# Vascular uptake on 18F-FDG PET/CT predicts relapse in new-onset PMR

## TL;DR

This study shows that vascular involvement seen on PET/CT scans in patients with PMR is a strong predictor of disease relapse.

## Contribution

The study identifies vascular uptake on 18F-FDG PET/CT as a novel predictor of relapse in patients with new-onset PMR.

## Key findings

- 17.5% of PMR patients had subclinical GCA, mostly with extracranial vessel involvement.
- Patients with vascular involvement had a 71% relapse rate compared to 29% without.
- Vascular involvement was a strong predictor of relapse with a hazard ratio of 3.731.

## Abstract

In this study, we utilize 18F-fluorodeoxyglucose (FDG) PET/CT to assess vascular involvement in patients with PMR, aiming to clarify its role in identifying subclinical GCA and its potential association with disease relapse.

We conducted a retrospective cohort study of 80 patients diagnosed with PMR who underwent PET/CT scanning at Ruijin hospital from September 2015 to December 2023. Based on PET/CT findings, patients were divided into two groups: those with vascular involvement and those without. We compared baseline clinical characteristics, treatments and relapse rates between the two groups. Multivariate Cox regression analysis was performed to identify independent predictors of relapse.

In our cohort, 14 patients (14/80, 17.5%) were identified as having subclinical GCA, with 93% (13/14) exhibiting extracranial vessel involvement. Relapse rates were significantly higher in patients with subclinical GCA compared with those with isolated PMR (71% vs 29%, P = 0.003). Vascular involvement was identified as a strong predictor of relapse with a hazard ratio (HR) of 3.731 (95% CI: 1.705–8.164). Conversely, arthralgia appeared to be a protective factor against relapse with a HR of 0.325 (95% CI: 0.148–0.711).

Our findings highlight vascular involvement as a critical predictor of relapse in PMR, underscoring the utility of 18F-FDG PET/CT in detecting subclinical GCA and predicting prognosis. Further research is needed to establish screening protocols and optimize relapse prevention strategies in this population.