Evaluation of the place and impact of positron emission tomography coupled with computed tomography in the rheumatological management of rheumatoid arthritis in Eastern Normandy. Seven-year retrospective multicenter analysis

Introduction: Pseudo-polyarthritis rheumatica (PPR) is one of the most frequent inflammatory rheumatic diseases in the aged patient. Its clinical polymorphism in both presentation and course, variable response to oral corticosteroid therapy and lack of specific biological markers have led to PPR being considered more as a syndrome than a disease. Metabolic imaging, mainly represented by positron emission tomography coupled with computed tomography (PET-CT), has gradually gained a prominent place in the diagnostic process, and its use in this indication has recently been framed by recommendations issued by nuclear medicine societies. Our study focused on the role and impact of PET-CT in the rheumatological management of PPR, through a retrospective analysis of the ways in which it has been prescribed by hospital rheumatologists in eastern Normandy over the past 7 years. Material and method: The files of patients for whom a PET-CT scan was prescribed by rheumatologists at 5 hospital centers in Eastern Normandy between January 1, 2014 and December 31, 2020 were analyzed. Then, files concerning a PPR diagnosed or suspected by a rheumatologist were selected. Clinico-biological characteristics, morphological imaging results, therapeutic stage, reason(s) for prescription and consequences of PET-CT during management were evaluated. In addition, selected examinations were reviewed using semi-quantitative visual scores. Results: A total of 670 files were analyzed. Then 133 examinations concerning confirmed or suspected PPR were retained. Of these, the diagnosis of PPR was clinically established before PET-CT was performed for 69 examinations (51.9%). Most patients had clinical and/or biological atypia at diagnosis. A CT scan had been performed in 65% of patients. The main reasons for prescribing PET-CT were to find evidence of underlying neoplasia and/or vasculitis, particularly in situations of therapeutic failure. The diagnosis of PPR was confirmed in 99 patients (74.4%) after PET-CT. Large-vessel vasculitis was identified in eleven patients, and a lesion described as suspicious on more than 20% of scans. A dosage adjustment or even a change of therapeutic step was carried out accordingly, and the PET-CT results led to a diagnostic reassessment for 22 patients. Overall, the PET-CT reading scores favoured the diagnosis of PPR compared with the literature. Discussion/Conclusion: This multicenter, 'real-life' study enabled us to evaluate a population of interest representative of the polymorphous presentation and management of PPR, and to analyze regional professional practices regarding the prescription of PET-CT scans in hospitals, both for diagnostic and therapeutic purposes, in the context of possible PPR or already established diagnosis. In addition, the use of validated reading scores enables systematization of the analysis. This work supports the increasingly frequent use of metabolic imaging in the management of clinical pictures suggestive of PPR, which enables both the search for specific sites and the elimination of differential diagnoses