摘要目的 评估MR弥散加权成像(DWI)和含钆造影剂对比增强磁共振成像(CE-MRI)对脑脓肿的诊断价值.方法 对49例脑内单发囊实性病变行常规T1WI、T2WI、液体反转恢复序列(FLAIR)、弥散加权成像和钆增强MRI检查.分析脑脓肿(22例)与囊变坏死性脑肿瘤(27例)DWI信号及强化特征并进行囊变坏死区ADC值测量.所有图像分三组与病理结果进行对照分析:Ⅰ组为DWI结合常规序列；Ⅱ组为CE-MRI结合常规序列；Ⅲ组为DWI、CE-MRI两种序列联合并结合常规序列.结果 DWI上20例脑脓肿呈高信号,24例囊变坏死性脑肿瘤为低信号；14例脑脓肿、12例囊变坏死性脑肿瘤呈壁较薄而均匀环形强化.大部分脑脓肿的ADC值明显低于囊变坏死性脑肿瘤(P＜0.05).Ⅰ组、Ⅱ组、Ⅲ组诊断脑脓肿的敏感性分别为90.9％、63.6％、95.5％,Ⅰ、Ⅱ组间及Ⅱ、Ⅲ组间均具有明显统计学差异(P＜0.05),但Ⅰ、Ⅲ组间没有统计学差异(P＞0.05).结论 DWI较CE-MRI能更敏感地发现脑脓肿,ADC值的测量可以为脑脓肿与囊变坏死性脑肿瘤的鉴别提供有价值的诊断信息.

abstractsObjective To evaluate the diagnostic values of diffusion weighted MRI(DWI)and contrast-enhanced magnetic resonance imaging(CE-MRI)using gadolinium chelates in patients with brain abscesses.Methods Conventional TlWI,T2WI,fluid attenuated inversion recovery(FLAIR),DWI and gadolinium-enhanced MRI were performed in 49 patients with single cystic/solid brain lesions.Retrospective analysis of the DWI signals and enhancement characteristics of patients with brain abscesses(n=22)and with cystic/necrotic brain tumors(n=27)was performed; meanwhile,measurement of the ADC values of the necrotic areas was performed.DWI combined with conventional sequences (group Ⅰ),CE-MRI combined with conventional sequences(group Ⅱ),and DWI,CE-MRI and conventional sequences(group Ⅲ)were employed to calculate their sensitivity,specificity,positive predictive value,negative predictive value and accuracy; these results were compared with the pathological results.Results The high DWI signal was noted in 20 patients with brain abscesses,and low DWI signal in 24 patients with cystic/necrotic brain tumors.Evenly thin walls and a ring enhancement under enhanced scan were noted in 14 patients with abscesses and 12 patients with cystic/necrotic brain tumors.Most of the ADC values in patients with brain abscesses were significantly lower than those in patients with cystic/necrotic brain tumors(P＜0.05).The diagnostic sensitivity to brain abscess in group I,group Ⅱ and group Ⅲ were 90.9％,63.6％ and 95.5％,respectively; the difference was statistically significant between group Ⅰ and group Ⅱ(P＜0.05),and between group Ⅱ and group Ⅲ(P＜0.05),but not between group Ⅰ and group Ⅲ(P＞0.05).Conclusion DWI is more sensitive in detecting the brain abscess than CE-MRI,and the measurement of ADC values can provide valuable differential diagnostic information for patients with brain abscess and cystic/necrotic brain tumor.