Neuroradiology Flashcards
List some indications to perform a CT scan:
Stroke
Head trauma
Headache (especially if suspected tumour or subarachnoid haemorrhage)
Cancer
Post surgical - hydrocephalus, haemorrhage
What are reasons not to perform a CT?
Minor head trauma in accordance to the head trauma exclusion criteria: NICE and SIGN guidelines
Seizure: Usually choose MRI, no imaging needed if primary idiopathic generalised epilepsy
What are the indications to perform an MRI scan?
Mostly under specialist physicians:
Epilepsy
Demyelination (MS?)
Spine (iintervertebral disk compression with resulting neural compression)
Cancer (Number, location and aggression of brain tumours)
Paediatric neurology (Disorders of development? head circumference, congeital malformations)
Stroke
Headache (benign intracranial hypertension?)
What are contraindications to perform an MRI?
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 (if they contain metallic pigment)
What are the ises of angiography in the diagnosis of neurological pathology?
Large vascular (arterial and venous) abnormalities Diagnosis and treatment
- Aneurysm
- Arteriovenous malformation
- Carotidocavernous fistula
- Unstoppable epistaxis
What is perfusion defined as?
The volume of blood passing through a defined volume of tissue per untit time
What imaging techniques are associated with perfusion imaging?
CT and MRI
What are the disorders of abnormal perfusion?
Stroke - decreased perfusion
Tumour - increased perfusion indicated angiogenesis and a more aggressive tumour
What body states are associated with an increase metabolism and would be subject to PET scan imaging?
Tumour - (Useful after brain tumour resection for differentiating granulation tissue (low energy usage) from leftover tumour (high energy usage)
Inflammation
Infection
What is the colour of soft tissue and air on a plain radiograph?
Plain radiographs
Multiple superimposed bones, bones are white
Soft tissue is grey
Air is black
What are the distinguishing features of a CT scan?
White circle of skull
Black CSF in sulci and ventricles. Air is black.
Grey brain with subtle grey-white matter difference Image quality:
– reconstructed by back projection from a rotating fan beam of X-rays
– beam hardening from radiodense objects • Metal produces white starbust artefacts
– slightly grainy
What are the diistinguishing features of MRI?
Better grey-white matter differentiation than CT
The skull is a thin black circle, immediately surrounded by a white circle of subcutaneous fat
White CSF is the best clue, but only true for T2- weighted MRI
– Same anatomy with different sequences often shown
• Image quality:
– reconstructed from Fourier transforms of radio signals
– has a JPEG-like quality, usually not grainy
What are the features of radionuclide radiology/nuclear medicine / PET?
Images often have bright and varied colours
Image is fuzzy
What are the distinguishing features of ultrasound?
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)
Noisy image
Objects which block the ultrasound beam (air, bone, stones) cast shadows cast downwards
