Head and neck Flashcards
What are the benefits of CT comparing to MRI for cerebral imaging?
Much easier and safer to use in emergency situation – quicker
Limitations of CT comparing to MRI?
Demonstrates anatomy only
cant show full extent of lesions into soft tissue
What pathologies is CT gold standard for?
Technique of choice for:
Serious head injury
Suspected ICH
Stroke
Infection
Other acute neurological emergencies
Very high dose of ionising radiation
What are the benefits of MRI comparing to CT?
Demonstrates anatomy and physiology; good for brain function (fMRI)
What are the limitations of MRI comparing to CT?
Constraints:
Availability
Patient acceptability (claustrophobia)
Patient handling in an emergency situation
Metal!
Not great bone detail; cannot detect calcium e.g. in a tumour
What does contrast highlight in CT images?
evaluate:
vessels from their origin at the aortic arch to the intracranial portion
non-vascular neck structures and brain parenchyma
Detection of small lesions
Lesion characterisation – post contrast (“+C”) certain lesions will enhance and others won’t, e.g. brain tumour v abscess
Lesion extent – often difficult to image boundaries of lesion due to distortion from surrounding oedema/necrosis – contrast depicts true size, shape and position of lesions
MRA – excellent anatomical picture; accurate representation of the size of stenoses; short acquisition time
What are the limitations of PET/NM in imaging the brain?
Not currently a gold standard in brain imaging/functionality,
- normal functioning brain has residual FDG activity which ‘masks’/makes it difficult to identify most pathologies
How is PET/NM useful in imaging the brain?
useful in identifying ‘active/involved’ brain tissue prior to surgical treatment for epilepsy (ictal and post-ictal)
provides another level of certainty prior to the management/treatment of neurological oncology patients, e.g. PET/CT can assess the homogeneity of brain tumour metabolic activity/hypoxic volumes etc. prior to RTh
future new PET/CT tracers will be able to identify early dementia type pathologies in-line with future treatments
Future PET tracers will lead to other imaging avenues also
What imaging is used for a glioblastoma?
head
ct - without + with (common to have associated necrosis and oedema)
MRI - t2 + contrast (midline shift/mass effect)
PET/CT/MRI
What imaging is used for a Meningioma?
CT - with/without contrast
MRI - T1W
Head and neck:
brain and spinal cord
associated erosion of inner table of skull
Brain metastasis radiographic appearances?
round
well defined
multiple or singular
sometimes associated oedema
enhancement with contrast
What are the advantages of MRI comparing cT for imaging brain tumours/mets?
And what do they appear as with different weighting?
More sensitive than CT (for lesions <5mm; 2-3x more lesions demonstrated than CT +C)
T1-W = hypointense/isointense lesions
T2-W = lesions and oedema hyperintense
T1-W+C = lesions hyperintense; oedema hypointense
What are the potential referring/initial pathways for a cerebrovascular disease (stroke)?
referral via GP if mild
A/E - most commonly
although can go unnoticed:
In some cases, there may be a delay, e.g. elderly person living alone; event goes un-noticed
What is the imaging modalities can be used for a cerebrovascular disease (stroke)?
Immediate imaging:
CT
Later:
MRI
CTA/MRA
Conventional angiography
Carotid U/S
Echocardiography
Ba Swallow (+SALT)
interventional
Imaging pathway for a TIA?
CT Brain + Carotid Doppler U/S (looking for stenosis)
CTA/MRA - looking for blockage (plaque or thrombus or haemorrhage or aneurysm)
Imaging pathway for an Ischemic stroke?
Radiographic appearance?
CT:
identify areas of ischemia
non-con rules out haemorrhage - before anticoagulant treatment
MRI:
more sensitive
not suitable on initial presentation for unstable patients
MRA/CTA can confirm a suspected blood vessel occlusion
CT:
Acute sign: hyperdense middle cerebral artery (not common)
Subacute signs: wedge shaped area of hypodensity
MRI T2W:
Acutely, may show vascular enhancement
Subacutely, hyperdensity of cortex
Imaging pathway for an INTRA-CEREBRAL HAEMORRHAGE stroke?
Radiographic appearance?
