KEY FACTS Terminology Synonyms: Hippocampal remnant cyst, hippocampal sulcal cavities Cyst or string of cysts along residual cavity of primitive hippocampal sulcus Imaging String of cysts along lateral margin of hippocampus Cysts follow cerebrospinal fluid signal on all MR sequences…
KEY FACTS Terminology Intracranial epidermoids: Congenital inclusion cysts Imaging Cerebrospinal fluid-like mass that insinuates cisterns and encases neurovascular structures Morphology: Lobulated, irregular, cauliflower-like mass with “fronds” FLAIR: Usually does not suppress completely DWI: Diffusion hyperintensity definitively distinguishes from arachnoid cyst…
KEY FACTS Terminology Benign, ectopic, squamous epithelial cyst containing dermal elements, including hair follicles and sebaceous and sweat glands Imaging Midline unilocular cystic lesion with fat Subarachnoid fatty droplets if ruptured Suprasellar or posterior fossa most common intracranial sites Extracranial…
KEY FACTS Terminology Unilocular mucin-containing 3rd ventricular cyst Imaging > 99% are wedged into foramen of Monro Pillars of fornix straddle, drape around cyst Majority are hyperdense on NECT Density correlates inversely with hydration state MR signal more variable Generally…
KEY FACTS Terminology Intraarachnoid cerebrospinal fluid (CSF)-filled sac that does not communicate with ventricular system Imaging General findings Sharply demarcated round/ovoid extraaxial cyst Isodense/isointense with CSF Location Middle cranial fossa (50-60%) Cerebellopontine angle (10%) Suprasellar (10%) Miscellaneous (10%) (convexity, quadrigeminal)…
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…