1374. Diagnostic Utility of Whole Body Positron Emission Tomography-Computerized Tomography (PET-CT) in Patients with Suspected Central Nervous System Tuberculosis: A Retrospective, Descriptive Study.

Background There is difficulty in diagnosing central nervous system (CNS) tuberculosis (TB) in the early stages because features mimic viral and pyogenic meningitis. There is a need to determine alternate methods to diagnose CNS TB. Whole-body PET-CT, used mainly in oncology, has shown promise in the detection of tuberculosis and monitoring response to anti-tuberculous therapy. Utility in CNS TB is unexplored. Methods Retrospective, cohort, single-center study. Patients were included if they fulfilled the following criteria: (1) Probable/possible tuberculous meningitis as per the Lancet Consensus Score; (2) undergone whole-body PET-CT with 18-fluorodeoxyglucose and intravenous contrast; (3) less than one week of anti-tuberculous therapy at the time of PET-CT; (4) clinical response to antituberculous treatment and steroids; (5) no other etiological agent identified. Results We identified 9 patients that fulfilled the above criteria. 5 of these patients were immunosuppressed (4 had advanced AIDS, one patient was on immunosuppressive therapy). We found that 86.4% of patients (7 out of 9) had radiological features suggestive of probable active TB outside the CNS (Figure 1). Of these 7 patients, 5 patients had definite TB (defined as positive Ziehl–Neelsen stain or Gene Xpert MTB/RIF assay or culture for tubercle bacilli) outside the CNS while 2 had histopathological evidence of TB (granulomatous inflammation) (Figure 2). All strains of TB were rifampin sensitive. The sites of isolation of tuberculosis were (Figure 3). (a) Abdominal lymph node in 2 patients (40%); (b) cervical lymph node in 2 patients (40%); (c) sputum in 1 patient (20%). In patients with evidence of disease outside the CNS, the average maximum standardized uptake value (SUV Max) in diverse anatomical locations was 5.75 (range 1.9–11.2). The most frequent manifestation PET-CT manifestation suggestive of TB outside the CNS in decreasing order of frequency was cervical lymphadenopathy (in 55.5% of patients), pleural and pulmonary parenchymal involvement (44.4% in each), followed by mediastinal nodes and abdominal lymph nodes in 33.3% (Figure 4). Conclusion PET-CT is a valuable tool in treatment-naive (less than 1 week of anti-tuberculous therapy) patients with suspected CNS tuberculosis. A large proportion of patients have evidence of TB outside the CNS. Disclosures All authors: No reported disclosures. [ABSTRACT FROM AUTHOR]