MR扩散加权成像鉴别颅内囊性病变的价值

MR diffusion-weighted imaging in differential diagnosis of intracranial cystic lesions

目的探讨 MR 扩散加权成像(DWI)在颅内囊性病变中的鉴别诊断价值。方法对76例经临床及手术病理证实的颅内囊性病变患者,行常规 MR、DWI 及增强 MR 检查,其中脑脓肿19例,原发性脑胶质瘤20例,小脑血管母细胞瘤4例,脑转移瘤10例,蛛网膜囊肿7例,表皮样囊肿16例。回顾性分析颅内囊性病变的 DWI 信号特征,定量测定囊性变区表观扩散系数(ADC)值。结果 DWI 上19例脑脓肿呈高信号;34例脑肿瘤患者中,除3例脑胶质瘤呈高信号、1例呈等信号,1例脑转移瘤呈高信号外,其余29例均呈低信号。各种病变 ADC 值分别为:脑脓肿(0.62±0.15)×10(-3)mm^2/s、脑胶质瘤(2.39±0.78)×10^(-3)mm^2/s、脑血管母细胞瘤(2.68±0.40)×10^(-3)mm^2/s、脑转移瘤(2.79±0.79)×10^(-3)mm^2/s。脑脓肿与脑胶质瘤、脑血管母细胞瘤、脑转移瘤的囊变坏死区ADC 值比较,差异均有统计学意义(P<0.01);脑胶质瘤与脑血管母细胞瘤、脑转移瘤的囊变坏死区ADC 值比较,差异均无统计学意义(p>0.05)。7例颅内蛛网膜囊肿的 DWI 呈低信号;16例表皮样囊肿 DWI 呈明显高信号。颅内蛛网膜囊肿和表皮样囊肿的 ADC 值分别为(2.96±0.36)×10^(-3)mm^2/s 和(0.94±0.13)×10^(-3)mm^2/S,二者之间差异有统计学意义(P<0.01)。结论 DWI 及ADC 值对鉴别脑脓肿和囊性或坏死性脑肿瘤具有重要的价值,DWI 表现为低信号的颅内囊性病变可除外脑脓肿。

Objective to evaluate the value fo diffusion-weighted imaging （DWI） on differential diagnosis of intracranial cystic lesions. Methods Seventy-six patients with surgically and pathologically confirmed intracranial cystic lesions undergone conventional MRI, DWI and contrast enhanced MRI examination. The signal characteristics of intracranial cystic lesions on DWI were analysed retrospectively, the apparent diffusion coefficient （ADC） values of cystic areas were measured quantitatively. Results Nineteen brain abscesses showed hyperintense signal on DWI. Among 34 brain tumors, 3 brain gliomas were hyperintense signal, 1 brain glioma was isointense signal and 1 metastasis was hyperintense signal; the other 29 brain tumors showed hypointense signal on DWI. The ADC values of all lesions were：（0.62±0.15 ）×10^-3 mm^2/s in brain abscesses,（2.39±0.78 ）×10^-3 mm^2/s in brain gliomas,（2.68±0.40 ）×10^-3 mm^2/s in brain hemangioblastomas, （2.79±0.79）×10^-3 mm^2/s in brain metastases, respectively. There were significant differences between the ADC values of brain abscess and the cystic or necrotic portions of brain glioma, hemangioblastoma, metastasis （P 〈0.01） , there were no significant differences among the ADC values of cystic or necrotic portions of brain gliomas, hemangioblastomas and metastases （ P 〉0.05 ）. Seven intracranial arachnoid cysts showed hypointense signal and 16 epidermoid cysts strikingly hyperintense signal on DWL. The ADC values of arachnoid cysts and epidermoid cysts were （2.96±0.36）×10^-3 mm^2/s and （0.94±0.13 ）×10^-3 mm^2/s respectively. There was significant difference between the ADC values of arachnoid cysts and epidermoid cysts （ P 〈0.01 ） . Conclusion DWI and ADC values have important contribution to the differentiation of brain abscesses from cystic or necrotic tumors, intracranial cystic lesions showing hypointense signal on DWI can exclude brain abscess.