MRI SEQUENCE PARAMETERS AND OPTIONS REVIEW QUESTIONS

The transmit bandwidth of the RF pulse affects: A. Spatial resolution B. Slice thickness C. Image contrast D. A and B

D. A and B

The receive bandwidth affects: A. Chemical shift artifact B. Slice thickness resolution C. SNR D. A and C

D. A and C

The 180 degree pulse that follows the initial 90 degree pulse in a spin echo sequence will cause the NMR signal to reappear while correcting for: A. Slight magnetic field inhomogeneties B. Chemical Shift C. Slight magnetic susceptibility effects D. All of the above

D. All of the above

Changing the size of the voxel in the frequency direction will: A. Double the scan time B. Decrease the scan time C. Increase the scan time D. Have no effect on scan time

D. Have no effect on scan time

When triggering a scan from the patient's ECG, the TR of sequences are determined by: A. The number of phase encodings selected B. The number of phases of the heart cycle being imaged C. The number of frequency encodings selected D. The patient's heart rate

D. The patient's heart rate

If a patient has an electronic implant that is compatible to scan on a 1.5 T it is NOT accepted practice to scan on an "open" 1T unit True or False

TRUE

Steep gradients are used to produce which of the following results? 1. Small FOV 2. Thin slices 3. Fine matrix

1, 2, and 3

The principle reason that the T2 signal muse to be detected a short time after the 90 degree pulse is turned of is: 1. Noise levels tend to increase with time 2. signal intensity decreases with time 3. Transverse magnetization increases within 80ms of the phase

2 only

An inversion recovery spin echo sequence begins with a: A. 45 degree RF pulse B. 60 degree RF degree C. 90 degree RF degree D. 180 degree RF degree

D. 180 degree RF degree

If a successive 180 degree RF pulses are used after a 90 degree RF pulse which echo will have the greatest signal? A. 1 B. 2 C. 3 D. 4 E. 5 F.6

A. 1

Reducing the slice thickness by a factor of 2 will reduce the SNR ( all other factors remaining constant) by a factor of: A. 2 B. 1.41 C. 2.5 D. 3

A. 2

If a given conventional spin echo pulse sequence takes 12 minutes to acquire, a fast spin echo sequence using the ETL of 6 with all other factors that affect the scan time remaining the same will take: A. 2 minutes B. 3 minutes C. 4 minutes D. 6 minutes

A. 2 minutes

While T1 recovery is defined as a gain of 63% of its value, the T2 relaxation is defined as the time it takes to decrease the transverse magnetism to: A. 37% of its original value B. 41% of its original value C. 63% of its original value D. 79% off its original value

A. 37% of its original value

If 6 successive 180 degree RF pulses are used after a 90 degree RF pulse how many echos will be created? A. 6 B. 1 C. 3 D. None

A. 6

In 3D acquisitions the slices are produced by: A. A phase encoding gradient applied in the slice selection direction B. Multiple 180 degree pulse along the slice selection direction C. Sampling multiple lines of k-space per pulse sequence repetition D. Very accurate RF pulses

A. A phase encoding gradient applied in the slice selection direction

Which of the following dephasing mechanisms presents with a void of signal on the high-frequency side and an addition of signal on the low-frequency side of the organ? A. Chemical shift B. Magnetic susceptibility C. Magnetic field inhomogeneties D. Spin-spin interactions

A. Chemical shift

Increasing bandwidth _____ the chemical shift artifact A. Decreases B. Increases C. Eliminates D. Has no effect

A. Decreases

This pulse sequence has one 180 degree refocusing pulse: A. Spin echo B. Gradient echo C. Fast spin echo D. Inversion echo

A. Spin echo

If the TR of a gradient echo pulse sequence is considerably less than the T2 (and T2*), the condition that will exist is known as: A. Steady state B. Spin dephasing C. Spin rephasing D. Spin cancellation

A. Steady state

If a STIR sequence using a TR of 3000, a TE of 70, and a TI of 140 produces an image with dark fat and bright water; the contrast resembles which contrast weighted image a T1 or T2? A. T2 B. T1 C. PD D. NONE

A. T2

Reducing the NSA (NEX) will reduce the scan time and : A. decrease the SNR B. increase the SNR by a factor of 1.41 C. Not affect the SNR D. Double the SNR

