Management of ocular tuberculosis(OTB): The role of CT and Positron Emission Tomography(PET) imaging

<b>Background:</b> Mycobacterium tuberculosis (M.tb) is rarely cultured from ocular/periocular tissues; this contributes to the diagnostic and therapeutic conundrum of OTB. Published consensus has not defined how far a suspected case of OTB should be investigated (1). <b>Aim:</b> To test the hypothesis that CT and FDG-PET-CT offers additional diagnostic yield in these patients, over more conventional imaging. <b>Results:</b> 107 patients were referred between 2010 and 2020. The mean age was 40 years. 14/107 were UK born individuals. 35 patients had normal imaging (chest radiograph) at the start of their treatment episode. 55/107 had PET-CT imaging and 49/107 CT thorax. 36/55 demonstrated avidity on PET-CT of which 22/36 identified additional extra-thoracic sites. 18/49 had a normal CT thorax and 22/49 demonstrated lymphadenopathy. 37/107 had investigation with endobronchial ultrasound (EBUS) sampling. Treatment length ranged from 6-12 months, mostly with Rifamipicin, Isoniazid, Pyrazinamide and Moxifloxacin. 12/107 had treatment for latent TB infection. <b>Conclusion:</b> Individuals, with suspected OTB, with a normal chest radiograph on presentation commonly demonstrate abnormalities in CT or CT-PET imaging, most commonly with mediastinal lymphadenopathy. CT PET identifies additional extra-thoracic sites for lymph node sampling, which may help confirm a microbiological diagnosis. <b>Reference:</b> 1) Gunasekeran DV et al. THE COLLABORATIVE OCULAR TUBERCULOSIS STUDY (COTS)-1.Retina. 2019 Aug;39(8):1623-1630.