Safe Follow-Up after Endovascular Aortic Repair with Unenhanced MRI: The SAFEVAR Study

Secchi F, Capra D, Monti CB, Mobini N, Ortiz MDMG, Trimarchi S, Mazzaccaro D, Righini P, Nano G, Sardanelli F. Safe Follow-Up after Endovascular Aortic Repair with Unenhanced MRI: The SAFEVAR Study. Diagnostics (Basel). 2022 Dec 21;13(1):20. doi: 10.3390/diagnostics13010020. PMID: 36611311; PMCID: PMC9818075. Abstract We aimed to investigate whether unenhanced magnetic resonance imaging (MRI) could represent a safe and highly sensitive tool for endoleak screening in patients treated with endovascular aneurysm repair (EVAR) using computed tomography angiography (CTA) as a reference standard. Patients who underwent CTA for EVAR follow-up at our institution were prospectively enrolled. All MRI examinations were performed with a 1.5 T unit. The true-FISP and HASTE sequences of the MRI scans were assessed for the presence of hyperintensity within the aneurysm sac outside the graft, whereas phase-contrast through-plane sequences were used for blood flow quantification. We included 45 patients, 5 (11%) of whom were female. The median age was 73 years (IQR 68-78 years). Among our patients, 19 (42%) were positive for endoleaks at CTA, of whom 13 (68%) had type II endoleaks and 6 (32%) had type I endoleaks. There were no significant differences in age, sex, aneurysm type, prosthesis type, or contrast-to-noise ratio between hyperintensity and thrombus between patients with and without endoleaks (<em>p</em> &amp;gt; 0.300). The combined evaluation of true-FISP and HASTE yielded 100% sensitivity (95% CI: 79-100%) and 19% specificity (95% CI: 7-40%). Patients with a positive CTA had a median thrombus flow of 0.06 L/min (IQR 0.03-0.23 L/min), significantly greater than that of patients with a negative CTA (<em>p</em> = 0.007). Setting a threshold at 0.01 L/min, our MRI protocol yielded 100% sensitivity, 56% specificity, and an AUC of 0.76 (95% CI 0.60-0.91). In conclusion, unenhanced MRI has perfect sensitivity for endoleak detection, although with subpar specificity that could be improved with phase-contrast flow analysis.Secchi F、Capra D、Monti CB、Mobini N、Ortiz MDMG、Trimarchi S、Mazzaccaro D、Righini P、Nano G、Sardanelli F. 无增强磁共振成像用于血管内主动脉修复术后安全随访：SAFEVAR研究. 诊断学（巴塞尔）, 2022年12月21日;13(1):20. DOI: 10.3390/diagnostics13010020. PMID: 36611311; PMCID: PMC9818075. 摘要 本研究旨在探讨未增强磁共振成像（unenhanced magnetic resonance imaging, MRI）能否作为以计算机断层血管造影（computed tomography angiography, CTA）为参考标准的血管内动脉瘤修复（endovascular aneurysm repair, EVAR）术后患者内漏（endoleak）筛查的安全且高灵敏度工具。 本研究前瞻性纳入于本机构接受EVAR术后随访CTA检查的患者。所有MRI检查均采用1.5 T磁共振扫描仪完成。针对MRI扫描的true-FISP与HASTE序列，我们评估了移植物外动脉瘤囊内是否存在高信号；而相位对比穿层面序列则用于血流量定量。 本研究共纳入45例患者，其中5例（11%）为女性，年龄中位数为73岁（四分位间距（interquartile range, IQR）：68~78岁）。入组患者中，19例（42%）经CTA检测为内漏阳性，其中13例（68%）为II型内漏，6例（32%）为I型内漏。 有无内漏的患者之间，年龄、性别、动脉瘤类型、移植物类型以及高信号与血栓间的对比噪声比均无显著统计学差异（p>0.300）。 联合评估true-FISP与HASTE序列后，内漏检测的灵敏度达100%（95%置信区间：79%~100%），特异度为19%（95%置信区间：7%~40%）。 CTA阳性患者的血栓血流量中位数为0.06 L/min（IQR：0.03~0.23 L/min），显著高于CTA阴性患者（p=0.007）。将血流量阈值设定为0.01 L/min时，本MRI检测方案的灵敏度为100%，特异度为56%，曲线下面积（Area Under the Curve, AUC）为0.76（95%置信区间：0.60~0.91）。 综上，未增强MRI在内漏检测中具有极佳的灵敏度，但其特异度欠佳，可通过相位对比血流分析进一步提升。