Brain imaging (8.9)

Question 1

Describe how MRI scans work and give pros/cons

Answer 1

Use radio waves and a magnetic field to produce clear image. Do this by shifting hydrogen atoms and detecting signals as the hydrogen realigns.

Pros: Does not carry the risk of radiation, higher resolution than CT scans
Cons: Expensive, magnetic field can interfere with medical devices (pacemakers and insulin pumps)

Question 2

Describe how a fMRi works and give the pros/cons

Answer 2

This also uses radio waves and a magnetic field but insteead also measures the ratio of oxygenated to deoxygenated haemoglobin. Therefore, these scans can depict which areas of the brain are active during certain tasks.

Pros: Shows structure but also function, does not carry the risk of radiation
Cons: Interferes with medical devices and is expensive

Question 3

Describe how a PET scan works and give the pros/cons

Answer 3

This involves the ingestion or introduction of a radioactive tracer into the body. This works similarly to the fMRI which followed bloodlfow. As areas of the brain become more active more blood will flow to this area, therefore more of the radioactive tracer will accumulate in this region.

Pros: Can study function and structure in real time
Cons: Radioactive subtances must be ingested

Question 4

Describe how a CT scan works and give pros/cons

Answer 4

Beams of x-rays are aimed at angles all around the body. Detectors pick up the x-rays as they exit the opposite side of the body. Denser tissues will absorb more of the x-ray so will appear lighter on scans

Pros: Shows the structures of the brain and can help visualise areas of damage
Cons: Not as clear as MRI, higher dosage of radiation that regular x-ray and it only produces a still 2D image