Neuroradiology

Question 1

What are the indications to perform a CT scan?

Answer 1

Head trauma: NICE and SIGN guidelines

Stroke: NICE

Cancer: looking for metastatic or primary brain tumours

Headache: SIGN guidelines, red flags for suspected tumour or subarachnoid haemorrhage

Post-surgical: hydrocephalus, haemorrhage

Question 2

What are the NICE and SIGN guidlines for perhaps not performing a CT scan in minor head trauma?

Answer 2

Minor head trauma exclusion criteria:
-GSC 15
-No suspected open or depressed skull fracture
-No haemotympanum
-No "panda" eyes
-No CSF leakage from ears or nose
-No post- traumatic seizure
-No focal neurological deficit
-

Question 3

In minor head trauma what are the NICE guidlines for seizures?

Answer 3

Usually choose MRI over CT

• Primary idiopathic generalised epilepsy (no imaging)
• Complete recovery after a 1st seizure is not epilepsy

Question 4

What are the indications to perform an MRI for the spine?

Answer 4

Intervertebral disc degeneration causing neural compression

Question 5

What are the indications for performing an MRI for cancer?

Answer 5

Classifying the number, location and aggressiveness of brain tumours

Question 6

What are the indications for performing an MRI scan for headache?

Answer 6

Benign intracranial hypertension

Question 7

What are the indications for performing an MRI scan for epilepsy?

Answer 7

Check NICE and SIGN guidelines

-And if surgery is contemplated

Question 8

What are the indications for performing an MRI in paediatric neurology?

Answer 8

Disorders of development
Head circumference
Congenital malformations

Question 9

What are the indications for performing an MRI in people who suffer from stroke?

Answer 9

Usually second line to CT because MRI is difficult in acutely unwell patients.

Diffusion techniques are sensitive and used in TIA clinics

Question 10

State the contraindications to perform an MRI scan

Answer 10

Implant electronics (check with manufacturer)

Movable metallic implants (check with manufacturer)

Relative contraindications

• Claustrophobia
• Pregnancy
• Tatoos

Question 11

What implant eletronics may contraindicate an MRI scan?

Answer 11

• Most cardiac PACEMAKERS,
• Implantable defibrillators,
• COCHLEAR IMPLANTS

-Relative contraindication for programmable shunts, insulin pumps

Question 12

What movable metallic implants may contraindicate an MRI scan?

Answer 12

Aneurysm CLIPS
Heart VALVES
Recent intra-abdominal clips

Question 13

When would you use angiography in the diagnosis of neurological pathology?

Answer 13

Large vascular (arterial and venous) abnormalities

Diagnosis and treatment

1. ANEURYSM
2. Arteriovenous malformation
3. Carotidcavernous fistula
4. Unstoppable epistaxis

Question 14

What is perfusion?

Answer 14

Defined as the volume of blood passing through a defined volume of tissue per unit time

Units = ml blood/ 100g tissue/ min

Question 15

What disorders of abnormal perfusion may you consider the use of CT perfusion scan?

Answer 15

Stroke (decreased perfusion)

Tumour (Increased perfusion indicates angiogenesis and a more aggressive tumour)

Question 16

What are the uses for a PET scan?

Answer 16

PET is usually used to map out glucose usage

Increased metabolism seen in:

• Tumour
• Inflammation
• Infection

Usefull after brain tumour resection for differentiating granulation tissue (low energy usage) from leftover tumour (high energy usage)

Question 17

What are the clues for recognising plain radiographs?

Answer 17

(All rules have exceptions)

Plain radiographs

• Multiple superimposed bones (white)
• Soft tissue is grey
• Air is black

Question 18

What are the clues for identifying a CT of the skull?

Answer 18

• White circle of skull
• Black CSF in sulci and ventricles (Air is black)
• Grey brain with subtle grey-white matter difference

Question 19

What are the clues for identifying an MRI of the skull?

Answer 19

• White CSF is the best clue (but only true for T2-weighted MRI)
• Better grey-white matter differentiation than CT
• The skull is a thin black circle, immediately surrounded by a white circ;e of subcutaneous fat

Question 20

What are the clues for identifying Radionuclide radiology/ Nuclear medicine/ PET?

Answer 20

Images often have bright and varied colours

Image is fuzzy

Question 21

What are the advantages of plain radiographs?

Answer 21

Almost universal availability

Fast

Sequential images in subtraction angiography

Question 22

What are the disadvantages of plain radiographs?

Answer 22

Lacks soft tissue detail

Question 23

What are the advantages of ultrasound?

Answer 23

No radiation

Less expensive equipment

Can be performed in the neonatal unit

Movement tolerant

Question 24

What are the disadvantages of ultrasound for neuro examination?

Answer 24

Requires a wide enough open fontanelle (i.e. up to about 1 year of age)

Image quality and interpretation based on operator skill

Question 25

What are the advantages of CT?

Answer 25

• Rapid
• Metal and pacemaker tolerance
• Good for demonstrating acute haemorrhage

Question 26

What are the diadvantages of CT?

Answer 26

Radiation (2mSv)

More expensive cumbersome equipment

Question 27

What are the advantages of radionuclide radiology?

Answer 27

Physiological information:

• Glucose metabolism
• Perfusion
• Dopamine reuptake receptors

Question 28

What are the disadvantages of Radionuclide radiology?

Answer 28

Unclear anatomical information

Medium cost of equipment

Radiotracers can be very expensive

Question 29

What are the advantages of MRI?

Answer 29

No radiation

Soft tissue differentiation

Physiological information:

• Blood flow
• Diffusion restriction
• Metabolite concentrations

Question 30

What are the disadvantages of MRI?

Answer 30

Poor tolerance of metalwork

Magnetic sensitive electronics may fail or are contraindicated

• Programmable shunts
• Pumps
• Cochlear implants absolutely contraindicated

Least movement tolerance

Slow, must limit sequences

Most expensive equipment

Danger of metallic objects becoming projectiles