Today’s standard of care, in the congenital heart disease (CHD) population, involves performing cardiac catheterization under x-ray fluoroscopy and cardiac magnetic resonance (CMR) imaging separately. The unique ability of CMR to provide real-time functional imaging in multiple views without ionizing radiation exposure has the potential to be a powerful tool for diagnostic and interventional procedures. Limiting fluoroscopic radiation exposure remains a challenge for pediatric interventional cardiologists. This pilot study’s objective is to establish feasibility of right (RHC) and left heart catheterization (LHC) during invasive CMR (iCMR) procedures at our institution in the CHD population. Furthermore, we aim to improve simultaneous visualization of the catheter balloon tip, MR-conditional guidewire, and cardiac/vessel anatomy during iCMR procedures. Subjects with CHD were enrolled in a pilot study for iCMR procedures at 1.5 T with an MR-conditional guidewire. The CMR area is located adjacent to a standard catheterization laboratory. Using the interactive scanning mode for real-time control of the imaging location, a dilute gadolinium-filled balloon-tip catheter was used in combination with an MR-conditional guidewire to obtain cardiac saturations and hemodynamics. A recently developed catheter tracking technique using a real-time single-shot balanced steady-state free precession (bSSFP), flip angle (FA) 35–45°, echo time (TE) 1.3 ms, repetition time (TR) 2.7 ms, 40° partial saturation (pSAT) pre-pulse was used to visualize the gadolinium-filled balloon, MR-conditional guidewire, and cardiac structures simultaneously. MR-conditional guidewire visualization was enabled due to susceptibility artifact created by distal markers. Pre-clinical phantom testing was performed to determine the optimum imaging FA-pSAT combination. The iCMR procedure was successfully performed to completion in 31/34 (91%) subjects between August 1st, 2017 to December 13th, 2018. Median age and weight were 7.7 years and 25.2 kg (range: 3 months – 33 years and 8 – 80 kg). Twenty-one subjects had single ventricle (SV) anatomy: one subject was referred for pre-Glenn evaluation, 11 were pre-Fontan evaluations and 9 post-Fontan evaluations for protein losing enteropathy (PLE) and/or cyanosis. Thirteen subjects had bi-ventricular (BiV) anatomy, 4 were referred for coarctation of the aorta (CoA) evaluations, 3 underwent vaso-reactivity testing with inhaled nitric oxide, 3 investigated RV volume dimensions, two underwent branch PA stenosis evaluation, and the remaining subject was status post heart transplant. No catheter related complications were encountered. Average time taken for first pass RHC, LHC/aortic pull back, and to cross the Fontan fenestration was 5.2, 3.0, and 6.5 min, respectively. Total success rate to obtain required data points to complete Fick principle calculations for all patients was 331/337 (98%). Subjects were transferred to the x-ray fluoroscopy lab if further intervention was required including Fontan fenestration device closure, balloon angioplasty of pulmonary arteries/conduits, CoA stenting, and/or coiling of aortopulmonary (AP) collaterals. Starting with subject #10, an MR-conditional guidewire was used in all subsequent subjects (15 SV and 10 BiV) with a success rate of 96% (24/25). Real-time CMR-guided RHC (25/25 subjects, 100%), retrograde and prograde LHC/aortic pull back (24/25 subjects, 96%), CoA crossing (3/4 subjects, 75%) and Fontan fenestration test occlusion (2/3 subjects, 67%) were successfully performed in the majority of subjects when an MR-conditional guidewire was utilized. Feasibility for detailed diagnostic RHC, LHC, and Fontan fenestration test occlusion iCMR procedures in SV and BiV pediatric subjects with complex CHD is demonstrated with the aid of an MR-conditional guidewire. A novel real-time pSAT GRE sequence with optimized FA-pSAT angle has facilitated simultaneous visualization of the catheter balloon tip, MR-conditional guidewire, and cardiac/vessel anatomy during iCMR procedures.

