AB1342 THE EVALUATION OF 18F-PET-CT USE IN RHEUMATOLOGY CLINICAL PRACTICE WITH DEMOGRAPHIC AND CLINICAL FINDINGS

BackgroundThere is an increasing number of studies in the literature on the use of 18 F-FDG-PET/CT in the diagnosis and treatment follow-up of inflammatory rheumatic and musculoskeletal diseases (iRMD) (1). PET/CT do have an important place in the diagnosis of large-vessel vasculitis (LVV), which shows increased involvement in the walls of large vessels (2).ObjectivesIn this study, the aim was to evaluate the demographic, clinical, and laboratory characteristics, compatibility of PET/CT with other imaging methods, and the role of PET/CT in treatment follow-up of the patients who underwent PET/CT at the Rheumatology Clinic between 01.01.2010 and 31.12.2020.MethodsThe patients’ age, gender, comorbidities, iRMD types, medications, PET/CT, and ages at the time of iRMD diagnosis were collected. In addition, the compatibility of PET/CT with other imaging methods (MR angiography, Doppler US, and CT angiography) was evaluated in vasculitis subgroups. Control PET/CT images of the patients were evaluated by comparing them with previous imaging findings.ResultsA total of 280 patients, 179 (63.9%) women, with a mean age of 58±15 years, underwent PET/CT in the rheumatology department. 202 (72.1%) patients had a diagnosis of iRMD before PET/CT. After PET/CT, 40 (48.2%) patients were diagnosed with a new iRMD, and 43 (41.8%) were diagnosed with a non-iRMD. No rheumatic disease was detected in 33 (11.8%) patients.iRMD diagnosed by PET/CT are respectively; LVV (n=11), IgG4-RD (n=10), sarcoidosis (n=9), and other (n=10). It was determined that 22 (26.5%) of newly diagnosed patients other than iRMD had malignancy [Bronchial (n=8), lymphoma (n=3), breast (n=3), other (n=8) cancer].PET/CT revealed lymphadenopathy (LAP) in 119 of 165 patients who underwent the scan to exclude malignancy, and 22 of 91 patients who underwent PET/CT for rheumatologic diagnosis. LAP was found in 45% of those diagnosed with iRMD and 74.4% of those diagnosed with non-iRMD (p=0.002).PET/CT imaging was performed on 18 patients for follow-up. The treatment of 4 out of 18 patients with follow-up PET/CT and 76 out of 280 total patients was changed after imaging. In patients with a diagnosis of giant cell arteritis (GCA), the compatibility of PET/CT with MRA was 62.5%, while its agreement with CTA was 100%, and with Doppler US was 40%. In patients diagnosed with Takayasu’s arteritis, the compatibility of PET/CT with MRA was 40%, while its compatibility with CTA was 50% and with Doppler USG was 38%.ConclusionPET/CT imaging was found to be an important adjunctive examination in the diagnosis and follow-up of sarcoidosis, LVV, and IgG4-RD in patients evaluated in the rheumatology clinic. It has been observed that it is often used in the diagnosis and follow-up of RA, SpA, and autoinflammatory diseases, to investigate the malignancies accompanying rheumatic diseases and to evaluate the characteristics of LAP. PET/CT findings provide significant benefits to the clinician in the early diagnosis of iRMDs and differentiation of malignant and/or infectious etiologies.References[1]Jamar F, et al. EANM/SNMMI Guideline for 18 F-FDG Use in Inflammation and Infection. J Nucl Med. 2013 Apr;54(4):647–58.[2]Schönau V, et al. Ann Rheum Dis. 2018 Jan;77(1):70–7.Table 1.DemographicsAge (mean±SD.)58±15Female/Male179 (63.9)/101 (36.1)CRP (mg/L), median (Min.-Max.)16.9 (0.2-431)ESR (mm/h), median (Min.-Max.)43 (1-120)iRMD Subgroups, n (%)Connective Tissue Disease70 (28.4)Vasculitis63 (25.5)Rheumatoid Arthritis28 (11.3)İgG4-RD and Retroperitoneal Fibrosis22 (8.9)Spondyloarthropathies21 (8.5)Sarcoidosis16 (6.5)Polymyalgia Rheumatica8 (3.2)Others (Autoinflammatory Fever Syndromes, Crystal Arthropathies, CVID)19 (7.7)Reason for PET/CT scan, n (%)For Rheumatologic Diagnosis91 (32.5)Scan to Exclude Malignancy165 (58.9)Treatment Response Evaluation24 (8.6)PET/CT SUVmaxValuesiRMD SUVmax, median (Min.-Max.)4.6 (3.3-7.2)Malignancy SUVmax, median (Min.-Max.)8 (6.1-10.6)*iRMD: inflammatory rheumatic and musculoskeletal diseasesDisclosure of InterestsNone declared