General Approach to Brain Cysts General Considerations Overview : Cysts are common findings on MR and CT brain scans. There are many types of intracranial cysts, some significant, some incidental. In this section, we exclude cystic neoplasms (such as pilocytic…
KEY FACTS Terminology Antiangiogenic agents may substantially reduce contrast enhancement in glioblastoma multiforme related to reduced vascular permeability rather than actual tumor response Bevacizumab (Avastin): Anti-VEGF is main antiangiogenic agent currently used for treatment of recurrent malignant gliomas Cediranib :…
KEY FACTS Terminology Treatment-related increase in contrast enhancement mimics tumor progression Classically described after treatment with chemoradiation (temozolomide with radiation therapy) Typically occurs within 3-6 months after conclusion of radiation therapy (XRT) Imaging New enhancing lesion + ↑ FLAIR hyperintensity…
KEY FACTS Terminology Radiation-induced injury may be divided into acute, subacute/early delayed, late injury Imaging Radiation injury : Mild vasogenic edema to necrosis Radiation necrosis : Irregular enhancing lesion(s) MRS: Markedly ↓ metabolites (NAA, Cho, Cr), ± lactate/lipid peaks Perfusion…
KEY FACTS Terminology Remote neurological effects of cancer, associated with extra-CNS tumors Most common tumor: Small cell lung carcinoma Limbic encephalitis (LE) is most common clinical paraneoplastic syndrome Imaging Limbic encephalitis: Hyperintensity in mesial temporal lobes, limbic system Mimics herpes…
KEY FACTS Terminology Secondary CNS involvement in patients with systemic lymphoma (SCNSL) Imaging Secondary CNS lymphoma: Skull, dura, leptomeninges > > parenchymal mass Best diagnostic clue: Diffusely enhancing dural mass ± bone involvement May see leptomeningeal enhancement or nonsupression of…
KEY FACTS Terminology Brain metastases in locations other than skull/meninges or parenchyma Imaging General features > 95% of brain metastases parenchymal Only 1-2% in ventricles, pituitary gland, etc. Sites generally very vascular Extraventricular metastases more diffuse, infiltrative than parenchymal metastases…
KEY FACTS Terminology Secondary brain tumors (metastases) arise from Tumors outside CNS spreading to CNS (usually via hematogenous dissemination) Primary CNS neoplasms spreading from 1 site to another (usually geographic extension, e.g., along WM tracts) Imaging General features Round enhancing…
KEY FACTS Terminology Acute or chronic myeloid or lymphoid white blood cell neoplasia with spinal involvement as component of systemic disease Imaging Radiographs/CT Diffuse osteopenia with multiple vertebral fractures ± lytic spine lesions Variable enhancing isodense soft tissue mass with…
KEY FACTS Terminology Rare malignancy characterized by intravascular proliferation of lymphoid cells with predilection for CNS and skin Imaging T2/FLAIR multifocal hyperintensities in deep white matter, cortex, and basal ganglia May mimic infarct Diffusion restriction common GRE/SWI: Multifocal hemorrhage often…