MR QA

Question 1

How is the wavelength of an EM wave modified in a medium?

Answer 1

l=l_vacuum/(e_r * mu_r)

Question 2

relative magnetic permeability of water?

Answer 2

1

Question 3

relative permittivity of water?

Answer 3

80

Question 4

relative permittivity of oil?

Answer 4

5

Question 5

Why make RF properties of phantom similar to that of tissue?

Answer 5

keep receive gain the same as in vivo

Question 6

Equation for relaxation rate of a solution?

Answer 6

R1_sol=a*conc +R1_H2O
a is relaxivity

Question 7

MRI IPEM report number?

Answer 7

112

Question 8

Eqn for Standard deviation of thermal noise?

Answer 8

sigma \propto sqrt(4kTRBW)

Question 9

SNR equation for subtraction method?

Answer 9

SNR=sqrt(2)*mu_phantom/sigma_subtraction

Question 10

Form of noise dist. in magnitude reconstructed image?

Answer 10

Rician

Question 11

Integral uniformity formula?

Answer 11

U_int=100*(1-(Smax-Smin/Smax+Smin))

Question 12

Tolerance for integral uniformity?

Answer 12

80%

Question 13

Ghosting ratio formula?

Answer 13

G=(ghosting-noise)/S
G=((T+B)-(L+R))/2S

Question 14

Modulation transfer function from edge response function?

Answer 14

MTF=FFT (d/dx ERF(x))

Question 15

Tolerance for spatial resolution?

Answer 15

pixel size

Question 16

CoV formula?

Answer 16

CoV=100% * sigma/mu

Question 17

What is the slice profile?

Answer 17

Sensitivity of imaging in the direction perpendicular to the imaging plane

Question 18

What is the ACR phantom made of?

Answer 18

acrylic with NiCl2+NaCl paramagnetic salts in solution

Question 19

How to measure slice profile?

Answer 19

d/dx ERF on on slice through wedge

Question 20

How to measure slice width?

Answer 20

w=dtan(theta)
on slice through wedge

Question 21

How to measure slice position?

Answer 21

Image through crossed wedges in ACR phantom. Length difference between the two indicates slice position error.

Question 22

T1 QA range?

Answer 22

100 -> 1200 ms

Question 23

T2 QA range?

Answer 23

50 -> 400 ms

Question 24

SE signal eqn?

Answer 24

S=k[H].(1-exp(-TR/T1)).exp(-TE/T2)

Question 25

Name 4 pathologies that T1 measurement is useful for?

Answer 25

Amyloid disease
Anderson-Fabry disease
Edema
Necrosis

Question 26

What is the equation for fitting signal in IR experiment?

Answer 26

S=S0(1-lambda*exp(-TI/T1))

lambda is inversion recovery efficiency

Question 27

What is the gold standard method for T1 meas?

Answer 27

Series of IR experiments with varying TI.

Wait out TR = 5*T1 for full recovery of Mz

Question 28

What is the T1 of normal myocardium at 1.5 T?

Answer 28

1 second

Question 29

What is 5-3-3 MOLLI?

Answer 29

inversion, 5 * bSSFP readouts with different TI

then 3 beats for Mz recovery

then inversion, 3 * bSSFP readouts with different TI

ECG gated