Contribution à l’étude de l’imagerie optique et métabolique pour déterminer la rémission dans la polyarthrite rhumatoïde

Background: The primary goal in the treatment of rheumatoid arthritis (RA) is to achieve remission in order to prevent joint damage. Remission is typically assessed using composite scores, which, however, may underestimate residual inflammation. Ultrasonography (US) is as an objective imaging technique that can be considered as a "gold standard" for defining remission. Nevertheless, its routine use in clinical practice is limited due to the need of a specialized operator and the relatively time-consuming nature of the exam.
Objective: To evaluate two alternative imaging modalities — HandScan optical imaging (a non-invasive examination that can be performed within minutes by a non-specialist operator) and [18F]FDG PET/CT metabolic imaging (commonly used in RA patients to investigate unexplained inflammation or suspected malignancy) — for their ability to identify remission at both the joint and patient level.
Methods: Two cohorts of RA patients underwent standardized clinical and US assessments, as well as HandScan and/or [18F]FDG PET/CT imaging. The sensitivity, specificity, and positive and negative predictive values of both techniques were calculated for detecting clinical- or US-defined remission, at both joint and patient levels. Remission thresholds were also explored.
Results: At the joint level, the SUVmax (maximum standardized uptake value) of [18F]FDG PET/CT showed high specificity for identifying clinically active joints. At the patient level, [18F]FDG PET/CT parameters (cumulative SUV and number of positive joints) did not reliably distinguish patients in clinical remission from those with ongoing disease activity. The HandScan, using the DAS-OST (disease activity score – optical spectral transmission), demonstrated good sensitivity for identifying patients in clinical remission. For US-defined remission, both HandScan and [18F]FDG PET/CT showed good sensitivity at both joint and patient levels. Remission thresholds were defined for [18F]FDG PET/CT parameters (SUVmax at the joint level, highest SUVmax and cumulative SUV at the patient level) and for HandScan parameters (OST and DAS-OST score respectively at joint and patient level).
Conclusion: [18F]FDG PET/CT and HandScan demonstrate acceptable diagnostic performance for determining remission at both the joint and the patient level, supporting their potential role as imaging tools in the assessment of remission in RA.