CT Brain Interpretation Dr. Chew Keng Sheng Professor/Emergency Physician FHMS, Universiti Malaysia Sarawak

Hounsfield Unit www.PresentationPro.com

Calcified structures The occipital lobes and the occipital horns of the lateral ventricles are located posteriorly and contain the choroid plexus, which is often calcified At the posterior margin of the third ventricle is the pineal gland, which also is often calcified

Caudate nucleus Lentiform nucleus (Putamen & Globus Pallidus) Internal capsule Thalamus

Suprasellar Cistern Also called the “pentagonal cistern” because it has the shape of a five-pointed star The circle of Willis lies within the suprasellar cistern and is the site of most aneurysmal subarachnoid hemorrhage The basilar artery can be seen just anterior to the pons The middle cerebral arteries are often visible in the lateral extensions of the suprasellar cistern extending into the Sylvian fissures. www.PresentationPro.com

http://www.med-ed.virginia.edu/courses/rad/headct/stroke6a.html A hyperdense vessel is defined as a vessel denser than its counterpart. This is seen in 25% of stroke patients. In patients presenting with middle cerebral artery stroke, the hyperdense vessel sign is present 35-50% of the cases

Hyperdense MCA sign is due to the presence of acute thrombus Hyperdense MCA sign is due to the presence of acute thrombus. It is one of the early signs of MCA infarct

Sylvian fissure Third ventricle Quadrigerminal cistern plate Cerebellum

Sylvian fissure Supracellar Cistern (Circle of Willis) Temporal lobe Temporal horn Pons

Sylvian fissure Supracellar Cistern (Circle of Willis) Temporal lobe Temporal horn Pons

Temporal Horns of Lateral Ventricles The temporal horns of the lateral ventricles, which normally appear as narrow, barely visible, slits. Enlargement of the temporal horns has a distinctive CT appearance and is a reliable indicator of hydrocephalus

Temporal lobe Pons Fourth ventricles

Useful Tips CROSS STAR

BEAN

Extradural Hematoma Associated with skull fracture Classic: Middle meningeal artery tear Lenticular / biconvex shaped Lucid interval Can be rapidly fatal Early evacuation essential www.PresentationPro.com

Subdural Hematoma Venous tear / brain laceration Involving the cortical bridging veins Morbidity / mortality due to underlying brain injury Rapid surgical evacuation recommended, especially if > 5 mm shift of midline www.PresentationPro.com

Differentiating EDH from SDH EDH does NOT cross the sutures. EDH CAN cross midline SDH CAN cross the sutures (not bound by the suture lines) SDH does NOT cross midline (bound by falx cerebri)

Features of hydrocephalus Narrowing of ventricular angle <40o Dilated third ventricle

Features of hydrocephalus Periventricular perilesional oedema Dilated frontal horns of lateral ventricles (“Mickey mouse”) Rounded third ventricle

Features of hydrocephalus FH/ID ratio >50% (normal FH/ID ratio <40%) where FH (widest diameter of frontal horn) and ID (internal diameter from inner table to inner table) Opening up of the temporal horn of lateral ventricles