Runck F, Steiner R P, Bautz W A, Lell M M
Department of Radiology and Neuroradiology, Klinikum Augsburg, Augsburg, Germany.
AJNR Am J Neuroradiol. 2008 Oct;29(9):1736-42. doi: 10.3174/ajnr.A1179. Epub 2008 Jul 17.
MR angiography (MRA) is increasingly used as an alternative to digital subtraction angiography (DSA) to evaluate internal carotid artery (ICA) stenosis. Because MRA is not standardized in data acquisition and postprocessing, we sought to evaluate the effects of different acquisition techniques (time-of-flight MRA [TOF-MRA]) and contrast-enhanced MRA [CE-MRA]) and postprocessing methods (maximum intensity projection [MIP], multiplanar reformation [MPR], and volume-rendering on stenosis grading.
Fifty patients (33 men, 17 women) with symptomatic ICA stenosis were examined at 1.5T. Two imaging techniques and 3 postprocessing methods resulted in 6 image datasets per patient. Two readers independently evaluated ICA stenosis according to the North American Symptomatic Carotid Endarterectomy Trial criteria. Interobserver variability was calculated with the Pearson correlation coefficient and simultaneous confidence intervals (CI). The relationship of the values of ICA stenosis between the techniques was assessed by means of simultaneous 95% Tukey CI.
Interobserver agreement was high. Higher concordance was found for postprocessing techniques with TOF- than with CE-MRA; the mean difference between TOF-MPR and TOF-MIP was 0.4% (95% CI, -2.9%-3.8%). Stenosis values for CE-MPR differed significantly from those of CE volume-rendering (7.2%; 95% CI, 3.9%-10.6%).
Stenosis grading was found to be independent of the postprocessing technique except for comparison of CE-MPR with CE volume-rendering, with the volume-rendering technique resulting in higher stenosis values. MPR seems to be best-suited for measurement of ICA stenosis. Parameter setting is critical with volume-rendering, in which stenosis values were consistently higher compared with the other methods.
磁共振血管造影（MRA）越来越多地被用作数字减影血管造影（DSA）的替代方法来评估颈内动脉（ICA）狭窄。由于MRA在数据采集和后处理方面未标准化，我们试图评估不同采集技术（时间飞跃MRA [TOF-MRA]）和对比增强MRA [CE-MRA]）以及后处理方法（最大强度投影[MIP]、多平面重组[MPR]和容积再现）对狭窄分级的影响。
对50例有症状的ICA狭窄患者（33例男性，17例女性）进行1.5T检查。两种成像技术和三种后处理方法为每位患者生成6个图像数据集。两名阅片者根据北美症状性颈动脉内膜切除术试验标准独立评估ICA狭窄情况。采用Pearson相关系数和同时置信区间（CI）计算观察者间的变异性。通过同时95%的Tukey CI评估不同技术之间ICA狭窄值的关系。
观察者间一致性较高。TOF-MRA的后处理技术比CE-MRA的一致性更高；TOF-MPR和TOF-MIP之间的平均差异为0.4%（95% CI，-2.9% - 3.8%）。CE-MPR的狭窄值与CE容积再现的狭窄值有显著差异（7.2%；95% CI，3.9% - 10.6%）。
除了CE-MPR与CE容积再现的比较外，狭窄分级与后处理技术无关，容积再现技术导致更高的狭窄值。MPR似乎最适合测量ICA狭窄。容积再现时参数设置至关重要，与其他方法相比，其狭窄值始终较高。
