Session: (1862–1894) Imaging of Rheumatic Diseases Poster II
1869: FDG-PET/CT for Diagnosing Polymyalgia Rheumatica Before, During and After a Short-term Prednisolone Cessation – a Prospective Study of 101 Patients
Andreas Wiggers Nielsen1, Ib Tønder Hansen2, Berit Dalsgaard Nielsen3, Søren Geill Kjær4, Jesper Blegvad-Nissen4, Christian Møller Sørensen3, Ellen-Margrethe Hauge1, Lars Christian Gormsen2 and Kresten Krarup Keller1, 1Aarhus University Hospital, Aarhus, Denmark, 2Aarhus University Hospital, Aarhus N, Denmark, 3Department of Internal Medicine, Horsens, Denmark, 4Diagnostic Centre, Silkeborg, Denmark
Background/Purpose: Polymyalgia rheumatica (PMR) can be challenging to diagnose since other diseases may present with similar symptoms. As a result, a significant number of patients are referred to rheumatologists for a second opinion. However, a notable proportion of patients are administered prednisolone prior to rheumatologic assessment, which can obscure the symptoms of PMR and important differential diagnoses. 18F-fluorodeoxyglucose(FDG) positron emission tomography and computed tomography (PET/CT) has been suggested as a potential tool to aid the clinician diagnosing PMR, but it is unclear whether PET/CT can be used after the initiation of prednisolone. This study aimed to investigate the diagnostic utility of FDG-PET/CT in patients suspected of PMR, specifically evaluating the diagnostic accuracy before, during, and after a short-term taper of prednisolone.
Methods: This study included 101 patients who were suspected of having PMR. All patients were clinically diagnosed with PMR or non-PMRat a baseline visit and subsequently had a PET/CT performed. Patients diagnosed with PMR were administered prednisolone with a starting dose of 15 mg following the first PET/CT. After 8 weeks of treatment a second PET/CT was performed when prednisolone had been tapered to 10 mg, according to an algorithm reflecting routine care. Afterwards, prednisolone was tapered with complete cessation at week 9 followed by a third PET/CT at week 10. A PET/CT assessment of PMR or non-PMR was given utilizing the validated Leuven score (Figure 1) [1]. The final diagnosis for all patients was confirmed at a 1-year follow-up visit.
Results: Preliminary results of the first 79 patients have been obtained, and the baseline characteristics of the PMR and non-PMR group are outlined in table 1. A baseline PET/CT diagnosis showed a sensitivity of 88.7% and a specificity of 61.5% using a clinical diagnosis at 1 year as the reference standard (Figure 1). The low specificity was partially explained by a high rate of false positive patients with a final diagnosis of other inflammatory diseases, since 8 out of 10 non-PMR patients with a final diagnosis of rheumatoid arthritis or reactive diseases had a PET/CT indicating PMR according to the Leuven score. After 8 weeks of prednisolone treatment the Leuven score decreased significantly, but in 14/46 patients the PET/CT diagnosis remained positive for PMR (Figure 2). After prednisolone cessation the Leuven score increased significantly, with a positive PET/CT diagnosis of PMR in 25/37.
Conclusion: Initiation of prednisolone treatment prior to PET/CT significantly reduces the diagnostic accuracy for a PMR diagnosis. Therefore, a short-term prednisolone taper is advisable before using PET/CT to diagnose PMR in patients treated with a medium dosage of prednisolone. Furthermore, PET/CT utilizing the Leuven score may not be reliable for differentiating PMR from other inflammatory disorders during the initial evaluation.
References [1] Henckaerts L, Gheysens O, Vanderschueren S, Goffin K, Blockmans D. Use of 18F-fluorodeoxyglucose positron emission tomography in the diagnosis of polymyalgia rheumatica-A prospective study of 99 patients. Rheumatology (Oxford) 2018;57(11):1908-16.
Table 1 – Baseline data of patients with a final diagnosis of PMR and non-PMR (control group) based on 1-year follow-up visit
Figure 1 – PET/CT diagnosis of PMR at baseline, 8 weeks and 10 weeks using the Leuven score.
Figure 2 – Box plot of Leuven score at baseline, after 8 weeks of prednisolone treatment and at 10 weeks after a 2 week prednisolone taper.
A. Nielsen: None; I. Hansen: None; B. Dalsgaard Nielsen: None; S. Kjær: None; J. Blegvad-Nissen: None; C. Sørensen: None; E. Hauge: AbbVie/Abbott, 2, 5, 6, Danish Regions Medicine Grants, 5, Danish Rheumatism Association, 5, Galapagos, 5, Novartis, 2, 6, Novo Nordic, 2, 5, 6, Sanofi, 2, 6, Sobi, 2, 6; L. Gormsen: None; K. Keller: None.
.jpg)
.jpg)
.jpg)
