Chapter 7

Question 1

In which direction does truncation occur

Answer 1

Phase Axis

Question 2

Which of the following best describes a remedy for cross excitation?

Answer 2

Excite alternate slices during the acquisition

Question 3

Which best describes the appearance of a zipper artifact?

Answer 3

A dense line on the image at a specific point.

Question 4

What unit is used to express the amount of chemical shift?

Answer 4

ppm

Question 5

In which direction does aliasing occur?

Answer 5

phase and frequency axis

Question 6

What is another term for phase ghosting?

Answer 6

Phase mismapping

Question 7

In some circumstances, magnetic susceptibility artifact can be useful in diagnosis. (T or F)

Answer 7

true

Question 8

Which of the following best describes the appearance of chemical shift artifact on an image?

Answer 8

Produces a dark edge at the interface between fat and water.

Question 9

Which of the following is a remedy for aliasing?

Answer 9

Using “no phase wrap” software

Question 10

To reduce chemical shift artifact, ALWAYS use the widest receive bandwidth in keeping with good SNR and the smallest FOV possible. (T or F)

Answer 10

true

Question 11

In which direction does chemical shift artifact occur?

Answer 11

Frequency Axis

Question 12

How can we reduce truncation?

Answer 12

Increase the number of phase encoding steps

Question 13

What is another name for a truncation artifact in a sagital cervical spine?

Answer 13

Gibbs

Question 14

In which direction does phase ghosting occur?

Answer 14

Phase Axis

Question 15

Which of the following is a possible cause of shading artifact?

Answer 15

Inhomogeneities in the main magnetic field

Question 16

Which of the following are methods of reducing phase ghosting

Answer 16

Using respiratory compensation techniques
Carefully explain the procedure to the patient
Swap phase and frequency
Use pre-saturation pulses

Question 17

Which of the following best describes Moire artifact?

Answer 17

Black and white banding artifact on the edge of the FOV

Question 18

remedy for Moire

Answer 18

keep anatomy w/in the FOV

Question 19

remedy for Magic Angle

Answer 19

move the body part or change TE

Question 20

remedy for aliasing

Answer 20

use no phase wrap software

Question 21

remedy for chemical misregistration

Answer 21

select a TE that matches periodicity of fat and water

Question 22

remedy for zipper

Answer 22

call an engineer

Question 23

remedy for cross excitation

Answer 23

gap between the slices, alternate slices

Question 24

remedy for chemical shift

Answer 24

use lower field strengths, wide RBW

Question 25

remedy for truncation

Answer 25

increase the # of phase encoding steps

Question 26

types of gating for EKG, ECG

Answer 26

lead wires on the patients chest.used when imaging chest heart and great vessels

Question 27

types of gating for peripheral gating

Answer 27

light sensor attached to patients finger to detect pulses thru capillaries. not as accurate

Question 28

types of gating for respiratory compensation

Answer 28

bellows around the chest. signal corresponds to max and minimum motion of chest. TR may be reduced

Question 29

types of gating for respiratory triggering

Answer 29

times the excitation RF w a certain phase of respiration. increased scan times

Question 30

appearance of phase mismapping artifact

Answer 30

produces replications of moving anatomy across image

Question 31

appearance of chemical shift artifact

Answer 31

dark edges at edge between fat and water

Question 32

appearance of magnetic susceptibilty

Answer 32

large signal voids

Question 33

appearance of cross excitation and cross talk artifact

Answer 33

adjacent slices in different image contrast

Question 34

appearance of zipper aritfact

Answer 34

dense line across the image

Question 35

appearance of magic angle

Answer 35

in tissues that contain collagen at high signal intensity

Question 36

appearance of aliasing

Answer 36

anatomy outside the FOV is folded on top of the anatomy inside FOV

Question 37

appearance of moire

Answer 37

black and white banding at the edge of FOV

Question 38

Which is true concerning chemical shift?

Answer 38

Expressed in parts per million (ppm). | equals 3.5 ppm

Question 39

direction of ghosting

Answer 39

phase only

Question 40

direction of aliasing

Answer 40

both phase and frequency

Question 41

direction of chemical shift

Answer 41

frequency only

Question 42

other name for phase mismapping

Answer 42

ghosting

Question 43

other name for aliasing

Answer 43

wrap around

Question 44

other name for truncation

Answer 44

Gibbs

Question 45

cause of ghosting

Answer 45

anatomy moving along the phase direction during pulse sequence

Question 46

cause of aliasing

Answer 46

anatomy outside the FOV is mapped inside FOV

Question 47

cause of chemical shift

Answer 47

different chemical environments of fat and water

Question 48

cause of truncation

Answer 48

undersampling of data

Question 49

cause of magnetic suscpetibility

Answer 49

braces, hair pins, implants, etc

Question 50

cause of cross excitation

Answer 50

RF pulse not square

Question 51

cause of zipper

Answer 51

leakin RF shielding

Question 52

cause of magic angle

Answer 52

collage is 55-degree angle to Bo

Question 53

cause of shading

Answer 53

inhomogeneities in the main magnetic field

Question 54

direction of zipper

Answer 54

frequency only

Question 55

direction of magnetic susceptibility

Answer 55

phase and frequency

Question 56

direction of truncation

Answer 56

phase only