Valid measurement of erosion volume in rheumatoid arthritis (RA) will facilitate the testing of treatments that may help to heal erosion. This study was undertaken to develop and validate a software method to measure erosion volume on computed tomography (CT) scans of the hand and wrist.
Duplicate CT acquisitions of both hands of 5 patients with RA were evaluated using a semiautomated software tool to measure erosion volume in the entire hand and wrist and in each of 6 subregions. Reproducibility was quantified using the intraclass correlation coefficient (ICC), root mean square standard deviation (RMSSD), and coefficient of variation (CV), and the analysis was performed at the level of the hand (n = 10) and the subject (n = 5).
The ICCs between 2 repositioned acquisitions were excellent, ranging from 0.97 to 1.00. At the hand level, the RMSSD was 15.6 mm(3) with a CV of 7.3%, and the CVs at the 6 regions ranged from 7.6% to 21.0%. At the subject level, the RMSSD was 31.2 mm(3) with a CV of 3.7%, and the CVs at the 6 regions ranged from 0.5% to 15.8%.
We have developed a novel semiautomated software method to measure erosion volume on hand and wrist CT scans. The method is reproducible and can be used to detect changes in erosion volume. This will facilitate the testing of treatments intended to reduce erosion volume.