Korchi Amine M, Garibotto Valentina, Lovblad Karl-Olof, Haller Sven, Weber Damien C
Can J Neurol Sci. 2013 Nov;40(6):800-6. doi: 10.1017/s0317167100015924.
Discrimination between radiation necrosis and tumor progression after radiation therapy represents a radiologic challenge. The aim of our investigation is to identify patterns of radiation necrosis on brain magnetic resonance imaging (MRI) and positron emission tomography (PET) with Fluoroethyltyrosin (FET) after proton beam therapy (PBT) for skull base tumors.
Five consecutive patients with extra-axial neoplasms were included, presenting a total of eight radiation necrosis lesions (three clival chordomas; two petroclival chondrosarcomas; two women; mean age: 49 ± 18.2 years). Radiation necrosis was defined as the appearance of abnormal enhancement on MRI after PBT decreasing over time, and additional histopathologic confirmation in one patient. MRI and PET imaging were retrospectively analyzed by two experienced radiologists in consensus.
All lesions were localized close to the primary tumor in the field of irradiation. Three patients showed bilateral symmetrical lesions. All lesions showed T2 hyperintensity and T1 hypointensity. Cerebral blood volume (CBV) was reduced in all available studies. None of the lesions showed a restricted diffusion. FET-PET (three patients) showed a higher uptake in four out of five lesions; three of which had a mean tumor-to-background (TBRmean) uptake lower than 1.95 and FET uptake increasing over time and were correctly classified into radiation necrosis.
Most radiation necroses were in direct continuity with the primary tumor mimicking tumor progression. The most consistent imaging findings for PBT radiation necrosis are low CBV without restricted diffusion and FET-PET TBRmean lower than 1.95 or increasing uptake over time. Bilateral symmetric involvement may be another indicator of radiation necrosis.
Critères radiologiques de la nécrose après protonthérapie des tumeurs de la base du crâne.
放疗后区分放射性坏死和肿瘤进展是一项放射学挑战。我们研究的目的是确定质子束治疗（PBT）颅底肿瘤后，脑磁共振成像（MRI）和氟代乙基酪氨酸（FET）正电子发射断层扫描（PET）上放射性坏死的模式。
纳入连续5例轴外肿瘤患者，共有8个放射性坏死病灶（3例斜坡脊索瘤；2例岩斜区软骨肉瘤；2例女性；平均年龄：49±18.2岁）。放射性坏死定义为PBT后MRI上异常强化随时间减弱，并在1例患者中得到组织病理学进一步证实。由两名经验丰富的放射科医生对MRI和PET成像进行回顾性分析并达成共识。
所有病灶均位于照射野内靠近原发肿瘤处。3例患者表现为双侧对称病灶。所有病灶T2加权像呈高信号，T1加权像呈低信号。所有可用研究中脑血容量（CBV）均降低。所有病灶均未显示扩散受限。FET-PET（3例患者）显示5个病灶中有4个摄取增加；其中3个病灶的平均肿瘤与本底（TBRmean）摄取低于1.95，且FET摄取随时间增加，被正确分类为放射性坏死。
大多数放射性坏死与原发肿瘤直接相连，类似肿瘤进展。PBT放射性坏死最一致的影像学表现是CBV低且无扩散受限，FET-PET的TBRmean低于1.95或摄取随时间增加。双侧对称受累可能是放射性坏死的另一个指标。
颅底肿瘤质子治疗后放射性坏死的放射学标准
