Chapter 2: image weighting and contrast

Question 1

intrinsic

Answer 1

cannot be changed
- body tissues

Question 2

extrinsic

Answer 2

can be changed
- parameter settings

Question 3

intrinsic contrast parameter

Answer 3

T1 recovery
T2 decay
Proton density
flow
apparent diffusion coefficient (ADC)

Question 4

Extrinsic contrast parameter

Answer 4

TE
TR
Flip angle
Turbo factor/ echo train length
b value

Question 5

thermodynamics

Answer 5

hydrogen nuclei will always seek its lowest energy state
- relaxation

Question 6

T1 recovery

Answer 6

longitudinal plane
- spin lattice energy transfer

Question 7

T2 decay

Answer 7

transverse plane
- spin-spin interactions

Question 8

dephasing also caused by

Answer 8

inhomogeneities in the B0

Question 9

Free induction decay

Answer 9

differences in processional frequency + dephasing + inhomogeneities

Question 10

contrast w/ high signal

Answer 10

hyperintense

Question 11

contrast w/ low signal

Answer 11

hypointense

Question 12

higher proton density

Answer 12

more signal

Question 13

T1 & T2 two factors

Answer 13

• molecular tumbling matches Larmor frequency
• molecules are packed close together

Question 14

Fat

Answer 14

hydrogen + oxygen + carbon
- large molecules packed together
- slow tumbling rate

Question 15

Water

Answer 15

2 hydrogen + oxygen
- molecules spaced far apart
- fast tumbling rate

Question 16

tissues w/ high PD

Answer 16

large transverse magnetization- hyperintense

Question 17

tissues w/ low PD

Answer 17

small transverse magnetization- hypointense

Question 18

signal intensity depends on

Answer 18

• PD
  -T1 recovery
  -T2 decay

Question 19

TR controls T1

Answer 19

visualizes anatomy

Question 20

TE controls T2

Answer 20

visualizes pathology

Question 21

PD- T1 & T2 is

Answer 21

dominated by PD to visualize anatomy and pathology

Question 22

to minimize intrinsic contrast parameters

Answer 22

we select extrinsic parameters to dominate

Question 23

to dominate T1, T2, PD weighting

Answer 23

we use TE or TR

Question 24

Diffusion weighting

Answer 24

contrast is due to the differences in ADC between the tissues

Question 25

apparent diffusion coefficient (ADC)

Answer 25

net displacement of molecules in an area of tissue per second

Question 26

functional MRI

Answer 26

for brain activity

Question 27

magnetic transfer contrast

Answer 27

suppresses background tissue and increases the CNR

Question 28

susceptibility weighted imaging

Answer 28

uses susceptibility between tissues for contrast

Question 29

contrast agents

Answer 29

gadolinium binded/ chelating with DTPA

Question 30

short T1 & T2 relaxation time

Answer 30

fat

Question 31

Long T1 & T2 decay time

Answer 31

water

Question 32

Gauss

Answer 32

unit of magnetic flux for small changes in field strength

Question 33

Tesla

Answer 33

unit of magnetic flux density for a large magnetic field

Question 34

signal

Answer 34

voltage that is induced in the receiver coil

Question 35

first few RF excitations pulses

Answer 35

preparatory

Question 36

saturation when NMV is flipped

Answer 36

180 degrees

Question 37

T1 weighted

Answer 37

short TE short TR

Question 38

T2 weighted

Answer 38

long TR long TE