Small bone lesions resembling erosions can frequently be found in bilateral wrist MRI of healthy individuals.

Objective: To examine magnetic resonance imaging (MRI) scans for bone lesions typical of rheumatoid arthritis (RA) in the wrist joints of healthy individuals. Methods: Thirty-one symptomless healthy persons (13/18 men/women), mean age 49 years (range 32-64 years), were included. MRI scans and radiographs of both wrists were obtained (62 wrists). The MRI scans and the radiographs were evaluated by two specialists according to OMERACT recommendations and the Larsen method, respectively. Results: MRI showed erosive-like lesions in either one or both wrists in 14 [45%, 95% confidence interval (CI) 27-64] out of 31 subjects. Altogether, 24 erosive-like changes were found in the 930 wrist bones evaluated (15 bones in each wrist). No more than two lesions per wrist were detected. All the changes were small (22 were grade 1 and two were grade 2; scale 0-10) and were found more often in the older subjects (55 vs. 43 years, p<0.001). Most lesions (54%) were located on the volar side of the wrist and adjacent to the ligament insertions. Intravenous administration of the contrast medium gadolinium diethylenetriaminepentaacetate (Gd-DTPA) was used in 10 subjects, and mild to moderate Gd-DTPA enhancement in the synovial compartments was seen in six of them: five had enhancement in both wrists and one in one wrist. The plain radiographs showed one erosive-like change in the wrist (pisiforme) that was not recorded with MRI. Conclusions: A few small bone lesions that could potentially be confused as erosions were detected in about half of the normal volunteers. These findings should always be evaluated with reference to the clinical picture.