FDG-PET in TBM may provide disease burden by highlighting extra-cranial sites of involvement, which may be amenable to biopsy/ tissue diagnosis, especially when other modalities are not able to confirm the diagnosis of suspected TBM. It may help in differentiating clinical worsening due to i) paradoxical immune response and ii) worsening of tubercular disease due to drug-resistant  organisms

To study the role of  whole body 18 FDG- PET CT in determining the extent of extracranial disease in Tuberculous meningitis (TBM) and assessing the response to treatment.

This prospective observational study was carried out in 70 patients of TBM attending Neurology emergency services of PGIMER, Chandigarh, India

MRI brain was abnormal in 95.7% patients in form of diffuse meningeal enhancement (68.6%), tuberculomas (57.1%), basal exudates (48.6%), perisylvian meningeal enhancement (38.6%), hydrocephalus (34.3%), cerebral infarction (28.6%) and border zone encephalitis (21.4%). Whole body FDG- PET revealed brain lesions in 74.3%. It revealed evidence of extracranial involvement in 94.1% of patients. The most common site of extracranial involvement was lung (88.6%) followed by lymph nodes (87.1%).   It revealed vertebral involvement in 27.1% of patients out of whom 57.9% did not have clinical correlate. FDG-PET detected extracranial tubercular involvement in significantly higher number of TBM patients compared to conventional methods. FDG-PET showed resolution of lesions in 79.3% patients, worsening in 13.8%, while lesions remained unchanged in 6.9% of patients. FDG-PET helped in modification of treatment in all the patients who did not show resolution or worsened on follow up.

Whole body FDG-PET is a good tool for assessment of disease burden at extracranial sites in TBM. This can help both in confirmation of suspected TBM as well as in determining the clinical severity of illness. It may also help in follow up of TBM by showing resolution/ nonresolution and paradoxical worsening of lesions.