Introduction To Neuroradiology Flashcards
What are the advantages of CT scans?
Relatively cheap
Fast
Repeatable
What clinical problems would you use CT scans for?
Trauma/emergencies Extracerebral bleeds/clots Calcified tumours Basic ventricular imaging (position, blood, enlargement) Cerebral arterial + venous system
What are the advantages of MRI scan?
Enhanced resolution
What clinical problems are MRI scans used for?
Acute stroke (can identify oedema/change in water content) Degeneration Neuroinfection Demmyelination Tumours Hydrocephalus Spinal cord
What are the disadvantages of MRI scan?
Expensive
Slower
Noisy
Claustrophobic
How are coronal sections viewed?
Looking at patient face on
How are axial sections viewed?
Looking at patient through binoculars from their feet
What are the different MRI resolutions?
1.5T: lowest resolution (not used anymore really)
3T: medium resolution (most common in hospitals)
7T: highest resolution (used for research)
What are the layers of the head (from outwards to inwards)?
Skin of scalp Periosteum Bone of skull Dura mater (periosteal + meningeal layer) Subdural space Arachnoid Subarachnoid space Pia mater Grey matter (cerebral cortex)
What is the falx cerebri?
Double layered vertical fold of dura mater which is a useful midline marker meaning you can look for deviation
Superior + inferior sagittal dural venous sinuses sit at top and bottom
What is the tentorium cerebelli?
Double layered horizontal fold of dura mater separating the cerebral hemispheres from the cerebellum
Transverse dural venous sinus sits at attachment to cranium
When will you see the dura mater folds on a image?
If you are posterior of the cranium
What would it suggest if the falx cerebri had deviated from the midline?
Pathology occupying space in the cranium pushing it over to one side e.g. tumour or increased ICP
What are ventricles?
Hollow regions within the brain and brainstem within which CSF is produced
C-shaped paired lateral ventricle drains into unpaired 3rd ventricle then 4th ventricle
What colour would the ventricles appear on scans?
MRI: white
CT: dark
Where are the brain ventricles?
Lateral: central parts sit under corpus callosum + by caudate nucleus whereas temporal horns sit low down in temporal lobes having close relation to the hippocampus
3rd ventricle: sit in midline with thalamus lateral
4th ventricle: between cerebellum + brainstem
What structures does the venous drainage of the brain pass through?
Dural venous sinuses
Name the dural venous sinuses.
Superior sagittal Inferior sagittal Straight Transverse Sigmoid Right cavernous
What major vein of the neck do most dural venous sinuses drain into?
Internal jugular vein
What type of imaging can aid you in looking for dural venous sinus blockage?
Magnetic resonance venogram
How is the brain interconnected?
Cerebral hemispheres interconnect via corpus callosum and connects to brainstem
When can images be off-axis?
If the patients head isn’t perfectly aligned in the CT/MRI
What hole does the brainstem drop through?
Foramen magnum
What colour would bone appear on scans?
MRI: black
CT: white
Why do bones often appear unsymmetrical within a CT image?
Due to the plane of the cross section taken by the CT which depends on the position of the patients head - DONT CONFUSE WITH PATHOLOGY
What is the sensory innervation of the frontal sinus?
Same as parts of the dura so referred pain from here will cause a headache
What would you do first when looking at an image?
Determine which level of section is being reviewed using local anatomical features, paranasal sinuses, fissures + cortical regions
What functions are looked superiorly of the frontal and parietal lobes?
Primary motor + sensory cortex respectively
What does the deep brain nuclei contain?
Cell bodies and synapses
What are the 2 parts of the globus pallidus?
Externus
Internus
What is the fornix?
Part of limbic system superior of thalamus
What is the thalamus?
Dense collection of nuclei in the diencephalon of the central brain connecting multiple neuronal pathways to the cerebral hemispheres
What is in the internal capsule?
Neurons running to and from the cortex
What scan shows better resolution of neural tissue?
MRI is better than CT so structure identification has to be carried out via region in CT scans
How can cortex and deep white matter be differentiated on an MRI?
Cerebral cortex is lighter grey whilst deep white matter is darker grey
What is the blood supply to the brainstem (superior to inferior)?
Post cerebral artery
Basilar artery
Vertebral artery
What is the function of the cochlea?
Transforms the vibrations of the cochlear liquids and associated structures into a neural signal
What are the semi-circular canals of the vestibular system?
3 tiny, fluid-filled tubes in your inner ear that help you keep your balance - as you move your head around, liquid moves around moving the tiny hairs that line each canal
How can deep brain nuclei be identified on a scan?
Position
Contrast difference
How does a stroke show up on a MRI scan?
Neural tissue infarction show as areas of high signal i.e. lighter coloured watershed affect
What are the arteries that supply the cerebral cortexes and hemispheres?
Anterior cerebral
Middle cerebral
Posterior cerebral
What arteries can be blocked if a stroke occurs in the pons?
Pontine arteries
Where is the basilar artery?
Single midline vessel running off of the centre of the brainstem
What cranial nerves pass through the internal acoustic meatus?
CN VII
CN VIII
What types of blood can haemorrhage in and around the meninges?
Arterial AND/OR venous
What are the 3 meningeal layers and spaces that surrounds the central nervous system (external to internal)?
Epi/extra dural space 1. Dura matter Subdural space 2. Arachnoid mater Subarachnoid 3. Pia mater
If there is a epi/extra dural space bleed, where is the blood coming from?
A meningeal artery e.g. a middle meningeal artery can be caused by lateral cranium fracture damaging the pterion region
If there is a subdural space bleed, where is the blood coming from?
Bridging veins as subdural space is a potential space containing veins draining the brain into the dura venous sinuses
If there is a subarachnoid space bleed, where is the blood coming from?
A cerebral artery e.g. due to small aneurysm
What is the subarachnoid space full of?
CSF
What will a cranial epidural haematoma look like?
Elliptical biconvex shape
Size can be limited by skull suture joints
Midline shift
May see air in the brain too (black dots) due to connection to outside world
Why might a cranial epidural haematoma patient have blood AND cerebrospinal fluid (CSF) coming out of there ear?
It may go into the middle ear and burst the ear drum
What can long-term warfarin use cause acute paraplegia?
Epidural haematoma which will cause compression of brain OR spinal cord and symptoms as a result
What will a subdural bleed look like on a CT scan?
Between dura and arachnoid mater
Blood will sit OVER sulci and gyri so has a fuzzy border
Midline shift
May look like bone in CT
What can help you distinguish between a subdural bleed and bone?
Imaging over different points in time
How can you determine how recent a brain bleed is?
Hyperdense area (lighter colour) = fresh bleed
Isodense (similar colour to surrounding neural tissue) = few weeks after
Hypodense area (darker colour) = chronic/long-term (previous bleed several months ago)
Where are subarachnoid bleeds?
In subarachoid space so they go into sulci, gyri and fissures
Commonly seen around circle of Willis, lateral fissure, interpeducular fossa + lateral ventricle
What type of imaging would you do first?
CT as its cheaper + quicker but MRI is more sensitive
How can you distinguish a subdural and epidural bleed?
Subdural bleeds sit between dura and arachnoid mater so its in closer contact with neural tissue so inner surface of bleed will not look as defined as the clean convex shape of the epidural bleed, it will look fuzzy and follow the contour of the brain
How can you detect a bleed in the isodense stage?
Sulci and gyri in that area will not be as evident
