Spinal osteoblastoma: a retrospective study of 35 patients' imaging findings with an emphasis on MRI.

OBJECTIVE: To investigate the values of multimodal imaging approaches in the diagnosis of spinal osteoblastomas with an emphasis on MRI findings.

MATERIALS AND METHODS: We retrospectively evaluated the imaging findings of 35 patients with spinal osteoblastomas. The imaging methods included radiography, whole-body bone scintigraphy (WBBS), CT and MRI.

RESULTS: Radiography detected 87.1% (27/31) of the lesions; WBBS demonstrated increased radionuclide activity in all the lesions. CT could precisely show and localize all niduses, and calcification was always detected. MRI usually could adequately delineate the niduses of osteoblastomas, especially on T2WI (88.2%; 30/34). 71.9% (23/32) of osteoblastomas were surrounded with moderate or extensive bone marrow edema (BME) with soft tissue edema (STE). STE always extended along the muscle bundle adjacent to the lesion; there was no subcutaneous fat involvement. BME was eccentrically distributed in the vertebral body and spread inward from the sides of the nidus. The extent of BME in the vertebral body tended to be inversely proportional to the distance from the nidus. In addition, rare magnifications of osteoblastoma including multifocal diseases (n = 2), vertebra plana (n = 1) or with aneurysmal bone cysts (n = 6) were also observed in our study.

CONCLUSIONS: In patients showing moderate or extensive BME together with STE on MRI, both CT and MRI should be used to confirm nidus presence. The above-mentioned characteristics of edema on MRI of patients with spinal osteoblastoma are helpful in not only localizing the nidus, but also enhancing the diagnostic confidence.