CT first line - Fast scanning ASAP at least 48hrs;
CTA/MRA/DSA later
Rupture of cerebral blood vessel (usually artery)
Timing determines appearances:
blood hyperdense initially, but fades as time goes on (blood is reabsorbed)
Imaging pathway for an Subarachnoid HAEMORRHAGE stroke?
Radiographic appearance?
CT first line;
CTA/MRA/DSA later
Conventional angiography - interventional suite
Usually due to ruptured berry (saccular) aneurysm
High-density acute blood in subarachnoid spaces
Traumatic brain injury potential initial/referring pathway/
Medical emergency,
so usually via A&E - consequences can worsen swiftly without treatment, therefore need to assess the situation rapidly
Trauma so usually ambulance
TBI pathway:
Physical examination
Imaging:
Normally CT first line (possibly MRI when stabilised), to look for:
Haemorrhage (same as ICH, in stroke)
Haematoma (clot)
Contusion (bruise)
Brain tissue swelling
Specialist referral:
Observation (minor)
ICP monitor (severe)
What injuries can a CT diagnose in regards to a TBI?
CT in a comatose patient may reveal:
No abnormality (30%)
Haemorrhagic contusion (20%)
Extradural or subdural haematoma (20%)
Areas of oedema (10%)
A combination of the above (20%)
What is a subdural haematoma?
What would be the radiographic sign?
Blood collects in space between dura and arachnoid mater (subdural space)
Classic crescent shaped area – conforms to shape of inner table of skull
ON CT:
Acute = hyperdense;
subacute = isodense, as reabsorption of blood occurs
ON MRI:
Acute = hypointense on both T1-W and T2-W
Subacute = hyperintense on T1-W, hypointense on T2-W
What is a extradural haematoma?
Located between bony skull and dura mater, in the epidural space (aka “epidural haematoma”)
Strongly associated with linear skull #, so temporo-parietal region common
haematoma is confined:
biconvex shape, with a well-defined margin
What are the radiographic signs for an extradural haematoma?
haematoma is confined:
biconvex shape, with a well-defined margin
ON CT:
Biconvex area, acutely hyperdense (will fade over time)
Mass effect (displaces brain from skull – midline shift of ventricles); ST swelling
Underlying #, more obvious on ‘bone windows’
ON MRI:
Acutely, isointense on T1-W,
hypointense on T2-W
Subacutely, hyperintense on both
What is cerebral contusion?
Bruise due to injury of blood vessel
Brain injury is at the opposite site of injury
Inferior frontal lobes and anterior temporal lobes are common sites after a blow to the back of the head
What are the radiographic appearances of a brain contusion?
ON CT:
- Ill-defined hypodense area (oedema) with area of hyperdensity (haemorrhage)
-Often very small, but may be present throughout the cerebral hemispheres
- Larger haemorrhages may occur in severe trauma, but may not be apparent on CT for a day or two
MRI is more sensitive to diffuse brain injury, particularly in the absence of haemorrhage
What are the radiological signs of ICP?
Midline shift
acute extradural haematoma
What is the potential initial/referring pathway for dementia?
GP:
symptoms
PMH
Physical examination
blood tests
MMSE (mini mental state examination) to assess a number of mental abilities, e.g.:
short- and long-term memory
attention span
concentration
language and communication skills
ability to plan
ability to understand instructions
Progressive condition so likely repeated e.g. every 6/12
Specialist referral,
e.g. neurologist, specialist psychiatrist, geriatrician
What imaging is used for dementia?
Imaging (often to ‘rule out’ other pathologies);
specialist PET/SPECT imaging to differentiate between Alzheimer’s and other forms of dementia
What is the potential initial/referring pathway for Parkinsons’ disease?
No conclusive tests
GP will base diagnosis on :
presenting symptoms,
PMH
results of some simple mental or physical tasks (e.g. moving or walking around)
Specialist referral
What imaging is used for Parkinsosn?
Radiographic appearances:
NM (DaTScan) -
detect the presence of dopamine transporters (DaT) in the brain (lacking in Parkinson’s patient)
Normal images characterised by two symmetrical comma or crescent shaped focal regions of activity
Abnormal images can include:
Asymmetry between the two sides (reduced activity on one side)
Reduced activity on both sides
Absence of activity (one or both sides)
What is Multiple sclerosis (MS)?
