Brain And CNS Flashcards
(34 cards)
Bony Components of CNS (Protective Function)
Structures:
• Skull/Facial Region
• Spinal Column
Imaging:
1. Skull X-rays – Rarely requested (CT preferred)
2. Facial Views – For trauma assessment
3. Spinal Radiographs – For trauma, positive neurology, or suspected pathology
SOFT TISSUE STRUCTURES of the cns
The soft tissue components of the CNS comprise the neurological system:
Brain
Spinal cord
Nerve roots
Problem with one or more of these structures results in the symptoms experienced.
Brain and cns imaging modalities
Plain film
Fluoroscopy
Angiography
MRI
CT
RNI (functional)
US (paediatrics)
- Imaging Modalities:
• CT, MRI, Ultrasound (for neonates), PET, X-ray (rare) - Advantages and Limitations:
• CT: Quick, good for acute trauma/bleeding; radiation exposure.
• MRI: High-resolution, no radiation; time-consuming, expensive, not for unstable patients.
• Ultrasound: Safe, portable; limited to neonates (open fontanelles).
• PET: Functional imaging; expensive, limited availability. - What They Image:
• CT/MRI: Brain structure, tumors, stroke, trauma.
• Ultrasound: Neonatal brain.
• PET: Brain metabolism and function. - How We Use Them:
• Diagnose stroke, tumors, trauma, infections, congenital anomalies, and metabolic activity (PET).
What is myelography?
Myelography is an imaging examination that involves the introduction of a spinal needle into the spinal canal and the injection ofcontrast materialin the space around thespinal cordand nerve roots (thesubarachnoid space) using a real-time form ofx-raycalledfluoroscopy. Usually done for nerve impingement when MR is not an option.
An x-ray exam helps doctors diagnose and treat medical conditions. It exposes you to a small dose ofionizing radiationto produce pictures of the inside of the body. X-rays are the oldest and most often used form of medical imaging.
When the contrast material is injected into the subarachnoid space, the radiologist is able to view and evaluate the status of the spinal cord, the nerve roots and the meninges.
Steroid can be injected to help relieve symptoms and avoid invasive neurosurgery such as laminectomy.
Patient care and management
Correct preparation inc. fasting
Introduction to patient
Explanation and reassurance
ID
LMP
Patient history
Previous imaging
Safety questionnaires/ screening forms
WHO checks
Full team for MDT procedures
IMAGING OF THE SPINEMODALITIES
Plain film
Myelography
Angiography
Radionuclide imaging
CT
MRI
Fluoroscopy (facet joint injections)
IMAGING OF THE SPINEPLAIN FILM
Often the initial modality of imaging of the spine where CT/MRI not indicated
Used for orthopaedic and neurological purpose
Weight-bearing
Flexion/extension views
Fulcrum side bending and traction for pre-operative purposes
Often used for pre-operative scoliosis, kyphosis and follow up imaging (whole spine imaging)
Dependent on local protocols
IMAGING OF THE SPINEPLAIN FILM advantages and disadvantages
Advantages
Fairly low radiation dose compared with CT
Readily available
Quick acquisition time
Good for comparative images
Limitations
Ionising radiation
Lower sensitivity and specificity
Patients may need further characterisation of pathology in another modality
IMAGING OF THE SPINEFLUOROSCOPY
Used for facet joint injections – therapeutic & diagnostic procedure
Patient who are symptomatic
Plain film may be used to correlate - ?degenerative disease
Requires fluoroscopy unit with ability to angle tube or table
Sometimes performed with a C-arm in pain clinic/theatre
Fluoroscopy used for needle guidance
Contrast used (tiny amount) and steroid (depo-medrone)
Local anaesthesia to numb injection site
IMAGING OF THE SPINEFLUOROSCOPY advantages and disadvantages
Advantages
Can be used for both therapeutic and diagnostic purposes
Easily accessible
Fairly low doses
Limitations
Invasive
Risk of contrast reaction
Ionising radiation
Field of view
Infection
IMAGING OF THE SPINEMYELOGRAPHY
Usually lumbar area
Used where MRI is not available or there are contraindications for the patient
CO2 or air is used with contrast agents
Introduced via lumbar puncture
Patient must sit upright for 6 hours post procedure to avoid contrast travelling to the brain
Requires fluoroscopy unit, tilting table, contrast and a skilled physician
IMAGING OF THE SPINEMYELOGRAPHY advantages and disadvantages
Advantages
Can be used for patients that are contraindicated to MRI
Relatively safe and painless
Demonstrates nerve root lesions
Disadvantages
Ionising radiation (appx 16 months background radiation exposure)
Contrast reactions
Infection
Headaches (due to leakage of a small amount of CSF from the needle insertion site)
Only visualises the spinal canal and adjacent spinal nerve roots
IMAGING OF THE SPINEANGIOGRAPHY
Primarily to demonstrate vertebral blood flow
Follow up any vascular anomalies shown on CT/MRI
Demonstrate vascularity of spinal tumours
IMAGING OF THE SPINEANGIOGRAPHY advantages and disadvantages
Advantages
Can be used for both therapeutic and interventional purposes
Limitations
Invasive
Risk of contrast reaction
Ionising radiation
Haemorrhage when IA
IMAGING OF THE SPINE MRI
Modality of choice for soft tissue demonstration
Can demonstrate character of discs, age changes, cord involvement in trauma, narrowing of spinal canal, tumours and characteristics
Sagittal selections allow full view of spinal cord and cauda equine
Shows alignment or impingement or cord such as in cauda equine syndrome (severe compression on the lower spinal nerves)
What is Cauda equina syndrome?
