Department of Radiology, University of California, San Francisco, 94143, USA.
AJNR Am J Neuroradiol. 2011 Feb;32(2):346-51. doi: 10.3174/ajnr.A2298. Epub 2010 Nov 18.
A comprehensive evaluation of aneurysmal morphometry requires appreciation of both the vascular lumen and the intraluminal thrombus. MR imaging methods can both evaluate the lumen and directly image the vessel wall. We investigated the ability of T1-weighted, T2-weighted, and steady-state MR imaging techniques to delineate thrombus morphology and reveal changes with time.
Nine patients with fusiform basilar or intracranial vertebral artery aneurysms that contained intraluminal thrombus were studied with MR imaging. All patients underwent at least 2 imaging sessions, which were separated by 4-22 months. Analysis of signal intensity to determine the mean signal intensity from thrombus, blood, CSF, and brain in matched regions was performed. Aneurysm maximal diameter and cross-sectional area were determined with and without thrombus.
Thrombus was identified on all image sequences, and its general appearance was consistent between imaging sessions. Thrombus produced the highest and most consistent signal intensities with T1-weighted and steady-state techniques, though the latter showed superior contrast between luminal blood and thrombus. Heterogeneity within clot was evident in 4/9 of patients, with peripheral hyperintensity being a common feature.
Steady-state imaging was found to be superior to T1- and T2-weighted imaging for delineating and characterizing intraluminal thrombus within aneurysms. The imaging characteristics of intraluminal thrombus proved to be very consistent for long periods. Assessment of overall aneurysm size, including thrombosed portions, permits more accurate evaluation of aneurysm growth and concomitantly may permit more informed clinical decision-making with regard to the timing and need for aneurysm treatment.
对动脉瘤形态学进行全面评估需要同时了解血管管腔和管腔内血栓。磁共振成像（MR）方法既能评估管腔，又能直接显示血管壁。我们研究了 T1 加权像、T2 加权像和稳态 MR 成像技术在描绘血栓形态和显示随时间变化方面的能力。
对 9 例包含管腔内血栓的梭形基底动脉或颅内椎动脉动脉瘤患者进行了 MR 成像研究。所有患者均至少进行了 2 次成像检查，两次检查间隔 4-22 个月。对信号强度进行分析，以确定匹配区域内血栓、血液、CSF 和脑的平均信号强度。在有和无血栓的情况下测量动脉瘤最大直径和截面积。
所有图像序列均能识别血栓，且各次检查的血栓外观基本一致。血栓在 T1 加权像和稳态技术上产生的信号强度最高且最一致，尽管后者显示了管腔内血液与血栓之间的对比度更好。4/9 例患者的血栓内存在不均质，周边高信号是常见特征。
稳态成像在描绘和特征化动脉瘤内管腔内血栓方面优于 T1 加权像和 T2 加权像。管腔内血栓的影像学特征在很长一段时间内非常一致。评估包括血栓部分在内的动脉瘤总大小，可以更准确地评估动脉瘤的生长，同时可能更明智地为动脉瘤治疗的时机和必要性做出临床决策。
