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The structural basis of MRI bone erosions: an assessment by microCT
Andreas Albrecht1, Stephanie Finzel, Matthias Englbrecht
1Department of Internal Medicine 3, University of Erlangen-Nuremberg, Erlangen, Germany.
Objective:
To determine whether erosions appearing in MRI in patients with rheumatoid arthritis (RA) represent true erosions.
Methods:
50 RA patients received 1.5 T MRI and microCT (μCT) of the dominant hand. Erosion counts were assessed in coronal T1 weighted MRI sections and in coronal as well as axial μCT sections of the metacarpophalangeal (MCP) joints II-IV. Extent of erosions was assessed by RA MRI Score (RAMRIS) erosion score (MRI) and by three-dimensional assessment of erosion volume (μCT).
Results:
111 of the 600 evaluated joint regions showed erosions in the MRI and 137 in the μCT. In only 28 regions false negative lesions (μCT positive, MRI negative) were found, all of which were very small lesions with a volume of less than 10 mm(3). Only two results were false-positive (μCT negative, MRI positive). RAMRIS erosion scores were strongly correlated to erosion volumes in the μCT (Pearson's r=0.514, p<0.001). Mean RAMRIS erosion scores were below 1 with erosion volumes up to 1.5 mm(3), below 2 with erosion volumes up to 20 mm(3) and over 2 with volumes of more than 20 mm(3).
Discussion:
MRI erosions are generally based on true cortical breaks as shown by μCT. MRI is sensitive to detect bone erosions and only very small lesions escape detection. Moreover, RAMRIS erosion scores are closely linked to the absolute size of bone erosions in the μCT.
Insights
Magnetic resonance imaging (MRI) accurately detects rheumatoid arthritis (RA) bone erosions, with micro-computed tomography (μCT) confirming most MRI findings. Very small erosions may be missed by MRI, but scores correlate well with actual erosion size.
Area of Science:
- Rheumatology
- Medical Imaging
- Orthopedics
Background:
- Rheumatoid arthritis (RA) is a chronic autoimmune disease characterized by joint inflammation.
- Bone erosions are a hallmark of RA, leading to joint damage and disability.
- Magnetic resonance imaging (MRI) is widely used to assess RA activity, but the accuracy of MRI-detected erosions requires validation.
Purpose of the Study:
- To validate the accuracy of MRI in detecting bone erosions in patients with rheumatoid arthritis (RA).
- To compare MRI findings with high-resolution micro-computed tomography (μCT) for assessing erosion presence and extent.
- To evaluate the correlation between RA MRI Score (RAMRIS) erosion scores and actual erosion volumes.
Main Methods:
- Fifty RA patients underwent 1.5 T MRI and microCT (μCT) of their dominant hand.
- Erosion counts were assessed on coronal T1-weighted MRI and coronal/axial μCT of metacarpophalangeal (MCP) joints II-IV.
- Erosion extent was quantified using RAMRIS erosion score (MRI) and 3D erosion volume (μCT).
Main Results:
- MRI detected erosions in 111 of 600 evaluated joint regions, while μCT identified 137.
- Only 28 regions had μCT-positive, MRI-negative (false negative) lesions, all very small (<10 mm³).
- RAMRIS erosion scores strongly correlated with μCT erosion volumes (Pearson's r=0.514, p<0.001).
Conclusions:
- MRI erosions generally represent true cortical breaks confirmed by μCT.
- MRI is sensitive for detecting bone erosions, with only very small lesions potentially missed.
- RAMRIS erosion scores are closely linked to the absolute size of bone erosions measured by μCT.
