RADIOLOGY B

20%

What percentage of blood from the heart does the brain receive?

Anterior (ICA) and posterior circulation

From where does the brain receive blood?

Internal Carotid Artery (ICA)

What is the main blood vessel in anterior circulation?

Middle Cerebral Artery (MCA)

What does the ICA become?

MCA and Anterior Cerebral Artery (ACA)

What does the ICA branch into?

Laterally

In which direction does the MCA go?

MCA candelabra

What is another name for the MCA?

Medially

In which direction does the ACA go?

4

How many segments does the MCA have?

M4

Which segment of the MCA is seen on the lateral surfaces of the brain?

Anterior communicating artery (ACOM)

What artery connects both left and right ACAs?

Not all people

Is the ACOM present in everyone?

Vertebral artery

What is the main blood vessel in posterior circulation?

Subclavian artery

Where does the vertebral artery come from?

Vertebral transverse foramen

Through what structure in the cervical vertebrae does the vertebral artery go?

C6

The vertebral artery passes through C6 and goes up then out to which vertebra?

Paired

Are the vertebral arteries single or paired?

Basilar artery

What is the meeting point of the vertebral arteries called?

Posterior inferior cerebellar artery (PICA)

What artery does the vertebral artery become before the basilar artery?

Rule of 3s

What rule helps remember the main blood vessels of the cerebrum and cerebellum?

Anterior cerebral artery (ACA), Middle cerebral artery (MCA), Posterior cerebral artery (PCA)

According to the Rule of 3s, what are the 3 main blood vessels of the cerebrum?

Superior cerebellar artery (SCA), Posterior inferior cerebellar artery (PICA), Anterior inferior cerebellar artery (AICA)

According to the Rule of 3s, what are the 3 main blood vessels for the cerebellum?

PCA

What is the destiny of the vertebral arteries?

Labyrinth arteries

What variable arteries are related to the internal acoustic canal (IAC)?

Posterior communicating arteries (PCOM)

What arteries connect the anterior and posterior circulation?

ICA

Where is the PCOM located before connecting to the PCA?

Circle of Willis

What structure connects the anterior and posterior circulation?

ACOM, PCOM, ICA, ACA

What comprises the Circle of Willis?

Protection from stroke

What is an importance of the Circle of Willis?

Backflow from other arteries

How does a complete Circle of Willis help protect from stroke in case of a blockage?

People with complete ones

Who are more protected from stroke, people with complete or incomplete Circles of Willis?

Pons

The Basilar Artery is related to what structure of the brain stem?

A groove for Basilar Artery

What feature does the Pons have related to the Basilar Artery?

A groove for Basilar Artery

What feature does the bone in front of the pons have related to the Basilar Artery?

Many segments

What feature characterizes the ICA regarding curves?

Medial surface

Where do the Anterior Cerebral Arteries go together?

Small

What is a characteristic of the Anterior Communicating Artery?

Up to 3

How many ACOMs can anatomically vary?

One is usually hypoplastic or smaller

What is a common characteristic of one of the vertebral arteries?

Vertebral artery

PICA is a branch of which artery?

Carotid Canal

What is the delineation between the ICA and MCA called?

Pierces the bone (carotid canal)

When does the ICA into MCA delineation occur?

Fluorodeoxyglucose positron emission tomography (FDG PET)

What imaging modality is utilized to map speech and language in the brain?

Map speech and language

What is FDG PET used for in the brain?

Interhemispheric fissure

Starting from the top of a head CT scan, what structure do you see first?

Skull

What is the surrounding white structure seen from the top of a head CT?

Scalp

What is the outer white layer seen from the top of a head CT?

Superior frontal gyrus

As you go lower on a CT scan, which gyrus is likely seen first?

Lateral ventricles

What structure serves as a landmark for the midline on a normal head CT?

Internal Occipital Protuberance

What is a midline landmark at the posterior end on a head CT?

Crista galli

What structure, where falx cerebri attaches, serves as a midline landmark at the front on a head CT?

