区）、这些数据的多平面重建（MPR）以及最大密度投影（MIP）和三维等值面图像与动脉内数字减影血管造影（IA-DSA）进行了比较。
对29例患有42个脑内动脉瘤的患者进行了研究。以四种不同形式检查MRA数据——轴向源数据、源数据的MPR图像以及MIP和三维等值面渲染图像。然后，通过查看动脉瘤检出率、动脉瘤形态、颈部解读以及分支血管与动脉瘤的关系，将这些信息与IA-DSA结果相结合，为每个动脉瘤构建一个综合参考标准。然后，将包括传统IA-DSA在内的所有技术，就每个动脉瘤组成部分与综合图像相比，按照从1（非诊断性）到5（与参考标准高度相关）的五分制进行独立评分。还获得了每种技术的总体评分。
在检查的42个动脉瘤中，34个较小（<10 mm），6个较大（10 - 25 mm），2个巨大（>25 mm）。MRA未检测到3个动脉瘤。这些动脉瘤小于3 mm，要么位于解剖结构复杂的部位（大脑中动脉分叉处），要么被相邻血肿遮挡。由于MRA轴向源数据显示存在壁内血栓，2个大动脉瘤被IA-DSA显示为尺寸偏小。IA-DSA在总体以及四个亚组中的三个亚组中获得了最高分。三维等值面重建在描绘动脉瘤颈部方面得分高于IA-DSA，尽管这种差异不显著。MPR和三维等值面图像在所有类别中与IA-DSA相当。MPR图像在定义分支血管和动脉瘤颈部方面特别有用。与IA-DSA结果相比，MIP图像在所有亚组中的得分都很低（P <.005），除了在动脉瘤检测方面。源数据图像在所有类别中均明显逊于IA-DSA（P <.005）。
目前MRA在颅内动脉瘤术前评估中不如IA-DSA，并且可能遗漏小病变（<3 mm）。然而，它可以为IA-DSA提供补充信息，特别是在解剖结构复杂的区域或存在壁内血栓的情况下。如果将MRA用于动脉瘤评估，必须采用同时参考轴向源数据和MPR的精细技术。不应孤立地解读轴向源数据。三维等值面图像与IA-DSA相当，并且比MIP图像更可靠，对MIP图像应谨慎解读。
