The Utility of 18F‐FDG PET/CT in Patients With Clinical Suspicion of Polymyalgia Rheumatica and Giant Cell Arteritis: A Prospective, Observational, and Cross‐sectional Study

Abstract

Objective To define the proportions of agreement between fluorine‐18‐fluorodeoxyglucose (18F‐FDG) positron emission tomography/computed tomography (PET/CT), clinical diagnosis, and temporal artery biopsy (TAB) in patients with polymyalgia rheumatica (PMR) and giant cell arteritis (GCA). Furthermore, the association of 18F‐FDG PET/CT uptake patterns and clinical presentation of newly diagnosed PMR and GCA was investigated. Methods Eighty patients newly suspected of having PMR, GCA, or concomitant PMR and GCA were included and followed for 40 weeks. Every patient underwent an 18F‐FDG PET/CT scan before or within 3 days of initiation of steroids in case of GCA. FDG uptakes in 8 paired articular/periarticular sites and 14 arterial segments were evaluated based on a 4‐point visual grading scale. Results Of the 80 patients (female: 50 [62.5%]; mean age ± SD: 72.0 ± 7.9), 64 (80.0%) patients were diagnosed with pure PMR, 3 (3.7%) with pure GCA, and 10 (12.5%) with concomitant PMR and GCA. Additionally, three (3.7%) patients were diagnosed with seronegative rheumatoid arthritis during the follow‐up period. For the diagnosis of PMR, 18F‐FDG PET/CT had a proportion of agreement of 75.3 (64.2‐84.4), compared with clinical diagnosis. When comparing findings of 18F‐FDG PET/CT with TAB, 18F‐FDG PET/CT had a proportion of agreement of 93.0 (84.3‐97.7) in all included patients and 69.2 (38.6‐90.9) in the subgroup of patients with vasculitis. C‐reactive protein was significantly higher in patients with PMR activity on 18F‐FDG PET/CT compared with those without 18F‐FDG PET/CT activity ( P value = 0.006). Conclusions 18F‐FDG PET/CT is a powerful imaging technique in PMR and GCA that was in good agreement with clinical diagnosis and TAB.

Prognostic impacts of glucocorticoid treatment in patients with polymyalgia rheumatica and giant cell arteritis

“…The mean age of the patients was 71.8 ± 8.0 years and 49 (63.6%) were women. Baseline demographic data have previously been published in detail 24,33 . Clinical data together with laboratory results at visit 1 to visit 5 are summarized in Table 1.…”

“…80 consecutive patients with newly suspected PMR, GCA, or concomitant PMR and GCA were included in the study. Inclusion and exclusion criteria have previously been described 23 , 24 . Briefly, PMR patients met the following criteria: 1.…”

“…Every included patient underwent an 18F-FDG PET/CT either before or in the case of GCA within 3 days of initiation of glucocorticoid treatment 23 , 24 . Based on previously described methodology, FDG uptakes in 8 paired articular/periarticular sites and 14 arterial segments were described visually based on a 4-point visual grading scale (VGS) with 0 = no uptake; 1 = slight but not negligible uptake, lower than liver uptake; 2 = intermediate uptake, equivalent to liver uptake; 3 = high-grade uptake, higher than liver uptake.…”

“…Based on previously described methodology, FDG uptakes in 8 paired articular/periarticular sites and 14 arterial segments were described visually based on a 4-point visual grading scale (VGS) with 0 = no uptake; 1 = slight but not negligible uptake, lower than liver uptake; 2 = intermediate uptake, equivalent to liver uptake; 3 = high-grade uptake, higher than liver uptake. Two pathologic cutoff values of VGS ≥ 3 and VGS ≥ 2 were used to analyze the results of 18F-FDG PET/CT 24 . Total PMR and GCA scores were defined as the sum of VGS at each articular/periarticular site or arterial segment.…”

“…Every included patient underwent an 18F-FDG PET/CT either before or in the case of GCA within 3 days of initiation of glucocorticoid treatment 23,24 . Based on previously described methodology, FDG uptakes in 8 paired Total body DXA.…”