Study of MRI features of intracranial tuberculosis and its dynamic evolution during antituberculous treatment

Objective To explore MRI features of intracranial tuberculosis,and the dynamic evolution of intracranial tuberculosis during antituberculous treatment.Methods From September 2009 to February 2012,seventy-two patients with intracranial tuberculosis were reviewed retrospectively.Intracranial tuberculosis lesions were divided into 3 categories:pure parenchymal tuberculosis,tuberculous meningitis and hybrid type with both parenchymal tuberculosis and tuberculous meningitis.The MRI characteristics of these lesions were analysed.According to the lesion size,pure parenchymal tuberculosis was divided into 3 subtypes:0.3 cm or less was defined as miliary,＞ 0.3 cm and ＜ 1.0 cm as nodule,greater than or equal to 1.0 cm as tuberculoma.Serial follow-up scans were performed in 36 patients,and dynamic MRI changes in the process of anti-tuberculosis treatment during 3 to 6 months were observed.The disappearance rate of the lesions was calculated and statistically analysed by using Chi-square test.Results There were 883 lesions in 38 cases with parenchymal tuberculosis.Multiple lesions distributed widely,423 lesions (47.9％) ≤0.3 cm,330 lesions (37.4％) between 0.3-1.0 cm,and 130 lesions (14.7％) ≥ 1.0 cm.Twenty-four cases with tuberculous meningitis showed meningeal enhancement at basilar cistern.Ten cases with hybrid type presented both parenchymal tuberculosis and meningitis.Among 36 patients with serial MRI follow-up scans,22 cases were pure parenchymal tuberculosis.The disappearance rates of military,nodules and tuberculomas were 52.2％ (59/113),33.3％ (33/99) and 0,respectively,after 3 months treatment.The disappearance rates were 87.6％ (99/113),50.5％ (50/99) and 18.2％ (2/11),respectively,after 6 months treatment.Disappearance rate of miliary lesions was obviously higher than that of nodules at both 3 and 6 months,and the difference was statistically significant,(x2 =7.657,34.786,P ＜ 0.01).Nine lesions of parenchymal tuberculosis enlarged with paradoxical response to antituberculous chemotherapy at 3 months,and 8 of them disappeared after 6 months of therapy.The outcome of tuberculous meningitis was relatively poor.Conclusions It is objective to classify parenchymal tuberculosis into three types:miliary,nodules and tuberculoma.Dynamic MRI changes of intracranial tuberculosis is helpful for understanding the disease better. Key words: Tuberculosis, central nervous system;  Magnetic resonance imaging