Comprehensive Arrhythmia Research and Management Center, School of Medicine, University of Utah, Salt Lake City, Utah, USA.
Heart Rhythm. 2011 Feb;8(2):295-303. doi: 10.1016/j.hrthm.2010.10.032. Epub 2010 Oct 27.
Magnetic resonance imaging (MRI) allows visualization of location and extent of radiofrequency (RF) ablation lesion, myocardial scar formation, and real-time (RT) assessment of lesion formation. In this study, we report a novel 3-Tesla RT -RI based porcine RF ablation model and visualization of lesion formation in the atrium during RF energy delivery.
The purpose of this study was to develop a 3-Tesla RT MRI-based catheter ablation and lesion visualization system.
RF energy was delivered to six pigs under RT MRI guidance. A novel MRI-compatible mapping and ablation catheter was used. Under RT MRI, this catheter was safely guided and positioned within either the left or right atrium. Unipolar and bipolar electrograms were recorded. The catheter tip-tissue interface was visualized with a T1-weighted gradient echo sequence. RF energy was then delivered in a power-controlled fashion. Myocardial changes and lesion formation were visualized with a T2-weighted (T2W) half Fourier acquisition with single-shot turbo spin echo (HASTE) sequence during ablation.
RT visualization of lesion formation was achieved in 30% of the ablations performed. In the other cases, either the lesion was formed outside the imaged region (25%) or the lesion was not created (45%) presumably due to poor tissue-catheter tip contact. The presence of lesions was confirmed by late gadolinium enhancement MRI and macroscopic tissue examination.
MRI-compatible catheters can be navigated and RF energy safely delivered under 3-Tesla RT MRI guidance. Recording electrograms during RT imaging also is feasible. RT visualization of lesion as it forms during RF energy delivery is possible and was demonstrated using T2W HASTE imaging.
磁共振成像（MRI）可用于观察射频（RF）消融损伤的位置和范围、心肌瘢痕形成以及实时（RT）评估损伤形成。本研究报告了一种新型的基于 3T 实时-弛豫增强（RT-RI）的猪 RF 消融模型，以及在 RF 能量传递过程中实时观察心房内损伤形成的方法。
本研究旨在开发一种基于 3T 实时 MRI 的导管消融和损伤可视化系统。
在 RT MRI 引导下向 6 只猪传递 RF 能量。使用一种新型的兼容 MRI 的标测和消融导管。在 RT MRI 下，该导管可安全引导并定位在左心房或右心房内。记录单极和双极电图。使用 T1 加权梯度回波序列可视化导管尖端-组织界面。然后以功率控制的方式传递 RF 能量。在消融过程中，使用 T2 加权（T2W）半傅里叶采集单次激发涡轮自旋回波（HASTE）序列进行实时观察心肌变化和损伤形成。
在进行的 30%消融中实现了 RT 可视化损伤形成。在其他情况下，要么损伤形成在成像区域之外（25%），要么没有形成损伤（45%），可能是由于组织-导管尖端接触不良所致。通过钆延迟增强 MRI 和宏观组织检查确认了损伤的存在。
兼容 MRI 的导管可在 3T RT MRI 引导下进行导航和安全传递 RF 能量。在 RT 成像期间记录电图也是可行的。在 RF 能量传递过程中实时观察损伤形成是可能的，本研究使用 T2W HASTE 成像进行了演示。
