鼻咽癌放射治疗后放射性脑损伤的影像学表现

Comparative imaging study in radiation injuries following radiotherapy for nasopharyngeal carcinoma

目的 探讨鼻咽癌放射治疗 (简称放疗 )后放射性脑损伤的CT、MRI、正电子发射计算机体层摄影术 (PET)的影像学以及组织病理学特征。方法 回顾分析鼻咽癌 (NPC)放疗后放射性脑损伤 71例患者的临床、CT、MRI、PET以及手术病理学资料。结果 病变位于颞叶、脑干或小脑 ,其CT表现为均匀或不均匀的低密度 ,位于颞叶者 ,呈“指状”低密度。 2 3例患者 (2 9个病灶 )行CT增强扫描 ,86 2 % (2 5/ 2 9)的病灶无强化。MRI示损伤脑组织的T1 、T2 弛豫时间延长 ,可呈不均匀信号改变。 2 0例患者 (2 9个病灶 )行MR增强扫描 ,65 5 % (1 9/ 2 9)的病灶呈“花环状”强化。 2例病人行PET扫描 ,1例与CT及MRI所示病变相符合。 3例患者颞叶手术切除术及组织病理学检查均为放射性脑坏死。结论 (1 )MR平扫或增强扫描发现病变的敏感度均高于CT和PET。 (2 )T1 WI和T2 WI显示的不均匀信号提示为坏死 ,且均位于照射野内。 (3)增强MRI所示的“花环状”强化 ,是放射性脑坏死的特征。 (4)

Objective To evaluate the characteristics of CT, MRI, PET and histopathology of brain radiation injuries following radiotherapy for nasopharyngeal carcinoma. Methods We reviewed the imaging records of 71 patients with brain radiation injuries following radiotherapy for nasopharyngeal carcinoma examined over a 10 year period. Results The radiation injury lesions occurred in the temporal lobes, brain stems or cerebella. Their CT appears were homogeneous or heterogeneous density. If the lesions situated in temporal lobes, they presented as 'finger like' hypointensity. Twenty three patients(29 lesions) undenwent contrast enhanced CT scan, 86.2 percent(25/29)of the lesions showed no enhancement. MRI demonstrated prolonged T 1 and T 2 relaxation time of the injured tissue, they might showed homogeneous or heterogeneous signal intensity. MR enhanced T 1WI were performed in 20 cases(29 lesions),and 65.5 percent(19/29)of the lesions presented 'Flower lace' enhancement. Two patients were carried on PET scan. One patient′s PET appearance is similar to the CT or MRI finding. Resections and histopathologic observations of temporal lobes′ lesions were performed on 3 cases, which showed cerebral necrosis. Conclusion (1) MRI plain or contrast enhanced scan is more sensitive than that of CT or PET. (2)The heterogeneous signal intensity on T 1WI and T 2WI represent necrosis,and all are located in the radiation field. (3)'Flower lace' enhancement on contrast MRI is the characteristic of brain radionecrosis. (4)PET may serve as a complementarity in the diagnosis of radiation induced injuries.