Division of Radiology, Department of Pathophysiological and Therapeutic Science, Faculty of Medicine, Tottori University, 36-1 Nishi-cho, Yonago 683-8503, Japan.
Eur J Radiol. 2011 May;78(2):282-6. doi: 10.1016/j.ejrad.2011.01.048. Epub 2011 Feb 5.
To evaluate the usefulness of administration of superparamagnetic iron oxide (SPIO) and magnetic resonance (MR) imaging for assessing the efficacy of radiofrequency (RF) liver ablation.
Using a protocol approved by the animal research committee of our university, nine RF liver ablations were performed in three miniature pigs. Six ablations were performed after administration of SPIO in two pigs (group A). Three ablations were performed in the other pig without administration of SPIO (group B). All pigs were sacrificed 4 days after the procedure. Harvested livers were scanned with a 1.5T MR system before and after fixation with 10% buffered formalin, and MR images were precisely compared with histological specimens.
There were no histological differences between the two groups. All ablated liver lesions showed coagulation necrosis at the external layer. There were no viable cells inside the coagulation necrosis. All ablated lesions had a hypointense rim on fast low angle shot (FLASH) images. The rims of group A were thicker than those of group B. The rims of group B corresponded histologically to congestion and hemorrhagic necrosis area. The rims of the group A corresponded to hemorrhagic necrosis and coagulation necrosis areas. In group A, the hypointense rim reflected necrotic Kupffer cells that took up SPIO before RF liver ablation.
Administration of SPIO made it possible to precisely evaluate ablated liver parenchyma by hypointense rim on FLASH images. This method is helpful for the evaluation of safety margin after RF ablation for liver tumors.
评估超顺磁氧化铁（SPIO）和磁共振（MR）成像在评估射频（RF）肝消融疗效中的作用。
使用大学动物研究委员会批准的方案，在三只小型猪中进行了 9 次 RF 肝消融。在两只猪（A 组）中进行 SPIO 给药后进行了 6 次消融。另一只猪（B 组）未进行 SPIO 给药进行了 3 次消融。所有猪均在手术后 4 天被处死。使用 1.5T MR 系统在固定于 10%缓冲福尔马林之前和之后对收获的肝脏进行扫描，并精确地将 MR 图像与组织学标本进行比较。
两组之间没有组织学差异。所有消融的肝病变在外层均显示凝固性坏死。凝固性坏死内没有存活的细胞。所有消融的病变在快速低角射击（FLASH）图像上均显示低信号边缘。A 组的边缘比 B 组的边缘厚。B 组的边缘在组织学上对应于充血和出血性坏死区。A 组的边缘对应于出血性坏死和凝固性坏死区。在 A 组中，低信号边缘反映了在 RF 肝消融之前摄取 SPIO 的坏死枯否细胞。
SPIO 的给药使得通过 FLASH 图像上的低信号边缘精确评估消融的肝实质成为可能。这种方法有助于评估肝肿瘤 RF 消融后的安全边界。
