Safety

Question 1

Name four regulatory bodies for MRI safety

Answer 1

MHRA, HPA, IEC, ICNIRP

Question 2

What are the three operating modes defined by the regulatory bodies?

Answer 2

Normal - minimal risk
Controlled - some effects, patient benefits, monitor
Experimental - limit exposure to prevent harm, REC approval, patient monitor

Question 3

What are the static field limits for normal, controlled and experimental modes for (HPA & ICNIRP)

Answer 3

N <4 T
C 4-8 T
E > 8 T

Question 4

What are the temperature rise limits for each mode (IEC and ICNIRP)?

Answer 4

N <0.5 degC
1st level C <1 degC
E > 1 deg C

Question 5

When is 1st level controlled mode use restricted?

Answer 5

Fetal and paediatric imaging

Question 6

What are the whole body SAR limits for each operating mode (IEC and ICNIRP)

Answer 6

N 2 W/kg
C 4 W/kg
E >4 W/kg

Question 7

What are the anatomical SAR categories for each operating mode?

Answer 7

WB, PB head, PB other, local head, local trunk, local other

Question 8

What does the IEC limit for dB/dt correspond to and how is it determined?

Answer 8

cardiac stimulation
dB/dt < 20/(1-exp(-teff/3))

Question 9

What are the dB/dt limits for each operation mode?

Answer 9

N 80% median threshold for PNS
C 80-100%
E 100-120%

Question 10

CA for T1 and CA for T2?

Answer 10

Gd, FeO2

Question 11

What is NSF, what are the risk factors, and how does it occur?

Answer 11

fibrosis of skin, lungs, muscle, heart

risk factors - high dose, long exposure, Gd disociation from chelate

Gd dissociates from chelate
reacts with PO4
immune response to GdPO4