Cranium and Brain

positioning for a head CT

patient is supine

remove all metal

centered at EAM and MSP

chin tucked down 

why is the chin tucked for a head CT

gets more of the brain

less dose for the eyes

CT head scout

usually just a lateral view

used to set up SFOV

motion artifact 

voluntary motion will cause a repeat scan 

control motion with

• good explanation of scan to the pt 

• sponges

• straps

non contrast CT head exam reasons

altered consciousness

altered speech

cerebrovascular disease

CVA/stroke

dementia

headache

injury/trauma

seizure

syncope

weakness

vertigo

reasons for CT head with contrast

fever

meningitis

metastasis

neoplasm

Contrast used for regular CT head

100cc Omni 300

Contrast used for angiogram CT head

15cc Omni350

reasons for CT angiogram

headache

aneurysm 

cerebral vascular disease

epidural hematoma

above the dura mater

has more rounded shape

• lemon

subdural hematoma

below the dura mater

has more crescent shape

• banana

grey mater

unmyelinated neurons

centrum semiovale

centrally located white matter

basal ganglia 

deep pockets of grey matter within the white matter 

for motor control and motivation

longitudinal fissure

divides hemispheres of the cerebrum into right and left

central fissure 

divides frontal lobe from parietal lobe 

lateral fissure

AKA: sylvian fissure

divides frontal, parietal, and temporal lobes

transverse fissure

divides cerebrum from cerebellum

falx cerebri

a fold of dura mater that dips into the longitudinal fissure

tentorium cerebelli 

a fold of dura mater that dips into the transverse fissure 

parts of the forebrain

cerebrum

diencephalon

• thalamus 

• hypothalamus 

parts of the midbrain

peduncles

tectum

parts of the hindbrain

pons

medulla oblongata

cerebellum

thalamus

large oval masses of grey matter that form the lateral walls of the 3rd ventricles

hypothalamus 

regulates functions of homeostasis 

located below the thalamus 

infundibulum connects the hypothalamus to the pituitary gland 

pituitary gland

secretes hormones and stimulates other endocrine glands

pons 

large expansion of the brainstem between the midbrain and medulla oblongata 

vermis 

connects the right and left hemispheres of the cerebellum 

pineal gland

endocrine land that is not actually part of the hindbrain

sits beneath the splenium of the corpus callosum

calcifies early in life

secretes melatonin

caudate nucleus

sits above the thalamus next to the anterior horns of the lateral ventricles

important for learning and memory

claustrum

almond-shaped structure located in the insula, lateral to the caudate nucleus

choroid plexus

cluster of capillaries that lines part of the ventricles

manufactures CSF by filtration and secretion

helps form BBB

blood brain barrier 

protects the brain by blocking certain substances from passing from the blood into the brain and ventricles 

collateral trigone

area in the lateral ventricles where there is a heavy concentration of choroid plexus

septum pellucidum

separates the two lateral ventricles

seen on axial cuts

cerebral aqueduct

connects the 3rd and 4th ventricles

cerebrospinal fluid

fills the ventricles of the brain

mostly formed in the lateral ventricles 

manufactured by the choroid plexus 

serves as a shock absorber for the brain and spinal cord 

hydrocephalus

choroid plexus constantly manufactures the CSF and if a draining mechanism fails an over accumulation of fluid inn the ventricles will occur

ventricles will appear grossly enlarged

• can cause intracranial pressure

post processing 

reconstructions

• coronal

• sagittal

• MIPS

3D lab

changing algorithms 

window width for CT head

80-100

window level for CT head

20-40