Midline landmarks

What helps orient you to estimate gyri and sulci on a CT?

Choroid plexus

What is classified as one of the normal calcifications of the brain?

Inside the ventricles

Where is the choroid plexus located?

Pineal gland, Lamic calcification system

What are other normal brain calcifications?

Third ventricle

What is the black structure in the middle of a CT slice showing the thalamus?

Thalamus

What are the two wide and dark egg-like structures near the third ventricle on a CT?

Caudate horn

What structure is located just beside the frontal horn on a CT?

Gets more visible

As the view of the CT scan lowers, what happens to the third ventricle image?

Sylvian fissure

What prominent fissure is evident between the areas of the frontal and temporal lobes on a CT?

Frontal Sinus

What is an empty space inside the bone located at the forehead area on a CT?

Tentorial incisura

What is a good indicator on a CT to determine if the structure is cerebellum or occipital lobe?

Cerebellum

What structure can be seen peeking through the tentorial incisura on a CT?

Parietal lobe or occipital lobe

What structures could be located outside the tentorial incisura on a CT?

Wider

What happens to the tentorial incisura as the CT view lowers, making the cerebellum more prominent?

Midbrain

What mickey mouse-like structure becomes evident after following the thalamus on a CT?

Cerebral peduncle

What structure is located at the anterior (ventral) aspect of the midbrain?

Basal cisterns

What are the empty spaces located at the base of the brain on a CT?

Ventricles

What are basal cisterns often mistaken for?

Medially

In the medial view, where does the Sylvian fissure separate the temporal and parietal lobes?

Optico-carotid cistern

What space is occupied by the optic nerve, ICA, and anterior circulation on a CT?

Medial

Where is the optico-carotid cistern located relative to the Sylvian fissure?

Pons

What does the midbrain become as the CT scan views lower?

Basilar artery

What hyperdense blood vessel is a good indicator that the structure being identified is the pons on a CT?

The only blood vessel that may be found in the pons

What is unique about the Basilar artery's location in the pons on a CT?

Cannot completely and accurately show all soft tissues

What is a limitation of CT scans?

Identifying bones and localization of bleedings

What are CT scans more suitable for?

Coronal suture

What front suture is often mistaken as a fracture on a CT scan?

Blood vessels within the bone

What are the dark lines on a bone window CT that are not sutures?

Outer Table, Diploe, Inner Table

What are the three parts of the bone seen on a CT?

Frontal sinus, Eyes, Orbital roof

What structures may be found as the CT scan views more ventrally?

Orbital gyrus

What structure rests within the orbital roof?

Rectus Gyrus

What structure is located at the medial part above the cribriform plate?

Ethmoid Sinus

What structure seen on a bone window CT is described as a bony net with many septations?

Sphenoid Bone

What structure goes from the anterior to medial fossa on a CT?

Clinoid Process

What area where the ICA exits is located very near the optical canal on a CT?

Top of the Sella

What part of the sella can be seen on a CT?

Tuberculum sellae

What is the anterior part of the sella called?

Dorsum sellae

What is the posterior part of the sella called?

Petrous Bone

What structure seen on a CT is a clue because ear structures are visible laterally?

Labyrinth of semicircular canals and the cochlea

What ear structures can be appreciated laterally near the Petrous Bone on an axial CT?

Internal Acoustic Canal/Meatus

What is highlighted by an orange circle near the petrous bone on a CT?

Mastoid Air Cells

What appear dark near the petrous bone on a CT and are highlighted by a green circle?

Petrous Ridge

What is highlighted by a red line near the petrous bone on a CT?

Occipital Bone

What is highlighted by a violet arrow near the petrous bone on a CT?

Sphenoid Sinus

What sinus is posterior to the ethmoids on a CT?

Orbits

What can also be appreciated near the Sphenoid Sinus on a CT?

Auditory ossicles

What structures form the "Ice Cream Cone Sign" on a CT?

Clivus

What bone structure is where the pons rests on a CT?

Basilar groove

What feature is located on the Clivus bone where the basilar arteries pass?