MR imaging of avacular necrosis of the femoral head

ABSTRACT

We evalusted the magnetic resonance imaging (MRI) findings of the femoral heads in 20 normal and 45 abnormal patients. The bone marrow in the healthy adults consisted of a combination of hematopoietic and fatty marrow, which showed age-related dirtribation, that is the component of fatty marrow was increased and the marrow vascularity was dereased with age. Avascular necrosis (AVN) showed a decreased bone marrow signal within an normal appearing femoral head on T1 and T2-weighted images. In addition, we could see inhomogenous low signal intensity (31 cases), a ring of low intensity with central normal signal intensity (25cases), focal low signal intensity (12 cases), or a band of low signal intensity (4 cases). MRI findings were abnormal in 10 cases with normal radiographic findings as well as in all the cases with abnormal ones. In conclusion, MRI should be the choice of the imaging modality for the evaluation of early bone marrow chages of AVN.