Figure 2: A 32-year-old female patient with bilateral hip pain for 6 months: (a) Coronal positron emission tomography, (d) Axial positron emission tomography, and (e) Fused axial positron emission tomography/computed tomography images show photopenic areas (arrows) in the antero-superior regions of both femoral heads, with no definite morphological changes on computed tomography (b and f) and nonspecific marrow edema on MRI (c). A diagnosis of bilateral early femoral head avascular necrosis was made on positron emission tomography/computed tomography while magnetic resonance imaging was indeterminate for avascular necrosis. During 13 months of follow-up, the patient continued to have pain in both hips and a subsequent magnetic resonance imaging showed Ficat Stage I femoral head avascular necrosis on the right side and Stage II femoral head avascular necrosis on the left side