Proposed definitions and scaling (category description) of HOA features included in the proposed OHOA-MRI score
| Definition | Scoring | |
|---|---|---|
| Synovitis | An area in the synovial compartment that shows post-Gd enhancement* of a thickness greater than the width of normal synovium (as shown in the atlas). *Enhancement (signal intensity increased) is judged by comparison of T1w images obtained before and after intravenous Gd contrast. | Synovitis is scored by thirds of the maximum potential volume of enhancing tissue in the synovial compartment, where 0=normal, 1=mild, 2=moderate, 3=severe |
| Flexor tenosynovitis | An area in the flexor tendon sheath that shows post-Gd enhancement* of a thickness greater than the normal width of the tendon sheath (as shown in the atlas). *Enhancement is judged by comparison of T1w images obtained before and after intravenous Gd contrast. | When measuring the maximal thickness of the tendon sheath with Gd enhancement, tenosynovitis is scored as follows: 0=normal, 1=<0.5 tendon thickness, 2=≥0.5 and <1 tendon thickness, 3=≥1 tendon thickness |
| Erosion | A sharply marginated bone lesion with typical signal characteristics*, which is visible in two planes with a cortical break seen in at least one plane. *Increased signal intensity in the area of cortical bone and bone marrow fat on T1w fs images. | Distal and proximal part of the joint are scored separately, as follows: 0=no erosion, 1=1–2 small erosion(s) and/ or subchondral bone collapse (‘seagull wing’), 2=moderate erosion(s) or ≥3 small erosions with total size as a moderate erosion, 3=large erosion(s) or several small/moderate erosions with total size as a large erosion |
| Cyst | A sharply marginated bone lesion with typical signal characteristics*, which is visible in two planes without a cortical break. *Increased signal intensity of cortical bone and bone marrow fat on T1w fs images. | Distal and proximal part of the joint are scored separately, as follows: 0=no cyst, 1=≥1 cyst(s) |
| Osteophyte (OP) | Abnormal bone formation in the periarticular region on T1w fs images. | Distal and proximal part of the joint separately are scored separately, as follows: 0=no OP, 1=1–2 small OP, 2=≥3 small OP or moderate OP(s), 3=large OP(s) |
| Joint space narrowing (JSN) | Narrowing of the joint width on T1w fs images | 0=no JSN, 1=mild JSN, 2=bone-to-bone contact in part of the joint, 3=bone-to bone contact in the whole joint |
| Malalignment | Subluxation/luxation of joints in either frontal (≥15°) or sagittal plane (crossing the midline) on T1w fs images | Malalignment in the frontal and sagittal plane are scored separately, as follows: 0=no malalignment, 1=malalignment |
| Bone marrow lesion (BML) | A lesion* within the trabecular bone with signal characteristic consistent with increased water content** and often with ill-defined margins. *May occur alone or surrounding an erosion or other bone abnormalities. **High signal intensity on STIR images. | Scored as the proportion of bone with BML in the distal and proximal part of the joint separately: 0=no BML, 1=1–33% of bone with BML, 2=34% to 66% of bone with BML, 3=67% to 100% of bone with BML |
| Collateral ligament (CL) | (1) Absence of CL: non-visible or non-continuous CL on T1w fs images(2) BML at CL insertion sites: a lesion within the trabecular bone at the CL insertion sites with signal characteristics consistent with increased water content* and often with ill-defined margins. *High signal on STIR images. | (1) Radial and ulnar part of the joint are scored separately, as follows: 0=visible CL, 1=non-visible CL(2) Radial and ulnar part of the distal and proximal joint are scored separately, as follows: 0=no BML, 1=present BML(s) at CL insertion sites |
fs, fat suppressed; Gd, gadolinium; HOA, hand osteoarthritis; OHOA-MRI, Oslo hand osteoarthritis MRI; STIR, Short T1 Inversion Recovery; T1w, T1-weighted.