Kishimoto Riwa, Mizoe Jun-etsu, Komatsu Shuhei, Kandatsu Susumu, Obata Takayuki, Tsujii Hirohiko
Center Hospital, National Institute of Radiological Sciences, Chiba, Japan.
Magn Reson Med Sci. 2005 Dec 31;4(4):159-64. doi: 10.2463/mrms.4.159.
To clarify the characteristics of magnetic resonance (MR) imaging of radiation-induced brain injury following carbon ion radiotherapy and to observe the changes in lesions over time, we evaluated 40 patients with radiation-induced brain injury from carbon ion radiotherapy for head and neck tumors. Their primary lesions received a radiation dose of 48 to 70.4 Gray equivalent (GyE) in 16 to 18 fractions. MR imaging of radiation-induced brain injury was graded as follows: Grade 1: change in focal white matter; focal contrast enhancement and surrounding edema; Grade 2: nonenhanced area or cystic lesion in enhanced lesion; Grade 3: focal necrosis with mass effect; and Grade 4: mass effect requiring surgical intervention. Radiation-induced brain injury appeared as early as 2 months and as late as 57 months after carbon ion therapy (mean interval, 22.2 months). MR findings of initial lesion were Grade 1 in 26 cases (65.0%), Grade 2 in 13 (32.5%), and Grade 3 in 1 (2.5%). Brain injury was always found in the radiation field initially, but cystic lesion and edema later extended outside the field in 10 cases (25.0%). In follow-up MR studies, size of edema or enhanced lesion was reduced in 17 patients (42.5%) without treatment. Two cases with large cystic lesions required surgery. Improvement of radiation-induced brain injury was observed more often than had been previously described. Because edema and cystic lesion can occasionally extend outside the radiation field, such findings do not exclude the possibility of radiation-induced brain injury. Careful observation is recommended because cystic lesions can enlarge enough to require surgical treatment in some cases.
为阐明碳离子放疗后放射性脑损伤的磁共振（MR）成像特征，并观察病变随时间的变化，我们评估了40例因头颈部肿瘤接受碳离子放疗后发生放射性脑损伤的患者。其原发灶接受的辐射剂量为48至70.4格雷当量（GyE），分16至18次给予。放射性脑损伤的MR成像分级如下：1级：局灶性白质改变；局灶性对比增强及周围水肿；2级：增强病变内的无强化区或囊性病变；3级：伴有占位效应的局灶性坏死；4级：需要手术干预的占位效应。放射性脑损伤最早在碳离子治疗后2个月出现，最晚在57个月出现（平均间隔22.2个月）。初始病变的MR表现为1级26例（65.0%），2级13例（32.5%），3级1例（2.5%）。脑损伤最初总是出现在放疗野内，但10例（25.0%）患者的囊性病变和水肿后来扩展到野外。在后续的MR研究中，17例患者（42.5%）未经治疗水肿或增强病变的大小减小。2例有大囊性病变的患者需要手术。放射性脑损伤的改善情况比之前描述的更为常见。由于水肿和囊性病变偶尔可扩展到放疗野外，这些表现不能排除放射性脑损伤的可能性。建议仔细观察，因为在某些情况下囊性病变可能会增大到需要手术治疗。
