MRI

Question 1

What does MRI not rely on

Answer 1

Ionizing radiation

Question 2

What is the earth’s magnetic field

Answer 2

25-65uT

Question 3

Magnetization

Answer 3

The vector sum of all the magnetic moments

Question 4

Resonance

Answer 4

Any oscillating system has a resonance frequency

Question 5

What is the chemical shift of water and fat

Answer 5

4. 7 ppm

3. 5 ppm

Question 6

Relaxation time

Answer 6

T1: longitudinal or spin lattice relaxation time

T2: is the transverse or spin-spin relaxation time

Question 7

Examples of pulse sequence

Answer 7

Saturation recovery sequence
Spin-echo sequence
Gradient echo sequence
Inversion recovery sequence

Question 8

What are shimmings used for

Answer 8

Is done to create uniform field

Question 9

Slice thickness can be altered by

Answer 9

Changing the range of frequencies in the RF (bandwidth)

Keeping the bandwidth constant and altering gradient strength-slope

Question 10

Cross talk

Answer 10

If the next slice that is excited is adjacent to the previous slice, some nuclei will be excited again before they return to equilibrium

Question 11

2D data collection process

Answer 11

1. Slice encoding ( gradient in z direction)
2. Phase encoding (y direction)
3. Frequency encoding (x direction )