Department of Radiology / Image Sciences Institute, UMC Utrecht, The Netherlands.
J Endovasc Ther. 2011 Jun;18(3):274-9. doi: 10.1583/10-3271.1.
To validate a newly developed semi-automatic multispectral magnetic resonance imaging (MRI) tool for quantitatively monitoring aneurysm sac contents in patients after endovascular aneurysm repair (EVAR).
MRI studies from 24 EVAR patients were retrospectively analyzed. The precontrast T₁-weighted and T₂-weighted and the postcontrast T₁-weighted images were displayed simultaneously. Two independent observers classified the aneurysm sac voxels into categories for endoleak, unorganized thrombus, or organized thrombus by interactively thresholding the multispectral images relative to the signal intensity of fat. Voxel classification was visualized as a color overlay on the MR images; when the observer changed the thresholds, the color overlay was updated immediately. The volumes of the voxels in each category were calculated and expressed in milliliters. The intra- and interobserver variability for measuring the volumes of endoleak and unorganized and organized thrombus were calculated; a Bland and Altman analysis was applied to determine the mean differences and the repeatability coefficient (RC).
Mean aneurysm sac volume was 78 ± 42 mL. The intraobserver mean difference for the endoleak volume was 0.5 ± 1.9 mL with an RC of 3.7 mL; the interobserver mean difference was -0.8 ± 3.6 mL (RC 7.1 mL). The intraobserver mean difference for unorganized thrombus volume was -1.2 ± 4.4 mL (RC 8.6 mL); the interobserver mean difference was 0.3 ± 6.3 mL with an RC of 12.3 mL. The intraobserver mean difference for organized thrombus volume was 0.8 ± 5.0 mL (RC 9.7 mL); the interobserver mean difference was 0.4 ± 6.3 mL (RC 12.4 mL).
Reproducible monitoring of aneurysm sac contents in EVAR patients is feasible with multispectral MRI in combination with our semi-automatic post-processing tool.
验证一种新开发的半自动多光谱磁共振成像（MRI）工具，用于定量监测血管内动脉瘤修复（EVAR）后患者的动脉瘤囊内容物。
回顾性分析 24 例 EVAR 患者的 MRI 研究。同时显示术前 T₁ 加权和 T₂ 加权及对比后 T₁ 加权图像。两名独立观察者通过相对于脂肪信号强度交互式阈值处理多光谱图像，将动脉瘤囊体素分类为内漏、无组织血栓或有组织血栓。体素分类以 MR 图像上的颜色叠加可视化；当观察者改变阈值时，颜色叠加会立即更新。计算每个类别的体素体积，并以毫升表示。计算测量内漏和无组织及有组织血栓体积的观察者内和观察者间变异性；应用 Bland 和 Altman 分析确定平均差异和重复性系数（RC）。
平均动脉瘤囊体积为 78 ± 42 mL。内漏体积的观察者内平均差异为 0.5 ± 1.9 mL，RC 为 3.7 mL；观察者间平均差异为-0.8 ± 3.6 mL（RC 为 7.1 mL）。无组织血栓体积的观察者内平均差异为-1.2 ± 4.4 mL（RC 为 8.6 mL）；观察者间平均差异为 0.3 ± 6.3 mL，RC 为 12.3 mL。有组织血栓体积的观察者内平均差异为 0.8 ± 5.0 mL（RC 为 9.7 mL）；观察者间平均差异为 0.4 ± 6.3 mL（RC 为 12.4 mL）。
使用多光谱 MRI 结合我们的半自动后处理工具，可对 EVAR 患者的动脉瘤囊内容物进行可重复监测。
