Blood
Location
Extracranial, extradural, SDH, SAH, ICH, IVH
Extracranial Haemorrhage
Subgaleal haematoma
Extradural Haemorrhage
Biconvex, localised and not crossing suture lines
Subdural Haemorrhage
Crescent-shaped, crossing suture lines
Subarachnoid Haemorrhage
Into CSF / cisterns
Intracerebral Haemorrhage
Within cerebral parenchyma
Intraventricular Haemorrhage
Within ventricles
Chronicity
Acute / subacute / chronic
Acute
Hours to days
Hyperdense (white)
Subacute
1-4 weeks
Isodense (same as parenchyma)
Chronic
4-6 weeks
Hypodense (darker than parenchyma)
Cisterns
Perimesencephalic Cistern
Surrounding midbrain
Suprasellar Cistern
Around Circle of Willis
Quadrigeminal Cistern
At top of midbrain
Sylvian Cistern
Between temporal and frontal lobes
Blood
Subarachnoid haemorrhage
Asymmetry
Look for midline shift
Effacement
Reduction in size / squashing of cisterns
Brain
Sulci & Gyri
Effacement, symmetry
Shift
Midline shift, rostro-caudal shift
Herniation
Subfalcine, transtentorial, cerebellar tonsillar
Subfalcine
Herniation of cingulate gyrus under falx to opposite side
Transtentorial
Herniation of medial temporal lobe through the incisura
Cerebellar Tonsillar
Hernation of tonsil into the spinal cord via foramen magnum
Abnormal Density
Hyper / hypodensity, loss of grey-white differentiation
Hyperdensity
Blood, contrast, calcification
Hypodensity
Air / gas, fat, ischaemia, tumour
Loss of Grey-White Differentation
Masses
Tumour, abscess
Infarcts
Loss of grey-white differentiation, oedema
Ventricles
Lateral Ventricles
Especially temporal horns, for dilatation
Choroid Plexus
Produces CSF
Normal calcification within lateral ventricles
3rd Ventricle
4th Ventricle
Asymmetry
Look for midline shift
Dilatation
Enlargement of ventricles
Effacement
Reduction in ventricular size
Intraventricular Haemorrhage
Look for subarachnoid / intracerebral blood
Bone
Fractures
Cranium, orbit, facial bones
Differentiate from cranial sutures, look for displacement and intracranial air
Air Spaces
Sinuses, mastoid air cells