Presentation
Young woman complains of chronic left shoulder pain. She has a history of chronic steroid use because of asthma. Examination revealed diminished shoulder abduction strength.
Patient Data
Coronal PD fat sat-weighted image shows a bright band, corresponding to hyperemic granulation tissue in the superior articular surface of the subchondral necrotic bone (double line sign). In Coronal T1 weighted image there is a single band-like area of low signal intensity from ischemic marrow.
There is a relative increase in the bone density of the articular surface in the superior portion of the humeral head but subchondral fractures are not appreciable (crescent sign).
Case Discussion
The main imaging modalities used in the diagnosis of humeral head osteonecrosis are radiography, MR imaging and CT. MR imaging is more sensitive and useful in the diagnosis of the humeral head osteonecrosis.
In earlier stages, sclerosis which may be focal or diffuse, results from subchondral microfracture without articular collapse. It typically appears in the superior portion of the humeral head and as an hyposignal on T1-weighted images. A double line sign representing lines of alternating high and low signal intensity on PD fat sat, STIR and T2-weighted images. The inner hypersignal line corresponds to hyperemic granulation tissue and the outer dark band corresponds to fibrosis or sclerosis. In later stages, fragmentation and articular collapse can occur.
CT is the best technique to determine the area of bone death.