Multiple inflammatory ‘plaques’ of demyelination (breakdown of myelin sheath that insulates axon part of nerve cell)
Brain and spinal cord
What is the initial/referring pathway for Multiple sclerosis (MS)?
GP:
symptoms
PMH
Referral to Neurologist:
ideally within 6/52
Neurological examination, to see if nerve pathways are damaged (changes/weakness in eye movements, leg or hand co-ordination, balance, speech and reflexes)
Imaging – MRI
Evoked potentials test :
electrodes on head to monitor brain wave response to what patient sees and hears; looking to see if it takes the brain longer than normal to receive messages
Blood tests +/- lumbar puncture
MRI radiographic appearances for MS?
T1-W = plaques isointense/hypointense
T2-W = plaques hyperintense
T1-W +C = active plaques enhance
Brain atrophy
What is epilepsy?
Defined as a tendency to have recurrent seizures
A seizure is caused by a sudden burst of excess electrical activity in the brain, causing a temporary disruption in the normal message passing between brain cells
This disruption results in the brain’s messages becoming halted or mixed up
What is the initial/referring pathway for epilepsy?
Diagnosis cannot be confirmed until patient has had more than one seizure
Difficult, as migraine and panic attacks can cause same symptoms
Discuss with GP:
presenting symptoms
including details of seizures,
PMH
personal history (drugs, alcohol, etc.)
EEG
What imaging is used for epilepsy?
Imaging – MRI
PET - useful in identifying ‘active/involved’ brain tissue prior to surgical treatment for epilepsy - ictal and post-ictal
SPECT-MRI
What are causes of spinal cord compression?
Bone: vertebral fracture/dislocation; abnormal growth, e.g. spondylosis
Connective tissue: e.g. posterior longitudinal ligament (PLL), can enlarge and harden as people age
Haematoma: blood may accumulate in or around the spinal cord, due to e.g. trauma
Tumours: spinal mets most common, or thecal sac, e.g. meningioma
Abscess: pus usually accumulates in thecal sac
Ruptured/herniated disc (traumatic or degenerative): can compress spinal nerve roots and occasionally the spinal cord itself
What is the initial/referring pathway for spinal cord compression?
Immediate specialist medical attention prompt diagnosis and treatment may reverse/lessen loss of function
GP OR A/E - Physical examination
Imaging – CT, MRI
FMRI
what is it and how does it work?
Technique for measuring brain activity
Works by detecting the changes in blood oxygenation and flow that occur in response to neural activity – when a brain area is more active it consumes more oxygen and to meet this increased demand blood flow increases to the active area
fMRI can be used to produce activation maps showing which parts of the brain are involved in a particular mental process/in response to external stimuli
fMRI has become a popular tool for imaging normal brain function – especially for psychologists
Over the last decade it has provided new insight to the investigation of how memories are formed, language, pain, learning and emotion to name but a few areas of research
It is also used in pre-surgical planning to detect brain function
What is the future trend of US intra-operative - what situations/what does intraoperative mean?
Intra-operative US used by neurosurgeons to locate brain tumours
- probe placed directly on brain surface, providing information about location/depth of lesion
- Infant brain (neonate to 1 year), via fontanelles, to demonstrate haemorrhage/ischaemia, developmental malformations and hydrocephalus
- Adult transcranial doppler US (TDO):
- intra-operatively for the evaluation of spinal cord lesions
Specially designed transducer placed directly on dura – exact location of e.g. tumour
Future trend transcranial doppler:
what can it be used for?
- Adult transcranial doppler US (TDO)
- examines the arteries within the brain
- measures blood flow
- looks for signs of vasospasm
- Intraoperatively - spinal dura
Future trend transcranial doppler:
Benefits:
Less invasive
fast
no radiation
useful for monitoring
What is the treatment for brain tumours?
