MIDTERMS

Question 1

_________ coils acts as an antenna to produce or transmit and detect or receive radiowaves that are referred to as the MRI signal

Answer 1

radiofrequency coils

Question 2

a typical _____ coil is enclosed in the gantry of the magnet

Answer 2

radiofrequency coil

Question 3

most homegenous coils are of a ______ design

Answer 3

birdcage

Question 4

coil that is integrated into the scanner bore and cannot be seen by the patient

this completely surrounds the patient

acts as transceivers

Answer 4

body coils

Question 5

it is a head coil

acts as transceivers

provides best radiofrequency homogeneity

Answer 5

volume/birdcage coils

Question 6

a coil that has simple loop designs, either circular or rectangular and have excellent SNR close to the coil but the sensitivity drops off rapidly with distance from the coil

these are only used as receivers, the body coil will act as transmitter

Answer 6

surface/local coils

Question 7

coil used for imaging anatomy near the coil

the depth of the image of a _____ coil is generally limited to about one radius

Answer 7

surface/local coils

Question 8

coil commonly used for the knee

these coils provide better homogeneity of the RF in the area of interest and are used as volume coils, unlike surface coils

also used for the x and y gradient coils

Answer 8

paired saddle coils

Question 9

this is required to protect the environment from the effects of fringe fields which surround magnet

Answer 9

radiofrequency shielding

Question 10

to maintain magnetic field homogeneity, ______ is necessary for the field to be protected from being distorted by the external environment

Answer 10

shielding

Question 11

magnetic field outside the patient aperture

Answer 11

fringe magnetic field

Question 12

an advance technique used to acquire images from moving body parts like chest, abdomen, cardiac and blood vessels studies reducing motion artifacts

Answer 12

gating

Question 13

3 types of gating

Answer 13

cardiac gating
respiratory gating
breath holding

Question 14

carding gating acquisition is generally triggered by an _______, this eliminate the blurring and artifact problem inherent

Answer 14

electrocardiogram

Question 15

cardiac gating uses programmed ____ __ ______ (TR) to deliver RF pulse and to monitor the cardiac cycle to determine which signal it uses for reconstruction

Answer 15

time of repetition

Question 16

this suppress breathing motion

acquisition takes place only during the gate when respiratory is minimal

Answer 16

respiratory gating

Question 17

respiratory gating is effective in minimizing _____ motion but increases imaging time and resolution

Answer 17

breathing

Question 18

gatings used in MRI of the chest, abdomen, liver perfusion and dynamics, kidneys, spleen, adrenals and MRCP

Answer 18

respiratory gating
breath holding

Question 19

gating where image acquisition every breath holds after exhalation

Answer 19

breath holding

Question 20

is a provrammed set of changing magnetic gradients

defined by multiple parameters

Answer 20

pulse sequences

Question 21

time required for the external magnetic field to go to two third of its original value

gives informatjon about the thermal conductivity of the surrounding tissue

anatomy

Answer 21

T1 weighted images

Question 22

time required for the transverse magnetic field to decay to a third of its original value

gives information about the homogeneity of the surrounding atoms

pathology

Answer 22

T2 weighted images

Question 23

is commonly used in MRI to suppress the signal from adipose tissue or detect adipose tissue

it can be applied to both T1 and T2 weighted sequences

Answer 23

fat suppression pulse sequence

Question 24

areas contain adipose tissues appear ____ on T2 weighted fat saturated images

Answer 24

dark

Question 25

due to added fat suppression, pathological processes are usually very bright

Answer 25

T2 fatsat

Question 26

water has low signal and appears dark

fat will appear bright

Answer 26

T1 weighted images

Question 27

water appears bright and fat will appear intermediate bright

Answer 27

T2 weighted images