Imaging guidelines and findings of extracranial glioblastoma

Extracranial manifestations of glioblastoma are uncommon and include a wide spectrum of entities, such as primary spinal cord glioblastoma, spinal leptomeningeal metastasis, seeding into the scalp following intracranial glioblastoma resection, direct extension of an intracranial glioblastoma though a craniotomy defect, dissemination via shunt catheter, and systemic metastasis, including lymphatic and hematogenous spread. Imaging plays an important role in the management of patients with extracranial glioblastomas and guidelines for the imaging evaluation of these lesions are reviewed. For example, MRI is the modality of choice for evaluating glioblastoma involving the scalp and spine. In particular, advanced imaging techniques such as MR spectroscopy, MR perfusion, diffusion-weighted imaging, and diffusion-tensor imaging can be useful for early detection and characterization of these lesions. CT and (18)FDG-PET are suitable modalities for evaluating systemic and CSF shunt-related metastases.