BONE LESIONS IN THE HANDS AND FEET OF HEALTHY INDIVIDUALS ON MAGNETIC RESONANCE IMAGING RESEMBLE RHEUMATOID ARTHRITIS EROSIONS

[2007] [SAT0458] BONE LESIONS IN THE HANDS AND FEET OF HEALTHY INDIVIDUALS ON MAGNETIC RESONANCE IMAGING RESEMBLE RHEUMATOID ARTHRITIS EROSIONS

E. Olech ¹, D.E. Yocum ², P. Kamp ¹, J. Hutcheson ¹, J.T. Merrill ¹ ¹Clinical Pharmacology, Oklahoma Medical Research Foundation, Oklahoma City, ²Immunology, Tissue Growth and Repair, Genentech, Inc, San Francisco, United States

Background: Magnetic Resonance Imaging (MRI) is known to be a sensitive tool for the detection of Rheumatoid Arthritis (RA) joint pathologies but its specificity has not been well established. There are few studies assessing bony lesions or synovitis-like changes in healthy subjects. In one study with low-field extremity MR and thin-cuts imaging protocol, out of 9 healthy individuals, 5 (56%) were found to have erosion-like bone changes [1].
Objectives: The prevalence of changes resembling RA erosions, bone edema and synovitis in the metacarpophalangeal and wrist joints of 17 healthy subjects on 0.2 Tesla, extremity MRI was examined.
Methods: The study had institutional review board approval. MRI of the bilateral hands and wrist was performed using a 0.2 T dedicated-extremity MRI unit (C-scan). Coronal T1-weighted 3-dimensional gradient echo, subsequent multiplanar reconstruction with thin slices (0.6 - 0.9 mm) and coronal fat-suppressed short tau inversion recovery (STIR) sequences were obtained. The images were evaluated for bone erosions, bone marrow edema and synovitis by the same observer, using the OMERACT MRI scoring system (RAMRIS).
Results: The study group included 11 women and 6 men with no evidence of arthritis; 11 Caucasian, 3 African American, 2 of Asian descent, and 1 Native American. The mean age was 37, median 33 years old.
Twenty seven erosion-like lesions were identified, and 12 (71%) of the subjects had at least one lesion. 19 lesions (70%) were found in the dominant hand/wrist. Only 3 people had more than 4 lesions. One individual had bone marrow edema in the triquetrum unilaterally. There was increased enhancement seen on STIR images resembling low grade synovitis in one hand and wrist of one subject.
The mean number of lesions per person was 2.7, median: 2 (range 0- 10). The mean RAMRIS score for erosions was 4.6, median 3 per subject. Only 14 (30%) lesions were scored above 1.
A total of 782 bones were evaluated. In the wrist, erosion-like changes were found in 14 out of 510 bones (2.7%), in the hands 13 out of 272 (4.8%). The majority of the erosion-like lesions were found in the 3rd metacarpal head (10 lesions) followed by the lunate (6) and 3rd metacarpal base (6). The RAMRIS results were similar. The highest scores were found in the 3rd metacarpal head (total score: 22, 1-5 range), followed by lunate (14 total, range: 1-7), followed by 3rd metacarpal base (total score: 8, range 1-7).
Conclusion: 1. While very sensitive, MRI may not be completely specific for RA bone erosions especially when a thin cut imaging protocol is used.
2. Majority of the erosion-like lesions are found in the dominant hand/ wrist, which suggests that they may be traumatic origin.
3. Most of the non-specific lesions are small in size, less than 10% of the eroded bone and possibly those should be excluded from scoring in RA.
4. The most common sites for erosion-like lesions in healthy subjects are 3rd metacarpal head, lunate and 3rd metacarpal base, sites that might be considered relatively non-specific when assessing RA patients.
5. Bone edema and synovitis-like changes appear be rare in healthy controls and thus may prove to be more specific for RA.
References: 1. Ejbjerg BJ, Vestergaard A, Jacobsen S, Thomsen HS, Østergaard M. The Smallest Detectable Difference and Sensitivity to Change of Magnetic Resonance Imaging and Radiographic Scoring of Structural Joint Damage in Rheumatoid Arthritis Finger, Wrist, and Toe Joints. A&R Vol. 52, No. 8, August 2005, pp 2300-2306.

Diagnostics and imaging procedures

Citation: Ann Rheum Dis 2007;66(Suppl II):569