Fig. 4

Aggressive osteoblastoma in a 16-year-old female, Enneking stage 3 on both CT and MRI. This case was diagnosed as Ewing’s sarcoma or osteosarcoma before needle biopsy. a Axial CT soft tissue window shows extensive osteolytic destruction in the vertebral body, left pedicle and lamina of T2 vertebrae, with scattered internal nodular calcifications and a sclerotic rim (arrows). Note that the structures in the spinal canal are not clearly depicted. b Axial MRI contrast-enhanced T1WI shows a diffuse mass (arrowheads) with avid enhancement greater than that observed on CT, involving the T2 vertebral body and anterior soft tissues, bilateral lamina, spinous process, left pedicle, head and neck of the left 2nd rib and their surroundings, as well as soft tissues inside the spinal canal encapsulating the cord. c and d Axial and sagittal F18-FDG PET/CT images show both the mass and flares with high uptake of FDG (SUVmax: 15.7), which indicates tumor extension into the surrounding soft tissues. Note that PET does not clearly show the spinal cord due to its low spatial resolution. e Sagittal T2WI shows the tumor (asterisk) and extensively swollen tissues surrounding it that display the flare phenomenon (arrowheads). f Co-registered PET and T2WI sagittal image shows that a lesion visible on MRI (arrowheads) is significantly larger than the foci of high uptake on PET-CT, which indicates the existence of inflammatory issues in the flares