Lecture 24: Neuro radiology

Question 1

What factors do you need to know to describe a lesion

Answer 1

1. What scan
2. Patient age, where, what time
3. What side is lesion
4. What is the appearance: shape, intensity,
   5 Where is the lesion
5. Other features overall

Question 2

What does using contrast media help with seeing in the head and what are the dangers

Answer 2

Usually it will not cross the BBB unless compromised so helps to see Areas of pathology- eg. tumour/stroke that have leaky vessels. Washout is slow in abnormal tissues so will have high intensity.

Danger is in patients with poor renal function (<30ml/min). Rate of contrast reaction is high, with Gadolinium used in MRI contrast causing Nephrogenic systemic fibrosis, as well as deposition in brain and bones of people with healthy renal function.

Question 3

What is the use of plain film Xray for head and neck

Answer 3

Spine trauma: looking at alignment of vertebral bodies and processes from anterior to spinolaminar line, vertebral height loss etc.
Digital substraction angiography with contrast media.

Question 4

What is the use of CT for head and neck

Answer 4

Can be used for density quantifications. Better with bone than soft tissues

• Bright blood shows fresh haemorrhage: change acute stroke management
• Light grey wash over with loss of definition : old blood/chronic bleed
• Loss of definition between grey and white matter, ill defined capsule: early signs of ischaemia - however MRI picks up these changes much better

Question 5

What is the difference between epidural, subdural and subarachnoid bleed on CT, their causes

Answer 5

Epidural: Middle meningeal artery bleed between inner aspect of skull and stripped dura. Lentiform/ lemon shape

Subdural: Veins between dura and arachnoid mater collects blood. Generally elderly. Has crescent shape

Subarachnoid: Caused by hypertension with rupture of aneurysms in cerebral vessels. Blood seen as bright signal on surface of brain and in basal cisterns immediately after bleed. (star)

Question 6

How do you distinguish MRI T1, T2 and CT scan from each other

Answer 6

On CT: Bone is white, white matter is darker grey than grey matter.
on MRI: Bone is black.
T1: Fat/ bone marrow is white. CSF is black
T2: CSF/ eyeball water is white. Fat is black

Question 7

What is the use of MRI for head and neck

Answer 7

See soft structures more easily;

• DTI tractography for white matter tracts.
• Surgical planning using reconstruction from MR imaging
• Angiography, stroke,tumour and spine imaging

Question 8

What is the use of ultrasound for head and neck

Answer 8

Neonatal brain evaluation for intracranial haemorrhage using the fontanelle as a window
Can evaluate sequelae of perinatal hypoxemia- stroke and intraventricular haemorrhage