Formulas

Question 1

What is the formula for :

spin echo

Answer 1

TR x Phase X NSA = scan time

then divide by 1000 to convert to ms into seconds

Question 2

What is the formula for :

fast spin echo

Answer 2

TR x Phase x NEX / ETL = scan time

then divide by 1000 to convert to ms into seconds

Question 3

What is the formula for :

3D gradient echo

Answer 3

TR x Phase X NSA x # of slices = 3D scan time

divide by 1000 to convert ms into seconds

Question 4

What is the formula for :

pixel size

Answer 4

FOV / matrix = pixel size

Question 5

What is the formula for :

voxel volume

Answer 5

pixel area x slice thickness = voxel volume

Question 6

What is the formula for :

NSA/NEX and SNR

Answer 6

SNR increases by the square root of the increase

Question 7

What is the formula for :

bandwidth and SNR

Answer 7

decrease BW by a factor of 2 increases the SNR by square root of 2

Question 8

What is the formula for :

FOV and SNR

Answer 8

reducing FOV = decreases SNR by factor of the FOV to second power

Question 9

What is the formula for :

cardiac effective TR

Answer 9

60,000 / heart rate

Question 10

What is the formula for :

slice coverage

Answer 10

slice thickness + interslice gap x # of slices

Question 11

What is the formula for :

contrast dosage

Answer 11

0.2ml/kg

1) then divide pt weight in pounds by 2.2 (pounds to kg)
2) multiply that by 0.2 ml/kg

Question 12

Water fat shift

at 1T

Answer 12

147 Hz

Question 13

Water fat shift

at 1.5 T

Answer 13

220 Hz