MRI and CT Flashcards
How does a CT work
Takes multiple X-rays around patient and computer reconstructs them to produce sliced images
Drawbacks of radiography and CT (2)
- Radiation dosing
- Relatively poor soft tissue resolution
How does MRI work
Relied on protons of hydrogen atoms resonating in a magnetic field
Different physical properties of protons allow us to produce different contrasts- shows more than just radiopacity, can tell difference between fluid and fat and tissue
Colour of Fat, Bone, Fluid, Pathology, Constrast on T1 MRI
T1-
Fat: High
Bone: Low
Fluid: Low
Pathology: Low
Contrast: High
Colour of Fat, Bone, Fluid, Pathology, Constrast on T2 MRI
T2-
Fat: High
Bone: Low
Fluid: High
Pathology: High
Contrast: Iso
Problems with MRI (5)
Very susceptible to movement- not good for chest or thorax
Relatively poor bone detail
Metallic artefacts
Implanted medical devices
Slower
Positive contrasts for CT and Radiogrpahy
Radiodense material
Iodine/Barium
Negative contrast for CT and radiography
Radiolucent material
Air
Positive contrast for MRI
High signal material
Gadolinium (iv)
Negative contrast for MRI
Low signal material
Air
When to use MRI
soft tissue detail
When to use CT (3)
Bone detail
Movement artefact
incompatible with MRI
Health and safety risks with MRI
Magnetic fields
Implanted medical devices
Metallic implants
Missile risk
Magnetic media
what is discospondylitis
an inflammatory disease of the spine characterized by infection of the intervertebral disc, adjacent vertebral endplates, and vertebral bodies.
What is spondylosis
new bone formation on vertebral column
