Figure 1: 48-year-old male with osteonecrosis of the both femoral heads. To check amount of osteonecrosis we evaluated T1-weighted coronal and sagittal MR image. (A) Absolute value of the osteonecrosis was evaluated by the tool measuring size in the PACS. (B) Necrotic angle of the osteonecrosis was evaluated by the tool measuring angle in the PACS.