Ohira Tomohiro, Okuma Tomohisa, Matsuoka Toshiyuki, Wada Yasuhiro, Nakamura Kenji, Watanabe Yasuyoshi, Inoue Yuichi
Department of Radiology, Osaka City University Graduate School of Medicine, Osaka, Japan.
Cardiovasc Intervent Radiol. 2009 Jan;32(1):114-20. doi: 10.1007/s00270-008-9394-5. Epub 2008 Aug 12.
The objective of this study was to evaluate the early changes after radiofrequency ablation (RFA) in VX2 rabbit tumors implanted into the back muscles by diffusion-weighted magnetic resonance (MR) imaging and (18)F-2-fluoro-2-deoxy-D-glucose positron emission tomography ((18)F-FDG PET). Percutaneous CT-guided RFA was conducted in seven rabbits with implanted VX2 tumors. VX2 tumors on the other side were untreated and served as the control. MR imaging was performed with a clinical 1.5-T instrument 2 days after RFA, and FDG-PET, using a high-resolution PET scanner for small animals, was obtained 3 days after the procedure. The mean apparent diffusion coefficient (ADC) values and radioactivity count of untreated and ablated tumors were calculated. Untreated VX2 tumors showed hyperintensity on T1-, T2-, and diffusion-weighted MR images, ring-enhanced on contrast-enhanced T1-weighted imaging, and ring-shaped FDG accumulation on FDG-PET. Ablated VX2 tumors showed slight hyperintensity on T1-, T2-, and diffusion-weighed images, slight enhancement on contrast-enhanced T1-weighted images, and low accumulation on FDG-PET. The ADC value of ablated VX2 tumors (1.52 +/- 0.24 x 10(-3) mm(2)/s) was significantly higher than that of untreated tumors (1.09 +/- 0.12 x 10(-3); p < 0.05). The tumor/muscle ratio of ablated tumors (0.5 +/- 0.3) was significantly lower than that of untreated tumors (11.6 +/- 3.2; p < 0.05). Histopathological examination confirmed the lack of viable tumor cells in the ablated lesions. The results indicate that both ADC value and FDG-PET are potentially useful markers for monitoring the early effects of RFA.
本研究的目的是通过扩散加权磁共振（MR）成像和（18）F-2-氟-2-脱氧-D-葡萄糖正电子发射断层扫描（（18）F-FDG PET）评估植入背部肌肉的VX2兔肿瘤在射频消融（RFA）后的早期变化。对7只植入VX2肿瘤的兔子进行了经皮CT引导下的RFA。另一侧的VX2肿瘤未治疗，作为对照。RFA后2天用临床1.5-T仪器进行MR成像，术后3天使用小动物高分辨率PET扫描仪进行FDG-PET检查。计算未治疗和消融肿瘤的平均表观扩散系数（ADC）值和放射性计数。未治疗的VX2肿瘤在T1、T2和扩散加权MR图像上呈高信号，在对比增强T1加权成像上呈环形强化，在FDG-PET上呈环形FDG聚集。消融后的VX2肿瘤在T1、T2和扩散加权图像上呈轻度高信号，在对比增强T1加权图像上呈轻度强化，在FDG-PET上呈低聚集。消融后VX2肿瘤的ADC值（1.52±0.24×10（-3）mm（2）/s）显著高于未治疗肿瘤（1.09±0.12×10（-3）；p<0.05）。消融肿瘤的肿瘤/肌肉比值（0.5±0.3）显著低于未治疗肿瘤（11.6±3.2；p<0.05）。组织病理学检查证实消融灶内无存活肿瘤细胞。结果表明，ADC值和FDG-PET均可能是监测RFA早期疗效的有用标志物。
