Magnetic resonance imaging of subchondral bone marrow lesions in association with osteoarthritis

Abstract

Objectives: This nonsystematic literature review provides an overview of magnetic resonance imaging (MRI) of subchondral bone marrow lesions (BMLs) in association with osteoarthritis (OA), with particular attention to the selection of MRI sequences and semiquantitative scoring systems, characteristic morphology, and differential diagnosis. Histologic basis, natural history, and clinical significance are also briefly discussed.

Methods: PubMed was searched for articles published up to 2011, using the keywords bone marrow lesion, osteoarthritis, magnetic resonance imaging, bone marrow edema, histology, pain, and subchondral.

Results: BMLs in association with OA correspond to fibrosis, necrosis, edema, and bleeding of fatty marrow as well as abnormal trabeculae on histopathology. Lesions may fluctuate in size within a short time and are associated with the progression of articular cartilage loss and fluctuation of pain in knee OA. The characteristic subchondral edema-like signal intensity of BMLs should be assessed using T2-weighted, proton density-weighted, intermediate-weighted fat-suppressed fast spin echo or short tau inversion recovery. Several semiquantitative scoring systems are available to characterize and grade the severity of BMLs. Quantitative approaches have also been introduced. Differential diagnoses of degenerative BMLs include a variety of traumatic or nontraumatic pathologies that may appear similar to OA-related BMLs on MRI.

Conclusions: Subchondral BMLs are a common imaging feature of OA with clinical significance and typical signal alteration patterns, which can be assessed and graded by semiquantitative scoring systems using sensitive MRI sequences.

Figure 1

Different compartments of the tibiofemoral joint of the knee. (Color version of figure is available online.)

Figure 2

BMLs in knee osteoarthritis in a 65-year-old woman. (A) Sagittal fat-suppressed proton density-weighted MRI (TR/TE = 3500/20) shows a large BML (short white arrows) involving the central and posterior subregions of the lateral tibia. In the Magnetic Resonance Imaging Osteoarthritis Knee Score (MOAKS), the BML is scored grade 3 (3 = >66% of the region) for size in both the central and the posterior subregions. This lesion would also be scored as a 3 using the Whole Organ Magnetic Resonance Imaging Score (WORMS). (B) Sagittal fat-suppressed intermediate-weighted MRI (TR/TE = 3200/30) shows a subchondral BML in the lateral trochlea (short white arrows), which is scored as grade 2 by MOAKS and grade 3 by WORMS. Also note that the presence of a septated proximal tibiofibular joint cyst (long gray arrow), which represents a synovial cystic change related to the degenerative disease, and superficial diffuse thinning of trochlear cartilage (no arrow). (C) Sagittal DESS sequence (TR/TE = 16.3/4.7, flip angle = 25°) only shows the small subchondral cysts, which are located within the BML depicted in (B). Note that the DESS fails to show the ill-defined hyperintensity representing BML and consequently offers clearer delineation of subchondral cysts than in (B), in which hyperintensity from the cysts is not as clearly differentiated from overlapping ill-defined hyperintensity representing BML. The proximal tibiofibular joint cyst (long gray arrow) seen in (B) is also visualized in (C).

Figure 3

BMLs in hip osteoarthritis in a 60-year-old woman. (A) Coronal T1-weighted image (TR/TE = 720/15) shows diffuse BML in the central weight-bearing part of the femoral head depicted as hypointensity (white arrows). (B) Sagittal intermediate-weighted fat-suppressed image (TR/TE = 3200/35) shows the same lesion in the femoral head (arrows). A subchondral BML in the weight-bearing part of the acetabulum is also visualized (arrowheads). Note diffuse acetabular and femoral cartilage loss in the central weight-bearing part of the joint (no arrows). (C) Coronal T1-weighted contrast-enhanced sequence (TR/TE = 720/15) shows the same BML in the femoral head depicted with marked enhancement (arrowheads). In addition, there is severe synovitis visualized by marked thickening and enhancement of the synovial tissue (arrowheads). Note small osteophytes at the medial femoral head-neck junction (black arrow).

Figure 4

BMLs in foot osteoarthritis in a 58-year-old man. (A) Sagittal fat-suppressed T2-weighted MRI (TR/TE = 3500/100) shows multiple subchondral BMLs (asterisk) involving the subtalar, talonavicular, cuneonavicular, and tarsometa-tarsal joints. A cystic portion (white arrow) is depicted within the BML in the navicular. (B) Sagittal proton density-weighted MRI (TR/TE = 3500/15) shows diffuse intertarsal cartilage loss (black arrow).

Figure 5

BMLs of the shoulder OA in a 40-year-old man. (A) Axial intermediate-weighted fat-suppressed image (TR/TE = 3250/55) shows diffuse subchondral hyperintensity in the humeral head reflecting a large BML (arrows). In addition there is a BML in the subchondral glenoid (asterisk). Note an OA-associated large loose body in the anterior recessus subscapularis (arrowhead). Diffuse cartilage loss of the humeral head and the glenoid is depicted (no arrows). (B) Corresponding sagittal MRI (TR/TE = 3850/55) shows cystic lesions within noncystic BML (arrows). (C) Cysts are well depicted by corresponding sagittal CT image (black arrows); however, the poorly defined BML cannot be visualized by CT.