Unit 4 Q. MR Imaging Parameters (16 Q 32 MIn)

600ms TR 5mm Slice Thickness20ms TE 18cm Field of View256 Phase Encoding 2 = Number of Signal Averages256 Frequency Encoding 13 SlicesThe dimensions of the voxel in this sequence are: Select one: a. .7mm x .7mm x 5mm b. 1.4mm x 1.4mm x 5mm c. not able to determined by these parameters d. .07mm x .07mm x 5mm

a. .7mm x .7mm x 5mm

Combined with a 25.6cm Field of View, which of the following parameterswould create isotropic voxels? Select one: a. 256 x 256 matrix, 1mm slice thickness b. 192 x 256 matrix, 5mm slice thickness c. 128 x 128 matrix, 1mm slice thickness d. 256 x 256 matrix, 5mm slice thickness

a. 256 x 256 matrix, 1mm slice thickness

TR = 50ms Number of signal Averages = 1TE = 10ms Field of View = 18cmFlip Angle = 35 degrees Bandwidth = 32KhzPhase Encoding = 192 Number of Slices = 32Frequency Encoding = 256 Slab Thickness = 32mmScan time for this sequence is? Select one: a. 307.2 seconds b. unable to determined with the given parameters c. 10.24 minutes d. 30,720ms

a. 307.2 seconds

Which of the following bandwidths result in the highest SNR? Select one: a. 8Khz b. 12Khz c. 10Khz d. 16Khz

a. 8Khz

As the slice gap decreases: Select one: a. SNR decreases, spatial resolution is unaffected b. SNR decreases, spatial resolution decreases c. SNR increases, spatial resolution is unaffected d. SNR increases, spatial resolution decreases

a. SNR decreases, spatial resolution is unaffected

As the number of signal averages (NSA, NEX) double: Select one or more: a. scan time doubles b. SNR doubles c. SNR increases by the square root of the NSA

a. scan time doubles c. SNR increases by the square root of the NSA

Which of the following changes would increase scan time? (Two answers) Select one or more: a. Increase Echo Train Length b. Decrease Echo Train Length c. Increase Phase Encoding d. Increase Echo Spacing

b. Decrease Echo Train Length c. Increase Phase Encoding

As either Field of View increases or Matrix decreases, what is theeffect? Select one: a. SNR decreases, spatial resolution decreases b. SNR increases; spatial resolution decreases c. SNR increases, spatial resolution increases d. SNR decreases, spatial resolution increases

b. SNR increases; spatial resolution decreases

5000ms TR 256 Frequency Encoding80ms Target TE 2 = Number of Signal Averages15ms Echo Spacing 230mm Field of View6 Echo Train Length 32Khz Bandwidth192 Phase Encoding 21 SlicesThe scan time for this sequence is: Select one: a. 3,020 seconds b. 30,200 milliseconds c. 5.33 minutes d. 3.02 minutes

c. 5.33 minutes

As the slice thickness increases: Select one: a. SNR decreases, spatial resolution is unaffected b. SNR decreases, spatial resolution increases c. SNR increases, spatial resolution decreases d. SNR increases, spatial resolution is unaffected

c. SNR increases, spatial resolution decreases

600ms TR 5mm Slice Thickness20ms TE 18cm Field of View256 Phase Encoding 2 = Number of Signal Averages256 Frequency Encoding 13 SlicesThe voxel in this image are described as: Select one: a. isotropic b. square c. anisotropic d. tropical

c. anisotropic

600ms TR 5mm Slice Thickness20ms TE 18cm Field of View256 Phase Encoding 2 = Number of Signal Averages256 Frequency Encoding 13 SlicesIf the number of Phase Encoding was changed to 192, the tradeoff wouldbe: Select one: a. increase SNR, increase scan time, decrease voxel volume b. decrease SNR, increase scan time, increase voxel volume c. increase SNR, decrease scan time, increase voxel volume d. increase SNR, decrease scan time, decrease voxel volume

c. increase SNR, decrease scan time, increase voxel volume

Which of the following order of slice excitation results in the highestSNR? Select one: a. ascending b. contiguous c. interleaved d. descending

c. interleaved

600ms TR 5mm Slice Thickness20ms TE 18cm Field of View256 Phase Encoding 2 = Number of Signal Averages256 Frequency Encoding 13 SlicesScan time for this sequence is: Select one: a. not able to determined by these parameters b. 5.01 minutes c. 512 seconds d. 5 min 7 seconds

d. 5 min 7 seconds

As either Field of View increases or Matrix decreases SNR increases andresolution decreases, what is the reason for the trade-off caused byeither a change in the Field of View or Matrix? Select one: a. Field of View and Matrix both affect scan time b. Field of View and Matrix both affect longitudinal relaxation c. Field of View and Matrix, both affect transverse relaxation d. Field of View and Matrix, both affect voxel volume

d. Field of View and Matrix, both affect voxel volume

In order to reduce chemical shift misregistration artifact: Select one: a. decrease the Receiver BW b. decrease the Transmitted BW c. increase the Transmitted BW d. increase the Receiver BW

d. increase the Receiver BW