Part D: Quality control

Question 1

131. If the slice thickness is reduced by a factor of 2, the factor by which the NSA must be increased to maintain the same SNR (all other factors remaining constant) is:
     a. 8
     b. 1.41
     c. 4
     d. 2

Answer 1

c. 4

Question 2

132. If the slice thickness is increased by a factor of 2 (from 5 to 10mm thickness), the SNR (all other factors remaining constant):
     a. Increases by the square root of two
     b. increases by a factor of 2
     c. Reduces by a factor of 2
     d. Reduces by a factor of the square root of 2

Answer 2

b. increases by a factor of 2

Question 3

133. If the slice thickness increases, SNR (all other factors remaining constant):
     a. Increases
     b. Decreases
     c. Stays the same
     d. Is not affected

Answer 3

a. Increases

Question 4

134. If the slice thickness increases, the spatial resolution (all other factors remaining constant):
     a. Increases
     b. Decreases
     c. Stays the same
     d. Is not affected

Answer 4

b. Decreases

Question 5

135. Changing the size of the voxel in the frequency direction will:
     a. Double the scan time
     b. Decrease the scan time
     c. Have no effect on the scan time
     d. Increase the scan time by a factor of 0.5

Answer 5

c. Have no effect on the scan time

Question 6

136. Factors that affect contrast (contrast to noise or contrast resolution) include all of the following EXCEPT:
     a. TR
     b. TE
     c. TI
     d. Flip angle
     e. Matrix

Answer 6

e. Matrix

Question 7

137. SNR is a factor that is measured.
     a. True
     b. False

Answer 7

a. True

Question 8

138. CNR is a factor that is measured.
     a. True
     b. False

Answer 8

b. False

Question 9

139. Factors that affect spatial resolution (resolution in ‘space’ or detail) include all of the following EXCEPT:
     a. FOV
     b. Slice thickness
     c. Flip angle
     d. Matrix

Answer 9

c. Flip angle

Question 10

140. Factors that affect SNR (signal to noise) include all of the following EXCEPT:
     a. TR
     b. Field strength
     c. FOV
     d. Matrix
     e. Hour of the day

Answer 10

e. Hour of the day

Question 11

141. Center frequency is a factor that determines the:
     a. Frequency of RF used for excitation
     b. Frequency of RF used for signal detection
     c. a and b
     d. Amplitude and/ or duration of the RF pulse (to determine flip angle)

Answer 11

c. a and b

Question 12

142. Transmit gain is a factor that determines the:
     a. Frequency of RF used for excitation
     b. Frequency of RF used for signal detection
     c. a and b
     d. Amplitude and/ or duration of the RF pulse (to determine flip angle)

Answer 12

d. Amplitude and/ or duration of the RF pulse (to determine flip angle)

Question 13

143. Geometric accuracy is determined by the:
     a. RF system
     b. Shim system
     c. Gradient system
     d. Main magnet system

Answer 13

c. Gradient system

Question 14

144. During MR imaging, all equipment should be inspected prior to use to be sure that components are in proper working order. Components include:
     a. RF coils and cables
     b. RF coils and door seals
     c. Cables and door seals
     d. Quench system
     e. All of the above

Answer 14

e. All of the above

Question 15

145. 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. 1.5

Answer 15

a. 2

Question 16

146. The methods for shimming the main magnetic field are:
     a. Retroactive shimming
     b. Active shimming
     c. Passive shimming
     d. b and c
     e. a, b, and c

Answer 16

d. b and c

Question 17

147. The purpose of shimming a magnet is to:
     a. Make the B1 field as homogenous as possible
     b. Make the B0 field as homogenous as possible
     c. Make the scan times as short as possible
     d. Correct for improperly tuned gradient coils

Answer 17

b. Make the B0 field as homogenous as possible