(18)FDG PET CT imaging in the diagnosis and monitoring of large vessel vasculitis

Background: Large vessel vasculitis (LVV) is an autoimmune inflamma- tory disease of large vessels. Diagnosis and monitoring can be challenging. Traditionally clinical review, infl ammatory markers and angiography /computed tomography (CT) have been utilised to identify the destructive results of vessel inflammation. Positron emission tomography (PET) with 18-fluorodeoxyglucose (18FDG) can provide additional information including active large vessel inflammation in the context of otherwise reassuring clinical, biochemical and radiology data. Aim: To investigate the clinical utili ty of 18 FDG PET for the detection and management of vasculitis in a hospital setting. Method: A retrospect ive audit of adult patients who had PET between 1 August 2010 and 31 August 2015 where the term ‘vasculitis’ was utilised in the scan report. Case notes, laboratory and radiologic data was audited. Information was collected on the initial diagnosis, any change in diag nosis, histologic data, inflammatory markers, treatment including doses of immunosuppression, correlative imaging and clinical symptoms and signs as documented at outpatient appointments. Results: 67 patients were identified (66% Female), 13 were excluded due to inaccessible follow-up. Patients were referred for suspected LVV 41% (22/54 ), known LVV 15% (8/54), Pyrexia of Unknown Origin 15% (8/54), increased inflammatory markers 9% (5/54), known malignancy 4% (2/54) and other 16% (9/54). PET was positive for LVV in 17% (9/54) of patients, equivocal in 4% (2/54) and negative in 79% (43/53). 56% of pos itive patients were referred for suspected LVV, 22% with known LVV, and 22% as an incidental finding after investigation of a known malignancy. Conclusion: In this diverse patient group, PET scans were positive for vasculitis in a high proportion of patients with suspected or known LVV (78%). PET imaging has a potential role in the diagnosis of LVV for patients where vasculitis is suspected but not conclusive from routine clinical investigation.T Crowhurst, R Dobson, L Nguyen, D Bartholomeusz, C Hil