Mata Jaime, Sheng Ke, Hagspiel Klaus, Ruppert Kai, Sylvester Peter, Mugler John, Fernandes Carolina, Guan Steven, Larner James, Read Paul
1Departments of Radiology and 2Radiation-Oncology, University of Virginia, Charlottesville, Virginia.
Exp Lung Res. 2014 Aug;40(6):308-16. doi: 10.3109/01902148.2014.918213. Epub 2014 Jun 13.
This study aimed to assess the efficacy of the radioprotector amifostine in limiting radiation toxicity in a rabbit model of lung stereotactic body radiation therapy (SBRT) by correlating contrast-enhanced magnetic resonance angiography (ce-MRA), computed tomography (CT), and helium-3 (He-3) magnetic resonance imaging (MRI) with histopathology. Multiple MRI techniques were tested to obtain complementing physiologic information. Thirteen rabbits received SBRT to the right lower lobe of the lung. Specifically, 4 received 3 × 11 Gray (Gy), 6 received 3 × 11 Gy and 50 mg/kg of amifostine pre-SRBT, and 3 received 3 × 7, 3 × 9, or 3 × 13 Gy. Imaging was performed at baseline and 4, 8, 12, and 16 weeks post-SBRT. Ce-MRA perfusion difference between lungs in the irradiated group at 16 weeks post-treatment was statistically significant (P = .04) whereas the difference in the irradiated + amifostine group was not (P = .30). Histologically observed low red blood cell (RBC) count and CT hypodensity suggests changes were primarily related to perfusion; however, structural changes, such as increased alveolar size, were also present. No changes in He-3 MRI lung ventilation were observed in either group. Although radiation-induced injury detected in rabbits as CT hypodensity contrasted with increased density observed in humans/rodents, the changes in ce-MRA and CT were still significantly reduced after the addition of amifostine to SBRT. Use of CT and selected MRI techniques helped to pinpoint primary physiologic changes.
本研究旨在通过将对比增强磁共振血管造影（ce-MRA）、计算机断层扫描（CT）和氦-3（He-3）磁共振成像（MRI）与组织病理学相关联，评估放射防护剂氨磷汀在兔肺立体定向体部放射治疗（SBRT）模型中限制辐射毒性的疗效。测试了多种MRI技术以获取互补的生理信息。13只兔子接受了右肺下叶的SBRT。具体而言，4只接受3×11格雷（Gy），6只在SBRT前接受3×11 Gy和50 mg/kg氨磷汀，3只接受3×7、3×9或3×13 Gy。在基线以及SBRT后4、8、12和16周进行成像。治疗后16周，照射组肺之间的ce-MRA灌注差异具有统计学意义（P = 0.04），而照射+氨磷汀组的差异则无统计学意义（P = 0.30）。组织学观察到的低红细胞（RBC）计数和CT低密度表明变化主要与灌注有关；然而，也存在结构变化，如肺泡大小增加。两组He-3 MRI肺通气均未观察到变化。尽管在兔子中检测到的辐射诱导损伤表现为CT低密度，与在人类/啮齿动物中观察到的密度增加形成对比，但在SBRT中添加氨磷汀后，ce-MRA和CT的变化仍显著减少。使用CT和选定的MRI技术有助于确定主要的生理变化。
