Question

1. Which one of these are not an example of an MRI active nuclei? (23) Sodium (12) Carbon (1) Hydrogen (31) Phosphorus All of the Above

2. All of the following are reasons why we are able to use hydrogen in MRI EXCEPT:

Odd Mass #, Abundance In the Body, Has a Large Magnetic Moment, Increased RF Absorption

3.For excitation to occur via resonance at 1.5 T, we must deliver RF at approximately ________ MHz.

42, 21, 62, 124

4. The law that explains the relationship between a moving electrical field and the creation of a magnetic field is __________.

Faraday's Law, Einstein's Law, Kelvin's Law, Ohm's Law, Mansfield's Law

5. True or False: Although the fields strengths between all MRI machines can be different, the direction of the lines of magnetic flux will always be the same.

True

False

6. The precessional frequency of hydrogen at 1.5T is:

52.47 Hz

63.86 MHz

42.57 MHz

63.86 Hz

42.57 MHz.

7. True or False: There will always be more hydrogen protons that align with the direction of the main magnetic field than against it prior to receiving RF.

False

True

8. In order for resonance to occur for Hydrogen, the radio frequency (RF) excitation pulse must match the __________.

Signal to Noise Ratio, Gyromagnetic Ratio, Larmor Frequency, Larmor Frequency & Gyromagnetic Ratio, Signal to Noise Ratio & Gyromagnetic Ratio

9. The difference between the number of parallel and anti-parallel protons is known as the __________.

Phase

Free Induction Decay (FID)

Frequency

Net Magnetization Vector (NMV)

Gyromagnetic Ratio

10. The gyromagnetic ratio of Hydrogen is _________.

63.86 MHz x Tesla

42.57 Hz x Gauss

42.57 MHz x Tesla

127.71 MHz x Tesla

11. The difference between the number of parallel and anti-parallel spins is known as the __________.

Larmor Frequency

Ernst Angle

Electromagnetic Vector

Net Magnetization Vector

Answer 1

ANSWER 1) b. Carbon(12) cannot be used as MRI active nuclei.

Hydrogen is the most commonly used MRI active nucei as its found in abundance in body and have large magnetic moment. Sodium and phosphorous are also used as MRI active nuclei as they have uneven number of protons or uneven number of neutrons which which cause them to show spin. Spinning nuclei are MRI active. Whereas Carbon (12) donot have spinning nuclei so it cannot be used as MRI active nuclei but carbon (13) can be used due to the spinning property.

ANSWER 2) a. Odd mass

The hydrogen is found in abundance in body and have large magnetic moment. The hydrogen also has increased RF absorption which makes it an most feasible element as MRI active nuclei.

ANSWER 3) At 1.5T resonance field the RF delivered should be 62 MHz.

This is the requirement of the proton to spin in that magnetic field. If the RF more than 62 or less than 62 is applied then it will not cause the protons to spin in that particular given resonance.

ANSWER 4) Faraday's law explains the relationship between moving electric field and creation of magnetic field.

Magnetic field produced by the induced current will be in opposite direction to the change in the origional field. This was stated by Faraday's law. Einsteins law states that the speed of light within the vacuum is the same no matter the speed at which an observer travels. The Kelvin's law states that the most economical size of a conductor is that for which the annual interest and depriciation on a capital cost of the conductor is equal to annual cost of energy loss. The Ohm's law states that the current through the conductor between two points is directly proportional to the voltage across the two points. Mansfield studied the laws of nature which explained the behaviour of our physical environment.