中文翻译：

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使用 MR 条件导丝和被动可视化的侵入式心血管磁共振 (iCMR) 来诊断先天性心脏病的右心和左心导管插入术。


当今先天性心脏病 (CHD) 人群的护理标准包括分别在 X 射线透视和心脏磁共振 (CMR) 成像下进行心导管插入术。 CMR 具有在多个视图中提供实时功能成像而无需电离辐射暴露的独特能力，有可能成为诊断和介入手术的强大工具。限制荧光镜辐射暴露仍然是儿科介入心脏病专家面临的挑战。该试点研究的目的是确定在我们机构对 CHD 人群进行侵入性 CMR (iCMR) 手术期间进行右心 (RHC) 和左心导管插入术 (LHC) 的可行性。此外，我们的目标是在 iCMR 手术期间改善导管球囊尖端、MR 条件导丝和心脏/血管解剖结构的同步可视化。患有 CHD 的受试者参加了一项使用 MR 条件导丝在 1.5 T 下进行 iCMR 手术的试点研究。 CMR 区域毗邻标准导管实验室。利用交互式扫描模式实时控制成像位置，使用稀释钆填充球囊尖端导管与MR条件导丝相结合来获得心脏饱和度和血流动力学。最近开发的导管跟踪技术，使用实时单次平衡稳态自由进动 (bSSFP)，翻转角 (FA) 35–45°，回波时间 (TE) 1.3 ms，重复时间 (TR) 2.7 ms，使用 40° 部分饱和 (pSAT) 预脉冲同时观察钆填充球囊、MR 条件导丝和心脏结构。由于远端标记物产生磁敏度伪影，因此启用了 MR 条件导丝可视化。 进行临床前体模测试以确定最佳成像 FA-pSAT 组合。 2017 年 8 月 1 日至 2018 年 12 月 13 日期间，31/34 (91%) 受试者成功完成 iCMR 手术。中位年龄和体重为 7.7 岁和 25.2 公斤（范围：3 个月 – 33 岁和 8 – 80 岁）公斤）。 21 名受试者具有单心室 (SV) 解剖结构：一名受试者被转介进行 Glenn 前评估，11 名受试者进行 Fontan 前评估，9 名受试者进行 Fontan 后蛋白质丢失性肠病 (PLE) 和/或发绀评估。 13 名受试者具有双心室 (BiV) 解剖结构，4 名被转诊进行主动脉缩窄 (CoA) 评估，3 名接受吸入一氧化氮的血管反应性测试，3 名研究 RV 体积尺寸，2 名接受分支 PA 狭窄评估，剩下的受试者处于心脏移植后的状态。没有遇到导管相关的并发症。首次通过 RHC、LHC/主动脉拉回和穿过 Fontan 开窗所需的平均时间分别为 5.2 分钟、3.0 分钟和 6.5 分钟。所有患者获得完成 Fick 原理计算所需数据点的总成功率为 331/337 (98%)。如果需要进一步干预，包括 Fontan 开窗装置闭合、肺动脉/导管球囊血管成形术、CoA 支架置入术和/或主肺动脉 (AP) 侧枝循环术，受试者将被转移到 X 射线透视实验室。从受试者 #10 开始，所有后续受试者（15 SV 和 10 BiV）均使用 MR 条件导丝，成功率为 96% (24/25)。 实时 CMR 引导的 RHC（25/25 受试者，100%）、逆行和顺行 LHC/主动脉拉回（24/25 受试者，96%）、CoA 交叉（3/4 受试者，75%）和 Fontan 开窗测试当使用 MR 条件导丝时，大多数受试者成功进行了闭塞（2/3 受试者，67%）。借助 MR 条件导丝，证明了对患有复杂 CHD 的 SV 和 BiV 儿科受试者进行详细诊断 RHC、LHC 和 Fontan 开窗测试闭塞 iCMR 程序的可行性。具有优化 FA-pSAT 角度的新型实时 pSAT GRE 序列有助于在 iCMR 手术期间同时可视化导管球囊尖端、MR 条件导丝和心脏/血管解剖结构。