MRI

Question 1

Basis contrast of image contrast

Answer 1

time for the protons to relax back

Question 2

why hydrogen in mr

Answer 2

Abundant in body
sufficient SNR
higher field strength

Question 3

three magnetic field

Answer 3

B0: mostly 1.5or 3.0t
3t 60000 times stronger than earth field

B1: produced by radiofrequency coil
flips protons into transverse plane
cause tissue heating

Gradient magnetic field
fast switching gradients for spatial localisation
peripheral nerve stimulation and implant heating.

Question 4

how far should ferromagnetic objects not be existed

Answer 4

5 Gauss line

Question 5

which plane RF excitation pulse move photons into

Answer 5

transverse plane

Question 6

contrast mechanism

Answer 6

T1 recovery
t2 decay
proton density images

Question 7

strenght of mr

Answer 7

good soft tissue contrast and high spatial resolution

Question 8

limitation

Answer 8

expensive
imaging times
claustrophobe
contraindication like pacemaker

Question 9

brain imaging

Answer 9

structural imaging:
morphological imaging
exclude pathology

Functional imaging :
change in blood flow
surgical planning

spectroscopy:
provide metabolic information of brain tissue

Question 10

Spine imaging

Answer 10

high signal CSF is T2

Question 11

liver imagin

Answer 11

Structure: t1-w t2-w STIR in and out phase
Functional DWI ADC map

Question 12

MRCP

Answer 12

heavily t2-W
very bright fluid

Question 13

MSK

Answer 13

joints tendons lingaments
show in T2-w usually

Question 14

bone marrow

Answer 14

shown in T1

Question 15

angio

Answer 15

TOF

Question 16

whole body MR

Answer 16

provide comprehensive wholde body evaluation of systemic or multifocal benign or malignant disease.
Not for screening due to potential false positives

Question 17

Issue for mri RT planning

Answer 17

RT require image co-registration!!!
table not flat

Question 18

MR elastpgraphy

Answer 18

evaluate fibrosis
usually liver and brain