Neuroimaging Flashcards
What are the 3 different possible orientations?
- Sagittal,
- Transverse,
- Coronal
What are some technical points when looking at CT scans
- Caudal view so right is left and left is right! As if you are looking at the patient from the foot of the bed.
- Age effect - There is normal atrophy of the brain with age but alcohol and trauma can accelerate this. In neurodegenerative disorders the age effect may be disproportionate.
- Diagonal image place - as to avoid most of orbit. Not fully transverse.
- Image is generated by absorption of X-rays
What are cisternas?
Openings in the subarachnoid space in the brain create by the separation of the arachnoid and pia mater
What are the ABCS of CT/MRI interpretation?
A - Adequacy, alignment and artefact.
B - Bones, blood and brain,
C - Cisterns and ventricles,
S - Subcutaneous and surfaces and symmetry
What are some examples of artefact?
Beam hardening, Motion (can be caused by a confused patient or child) or medical such as metal clips or intraventricular shunts.
Describe the appearance of an extradural haematoma
Will be found between skull and outer later of dura. It will look biconvex (limited by cranial sutures)
Describe the appearance of a subdural haematome
This will be found between the dura and arachnoid mater. It will appear as a crescent shape. Old blood is a dark grey - indicates the bleed is chronic whereas in acute bleeds the blood will appear white
What is diffuse axonal injury?
It is a traumatic brain injury due to shearing forces. It will appear with poor grey-white matter differentiation and loss of sulci. may have association with haemorrhage.
Where will blood collect in a subarachnoid haemorrhage?
Within cisterns
How will obstructive hydrocephalus appear?
enlarged ventricles as there is a blockage in the ventricular system.
What areas do you want to be looking at under S - subcutaneous and soft tissues
- Skin/subcutaneous lesions,
- Orbit,
- Sinuses,
- Nasopharynx and oropharynx
Describe the appearance of a meningioma
Homogenous, well circumscribed, broad Dural base growth. Patients are often asymptomatic so accidental finding
What are the risk factors for an haemorrhagic stroke?
Hypertension, ischaemic stroke, anticoagulation and amyloid angiopathy.
What are the technical points for MRI?
- Caudal view,
- Age effect (white matter hyperintensities - allowed 1 per decade age)
- Any plane view
- Safety - Metal pacemakers, cochlear implants and metal around eyes/head
What do MRI measure?
The speed at which it takes nuclei to return to their original orientation after radiofrequency pulses cause them to flip.
