Department of Radiology, University Hospitals of Case Medical Center/Case Western Reserve University School of Medicine.
Radiology. 2010 Feb;254(2):449-59. doi: 10.1148/radiol.253180614. Epub 2010 Jan 20.
To test the hypothesis that magnetic resonance (MR) imaging can be used to monitor both intraparenchymal injection of NaCl solution and subsequent radiofrequency ablation (RFA) within tissues pretreated with NaCl, report the low- and high-field-strength MR appearance of NaCl-enhanced RFAs, and compare MR findings with pathologic findings.
Ten ex vivo calf liver specimens were injected with saturated NaCl (seven were mixed with methylene blue during MR fluoroscopic monitoring) and reexamined with fast imaging with steady-state progression (FISP), true FISP, reversed FISP (PSIF), and fast spin-echo T2-weighted MR sequences. The NaCl-to-liver contrast-to-noise ratio (CNR) was calculated for various sequences, and CNRs were compared with the Student t test. Distribution on MR images was compared with the results of pathologic analysis. Forty additional in vivo monopolar RFAs were performed in paraspinal muscles of seven minipigs after animal care committee approval (10 standard control ablations, 30 were preceded by direct injection of saturated NaCl at various volumes [3-9 mL] and rates [1 or 6mL/min]). Postablation low-field-strength (n = 20) and high-field-strength (n = 20) MR examinations consisted of T2-weighted imaging, short inversion time inversion-recovery (STIR) imaging, and contrast material-enhanced T1-weighted imaging. Ablation shape, conspicuity, volume, and signal intensity were compared between the two groups and with the results of pathologic analysis. The difference in volumes with and without NaCl injection was evaluated by using two-way analysis of variance.
Mean CNR was highest on fast spin-echo T2-weighted images and was significantly higher for PSIF than for FISP (P < .0001) or true FISP (P = .003). NaCl distribution on MR images corresponded with the results of pathologic analysis in ex vivo livers. Interactive in vivo monitoring of NaCl injection and electrode placement was feasible. NaCl-enhanced ablations had irregular shapes, a higher CNR, and significantly larger volumes (F = 22.0; df = 1, 90; P < .00001). All ablations had intermediate or low signal intensity with high-signal-intensity rims on all images. Fluid signals overlaid NaCl-enhanced ablations on fast spin-echo T2-weighted and STIR images, particularly on high-field-strength MR images.
MR imaging can be used to reliably monitor the distribution of injected NaCl solution in tissues. Interventional MR imaging techniques can be used to guide and monitor RFAs within NaCl pretreated tissues, with good correlation with pathologic results.
验证磁共振（MR）成像可用于监测经氯化钠预处理组织内的瘤内注射和随后的射频消融（RFA）的假说，报告低场强和高场强下氯化钠增强的 RFA 的 MR 表现，并将 MR 发现与病理发现进行比较。
10 个离体小牛肝标本注射饱和氯化钠（7 个在 MR 透视监测时混合亚甲蓝），用快速稳态进动（FISP）、真实 FISP、反转 FISP（PSIF）和快速自旋回波 T2 加权 MR 序列进行重新检查。计算了各种序列的氯化钠与肝的对比噪声比（CNR），并通过学生 t 检验进行比较。MR 图像上的分布与病理分析结果进行比较。在动物护理委员会批准后（10 个标准对照消融，30 个在各种体积[3-9 mL]和速度[1 或 6 mL/min]下直接注射饱和氯化钠之前），在 7 只小型猪的脊柱旁肌肉中进行了 40 次额外的单极 RFA。低场强（n = 20）和高场强（n = 20）MR 检查包括 T2 加权成像、短反转时间反转恢复（STIR）成像和对比增强 T1 加权成像。在两组之间以及与病理分析结果比较消融的形状、显著性、体积和信号强度。通过双因素方差分析评估有无氯化钠注射的体积差异。
快速自旋回波 T2 加权图像上的平均 CNR 最高，PSIF 显著高于 FISP（P <.0001）或真实 FISP（P =.003）。离体肝上的 MR 图像上的氯化钠分布与病理分析结果相对应。氯化钠注射和电极放置的交互式实时监测是可行的。氯化钠增强的消融具有不规则形状、更高的 CNR 和显著更大的体积（F = 22.0；df = 1, 90；P <.00001）。所有消融在所有图像上均具有中等或低信号强度，具有高信号强度边缘。在快速自旋回波 T2 加权和 STIR 图像上，特别是在高场强 MR 图像上，液体信号覆盖在氯化钠增强的消融上。
MR 成像可用于可靠地监测注射氯化钠溶液在组织中的分布。介入性磁共振成像技术可用于引导和监测经氯化钠预处理组织内的 RFA，与病理结果具有良好的相关性。
