PDF(Pubmed)
Abstract：
Radiofrequency catheter ablation is an established treatment strategy for ventricular tachycardia, but remains associated with a low success rate. MR guidance of ventricular tachycardia shows promises to improve the success rate of these procedures, especially due to its potential to provide real-time information on lesion formation using cardiac MR thermometry. Modern low field MRI scanners (<1 T) are of major interest for MR-guided ablations as the potential benefits include lower costs, increased patient access and device compatibility through reduced device-induced imaging artefacts and safety constraints. However, the feasibility of cardiac MR thermometry at low field remains unknown. In this study, we demonstrate the feasibility of cardiac MR thermometry at 0.55 T and characterized its in vivo stability (i.e., precision) using state-of-the-art techniques based on the proton resonance frequency shift method. Nine healthy volunteers were scanned using a cardiac MR thermometry protocol based on single-shot EPI imaging (3 slices in the left ventricle, 150 dynamics, TE = 41 ms). The reconstruction pipeline included image registration to align all the images, multi-baseline approach (look-up-table length = 30) to correct for respiration-induced phase variations, and temporal filtering to reduce noise in temperature maps. The stability of thermometry was defined as the pixel-wise standard deviation of temperature changes over time. Cardiac MR thermometry was successfully acquired in all subjects and the stability averaged across all subjects was 1.8 ± 1.0°C. Without multi-baseline correction, the overall stability was 2.8 ± 1.6°C. In conclusion, cardiac MR thermometry is feasible at 0.55 T and further studies on MR-guided catheter ablations at low field are warranted.
摘要：
射频导管消融是室性心动过速的既定治疗策略，但仍然与低成功率有关。MR指导室性心动过速显示有望提高这些手术的成功率，特别是由于它有可能使用心脏MR测温术提供有关病变形成的实时信息。现代低场MRI扫描仪（<1T）是MR引导消融的主要利益，因为潜在的好处包括更低的成本，通过减少设备引起的成像伪影和安全限制，增加了患者的访问和设备的兼容性。然而,低场心脏MR测温的可行性尚不清楚.在这项研究中,我们证明了在0.55T时心脏MR测温的可行性，并表征了其体内稳定性(即，精度)使用基于质子共振频率偏移方法的最先进技术。使用基于单次EPI成像的心脏MR测温协议扫描了9名健康志愿者（左心室3片，150个动态,TE=41ms)。重建管道包括图像配准以对齐所有图像，多基线方法（查找表长度=30）来校正呼吸引起的相位变化，和时间滤波来减少温度图中的噪声。测温的稳定性定义为温度随时间变化的逐像素标准偏差。在所有受试者中成功获得心脏MR测温，所有受试者的平均稳定性为1.8±1.0°C。没有多基线校正，总体稳定性为2.8±1.6°C。总之,心脏MR测温在0.55T时是可行的,并且有必要对低场MR引导导管消融进行进一步研究.
