Physical Address

304 North Cardinal St.
Dorchester Center, MA 02124

Polymicrogyria

KEY FACTS Terminology Malformation due to abnormality in late neuronal migration and cortical organization Neurons reach cortex but distribute abnormally, forming multiple small, undulating gyri Result is cortex containing multiple small sulci that often appear fused on gross pathology and imaging Imaging Excessively small and prominent convolutions Predilection for perisylvian regions; when bilateral, often syndromic Small irregular gyri, but cortex appears normal or thick on MR…

Heterotopic Gray Matter

KEY FACTS Terminology Heterotopia (HTP) Arrested/disrupted migration of groups of neurons from periventricular germinal zone (GZ) to cortex Imaging Ectopic nodule or ribbon, isointense with gray matter on every MR sequence Periventricular, subcortical/transcerebral, molecular layer Periventricular HTP located next to periventricular white matter (GZ of cerebral mantle) but not in corpus callosum (fiber tract) or next to basal ganglia (GZ of ganglionic eminence) Variable: From tiny…

Septooptic Dysplasia

KEY FACTS Terminology Septooptic dysplasia (SOD) De Morsier syndrome Imaging Absent septum pellucidum, small optic chiasm Optic nerves, pituitary gland, septum pellucidum Coronal imaging shows Flat-roofed ventricles Downward-pointing anterior horns 3 orthogonal planes crucial to identify all findings Absent septum pellucidum, flat roof of frontal horns, small optic chiasm Clinical Issues Newborns: Hypoglycemic seizures, apnea, cyanosis, hypotonia, prolonged conjugated jaundice, and (in boys) microphallus Abnormal endocrine…

Dandy-Walker Continuum

KEY FACTS Terminology Dandy-Walker spectrum (DWS) represents broad spectrum of cystic posterior fossa (PF) malformations DWS/complex “Classic” DW malformation (DWM) Hypoplastic vermis with rotation (HVR) Persistent embryonic Blake pouch cyst (BPC) Mega cisterna magna (MCM) Imaging “Classic” DWM Cystic dilatation of 4th ventricle → enlarged PF Vermis hypoplastic, rotated superiorly HVR Variable vermian hypoplasia PF/brainstem normal-sized No or small cyst, keyhole-shaped 4th ventricle BPC “Open” 4th…

Lipoma

KEY FACTS Terminology Intracranial lipoma (ICL) Mass of mature adipose tissue (congenital malformation, not true neoplasm) Imaging Well-delineated lobulated extraaxial mass with fat attenuation/intensity CT: -50 to -100 Hounsfield units (HU) (fat density); Ca++ varies from none to extensive MR: Hyperintense on T1WI (becomes hypointense with fat suppression); may encase vessels and cranial nerves; often occurs with corpus callosum dysgenesis 80% supratentorial 40-50% interhemispheric fissure (over…

Callosal Dysgenesis

KEY FACTS Terminology Partial or complete absence of corpus callosum (CC), hippocampal commissure, or anterior commissure (AC); can be isolated or associated with additional cerebral malformations Spectrum of congenital CC structural abnormalities Total agenesis (absence from birth of all anatomically defined regions of CC) Partial agenesis (absence from birth of at least 1, but not all, regions of CC) Hypoplasia (thinner CC with normal anteroposterior extent)…

Chiari 2

KEY FACTS Terminology Complex hindbrain malformation Virtually 100% associated with neural tube closure defect, usually lumbar myelomeningocele (MMC) Imaging Crowded posterior fossa, widened tentorial incisura, tectal beaking, inferior vermian displacement Cascade or waterfall of cerebellum/brainstem downward Uvula/nodulus/pyramid of vermis → sclerotic peg Cervicomedullary kink (70%) Towering cerebellum → compresses midbrain, associated beaked tectum 4th ventricle elongated with no posterior point (fastigium) Lacunar skull: Focal calvarial thinning…

Chiari 1

KEY FACTS Terminology Chiari 1 malformation (CM1): Constellation of findings (not disease, not simply measurement) No clear consensus definition of what constitutes CM1 Traditional: Elongated, peg-shaped cerebellar tonsils extend below foramen magnum (FM) into upper cervical spinal canal 5-mm criterion for tonsillar position (TP) below FM is flawed criterion – TP is morphometric distribution, also changes with time – TP plus shape/configuration (elongated, pointed) – TP…

You’re Reading a Preview Become a Clinical Tree membership for Full access and enjoy Unlimited articles Become membership If you are a member. Log in here

Hepatic Adenoma

KEY FACTS Imaging Key features (not always present): Hypervascular, fat-containing, hemorrhagic, encapsulated MR shows some elements better than CT (lipid & hemorrhage) T1WI: Mass: Heterogeneous signal intensity – Increased signal intensity (due to fat or recent hemorrhage) – Decreased signal intensity (necrosis, calcification, old hemorrhage) T2WI: Mass: Heterogeneous signal intensity – Increased signal intensity (old hemorrhage, necrosis) – Decreased signal intensity (fat, recent hemorrhage) Gadoxetate-enhanced MR…

Hepatic Transplantation

KEY FACTS Terminology Orthotopic liver transplantation (OLT) Imaging Allograft rejection No reliable imaging findings to suggest or confirm diagnosis Biliary leak From entry of T tube: Easily treated From biliary anastomosis: Requires revision From intrahepatic ducts: Biliary necrosis; catastrophic Biliary obstruction Responds to balloon dilation & stenting Hepatic artery (HA) stenosis US: Damped waveform in HA distal to stenosis: Slow systolic upstroke; decreased resistive index (RI)…

Transjugular Intrahepatic Portosystemic Shunt (TIPS)

KEY FACTS Terminology Shunt between main portal vein and hepatic vein created with balloon-expandable metallic stent Imaging US is primary imaging tool following t ransjugular intrahepatic portocaval shunt (TIPS) Goal of US: Detect stenosis before shunt occludes or symptoms recur Echogenic stent easily seen on US but does not block sound transmission Color Doppler shows patency and flow direction within TIPS, portal vein, hepatic veins, and…