Neuroradiology Flashcards
List five reasons to indicate to perform a CT scan
- Head trauma
- Acute stroke
- Headache: red flags for suspected tumour or subarachnoid haemorrhage
- Cancer: looking for metastatic brain tumours in patients with symptoms
- Post-surgical: hydrocephalus, haemorrhage
What are reasons not to perform a CT scan?
• Minor head trauma exclusion criteria
• Seizure
- Primary idiopathic generalised epilepsy
- Complete recovery after a first seizure is not epilepsy
List seven indications to perform an MRI scan
- Demyelination (diagnose MS)
- CNS tumours
- Spine – for intervertebral disc prolapse
- Transient ischaemic attacks • Epilepsy
- Paediatric neurology
- Headache (benign intracranial hypertension)
What are contraindications to perform an MRI scan?
Implanted electronics:
• Most cardiac pacemakers, implantable defibrillators, cochlear implants
• Relative contraindication for programmable shunts, insulin pumps
Moveable metallic implants:
• Aneurysm clips, heart valves, recent intra-abdominal clips
Relative contraindications:
• Claustrophobia, pregnancy, tattoos
List four neurological pathologies that angiography can diagnose
Large vascular abnormalities: • Aneurysm • Arteriovenous malformation • Carotidocavernous fistula • Unstoppable epistaxis
What is perfusion?
The volume of blood passing through a defined volume of tissue per unit time (ml/100g tissue/min)
Can be a CT or MRI technique
Name two disorders of abnormal perfusion seen with CT perfusion
- Stroke - decreased perfusion
* Tumour - increased perfusion indicated angiogenesis and a more aggressive tumour
What is the use to PET scans?
PET is used to map out glucose usage
Useful after brain tumour resection for differentiating granulation tissue (low energy usage) from leftover tumour (high energy usage)
Name three pathologies which involve increased metabolism of glucose which can be seen on a PET scan?
- Tumour
- Inflammation
- Infection
Name some features of plain radiographs
- Multiple superimposed bones, bones are white
- Soft tissue is grey
- Air is black
What are features of CT scan?
- White circle of skull
- Black CSF in sulci and ventricles. Air is black.
- Grey brain with subtle grey-white matter difference
What are the features on an MRI scan?
- Better grey-white matter differentiation than CT
* Skull is a thin black circle, immediately surrounded by a white circle of subcutaneous
What are the features of a PET scan?
- Images often have bright and varied colours
* Fuzzy image
What are the features of an ultrasound scan?
- Wedge-shaped image with the edges of the image diverging away from top to bottom
- Often has a curve at the top matching the ultrasound probe (exception: flat probes)
- Objects which block the ultrasound beam (air, bone, stones) cast shadows cast downwards
What are the advantages and disadvantages of plain radiographs?
Advantages:
• Universal availability
• Fast
• Sequential images in subtraction angiography
Disadvantages:
• Lack soft tissue detail
What are the advantages and disadvantages of ultrasound scans?
Advantages:
• No radiation
• Less expensive equipment
• Movement tolerant
Disadvantage:
• Requires wide enough open fontanelle
• Image quality and interpretation based on operator skill
What are the advantages and disadvantages of CT scans?
Advantages:
• Rapid
• Metal and pacemaker tolerance
• Good for demonstrating acute haemorrhage
Disadvantages:
• Radiation
• More expensive equipment
What are the advantages and disadvantages of radiology?
Advantages Physiology info: • Glucose metabolism • Perfusion • Dopamine reuptake receptors
Disadvantages:
• Unclear anatomical information
• Medium cost of equipment
• Radiotracers can be expensive
What are the advantages and disadvantage of MRI?
Advantages: • No radiation • Soft tissue differentiation • Physiological info: - Blood flow - Diffusion restriction - Metabolite concentrations
Disadvantages:
• Poor tolerance of metalwork
• Magnetic sensitive electronics may fail or are contraindicated; pacemakers, cochlear implants
• Least movement tolerance
• Most expensive equipment
• Danger of metallic objects becoming projectiles
