Fig. 4
From: Lesions involving the outer surface of the bone in children: a pictorial review
Sub-periosteal osteoid osteoma. A 15-year-old boy with sub-periosteal osteoid osteoma involving the right femur. Coronal a and axial b non-enhanced CT images show cortical thickening with reactive sclerosis (arrow) involving the postero-medial cortex of the femur, surrounding a low-attenuation nidus with central mineralization. Coronal STIR c and axial T1 post-contrast d images show avid contrast enhancement and edema within the bone marrow and soft tissue surrounding the nidus. The periphery of the nidus enhances more intensely than the central portion (arrow)