MRI

Question 1

name origianlly used for MR

disassociated from MRI because of public apprehension about nuclear energy

Answer 1

Nuclear Magnetic Resonance (NMR)

Question 2

bloch and purcell discovered properties of MR which led to the use of MRE spectroscopy

Answer 2

1940s

Question 3

bloch and purcell awared nobel prize in physics

Answer 3

1952

Question 4

damadian showed that the relaxation of water in a tumor differed from that of water in a normal tissue
relaxation time represents the rates of signal decay and the return pf protons to equilibrium

Answer 4

1960s

Question 5

paul lauterbur published the first crude cross-sectional images of objects obtained with MRI

Answer 5

1973

Question 6

Peter mansfield further showed how the signals could be mathmatically analyzed which made it possible to develop a useful imaging technique

Answer 6

1973

Question 7

nobel prize in physiology or medicine was awarded to bot lauterbur and mansfiel for their discovers in MRI

Answer 7

2003

Question 8

protons in certain nuclie, if placed in a magnetic field

can be stimulated by radio waves of the correct frequency

Answer 8

basic principle of MRI

Question 9

nucleus, electrons, protons,

Answer 9

structures of atom

Question 10

after protons align with magnetic field rotation occurs

action called precession

Answer 10

role of magnetic field

Question 11

RF introduced as very fast burst of radio waves

Answer 11

introdcution of RF pulses

Question 12

based on nuclear density, relaxation rates and flow

strong signals appear white, weak signals, appear black

Answer 12

MRI signals

Question 13

number of processing nuclie in a give volume of tissue

becuase the hydrogen nucleus is a single proton, its nuclear concenetration is referred to as

Answer 13

proton density

Question 14

one component of relaxation is the release of energy by the excited protons
occurs at different rates in different tissues

Answer 14

relaxation time

Question 15

process of nuclei releasing excess energy to the general environment or lattice, also called spin-lattice relaxation

Answer 15

T1 relaxation rate

Question 16

release of energy by excited nuclei through interaction amoung themselves

Answer 16

T2 realaxation rate

Question 17

moving substance usually have weak MRI signals

Answer 17

flow

Question 18

specific radio-wave pulses that stimulate the nuclei

Answer 18

pulse sequence

Question 19

controls the computer
displays the images
images may be printed

Answer 19

console

Question 20

houses the electronics necuessary for transmitting radio-wave pilse sequences
can store raw and reconstructed date temporarily

Answer 20

computer room

Question 21

contains major components of the MRI unit, the magnet

Answer 21

magnent room

Question 22

simple but large electromagnet consisting of coils of wires
large amount of current is passed through a large number of coils to produce high magnetic fields
requires cooling system to offset heat produced

Answer 22

resistive magnent

Question 23

wire loops are cooled to very low temperatures with liquid helium to reduce electrical resistance thereby producing higher magnetic field strenghts compared to resistive magnets

Answer 23

superconductive (cryogenic) magnent

Question 24

constant field that does not require additional electriciyt or cooling

Answer 24

permanent magnent

Question 25

antennas required for transmitting the RF pulse and receiving MRI signals

Answer 25

coils

Question 26

sagittal, coronal, transverse, oblique

Answer 26

planes

Question 27

important for visualizing pathology

Answer 27

slice thickness

Question 28

long time, more signal available

Answer 28

imaging time

Question 29

depending on pulse sequence, resulting images may be more weighted toward proton density, T1 or T2 information

Answer 29

imaging sequence

Question 30

classic sequence for T1 weighted images
can also provide proton density- weighted images and T2 weighted images
useful when high signal from extensive fat overwhelms small signal intenstiy differences in the tissue of interest

Answer 30

spin echo

Question 31

a sequence that accentulates T-1 information and provides timimg parameter to minimize signla intensity in tissue

Answer 31

inversion recovery

Question 32

useful when high signal from extensive fat overwhelms small signal intensity difference in the tissue of interest

Answer 32

fat-suppressed

Question 33

the only MRI contrast approved in the US, commonly used in CNS studies
metal with paramagentic effect shortens T1 relaxation time producing high contrast images
intravenoulsy administered

Answer 33

gadolinium

Question 34

imaging technique used to improve image quality

Answer 34

gating

Question 35

MRI superior over CT for imaging posterior fossa and white matter disease such as MS

Answer 35

Central Nervous System

Question 36

lungs and blood in the great vessel have low MRI signals

FDA approved MRI in 1991 for supplemental mammogrpahy

Answer 36

chest

Question 37

MRI more sensitive than CT in detecting primary and metastic tumors of the liver

Answer 37

abdomen

Question 38

MRI advantageou in coronal and saggittal plane in examing the curvature of the pelvis

Answer 38

pelvis

Question 39

limbs, bone marrow as well as joints are well visualized

Answer 39

musculoskeletal system

Question 40

carotid arteries for stenoses, aneurysms plaques

Answer 40

vessles