DWI结合T_2WI在包膜期脑脓肿与囊性转移瘤鉴别诊断中的价值

The Value of DWI and T_2WI in Distinguishing Between Integument-Term Brain Abscess and Cerebral Cystic Metastatic Neoplasm

目的探讨磁共振扩散加权成像(DWI)结合T_2WI在包膜期脑脓肿和囊性脑转移瘤鉴别诊断中的价值。方法回顾性分析经病理或临床随访证实的23例包膜期脑脓肿和24例脑囊性转移瘤患者的MRI常规平扫、增强及DWI检查资料,b值取0、500 s/mm^2、1000 s/mm^2,根据信噪比(SNR)及图像质量指数(QI)取最佳b值的DWI,分别测量病灶囊变区、囊壁、对侧正常脑组织平均ADC值并计算3项r ADC值,两组间采用两独立样本t检验进行统计学分析。结果包膜期脑脓肿T_2WI低信号暗带及靶环征是鉴别囊性转移瘤的MRI特征性表现。取b值1000s/mm^2时,脑囊性转移瘤囊变坏死区DWI呈低信号22例,高信号1例,囊变坏死区、囊壁、对侧正常脑组织平均ADC值分别为(0.64±0.14)×10^(-3)mm^2/s、(1.56±0.17)×10^(-3)mm^2/s、(0.79±0.18)×10^(-3)mm^2/s,脑囊性转移瘤囊壁r ADC值、病灶r ADC值、囊液r ADC值分别为1.19±0.37、0.48±0.25、2.74±0.75。包膜期脑脓肿囊液DWI呈高信号,包膜期脑脓肿囊变区、囊壁、对侧正常脑组织平均ADC值分别为(2.10±0.28)×10^(-3)mm^2/s、(1.51±0.09)×10^(-3)mm^2/s、(0.81±0.15)×10^(-3)mm^2/s,包膜期脑脓肿囊壁r ADC值、病灶r ADC值、囊液r ADC值分别为1.37±0.48、1.49±0.62、0.95±0.50。包膜期脑脓肿与脑囊性转移瘤囊液ADC值、病灶r ADC值、囊液r ADC值差异均有显著统计学意义(P<0.01),囊壁ADC值、囊壁r ADC值差异均无统计学意义(P>0.05)。结论包膜期脑脓肿壁上T_2WI特征性的低信号暗带及靶环征有别于囊性转移瘤,b值=1000 s/mm^2时囊液DWI、囊液ADC值、病灶r ADC值、囊液r ADC值能有效反映包膜期脑脓肿与囊性脑转移瘤的不同囊液性质,DWI结合T_2WI对包膜期脑脓肿与囊性脑转移瘤的鉴别诊断具有重要价值。

Objective To investigate the values of DWI,ADC,r ADC and T2WI in distinguishing integument-term brain abscess and cerebral cystic metastatic neoplasm. Methods Forty-seven patients who comprised 23 cases of integumentterm brain abscesses and 24 cases of cerebral cystic metastatic neoplasm confirmed by pathology underwent conventional plain and enhanced MRI and DWI scans. b value = 0 s / mm^2、500 s/mm^2、1000 s/mm^2,According to SNR,QI to choose the DWI of the best b value. We measured the ADC values of the necrosis,the wall of the lesions,the normal brain tissue,and calculated the r ADC values of necrosis,the wall of the lesions,and the lesions,then statistically analyzed. Results There was a low-signal zone and ring sign in the wall of integument-term brain abscesses. To choose the DWI OF b = 1000 s / mm^2,The cystic and necrotic area of cerebral metastatic neoplasm presented with low signal intensity on DWI except 1case showed high. The average ADC values of the necrosis,the wall of the lesions,the normal brain tissue was（ 0. 64 ±0. 14） × 10^-3mm^2/ s、（ 1. 56 ± 0. 17） × 10^-3mm^2/ s、（ 0. 79 ± 0. 18） × 10^-3mm^2/ s,The r ADC values of the necrosis,the wall of the lesions,the nidus was 1. 19 ± 0. 37、0. 48 ± 0. 25、2. 74 ± 0. 75. The cystic fluid of integument-term brain abscesses showed high signal intensity on DWI. The average ADC values of the necrosis,the wall of the lesions and the normal brain tissue was（ 2. 10 ± 0. 28） × 10^-3mm^2/ s、（ 1. 51 ± 0. 09） × 10^-3mm^2/ s and（ 0. 81 ± 0. 15） × 10^-3mm^2/ s respectively. The r ADC values of the necrosis,the wall of the lesions and the nidus was 1. 37 ± 0. 48、1. 49 ± 0. 62 and 0. 95 ±0. 50 respectively. There were significant differences in the average ADC values of the necrosis,the rA DC values of the necrosis and lesions（ P〈0. 01）,but there were no significant difference in average ADC and rA DC values of the lesions and wall（ P〈0. 05）. Conclusion On T2WI,the low-signal zone and ring sign in the cyst wall were characteristic for integument-term brain abscesses. DWI,ADC,rA DC value of b = 1000 s / mm^2 in the necrosis region can distinguish between the integument-term brain abscess and cerebral cystic metastatic neoplasm.