MRI INTRO 001

FINAL EXAM

Atomic number is

The sum of protons in the nucleus

Decay is

The amount of magnetization in the transverse plane which gradually decreases

How many motions does an atom have?

Three

What detects the MRI signal?

RF Coils

Magnetic moments have

vector properties and sign of direction

Pick the answer that best describes the Law of Electromagnetism

Any charged moving particle creates a magnetic field

Precession is

An additional motion of the nucleus around the Bo direction.

Recovery is

The amount of magnetization in the longitudinal plane which gradually increases

The atomic mass number is

The sum of protons and neutrons in the nucleus

The Larmor equation is used to determine

The nuclei precessional frequency

The length of the vector nominates

The size of the magnetic moments

The MR signal's strength depends on

The amount of Hydrogens excited by the RF pulse

The MRI signal is produced by

The coherent magnetization

The MRI signal is

Voltage induced into and received by the RF coil

The Precessional frequency is

Speed at which nuclei wobble around the Bo

The relaxation process is

When nuclei lose their acquired energy

The Resonance Is

The phenomenon which occurs when an object is exposed to an oscillating perturbation that has frequency close to the objects' own frequency

The unit of Precessional Frequency is

MHZ

What causes protons to align with or against the Bo direction?

B0

Short TE

minimizes T2W

TR controls

 T1W

Short TR

maximizes T1W

TE controls

T2W

Long TE

maximizes T2W

Long TR

maximizes PDW

In a conventional SE, A 180* RF pulse is applied to

Rephase nuclei

FID is

Free Induction decay

For the vector of water to recover fully, TR must be

Long

Gradient pulse sequence is composed of

45*RF-gradient

How does Spin echo differ from Gradient echo?

•a. Spin echo uses 90*RF initial pulse

• b. Gradient echo uses variable FA

• c. Spins are.rephased by 180*RF rephasing pulse

• d. All the above

Please choose parameters for T1-weighted Spin echo pulse sequence

 TR-short /TE-short

Please choose parameters for T2-weighted Spin echo pulse sequence

TR-long/ TE-long

Spin echo sequence is composed of

90*RF-180*RF

What does TAU stand for?

 It is the time that nuclei take to rephase after application 180*RF rephasing pulse, or time to dephase after removing 90*RF

What kind of weighting will we have by choosing TR long/ TE short

PD

When RF pulse is removed

• a. T1 and T2 relaxation starts immediately

• b. FID starts immediately

• c. Spins start decay and become incoherent

• d. All of the above

T or F

180 RF pulse is an RF pulse that has sufficient energy to move the NMV 180 degrees

True

True or False

Gradient Recalled Echo or GRE is a sequence that uses gradients to regenerate signal

true