Cauda equina syndrome is a rare and severe type of spinal stenosis where all of the nerves in the lower back suddenly become severely compressed.
Symptoms include:
sciaticaon both sides
weakness or numbness in both legs that is severe or getting worse
numbness around or under your genitals, or around your anus
finding it hard to start peeing, can’t pee or can’t control when you pee – and this isn’t normal for you
you don’t notice when you need to poo or can’t control when you poo – and this isn’t normal for you
Cauda equina syndrome requires emergency hospital admission and emergency surgery, because the longer it goes untreated, the greater the chance it will lead to permanent paralysis and incontinence.
Predominantly a clinical diagnosis
Non contrast when looking at a prolapsed disc
Contrast often used post surgery as allows differentiation between scar tissue and regrowth of disc tissue
Routine spinal scan would be T1 and T2 sagittal and T2 axial
T1 – cerebrospinal fluid is dark
T2 – CSF is light, allows for contrast between discs, spinal cord and CSF
IMAGING OF THE SPINEMRI advantages and disadvantages
Advantages
Non invasive
Non ionising radiation
Scan in multiple planes
High sensitivity/specificity
Ideal for imaging soft tissue
Limitations
Access
Long acquisition times
Patient tolerance
Extra
Magnets and RF waves
3 planes just like CT
Excellent spatial resolution
Limited slots for patients, usually not 247 365 like CT
Patients must stay still for a long period of time.
Pri MR xr may be required.
What is Spinal Ependymoma?
Most common type of intramedullary neoplasm
Originate from ependymal cells/ependymocytes which are a type of glial cell found in the brain and spinal cord.
Cause syring0hydromyelia.
Avg length of 4 vertebral bodies.
Can be isointense on T1
Hyperintense on T2 with oedema
Expansile Intra-medullary lesion extending from C3 to C7 level with peri-tumoural cysts and haemosiderin staining on T2 WI.
IMAGING OF THE SPINECT
CT/MRI has largely replaced myelography
Excellent for bone demonstration
Best for spinal injuries, bone tumours, spondylosis
Higher sensitivity than plain film
IMAGING OF THE SPINECT advantages and disadvantages
Advantages
High sensitivity
Bony detail
Availability
Quick acquisition times
Patients with contraindications from MRI
Bony windows
Multi-planar reconstructions
Disadvantages
Ionising radiation and fairly high dose
Body habitus of patient
Artefacts from sclerosed bone
Artefacts from spinal implants
IMAGING OF THE SPINERNI
Bone scanning of the whole skeleton
Frequently used for showing metastatic spread from a primary e.g. neurological in origin; correlating plain film required
Functional – shows change in bone cell turnover
Tc99m MDP & Gamma camera & collimator
Looks for ‘hotspots’ – anterior and posterior acquisitions
Low risk
IMAGING OF THE BRAIN AND HEADMODALITIES
Plain film
MRI
CT
Angiography
RNI (functional)
Ultrasound (paediatrics)
IMAGING OF THE BRAIN AND HEADPLAIN FILM and indications
Largely superseded by CT due to higher sensitivity and therefore only undertaken in very few instances.
Very limited applications for the skull
Indications:
Shunt series
Penetrating trauma
Skeletal survey for myeloma patients
Facial trauma where CT not indicated
Presence of palpable vault abnormality
Localisation of FBs
Pre MRI orbits
IMAGING OF THE BRAIN AND HEADMRI indications
Soft tissue differentiation
Primary diagnosis
Follow up of tumours and treatment
Often modality of choice due to high sensitivity
Ability to characterise tumours (ability to differentiate white from grey matter)
Non acutes
Indications:
Epilepsy
Stroke
Exclusion of tumours
Aneurysm
Only imaging platform for confirming MS (shows demyelination of the cord)
T1 weighted: radiofrequency pulses timing enables highlighting of fat tissue
T2 weighted: again timing of the pulses allows for demonstration of fat AND water within the subject