Excision/RTh/Chemotherapy – or combination of
Follow-up imaging as treatment progresses; MDT consultation
What is treatment for TIA and why is it so important?
prevent another TIA or full-blown stroke - TIA is a pre cursor of a stroke
First step, lifestyle changes:
e.g. losing weight,
eating a healthy balanced diet,
taking regular
exercise,
stopping smoking
reducing alcohol intake
Also, medication, e.g. Warfarin (anti-coagulant)
Carotid vessel(s):
- angioplasty,
- endarterectomy,
- stent (temporary fix)
Carotid endarterectomy:
To remove atherosclerotic deposit from lumen of vessel
Effective, but risky, and not suitable for all
What is the treatment for ischaemic stroke?
Thrombolysis:
dissolve blood clots
restore blood flow to brain
keep damage to a minimum
(If done more than four and a half hours have passed because it’s not clear how beneficial it is when used after this time)
In addition, the patient will be given the same advice as previously discussed for TIA regarding lifestyle changes
What long term medication can be used to treat and prevent strokes/TIA?
Depends on the individual, but may include:
Aspirin:
- reduce the ability of platelets to stick together and form clots when a blood vessel is damaged
Warfarin:
- anti-coagulant, if clot that caused TIA originated in your heart, most likely due to underlying atrial fibrillation
Medication to reduce BP (statins):
- if it is high, as hypertension is a risk factor for TIA/stroke
Medication to reduce cholesterol:
- if it is high, as this too is a risk factor for TIA/stroke (also changing to healthier eating, etc.)
Treatment for haemorrhagic stroke?
Initial care includes:
- Determining the cause of the bleeding
- Controlling the BP.
- Stopping any medication that could increase bleeding (eg, warfarin, aspirin)
- Measuring and controlling the ICP
Surgical intervention:
- stop bleeding
- reduce pressure within the skull
Aneurysm treatment (depends on size, location and shape of aneurysm):
- Endovascular coil embolisation
- Neurosurgical clipping, via craniotomy
Treatment for subdural haematoma?
Very small subdural haematoma may be monitored to see if it resolves itself
Surgery is usually recommended for acute subdural haematomas that are 10mm or larger:
Craniotomy:
- section of the skull is temporarily removed to allow access to remove the haematoma
Burr holes:
- small holes are drilled into the skull and a tube is inserted through the hole to drain the haematoma
Follow-up imaging required to ensure no damage/success of treatment
Treatment for extradural haematoma?
small extradural haematomas may be treated with observation and careful monitoring
Most medium or large extradural hematomas, all symptomatic will require surgery, often urgently:
Craniotomy:
- allows removal of the clot directly
- releases the pressure on the brain
- May also require elevation of depressed skull fracture, if present
Follow-up imaging
What is the treatment for a cerebral contusion?
Treatment depends on the severity of injury:
Minor:
- conservatively,
- on ward (may be HDU or ITU)
- observation > treat symptoms
Severe:
- induced coma
- IV medication
- varying periods of time
Occasionally:
- surgery (craniotomy) is necessary
- when contusions have caused swelling and raised ICP
Follow-up imaging
What is the treatment for a cerebral epilepsy?
Anti-epileptic drugs (AEDs):
- to control seizure
If unsuccessful:
- vagus nerve stimulation (VNS) therapy
If still poorly controlled after 2 years – specialist referral
Imaging
Surgery:
remove part of the brain
only recommended when:
- A single area of only one side of the brain is causing seizures
- Removing that part of the brain would not cause any significant loss of brain function
Alternative:
deep brain stimulation (DBS) therapy:
- for people with epilepsy that is difficult to control or who cannot have a part of their brain removed
- DBS involves implanting electrodes into specific areas of the brain to control seizures
- The electrodes are controlled by an external device called a neurostimulator
What is the treatment for a cerebral spinal cord?
Discography:
- several levels of disc abnormality (common over 40) have been identified, e.g. on MRI
- surgical fusion - of disc causing symptoms
- Fluoro/CT guidance
- needle inserted into nucleus pulposus and contrast injected
- Outlines margins of nucleus to show any herniation
(whilst also reproducing patient’s symptoms!)
Nerve Block:
- Fluoro/CT guidance
- long-acting LA + steroid
- To relive pain from impingement of disc herniations/osteophytes
Future trend O-arm surgical imaging system?
