Department of Medicine, Division of Cardiology, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA.
Department of Biomedical Engineering, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA.
Magn Reson Med. 2018 Feb;79(2):879-889. doi: 10.1002/mrm.26750. Epub 2017 May 11.
To demonstrate imaging of radiofrequency ablation lesions with non-contrast-enhanced T -weighted (T1w) MRI.
Fifteen swine underwent left ventricular ablation followed by MRI using different preparations: endocardial or epicardial ablation of naïve animal, or endocardial ablation of animal with myocardial infarction. Lesion imaging was performed using free-breathing, non-contrast-enhanced, T1w sequence with long inversion time (TI). Also acquired were T maps and delayed contrast-enhanced (DCE) imaging. Hearts were excised for ex vivo imaging, and sliced for gross pathology and histology.
All ablations were visibly enhanced in non-contrast-enhanced T1w imaging using TI = 700 ms. T1w enhancement agreed with regions of necrosis in gross pathology and histology. Enhanced lesion cores were surrounded by dark bands containing contraction band necrosis, hematoma, and edema. In animals with myocardial infarction, chronic scar was hypointense in T1w, whereas acute ablations were enhanced, allowing discrimination between chronic scar and acute lesions, unlike DCE. Contrast was sufficient to create 3D volume renderings of lesions after minor postprocessing.
Non-contrast-enhanced T1w imaging with long TI promises to be an effective method for visualizing necrosis within radiofrequency ablation lesions. Enhancement is more specific and stationary than that from DCE. The imaging can be repeated as needed, unlike DCE, and may be especially useful for assessing ablations during or after a procedure. Magn Reson Med 79:879-889, 2018. © 2017 International Society for Magnetic Resonance in Medicine.
演示非增强 T1 加权（T1w）MRI 对射频消融损伤的成像。
15 头猪接受左心室消融，随后进行 MRI 检查，使用不同的准备方法：对未经处理的动物进行心内膜或心外膜消融，或对心肌梗死动物进行心内膜消融。使用自由呼吸、非增强、长反转时间（TI）的 T1w 序列进行病变成像。还获取了 T 映射和延迟对比增强（DCE）成像。取出心脏进行离体成像，并对切片进行大体病理学和组织学检查。
所有消融术在 TI=700ms 的非增强 T1w 成像中均可见增强。T1w 增强与大体病理学和组织学中的坏死区域一致。增强的损伤核心周围是含有收缩带坏死、血肿和水肿的暗带。在心肌梗死动物中，慢性疤痕在 T1w 中呈低信号，而急性消融术增强，能够区分慢性疤痕和急性损伤，与 DCE 不同。对比足以在轻微后处理后创建损伤的 3D 容积渲染。
长 TI 的非增强 T1w 成像有望成为可视化射频消融损伤内坏死的有效方法。增强比 DCE 更具特异性和稳定性。与 DCE 不同，这种成像可以根据需要重复进行，并且可能特别有助于在手术期间或之后评估消融术。磁共振医学 79:879-889, 2018。©2017 国际磁共振学会。
