PET/CT imaging can predict treatment response in early rheumatoid arthritis: Study
Netherlands: A recent study stated that in rheumatoid arthritis (RA), PET imaging of immune cells involved in bone and joint damage can predict which patients will respond early to treatment. The findings of the study, published in the BMJ journal Rheumatic and Musculoskeletal Diseases, imply that early assessment of clinical response through macrophage PET imaging use could potentially improve the efficacy of treatment in patients with early RA.
PET imaging of the feet joints following 2 weeks of treatment corresponds significantly to clinical response after 3 months of treatment. This contributes independently from the Disease Activity Score of 44 joints score (DAS44) at 2 weeks to the prediction of the clinical response at 3 months.
Rheumatoid arthritis is an autoimmune disease that affects the synovial joints and causes chronic inflammation, which leads to bone and cartilage damage. Positron emission tomography (PET) is a non-invasive nuclear imaging technique with high sensitivity and through the use of specific tracers has the potential of high specificity.
There is an urgent need for new tools to evaluate treatment response in patients with early RA and PET has shown potential for predicting clinical response at an early stage in the treatment of patients with RA.
Against the above background, Nicki Verweij, Amsterdam UMC Locatie VUmc, Amsterdam, The Netherlands, and colleagues aimed to determine whether macrophage PET/CT imaging using (R)-[11C]PK11195 at 0 and 2 weeks are associated with the clinical response at 13 weeks in patients with early RA.
For this purpose, the researchers performed whole-body (R)-[11C]PK11195 PET/CT scans at baseline and after 2 weeks of COBRA-light (combination therapy of methotrexate and prednisone) treatment in 35 patients having clinically active early RA. Clinical assessment (DAS44) was performed at 0, 2, and 13 weeks of treatment.
Two blinded, experienced readers visually assessed PET/CT scans. The assessment was also done by calculating standardized uptake values (SUVs) for elbows, shoulders, hips, knees, and hand and feet joints.
The study showed the following findings:
- 18 males and 17 females were included (baseline DAS44=3.2 ± 1.0).
- 171 out of 1470 joints were visually PET-positive at baseline, decreasing to 100 joints after 2 weeks.
- In general, small feet joints showed the highest uptake at baseline, and the largest decrease after 2 weeks (Δ0-2).
- Neither baseline nor Δ0-2 PET measures correlated with DAS44 at 13 weeks.
- However, at 2 weeks, the average SUV of the feet significantly correlated with DAS44 at 13 weeks (R2=0.14).
- In a multivariable model, DAS44 and the average SUV of the feet at 2 weeks showed substantial combined predictive value (combined R2=0.297).
"Our findings showed that quantitative macrophage PET assessment of feet joints, together with DAS44, after 2 weeks of COBRA light treatment in patients with early RA corresponds with a clinical response after 3 months of treatment," the authors concluded.
Reference:
Verweij N, Zwezerijnen G, ter Wee M, et alEarly prediction of treatment response in rheumatoid arthritis by quantitative macrophage PETRMD Open 2022;8:e002108. doi: 10.1136/rmdopen-2021-002108
