Computed tomography thorax abnormalities in immunocompetent patients with tuberculous meningitis: An observational study

Objective: Computed tomography (CT) of the thorax is the imaging modality of choice to detect or demonstrate lesions suggestive of active pulmonary tuberculosis. We aimed to evaluate the imaging abnormalities detected on CT of the thorax in patients with tuberculous meningitis (TBM). Methods: In this prospective study, we enrolled consecutive newly-diagnosed patients with TBM. Patients were subjected to detailed clinical evaluation and laboratory investigations including MRI of brain and thoracic CT. Patients were administered WHO recommended treatment and followed-up for 6 months. At 6 months, disability assessment was done. Results: We included 81 patients. Fifty-six patients (69.1%) had abnormalities in CT of thorax. Miliary tuberculosis was seen in 10 (18%) patients. Centrilobular nodules were the commonest parenchymal abnormality seen in 23 (41%) patients. Pleural abnormalities and mediastinal lymphadenopathy were seen in 8 (14%) and 47 (84%) patients, respectively. On multivariate analysis, meningeal enhancement (OR = 3.5, 95%CI 1.2-9.8, P = 0.017) and CBNAAT positivity (OR = 8.7, 95%CI 1.0-73.0, P = 0.045) were independently associated with an abnormal CT of thorax. The sensitivity and specificity of CT thorax in identifying definite cases (CB-NAAT positive) of TBM were found to be 93.33% and 36.36%, respectively. Positive predictive value and negative predictive value of abnormal CT thorax in predicting definite TBM were 25% and 96%, respectively. Conclusion: CT thorax abnormalities were noted in approximately two-thirds of TBM patients, and were more frequent in definite TBM cases. CT thorax abnormalities helped in upgrading the diagnostic certainty level, in many patients with tuberculous meningitis, from possible to probable.