Role of PET CT scans in Tuberculous Meningitis

Background: The aim of this study is to assess the role of 18F-FDG PET CT in detecting the extra cranial involvement in patients with TBM(Tubercular Meningitis). This improves the probability of TBM, thus improves confidence in diagnosis and may reveal more accessible sites to obtain samples for confirming diagnosis and drug susceptibility patterns with appropriate tests. Methods: This is a prospective sub-study of a RePORT-Parent protocol TBM cohort. PET CT scan was done in patients admitted with a diagnosis of TBM based on consensus criteria (Definite, Probable or Possible). Results: 51 eligible patients underwent PET CT scan. Extra-cranial lesions with increased FDG uptake were present in 41(80.4%), cranial uptake was present only in 2(3.9%) and absent in 8(15.7%) patients. Of the positive PET scans, 38 FDG avid lesions were related to TB(74.5%). There were 5 non-significant avid lesions which were considered not related to TB. When PET CT positive results were included for scoring, in 10(19.6%) patients, TBM classification changed from possible to probable, in 2(3.9%) patients, TBM classification changed from possible to definite. Conclusion: 18F-FDG PET CT is a promising modality in the evaluation of suspected TBM and has an important role in detecting extra cranial involvement, thus improving diagnostic probability and provides an opportunity for obtaining specific diagnosis. Reference: (Marais S et al., Lancet Infect Dis.2010)