Artifacts

Question 1

[cause & app: mf &rf field distor] foreign material

Answer 1

C: ferromagnetic materials establish mf
A: no signal/signal void
metal no H = signal void

Question 2

distorts the linear mf gradient

Answer 2

magnetic susceptibility artifacts

Question 3

magnetic susceptibility artifacts [app]

Answer 3

adjacent bright areas and dark areas in or near the magnetic mat

Question 4

inhomogeneity of the primary static mf and transmitted RF pulse

Answer 4

body, shape, conductivity & extension

Question 5

chemical shift [app]

Answer 5

bright rim of signal at one interface and a dark on the opposite side of the particular organ

Question 6

chemical [orientation]

Answer 6

frequent encoded direction

Question 7

[cause] magic angle artifact

Answer 7

manifestation of anisotropic effects effects of collagen in MR (restricts mobility of H atoms)

Question 8

[location] magic angle artifact

Answer 8

tendons, ligaments

Question 9

[..] b/w the collagen fibers and axis of Bo (magic angle artifact

Answer 9

54.7

Question 10

[cause] aliasing/wraparound

Answer 10

occurs when portions of pt’s body are outside the prescribed FOV but w/in the area of RF excitation

Question 11

[cause] partial volume averaging

Answer 11

poi is contained w/in two contagious slices

Question 12

[app] truncation/”ringing” artifact

Answer 12

appears as multiple, well-defined curved lines regularly conforming to anatomic boundary

Question 13

[cause] zipper frequency artifact/zipper line/ zipper artifact

Answer 13

RF feeding thru from RF transmitter along freq encoding direction

Question 14

[app] zipper frequency artifact/zipper line/ zipper artifact

Answer 14

segmented line extending across the middle FOV in in FE direction and having zipperlike app

Question 15

[cause] motion artifact

Answer 15

voluntary, involuntary and microscopic physiologic motion

Question 16

[app] motion artifact

Answer 16

smeared /”ghost” appearance, irregular wavelike lines of increased and decreased signal

Question 17

[cause] misregistration

Answer 17

patient motion occurs b/w mask image and subsequent image

Question 18

[cause] off-resonance artifact

Answer 18

inexact tuning of RF transmitter and/or receiver to larmour freq

Question 19

[app] off-resonance artifact

Answer 19

noise image (grainy), may appear like truncation but not a regular, well defined artifact

Question 20

[cause] bleeding artifact

Answer 20

inexact duplication of rf pulses or gradient mf b/w each acquisition are incorrectly formed

Question 21

[app] bleeding artifact

Answer 21

smeared image of wavelike patterns