MIDTERM PT. 2

Question 1

THAT PORTION OF THE MAGNETIC FIELD EXTENDING AWAY FROM THE CONFINES OF THE MAGNET CANNOT BE USED FOR IMAGING BUT CAN AFFECT NEARBY EQUIPMENT OR PERSONNEL

Answer 1

FRINGE FIELD

Question 2

A SHORT BURST OF RADIO WAVES; THE LENGTH OF THE PULSE DETERMINES THE AMOUNT OF ENERGY GIVEN TO THE NUCLEI

Answer 2

RADIOFREQUENCY (RF) PULSE

Question 3

_____ USES THE SIGNAL FROM THE NUCLEI OF ________ FOR IMAGE GENERATION

Answer 3

MEDICAL MAGNETIC RESONANCE (MR) IMAGING
HYDROGEN ATOMS (1H)

Question 4

IS THE MR ACTIVE NUCLEUS USED IN CLINICAL MRI

Answer 4

HYDROGEN NUCLEUS

Question 5

HYDROGEN NUCLEUS IS USED BECAUSE: (2)

Answer 5

1. VERY ABUNDANT IN THE HUMAN BODY
2. ITS SINGLE PROTON GIVES A LARGE MAGNETIC MOMENT

Question 6

NUCLEI WITH ____ ARE SAID TO BE MR ACTIVE

Answer 6

ODD NUMBER OF PROTONS

Question 7

1. THEY ACT LIKE TINY BAR MAGNETS
2. THERE ARE MANY TYPES OF ELEMENTS THAT MR ACTIVE AND THEY ALL HAVE ODD MASS NUMBERS

Answer 7

NUCLEI WITH AN ODD NUMBER OF PROTONS

Question 8

ELEMENTS THAT ARE MR ACTIVE ARE:

Answer 8

1. HYDROGEN 1
2. CARBON 13
3. FLOURINE 19
4. PHOSPHORUS 31
5. NITROGEN 15
6. OXYGEN 17
7. SODIUM 23

Question 9

____ AND ____ SPIN ABOUT THEIR OWN AXES WITHIN THE NUCLEUS

Answer 9

PROTONS
NEUTRONS

Question 10

PROTONS AND NEUTRONS HAS A RANDOM DIRECTION OF SPIN ______ AND _____

Answer 10

CLOCKWISE AND ANTI-CLOCKWISE

Question 11

WHEN THE NUCLEUS HAS AN ____ THE SPINS ____ EACH OTHER OUT SO THE NUCLEUS HAS NO NET SPIN

Answer 11

EVEN MASS NUMBER
CANCEL

Question 12

WHEN THE NUCLEUS HAS AN ____ THE SPINS ____ EACH OTHER OUT AND THE NUCLEUS SPINS

Answer 12

ODD MASS NUMBER
DO NOT CANCEL

Question 13

IS THE RATE AT WHICH SPINS WOBBLE WHEN PLACED IN A MAGNETIC FIELD.

Answer 13

LARMOR OR PRECESSION FREQUENCY

Question 14

DIRECTLY PROPORTIONAL TO THE STRENGTH OF THE APPLIED MAGNETIC FIELD (B)

Answer 14

LARMOR OR PRECESSION FREQUENCY

Question 15

IT IS THE FREQUENCY AT WHICH THE NUCLEUS WILL ABSORB ENERGY THAT WILL CAUSE IT TO CHANGE ITS ALIGNMENT

Answer 15

LARMOR OR PRECESSION FREQUENCY

Question 16

LARMOR FREQUENCY IS ______ TO THE STRENGTH Bo OF THE MAGNETIC FIELD AND IS GIVEN BY THE

Answer 16

DIRECTLY PROPORTIONAL

Question 17

LARMOR FREQUENCY EQUATION

Answer 17

Wo= Yo x Bo

Question 18

IS THE LARMOR FREQUENCY IN MEGAHERTZ (MHz)

Answer 18

Wo

Question 19

THE GYROMAGNETIC RATIO, THE UNIT IS MEGAHERTZ/ TESLA (MHz/T)

Answer 19

Yo

Question 20

THE STRENGTH OF THE MAGNETIC FIELD IN TESLA (T).- STATIC EXTERNAL MAGNETIC FIELD

Answer 20

Bo

Question 21

PROTONS HAVE A GRYOMAGNETIC RATIO OF _____

Answer 21

y= 42.58 MHz/T

Question 22

THE MAIN MAGNETIC FIELD MEASURED IN TESLA

Answer 22

Bo

Question 23

the component of the net magnetization vector parallel to the magnetic fiekd is called the _____

Answer 23

longitudinal magnetization

Question 24

the component perpendicular to the magnetic field is called ______

Answer 24

transverse magnetization

Question 25

it is the rotating _____ that gives rise to the MR signal in the receiver coil

Answer 25

transverse magnetization

Question 26

magnetic moment of hydrogen

Answer 26

Net Magnetization Vector (NMV)

Question 27

is the basis of MRI

Answer 27

the interaction of NMV with the Bo

Question 28

the unit of Bo is ___

Answer 28

Tesla

Question 29

occurs when the net magnetization vector is perturbed from its equilibrium orientation

Answer 29

resonance

Question 30

with no external magnetic field present, the protons spins and rotate in their axis in ____

Answer 30

random direction

Question 31

RF tips the magnetization vector by exactly _____ degrees causing the entire longitudinal magnetization to flip over and rotate into _____

Answer 31

90 transverse magnetization

Question 32

emits MR signal from the receiver coil

Answer 32

transverse magnetization