Physics Basics From Book Mri In Practice Chapter 2

Front 1

HIGH SIGNAL IS CALLED -

Back 1

HYPER-INTENSE

Front 2

LOW SIGNAL IS CALLED -

Back 2

HYPO-INTENSE

Front 3

GREY SIGNAL IS CALLED -

Back 3

ISO-INTENSE

Front 4

GREY SIGNAL IS ALSO REFFERED TO AS -

Back 4

INTERMEDIATE SIGNAL

Front 5

FAT HAS ITS HYDROGEN ATOM LINKED TO -

Back 5

CARBON

Front 6

FAT MOLECULES CONTAIN -

Back 6

ATOMS OF HYDROGEN ARRANGED WITH CARBON AND OXYGEN

Front 7

FAT MOLECULES ARE CALLED 1______ AND ARE 2._______ ______ ______.

Back 7

1. LIPIDS
2. CLOSELY PACKED TOGETHER

Front 8

FAT MOLECULES MOLECULAR TUMBLING RATE IS-

Back 8

RELATIVELY SLOW

Front 9

WATER MOLECULES CONTAIN -

Back 9

TWO HYDROGEN ATOMS ARRAIGNED WITH ONE OXYGEN ATOM

Front 10

WATERS MOLECULES ARE;
1. _______ _____ AND HAVE A
2 ______ ____ MOLECULAR TUMBLING RATE

Back 10

1. SPACED APART
2. RELATIVELY FAST

Front 11

Image weighting and contrast are useful for?

Back 11

Demonstrate contrast between normal anatomical features and between anatomy and pathology

Excellent soft tissue discrimination of the images

Front 12

What is contrast?

Back 12

An image has contrast if there are areas of high signal (white on the image), as well as areas of low signal (dark on the image). Some areas have an intermediate signal (shades of grey in-between white and black)

Front 13

a range of shades of gray without apparent color is called?

Back 13

Grayscale

Front 14

the total absence of transmitted or reflected signal.

Back 14

The darkest possible shade is black, which is the total absence of transmitted or reflected signal.

Front 15

the total transmission or reflection of signal.

Back 15

The lightest possible shade is white, the total transmission or reflection of signal.

Front 16

Intermediate shades of gray are represented by

Back 16

equal brightness levels of the black and white.

Front 17

The NMV can be separated into the individual vectors of the tissues present in the patient . T or F

Back 17

True

Front 18

A tissue has a high signal (white) if it has

Back 18

a large transverse component of magnetization.

Front 19

A tissue gives a low signal (black), if it has

Back 19

a small transverse component of magnetization.

Front 20

A tissue gives an intermediate signal (grey), if it has

Back 20

a medium transverse component of magnetization

Front 21

White –
Black –
Gray –

Back 21

hyperintense
hypointense
isointense

Front 22

The factors that affect image contrast in diagnostic imaging are usually divided into two categories:
1.
2.
3
4
5

Back 22

Intrinsic contrast parameters are those that cannot be changed because they are inherent to the body’s tissues.
- Extrinsic contrast parameters are those that can be changed

Front 23

Intrinsic contrast parameters are?

Back 23

T1 recovery time
T2 decay time
Proton density
Flow
Apparent diffusion coefficient

Front 24

Extrinsic contrast parameters;
those that do come under the operators control are?

Back 24

TR
TE
Flip angle
TI
Turbo factor/echo train length
B value / b factor

Front 25

All substances possess molecules that are constantly in motion. This molecular motion is made up of rotational and transitional movements, so...

Back 25

The faster the molecular motion, the more difficult it is for a substance to release energy to its surroundings.

Front 26

Fat comprises hydrogen atoms linked to 1._____ that make up 2._____ molecules.

Back 26

1. carbon
2. large

Front 27

The large molecules in fat have a _____ rate of molecular motion

Back 27

1. slow

Front 28

They also have a low inherent energy which means ?

Back 28

they are able to absorb energy efficiently.

Front 29

Water comprises1_____. atoms linked to 2._____

Back 29

1.hydrogen
2.oxygen

Front 30

Water consists of 1._____ ______ with little inertia that have a 2.____ rate of molecular motion.

Back 30

1.small molecules
2.high

Front 31

Water molecules have a high inherent energy which means ?

Back 31

they are not able to absorb energy efficiently
.

Front 32

Because of the differences between fat and water, tissues that contain fat and water produce different image contrast. This is because there are different ______ _____ in each tissue.

Back 32

relaxation rates

Front 33

Images obtain contrast mainly through the mechanisms of

Back 33

T1 recovery,
T2 decay and
proton or spin density.

Front 34

the number of protons per unit volume of that tissue is ?

Back 34

The proton density (PD) of the tissue

Front 35

The higher the proton density of a tissue –

Back 35

the more signal available from that tissue

Front 36

If the inherent energy is low –

Back 36

molecular lattice is more able to absorb energy.

Front 37

there is more efficient energy exchanged between hydrogen nuclei when?

Back 37

– in tissues where molecules are closely spaced, or closely packed

Front 38

another contrast mechanism is How well the molecular tumbling rate matches the Larmor frequency of hydrogen. Molecules within fat are ____ __ the Larmor frequency

Back 38

closer to

Front 39

Relaxation in different tissues;
T1 – represents -

Back 39

time it takes for 63% of the total energy to be regained in the longitudinal plane via spin lattice energy transfer

Front 40

Relaxation in different tissues;..
T2 – represents -

Back 40

the time it takes for 63% of the total energy to be lost in the transverse plane via spin – spin energy transfer