5. Imaging

Question 1

Technical consideration of CT:
View?
Age?
Angle on imagine plane?
Colour range?

Answer 1

View: Caudal (so image is looking from the feet)
Age: As age increases there is loss of brain matter so more dark areas seen around edges and ventricles appear more visible
Angle: Diagonal image plane
Colour: Interpretting greyness. Bone= white, air = black.

Question 2

How to interpret a CT and MRI?

Answer 2

[A]

• Adequacy
• Alignment
• Artifact

[B]

• Bones
• Blood
• Brain

[C]
- Cisterns and ventricles

[S]

• Subcutaneous and soft tissue
• Surfaces

Question 3

What is the difference between SDH and EDH?

Answer 3

EDH

• Extradural haemorrhage
• More common in younger
• Lemon shaped due to tight bonding between layers of meninges

SDH:

• Subdural haematoma
• More common in older
• More of a diffuse ring around entire brain

Question 4

Use of contract agents in CT?

Answer 4

Rim and edges light up e.g. useful for meningioma

Enhances areas of low density

Question 5

What is more likely to cause a stroke, leakage or blockage?

Answer 5

Blockage of a blood vessel

Question 6

Order the following in terms of colour appearance in a CT:

Bone, air, blood clot, water, fat, grey mater, CSF, white mater

Answer 6

[White]
Bone
Blood clot
Grey M
White M
CSF
Water
Fat
Air
[black]

Question 7

Technical considerations of MR scanning:
View?
Age?
Plane?
Weighting?
Generated by?

Answer 7

View: Caudal
Age effect: Atrophy better shown on MR than CT. Need to establish if level of atrophy is due to age and not hydrocephalus
Plane? Any. Can be used to show pacemaker, cochlear implant, metal around eye/head
Weighting? T1 weighed means the spinal fluid is WHITE. T2 weighted means the spinal fluid is white
Generated by emission

Question 8

How does an MRI work?

Answer 8

Patient enters into a strong magnet
Atomic nuclei reorient themselves along the magnetic field
A radio frequency pulse flips the nuclei from the oriented position and synchronises the precession on their spinal axis
A receiver measures the time until the nuclei return to their original orientation (structural scans) or desynchronize (functional scans)

Question 9

Difference in T1 and T2 weighting in MRI?

Answer 9

T1 weighed means the spinal fluid is BLACK. T2 weighted means the spinal fluid is WHITE (WW2: Water, white 2 )

Question 10

What are the different MRI variants>

Answer 10

Diffusion weighted
ADC (Apparents diffusion coefficient)
FLAIR (Fluid attenuated inversion recovery)
GRE (Gradient echo imaging)
EPI (echo planar imaging, reduces motion artifact)
Perfusion
Angiography
Functional (spectrography)

Question 11

Best way to scan for spinal lesion?

Answer 11

MRI scanning

Question 12

What is SPECT?

Answer 12

Single photo emission tomogrpahy

Used radiosotope and gamma rays

Question 13

What is PET?

Answer 13

Positron emission tomography

Requires cyclotron