18F-Fluorodeoxyglucose Positron Emission Tomography–Computed Tomography Findings of Polymyalgia Rheumatica in Patients with Giant Cell Arteritis

Abstract

Objective: Giant cell arteritis (GCA) and polymyalgia rheumatica (PMR) are often overlapping conditions. We studied whether 18F-fluorodeoxyglucose (FDG) positron emission tomography–computed tomography (PET-CT) is useful in identifying PMR in the setting of large vessel (LV) GCA. Methods: LV-GCA patients diagnosed by PET-CT at a tertiary care center for a population of 450,000 people over a two-year period were reviewed. Scoring was performed based on potential significant FDG uptake at up to 16 sites in nine different extravascular areas (SCORE 16). Differences in extravascular sites of significant FDG uptake were evaluated between LV-GCA with a clinical diagnosis of PMR or not. Results: Fifty-four patients were diagnosed with LV-GCA by 18F-FDG-PET-CT. Of them, 21 (38.8%) were clinically diagnosed with PMR. Significant extravascular FDG uptake was more frequently observed in those with a clinical diagnosis of PMR. In this sense, the SCORE 16 was higher in those with clinical PMR (5.10 ± 4.05 versus 1.73 ± 2.31 in those without a clinical diagnosis of PMR; p < 0.001). A SCORE 16 involving more than four sites of significant FDG uptake yielded a sensitivity of 52% and a specificity of 91% for establishing a clinical diagnosis of PMR associated with LV-GCA. The best areas of significant FDG uptake to clinically identify PMR in patients with LV-GCA were the shoulder, the greater trochanter, and the lumbar interspinous regions, with an area under the ROC curve of 0.810 (0.691–0.930). Conclusions: Significant extravascular 18F-FDG-PET-CT uptake may help establish a clinical diagnosis of PMR in patients with LV-GCA. These patients are more commonly diagnosed with PMR if they have significant FDG uptake in the shoulder, greater trochanter, and lumbar interspinous areas.

PET-CT in Polymyalgia Rheumatica: When and for what—A Critical Review

“…1.73±2.31; p<0.001). These results indicated that the number of affected extravascular sites was greater in patients with PMR [57]. Therefore, according with our data we feel that significant 18F-FDG-PET-CT uptake in the shoulder, greater trochanter, and lumbar interspinous areas can help identify PMR in patients with large vessel-GCA.…”

“…We assessed the effectiveness of 18F-FDG-PET-CT in identifying PMR in patients with large vessel-GCA [56]. To explore this and determine the best predictors for using 18F-FDG-PET-CT to clinically identify PMR in large vessel-GCA patients, we analyzed a cohort of 54 patients diagnosed with large vessel-GCA using 18F-FDG-PET-CT in our hospital [56,57]. We evaluated nine extravascular areas, encompassing 16 potential sites of involvement: the acromioclavicular and sternoclavicular joints (2 each), hips (2), shoulders (2), greater trochanters (2), ischial tuberosities (2), symphysis pubis entheses (2), and the cervical and lumbar interspinous processes.…”

“…We evaluated nine extravascular areas, encompassing 16 potential sites of involvement: the acromioclavicular and sternoclavicular joints (2 each), hips (2), shoulders (2), greater trochanters (2), ischial tuberosities (2), symphysis pubis entheses (2), and the cervical and lumbar interspinous processes. For each patient, we calculated a total score ranging from 0 to 16, representing the sum of all sites with significant FDG uptake [57]. Twenty-one of the 54 patients with large vessel-GCA had been clinically diagnosed as having PMR [56].…”