Question

3) Describe, in words, the purpose of the magnetic field gradient employed in magnetic resonance imaging

Answer 1

Answer:
1.In magnetic resonance imaging, we place the human body in a strong magnetic field which makes the hydrogen nuclei in the body/cells to align with the magnetic field. When an radio frequency is applied to the system, it causes the hydrogen nuclei to change the state and when it is switched off they comes back to the steady state emitting the resonance frequency.

2.This is a basic principle for all the nuclear magnetic resonance type techniques. Please note that this is a very short description.

3.Now in MRI, a magnetic field gradient is also applied all over the body. This gradient makes the actual magnetic field vary slightly throughout the body and therefore the protons at different parts of the body resonate at different frequencies.

4.This allows us to scan specific parts of body and thus giving flexibility with image. Moreover intensity of the gradient field can determine the resolution of the image and speed of aquisition. Thus a gradient magnetic field is important in MRI.