Magnetic resonance imaging, radiography, and scintigraphy of the finger joints: one year follow up of patients with early arthritis. The TIRA Group

Abstract

Objectives: To evaluate synovial membrane hypertrophy, tenosynovitis, and erosion development of the 2nd to 5th metacarpophalangeal (MCP) and proximal interphalangeal (PIP) joints by magnetic resonance imaging in a group of patients with rheumatoid arthritis (RA) or suspected RA followed up for one year. Additionally, to compare the results with radiography, bone scintigraphy, and clinical findings.

Patients and methods: Fifty five patients were examined at baseline, of whom 34 were followed up for one year. Twenty one patients already fulfilled the American College of Rheumatology (ACR) criteria for RA at baseline, five fulfilled the criteria only after one year's follow up, whereas eight maintained the original diagnosis of early unclassified polyarthritis. The following MRI variables were assessed at baseline and one year: synovial membrane hypertrophy score, number of erosions, and tenosynovitis score.

Results: MRI detected progression of erosions earlier and more often than did radiography of the same joints; at baseline the MRI to radiography ratio was 28:4. Erosions were exclusively found in patients with RA at baseline or fulfilling the ACR criteria at one year. At one year follow up, scores of MR synovial membrane hypertrophy, tenosynovitis, and scintigraphic tracer accumulation had not changed significantly from baseline; in contrast, swollen and tender joint counts had declined significantly (p<0.05).

Conclusions: MRI detected more erosions than radiography. MR synovial membrane hypertrophy and scintigraphy scores did not parallel the changes seen over time in clinically assessed swollen and tender joint counts. Although joint disease activity may be assessed as quiescent by conventional clinical methods, a more detailed evaluation by MRI may show that a pathological condition is still present within the synovium.

Figure 1

(A) Distribution of magnetic resonance imaging synovial membrane hypertrophy scores (0-4) in each finger joint (given as a percentage for each score (0-4)). (B) Clinical assessment in individual 2nd to 5th metacarpophalangeal (MCP) and proximal interphalangeal (PIP) joints at baseline (55 patients); black indicates the percentage of joints without swelling and tenderness while white indicates the percentage of joints with swelling or tenderness, or both.

Figure 2

Distribution of magnetic resonance (MR) erosions at baseline and at the one year follow up of the 2nd to 5th metacarpophalangeal and proximal interphalangeal joints of the dominant hand (of 32 right handed and two left handed patients). A dot represents an MR erosion at baseline. A triangle represents a new MR erosion at the one year follow up.

Figure 3

Magnetic resonance images of the three new erosions (white arrows) developed within the observation period of one year in three patients. T1 weighted, spin echo, pre-contrast axial images (A) at baseline, and (B) at the one year follow up; a new erosion is seen in the 3rd metacarpophalangeal (MCP) joint. (C) T1 weighted, spin echo, pre-contrast coronal image at baseline and (D) at the one year follow up, a new erosion is seen in the 4th MCP joint. (E) T1 weighted, spin echo, pre-contrast coronal image at baseline and (F) at the one year follow up, a new erosion is seen in the 3rd MCP joint.

Figure 4

Distribution of radiographic erosions at baseline and at the one year follow up in both hands (34 patients). A dot represents an erosion at baseline. A triangle represents a new erosion at the one year follow up. Erosions found in dominant hands (32 right handed and two left handed) are indicated on the hand to the right in the figure, whereas erosions found in non dominant hands are indicated on the hand to the left.