Abstract
We aimed to compare the reliability of bone scintigraphy (BS) and fluorine-18-fluorodeoxyglucose (18F-FDG) positron emission tomography (PET)—derived parameters in the detection of active arthritis in 28-joint areas and evaluate the reliability of joint counts between BS and clinical assessment in patients with rheumatoid arthritis (RA). We enrolled 106 patients (67 in the development group and 39 in the validation groups) with active RA who underwent BS, 18F-FDG PET/computed tomography (CT), and clinical evaluation of disease activity. We compared the results of BS-derived joint assessment with those of PET-derived and clinical joint assessments. Subsequently we developed a disease activity score (DAS) using BS-positive joints and validated it in an independent group. The number of BS-positive joints in 28-joint areas significantly correlated with the swollen /tender joint counts (SJC/TJC) and PET-derived joint counts. A BS uptake score of 2 (strong positive) was significantly more sensitive compared with a BS uptake score of 1 (weak positive) in detecting a PET-positive joint among the 28-joints. After conducting multivariate analyses including erythrocyte sediment rate (ESR) and patient global assessment (PGA) in addition to BS-derived parameters, BS/DAS was obtained as follows: 0.056 × number of BS-positive joints in 28 joints + 0.012 × ESR + 0.030 × PGA. A significant correlation between BS/DAS and DAS28-ESR was confirmed in the validation group. Strong positive uptake of BS is sensitive and reproducible for the detection of active joints, and can complement the clinical assessment of disease activity in RA.
Highlights
We aimed to compare the reliability of bone scintigraphy (BS) and fluorine-18-fluorodeoxyglucose (18F-FDG) positron emission tomography (PET)—derived parameters in the detection of active arthritis in 28-joint areas and evaluate the reliability of joint counts between BS and clinical assessment in patients with rheumatoid arthritis (RA)
Joint counts performed by experienced physicians are considered crucial in the quantitative assessment of synovitis, which was included in the disease activity score (DAS) 28 for the measurement of RA a ctivity[2]
The mean DAS28-erythrocyte sediment rate (ESR) of the development and validation groups were 6.81 and 6.43, respectively, with all patients in both groups showing moderate to high disease activity
Summary
We aimed to compare the reliability of bone scintigraphy (BS) and fluorine-18-fluorodeoxyglucose (18F-FDG) positron emission tomography (PET)—derived parameters in the detection of active arthritis in 28-joint areas and evaluate the reliability of joint counts between BS and clinical assessment in patients with rheumatoid arthritis (RA). Abbreviations RA Rheumatoid arthritis DAS Disease activity score US Ultrasound MRI Magnetic resonance imaging FDG Fluorodeoxyglucose PET Positron emission tomography CT Computed tomography BS Bone scintigraphy SJC Swollen joint count TJC Tender joint count PGA Patient global assessment ESR Erythrocyte sedimentation CRP C-reactive protein VOI Volume of interest HDP Hydroxymethylene diphosphonate ROI Regions of interest ICC Intraclass correlation coefficient. Joint counts are limited by an inherent lack of objectivity related to both operator’s factors and patient’s factors[3,4], thereby increasing the need for more sensitive and reproducible tools to detect synovitis Imaging modalities such as ultrasound (US) and magnetic resonance imaging (MRI) are more sensitive than clinical assessment for detecting joint inflammation[5,6,7], it is difficult to assess systemic joint status in patients with RA with these tools[8,9,10,11]. No study has validated the usefulness of BS in the measurement of RA disease activity
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