A. decrease the SNR

In a SE technique, the signal that is created after the initial 90 degree pulse and terminal 180 degree pulse is called ( hint: 2 tau) A. echo time (TE) B. inversion time (TI) C. Repetition time (TR) D. Spin time

A. echo time (TE)

Following dephasing which of the following RF flip angles maximizes the component of the net magnetization in the transverse plane at the time of the spin echo: A. 45 B. 90 C. 120 D. 180

D. 180

The chemical shift between water and fat is 224 hz at _____ A. .5T B 1.5T C. 3T D. None

B 1.5T

For optimum operation of MRI systems, the ambient temperature and relative humidity should remain between: A. 30F and 50F/ 30% and 50% B. 65F and 75F/ 50% and 70% C. 70F and 90F/ 30% and 50% D. No specific temperature or humidity

B. 65F and 75F/ 50% and 70%

In T2 imaging, different tissues yield different levels of signal. This fact is responsible for the ______ seen in T2 images A. Density B. Contrast C. Artifact D. Susceptibility

B. Contrast

Increasing the number of phase encodings will produce an image with: A. Increased voxel volume B. Decrease voxel volume C. Higher SNR D. No changes

B. Decrease voxel volume

Increasing the matrix in the frequency direction from 256 to 512 will: A. Reduce scan time B. Have no effect on scan time C. Increase the scan time by a factor of 512/256 D. Double scan time

B. Have no effect on scan time

T1 is also termed: A. transverse magnetization B. Longitudinal relaxation C. Spin spin D. Spin excess

B. Longitudinal relaxation

Which of the following parameters control the amount of contrast seen in an image due to T2 relaxation? A. TI B. TE C. TR D. TD

B. TE

A gradient echo sequence in which any residual transverse magnetization is removed prior to the next excitation pulse is known as: A. non-phasic B. incoherent C. Non-residual D. Magnetization prepared

B. incoherent

Reducing the FOV by a factor of 2 will reduce the voxel volume by a factor of: A. 4^2 B. 2 C. 4 D. 8

C. 4

In a SE sequence the slice selection gradient in a conventional 2D Fourier transform imaging sequence is applied between the: A. 180 degree RF pulse and 90 degree RF pulse B. 60 degree RF pulse and 180 degree RF pulse C. 90 degree RF pulse and 180 degree RF pulse D. 270 degree RF pulse and 90 degree RF pulse

C. 90 degree RF pulse and 180 degree RF pulse

Coil field direction is termed: A. B B. Bo C. B1 D. B2

C. B1

Acquiring half of the phase views of k-space and then interpolating the data for the other half is a technique known as: A. Zero fill B. Fast spin echo C. Half fourier D. Power scanning

C. Half fourier

On short TR/TE spin echo imaging sequences, white matter appears A. Hypointense to gray matter B. Hypointense to CSF C. Hyperintense to gray matter

C. Hyperintense to gray matter

Increasing the number of excitations A. Reduces SNR B. Increases motion artifact C. Improves SNR D. Eliminates chemical shift

C. Improves SNR

Using a conventional spin echo multislice sequence, the number of slices allowed when increasing the TR: A. Decreases B. Is not affected C. Increases by a factor of TR/TE D. Doubles

C. Increases by a factor of TR/TE

Voxel that display no preferred direction of movement are called: A. Anisotropic B. Fractional anisotropy C. Isotropic D. None of the above

C. Isotropic

Which of the image weighting is likely to occur from the use of a 2,000ms (long) repetition time (TR) and a minimal 20ms echo time (TE)? A. T1 B. T2 C. Proton density D. Reverse spin density

C. Proton density

The scan time for a 3D acquisition is given by: A. TR X NSA X bandwidth X slice thickness B. TR X NSA X phase encoding X slice thickness C. TR X NSA X number of phase encoding X number of slices D. TR X NSA X number of phase encoding X slice thickness

C. TR X NSA X number of phase encoding X number of slices

On a 24cm FOV sagittal T-spine image that demonstrates a cord compression, the vertebral level can be determined by A. Using the xiphoid as a landmark and counting from T12 B. Using the sternal notch as a landmark and counting down from T1 C. Using a large FOV localizer and counting down from C2 D. Using lead markers to mark T12 and T1 on large FOV

C. Using a large FOV localizer and counting down from C2

Doubling the NSA (NEX) will increase the SNR by a factor of: A. 2.3 B. 4.2 C. 1.6 D. 1.41

D. 1.41