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40 Cards in this Set

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HIGH SIGNAL IS CALLED -
HYPER-INTENSE
LOW SIGNAL IS CALLED -
HYPO-INTENSE
GREY SIGNAL IS CALLED -
ISO-INTENSE
GREY SIGNAL IS ALSO REFFERED TO AS -
INTERMEDIATE SIGNAL
FAT HAS ITS HYDROGEN ATOM LINKED TO -
CARBON
FAT MOLECULES CONTAIN -
ATOMS OF HYDROGEN ARRANGED WITH CARBON AND OXYGEN
FAT MOLECULES ARE CALLED 1______ AND ARE 2._______ ______ ______.
1. LIPIDS
2. CLOSELY PACKED TOGETHER
FAT MOLECULES MOLECULAR TUMBLING RATE IS-
RELATIVELY SLOW
WATER MOLECULES CONTAIN -
TWO HYDROGEN ATOMS ARRAIGNED WITH ONE OXYGEN ATOM
WATERS MOLECULES ARE;
1. _______ _____ AND HAVE A
2 ______ ____ MOLECULAR TUMBLING RATE
1. SPACED APART
2. RELATIVELY FAST
Image weighting and contrast are useful for?
Demonstrate contrast between normal anatomical features and between anatomy and pathology

Excellent soft tissue discrimination of the images
What is contrast?
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)
a range of shades of gray without apparent color is called?
Grayscale
the total absence of transmitted or reflected signal.
The darkest possible shade is black, which is the total absence of transmitted or reflected signal.
the total transmission or reflection of signal.
The lightest possible shade is white, the total transmission or reflection of signal.
Intermediate shades of gray are represented by
equal brightness levels of the black and white.
The NMV can be separated into the individual vectors of the tissues present in the patient . T or F
True
A tissue has a high signal (white) if it has
a large transverse component of magnetization.
A tissue gives a low signal (black), if it has
a small transverse component of magnetization.
A tissue gives an intermediate signal (grey), if it has
a medium transverse component of magnetization
White –
Black –
Gray –
hyperintense
hypointense
isointense
The factors that affect image contrast in diagnostic imaging are usually divided into two categories:
1.
2.
3
4
5
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
Intrinsic contrast parameters are?
T1 recovery time
T2 decay time
Proton density
Flow
Apparent diffusion coefficient
Extrinsic contrast parameters;
those that do come under the operators control are?
TR
TE
Flip angle
TI
Turbo factor/echo train length
B value / b factor
All substances possess molecules that are constantly in motion. This molecular motion is made up of rotational and transitional movements, so...
The faster the molecular motion, the more difficult it is for a substance to release energy to its surroundings.
Fat comprises hydrogen atoms linked to 1._____ that make up 2._____ molecules.
1. carbon
2. large
The large molecules in fat have a _____ rate of molecular motion
1. slow
They also have a low inherent energy which means ?
they are able to absorb energy efficiently.
Water comprises1_____. atoms linked to 2._____
1.hydrogen
2.oxygen
Water consists of 1._____ ______ with little inertia that have a 2.____ rate of molecular motion.
1.small molecules
2.high
Water molecules have a high inherent energy which means ?
they are not able to absorb energy efficiently
.
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.
relaxation rates
Images obtain contrast mainly through the mechanisms of
T1 recovery,
T2 decay and
proton or spin density.
the number of protons per unit volume of that tissue is ?
The proton density (PD) of the tissue
The higher the proton density of a tissue –
the more signal available from that tissue
If the inherent energy is low –
molecular lattice is more able to absorb energy.
there is more efficient energy exchanged between hydrogen nuclei when?
– in tissues where molecules are closely spaced, or closely packed
another contrast mechanism is How well the molecular tumbling rate matches the Larmor frequency of hydrogen. Molecules within fat are ____ __ the Larmor frequency
closer to
Relaxation in different tissues;
T1 – represents -
time it takes for 63% of the total energy to be regained in the longitudinal plane via spin lattice energy transfer
Relaxation in different tissues;..
T2 – represents -
the time it takes for 63% of the total energy to be lost in the transverse plane via spin – spin energy transfer