Tomura N, Kokubun M, Saginoya T, Mizuno Y, Kikuchi Y
From the Departments of Neuroradiology, Radiology, and Neurosurgery, Southern Tohoku Research Institute for Neuroscience, Southern Tohoku General Hospital, Koriyama City, Fukushima, Japan.
AJNR Am J Neuroradiol. 2017 Aug;38(8):1520-1527. doi: 10.3174/ajnr.A5252. Epub 2017 Jun 15.
In patients with metastatic brain tumors after gamma knife radiosurgery, the superiority of PET using C-methionine for differentiating radiation necrosis and recurrent tumors has been accepted. To evaluate the feasibility of MR permeability imaging, it was compared with PET using C-methionine, FDG-PET, and DWI for differentiating radiation necrosis from recurrent tumors.
The study analyzed 18 lesions from 15 patients with metastatic brain tumors who underwent gamma knife radiosurgery. Ten lesions were identified as recurrent tumors by an operation. In MR permeability imaging, the transfer constant between intra- and extravascular extracellular spaces (/minute), extravascular extracellular space, the transfer constant from the extravascular extracellular space to plasma (/minute), the initial area under the signal intensity-time curve, contrast-enhancement ratio, bolus arrival time (seconds), maximum slope of increase (millimole/second), and fractional plasma volume were calculated. ADC was also acquired. On both PET using C-methionine and FDG-PET, the ratio of the maximum standard uptake value of the lesion divided by the maximum standard uptake value of the symmetric site in the contralateral cerebral hemisphere was measured (C-methionine ratio and FDG ratio, respectively). The receiver operating characteristic curve was used for analysis.
The area under the receiver operating characteristic curve for differentiating radiation necrosis from recurrent tumors was the best for the C-methionine ratio (0.90) followed by the contrast-enhancement ratio (0.81), maximum slope of increase (millimole/second) (0.80), the initial area under the signal intensity-time curve (0.78), fractional plasma volume (0.76), bolus arrival time (seconds) (0.76), the transfer constant between intra- and extravascular extracellular spaces (/minute) (0.74), extravascular extracellular space (0.68), minimum ADC (0.60), the transfer constant from the extravascular extracellular space to plasma (/minute) (0.55), and the FDG-ratio (0.53). A significant difference in the C-methionine ratio ( < .01), contrast-enhancement ratio ( < .01), maximum slope of increase (millimole/second) ( < .05), and the initial area under the signal intensity-time curve ( < .05) was evident between radiation necrosis and recurrent tumor.
The present study suggests that PET using C-methionine may be superior to MR permeability imaging, ADC, and FDG-PET for differentiating radiation necrosis from recurrent tumors after gamma knife radiosurgery for metastatic brain tumors.
在伽玛刀放射外科治疗后的脑转移瘤患者中，使用碳 - 蛋氨酸的正电子发射断层显像（PET）在鉴别放射性坏死和肿瘤复发方面的优越性已得到认可。为评估磁共振通透性成像的可行性，将其与使用碳 - 蛋氨酸的PET、氟代脱氧葡萄糖PET（FDG - PET）及扩散加权成像（DWI）进行比较，以鉴别放射性坏死与肿瘤复发。
本研究分析了15例接受伽玛刀放射外科治疗的脑转移瘤患者的18个病灶。其中10个病灶经手术确诊为肿瘤复发。在磁共振通透性成像中，计算血管内与血管外细胞外间隙之间的转运常数（/分钟）、血管外细胞外间隙、从血管外细胞外间隙到血浆的转运常数（/分钟）、信号强度 - 时间曲线下的初始面积、对比增强率、团注到达时间（秒）、最大上升斜率（毫摩尔/秒）及血浆分数体积。同时获取表观扩散系数（ADC）。在使用碳 - 蛋氨酸的PET和FDG - PET上，分别测量病灶最大标准摄取值与对侧脑半球对称部位最大标准摄取值的比值（分别为碳 - 蛋氨酸比值和FDG比值）。采用受试者工作特征曲线进行分析。
鉴别放射性坏死与肿瘤复发的受试者工作特征曲线下面积，碳 - 蛋氨酸比值最佳（0.90），其次为对比增强率（0.81）、最大上升斜率（毫摩尔/秒）（0.80）、信号强度 - 时间曲线下的初始面积（0.78）、血浆分数体积（0.76）、团注到达时间（秒）（0.76）、血管内与血管外细胞外间隙之间的转运常数（/分钟）（0.74）、血管外细胞外间隙（0.68）、最小ADC（0.60）、从血管外细胞外间隙到血浆的转运常数（/分钟）（0.55）及FDG比值（0.53）。放射性坏死与肿瘤复发之间，碳 - 蛋氨酸比值（<0.01）、对比增强率（<0.01）、最大上升斜率（毫摩尔/秒）（<0.05）及信号强度 - 时间曲线下的初始面积（<0.05）存在显著差异。
本研究提示，对于脑转移瘤伽玛刀放射外科治疗后的放射性坏死与肿瘤复发的鉴别，使用碳 - 蛋氨酸的PET可能优于磁共振通透性成像、ADC及FDG - PET。
