Table 4 Imaging features of focal signal abnormality marrow lesions (number of cases = 38/42, ~ 90.5%)

Osteonecrosis (34/38 cases ~ 89.5%) (n. of lesions = 153)

Patchy STIR high signals (acute lesion) *

105

~ 63.6%

Serpiginous STIR hyperintensity and central low signals of fat (chronic lesion) *

48

~ 31.4%

T1 hyperintensity on T1fs

83

~ 54.2%

Marginal enhancement **

61

N/A

Osteomyelitis (4/38 cases ~ 10.5%) (n. of lesions = 4)

Presence of extra-osseous signal abnormality

4

100%

Presence of sequestra

2

50%

Cortical defect

3

75%

Patchy enhancement

4

100%