Medical Imaging Flashcards
1
Q
How do MRI scans work?
A
- Patient placed in strong magnetic field
- Magnetic field aligns hydrogen atoms longitudinally
- Radiofrequency (RF) pulse applied to patient tipping hydrogen atoms which then together create a detectable magnetic field perpendicular to the main MRI magnetic field
- This induces an electric current in nearby cells
- Signal processed to create images
- The hydrogen atoms then relax back into alignment with the longitudinal magnetic field of the MRI magnet
- The contrast in MRI images is due to different relaxation times of the hydrogen atoms within different tissues
2
Q
What is a T1 weighted MRI scan?
A
- Fat is bright
- Water is dark
3
Q
What is a T2 weighted MRI scan?
A
- Fat is dark
- Water is bright
4
Q
What are the clinical uses of MRI?
A
- Central nervous system (brain and spinal cord)
- Bones and joints
- Soft tissue lesions
- Heart and blood vessels
- Gynaecological tumours
- In paediatrics/pregnancy to avoid radiation
5
Q
What are the advantages of MRI scans?
A
- No radiation
- Good contrast, resolution especially of soft tissues
6
Q
What are the disadvantages of MRI scans?
A
- Expensive
- Time consuming
- Fewer machines, fewer radiographers
- Contraindications (pacemakers, cochlear implants, claustrophobia, lack of mental capacity
- Contrast reactions
- Some other risks ie. overheating
7
Q
What projections are used in X-rays?
A
- Anteroposterior (AP)
- Posteroanterior (PA)
- Lateral
- Oblique
8
Q
What profections are used in CT/MRI scans?
A
- Axial
- Coronal
- Sagittal
