Values of DWI and ADC in differential diagnosis between brain abscesses and necrotic or cystic metastatic brain tumors

    HUANG Minª²Hua, GUO Yong, LIN Wei, QIAN Mingª²Zhu, ZHANG Yongª²Wen

    MRI Room, General Hospital of Navy, Beijing 100037, China

    ¡¾Abstract¡¿ AIM: To study the values of diffusionª²weighted imaging (DWI) and apparent diffusion coefficient (ADC) in the differential diagnosis between brain abscesses and necrotic or cystic metastatic brain tumors. METHODS: Fourteen patients proved pathologically as brain abscess and 17 cystic/necrotic metastatic tumor underwent conventional MRI and DWI examinations. DWI signal and ADC value were evaluated in cerebritis stage, capsule formation stage, and evolution stage of brain abscess and compared with those of cystic/necrotic metastatic tumor. Chiª²squared test and t test were performed for statistic analysis. RESULTS: The DWI signal was high and ADC value was low in the capsule stage of abscess, which was contrary to that of cystic/necrotic tumor. The DWI signal was low or equal and ADC value was high or equal in the evolution stage or cerebritis stage, which was similar to that of cystic/necrotic tumor. The mean ADC value of all brain abscesses was (0.88¡Á10-3) mm2/s, and that of cystic/necrotic tumor was (1.8¡Á10-3) mm2/s; the difference was statistically significant (P<0.05). The diagnostic sensitivity, specificity and accuracy of DWI signals were 64.5% (20/31), 100% (17/17), 77% (37/48) respectively. CONCLUSION: DWI and ADC value are helpful to differentiate capsule formation stage of abscess from cystic/necrotic tumor, but not helpful to distinguish evolution stage/cerebritis stage of abscess from cystic/necrotic tumor. ......