Avascular necrosis (T2 STIR sequence at the coronal level:Grade III Avascular necrosis of the right femoral head: Pathological focus on subchondral surface of the bone, which is surrounded by a double linear halo (yellow arrow) and an extensive bone edema (red arrow).Grade IV Avascular necrosis of the left femoral head. Pathological focus on the subchondral surface of the bone, which is surrounded by a double linear halo (yellow arrow) and a milder bone edema (red arrow). Deformity of the articular surface of the bone (green arrow).