[MRI features of cerebral parenchymal tuberculosis and the dynamic evolution during antituberculous treatment].

OBJECTIVE:To investigate the MRI features, classification and the evolution of cerebral parenchymal tuberculosis (TB) during anti-tuberculosis treatment. METHODS:A total of 134 patients with cerebral parenchymal TB registered in our hospital from Sep. 2010 to Aug. 2010 were studied retrospectively. There were 68 males and 66 females, aged 14 to 77 years. The MRI characteristics of these patients were analyzed after T1WI, T2WI, DWI and enhanced scan.The millet, small and large nodules were named by the lesion diameter of less than 0.3 cm, 0.3 to 1.0 cm and lager than 1.0 cm in brain parenchymal TB, respectively, and accordingly the cerebral parenchymal TB cases were divided into millet nodule type, small nodule type, large nodule type and mixed nodule type with at least 2 of 3 nodule sizes. According to the enhanced scanning patterns and signal characteristics, the cases were divided into hyperplastic nodule, tuberculoma type, abscess type and mixed type. Serial follow-up MRI scans were performed in 76 patients during their anti-tuberculosis treatment.Data on lesions of different size were analyzed by Chi-square test and the follow-up results were analyzed by single-factor logistic regression. RESULTS:Of all the 134 patients, the lesions were commonly found in the cerebral hemisphere and cerebellar hemisphere, often multiple in different locations. Three patterns of homogeneous enhancement, ring enhancement, and variegated enhancement were found in the 134 patients after the enhanced scan, of which 2 or more patterns co-existed in 72 cases. There were 124 cases with millet nodules, of which 116 were homogeneous enhancement and 32 were heterogeneous enhancement (including ring enhancement and variegated enhancement). Ninety cases were found to have small nodules, of which 34 were homogeneous enhancement and 69 were heterogeneous enhancement. Sixty cases were found to have large nodules, of which 1 was of homogeneous enhancement and 16 were of heterogeneous enhancement. The case number of the homogeneous enhancement and heterogeneous enhancement was significantly different for the 3 different sized nodules, respectively (P<0.05). Homogeneous enhancement was seen commonly in millet nodules, while heterogeneous enhancement in small nodules especially large nodules. In contrast to small nodule type (8 cases) and large nodule type (1 case), millet nodule type (68 cases) and mixed nodule type (57 cases) were predominant. The hyperplastic nodule type (64 cases) and mixed cerebral tuberculosis (60 cases) were predominant in contrast to tuberculoma type (9 cases) and abscess type (1 case) in the 134 patients. The cases with lesion diameter more than 0.5 cm mostly showed tuberculoma. The disappearance rates were 23 (30.3%) among 76 patients with serial MRI follow-up scans. The disappearance rate of hyperplastic nodule type (17/37) was significantly higher than that of the non-hyperplastic nodule type (including tuberculoma and mixed type) (6/39) (P=0.004). The disappearance rate of millet nodule type (15/38) was significantly higher than that of the non-millet nodule type (8/38) (P=0.02). Single-factor logistic regression analysis showed that, the results of the follow-up only related to 2 classifications (P<0.05). Fourteen patients were found to have enlarged lesions or newly appeared lesion during anti-tuberculosis treatment, of which 3 were refractory. CONCLUSIONS:Cerebral parenchymal TB showed certain MRI characteristics. Homogeneous enhancement, ring enhancement, and variegated enhancement. About half of the patients had more than 2 enhancement patterns. Homogeneous enhancement and heterogeneous enhancement were commonly seen in millet nodules and small nodules especially large nodules, respectively. According to the classification of lesion size, millet nodule type and mixed nodule type were predominant. According to the characteristics of the lesion enhancement pattern and signal characteristics, hyperplastic nodule type and mixed type were predominant. This classification would help to guide the treatment of cerebral parenchymal TB. The treatment effect of hyperplastic nodule type was better than non-hyperplastic nodule type, and millet nodule type was better than non-millet nodule types.