Objective: To carry out a prospective two year follow up study comparing conventional radiography, three-phase bone scintigraphy, ultrasonography (US), and three dimensional (3D) magnetic resonance imaging (MRI) with precontrast and dynamic postcontrast examination in detecting early arthritis. The aim of the follow up study was to monitor the course of erosions during treatment with disease modifying antirheumatic drugs by different modalities and to determine whether the radiographically occult changes like erosive bone lesions of the finger joints detected by MRI and US in the initial study would show up on conventional radiographs two years later. Additionally, to study the course of soft tissue lesions depicted in the initial study in comparison with the clinical findings.
Methods: The metacarpophalangeal, proximal interphalangeal, and distal interphalangeal joints (14 joints) of the clinically more severely affected hand (soft tissue swelling and joint tenderness) as determined in the initial study of 49 patients with various forms of arthritis were examined twice. The patients had initially been divided into two groups. The follow up group I included 28 subjects (392 joints) without radiographic signs of destructive arthritis (Larsen grades 0–1) of the investigated hand and wrist, and group II (control group) included 21 patients (294 joints) with radiographs showing erosions (Larsen grade 2) of the investigated hand or wrist, or both, at the initial examination.
Results: (1) Radiography at the two year follow up detected only two erosions (two patients) in group I and 10 (nine patients) additional erosions in group II. Initial MRI had already detected both erosions in group I and seven (seven patients) of the 10 erosions in group II. Initial US had depicted one erosion in group I and four of the 10 erosions in group II. (2) In contrast with conventional radiography, 3D MRI and US demonstrated an increase in erosions in comparison with the initial investigation. (3) The abnormal findings detected by scintigraphy were decreased at the two year follow up. (4) Both groups showed a marked clinical improvement of synovitis and tenosynovitis, as also shown by MRI and US. (5) There was a striking discrepancy between the decrease in the soft tissue lesions as demonstrated by clinical findings, MRI, and US, and the significant increase in erosive bone lesions, which were primarily evident at MRI and US.
Conclusions: Despite clinical improvement and a regression of inflammatory soft tissue lesions, erosive bone lesions were increased at the two year follow up, which were more pronounced with 3D MRI and less pronounced with US. The results of our study suggest that owing to the inadequate depiction of erosions and soft tissue lesions, conventional radiography alone has limitations in the intermediate term follow up of treatment. US has a high sensitivity for depicting inflammatory soft tissue lesions, but dynamic 3D MRI is more sensitive in differentiating minute erosions.