MRI Module 2

Which combination of TR and TE would produce a T1 weighted image? 1. Short TR 2. Long TR 3. Short TE 4. Long TE A) 1 & 3 B) 1 & 4 C) 2, & 3 D) 2 & 4

A) 1 & 3

Which condition will induce the maximum voltage in the receiver coil? A) Fat, after a short TR B) Fluid, after a short TR C) Fat after a long TE D) Fat or fluid after a short TR and long TE

A) Fat, after a short TR

Spin lattice relaxation time is also called? A) T1 relaxation B) T2 relaxation C) inversion time D) decay time

A) T1 relaxation

What is significant about the envelope of an FID? A) it contains T2* along with the other relaxation mechanisms B) it does not contain T2* C) It contains the signal intensity of only fat, which makes it bright D) It contains only true T2 relaxation signals

A) it contains T2* along with the other relaxation mechanisms

The time to echo (TE) is the time between the: A) 90 and 180 degrees RF pulses B) 90 degree RF pulse and the received signal C) 180 degrees RF pulses and the spin echo D) 180 degrees RF pulse and the next 90 degree pulse

B) 90 degree RF pulse and the received signal

When spin spin interactions decay transverse magnetization, how is this captured in the MR signal (FID or SE)? A) A change in frequency B) A change in voltage C) A change in direction of the pulses D) A change in the direction of spin.

B) A change in voltage

For a TR of 2300 ms and a TE of 85 ms what will the contrast be? A) T1 B) T2 C) T2* D) Proton density (PD)

B) T2

Spin spin relaxation time is also called: A) T1 relaxation B) T2 relaxation C) Inversion time D) longitudinal relaxation

B) T2 relaxation

T1 relaxation time is also known as: A) transverse relaxation B) longitudinal relaxation C) decay D) spin spin relaxation

B) longitudinal relaxation

Why is T1 _____ a tissue characteristic? A) recovery (regrowth), Because water relaxes faster than fat B) recovery (regrowth), Because different tissue have different T1 relaxation rates. C) decay, Because fat relaxes faster than water D) decay, Because different tissue have different T1 rates of decay.

B) recovery (regrowth), Because different tissue have different T1 relaxation rates. T1 is a measurement of regrowth of Mo to the longtitudinal plane. At TE the transverse component of magnetization will be different for each tissue type as well as pathology, making the signal intensity (and subsequently the tissue brightness) different for each tissue.

When the TR is made longer: A) the TE becomes shorter B) relaxation time before the next TR becomes longer C) the TE becomes longer D) relaxation time before the next TR becomes shorter

B) relaxation time before the next TR becomes longer

The process of excited nuclei returning to alignment with Bo is known as ___ and results in ___: A) Mxy, Mo B) relaxation, equilibrium C) equilibrium, relaxation D) decay, Mxy

B) relaxation, equilibrium

The list (1-5) are intrinsic and extrinsic factors that determine MR contrast. Which of these are intrinsic? 1. T1 2. T2 3. Proton density (PD) 4. TR 5. TE A) 1 & 2 B) 2 & 3 C) 1, 2, & 3 D) 3, 4, & 5 E) 4 & 5

C) 1, 2, & 3

Which of the following are effected by T2* 1. Bo 2. Mxy 3. Mo 4. The NMV A) 1 B) 2 & 3 C) 2 & 4 D) 3 & 4

C) 2 & 4

The reason fat tissue is bright on some MR images is that: A) Fat relaxes faster than water B) Water relaxes faster than fat C) the component of transverse magnetization from fat is the greatest D) Mo has regrown to its maximum value

C) the component of transverse magnetization from fat is the greatest

Which combination of TR and TE would produce a T2 weighted image? 1. Short TR 2. Long TR 3. Short TE 4. Long TE A) 1 & 3 B) 1 & 4 C) 2 & 3 D) 2 & 4

D) 2 & 4

_____ is the relaxation constant for T1 and T2, and _____ T1 times pass before full relaxation. A) 63%, 63 B) 5, 63. C) 37%, 5 D) 63%, 5

D) 63%, 5

Which statement best describes the relaxation of fat and water? A) Fat relaxes faster than water when sampled by T1 B) Fat relaxes faster than water when sampled by T2 C) Fat and water relax at equal rates D) Fat relaxes faster than water regardless of how the signal is sampled.

D) Fat relaxes faster than water regardless of how the signal is sampled.

Transverse magnetization is most closely associated with: A) proton density B) spin density C) T1 relaxation time D) T2 relaxation time

D) T2 relaxation time

In what order does relaxation occur? A) T1, T2, T2* B) T2, T2*, T1 C) T2*, T1, T2 D) T2*, T2, T1

D) T2*, T2, T1

A relaxation curve for fat and water shows the maximum differences in contrast where: A) Mxy is labeled B) Equilibrium is labeled C) The curves intersect D) The gap between the curves is widest

D) The gap between the curves is widest

Spin density is best described as the number of: A) tightly bound H nuclei in an imaging plane B) mobile H nuclei in a sample C) mobile H nuclei in a sample D) active and mobile H nuclei in a sample

D) active and mobile H nuclei in a sample Active H protons are the one in a million. Mobile H protons are those not so tightly bound to cortical bone or enamel that they will not absorb RF energy and flip.

What is the primary difference between an echo and FID? A) signal strength B) an FID follows an echo C) an FID is composed of rephasing protons only, an echo is composed of dephasing protons D) an FID is composed of dephasing protons only, an echo is composed of rephasing and dephasing protons

D) an FID is composed of dephasing protons only, an echo is composed of rephasing and dephasing protons

The appearance of a tissue with a short T1 relaxation time will be: A) undetectable B) black or very dark C) a medium shade of gray D) bright

D) bright

Why is T2 _____ a tissue characteristic? A) recovery (regrowth), Because water relaxes faster than fat B) Recovery (regrowth), Because different tissue have different T2 relaxation rates. C) decay, Because water relaxes faster than fat D) decay, Because different tissue have different T2 rates of decay.

D) decay, Because different tissue have different T2 rates of decay. T2 is a measurement of decay of Mxy (the NMV) from the transverse plane. At TE the transverse component of magnetization will be different for each tissue type as well as pathology, making the signal intensity (and subsequently the tissue brightness) different for each tissue.

The time necessary to measure T1: A) is typically greater than that of T2 B) is always the same as T2 C) is typically longer than T2 D) is always longer than T2 E) is dependent on the sequence of pulses

D) is always longer than T2

For T2 weighted images, tissues with a: A) low spin density will appear dark B) high Bo will appear bright C) short T2 will appear bright D) long T2 will appear bright

D) long T2 will appear bright

What causes dephasing of the NMV? 1. T1 2. T2 3. T2* 4. PD A) 1 & 2 B) 1 & 3 C) 1, 2 & 3 D) 2 & 3 E) 2, 3, & 4

E) 2, 3, & 4 T2 and T2star cause dephasing, and proton density is the factor that determines spin spin interactions. T1 is absorption of the energy lost to decay caused by T2 and T2*.