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MRI > MIDTERM- PT. 3 > Flashcards

MIDTERM- PT. 3 Flashcards

(62 cards)

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1
Q

_____ WORKS TOGETHER WITH COILS

A

RADIOFREQUENCY

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2
Q

THESE ARE USED FOR THE PX

A

COILS

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3
Q

THE ELECTROMAGNETIC COMPONENTS OF THE RF SYSTEM; ATTACHED TO THE RF COILS

A

RF SYSTEM

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4
Q

ARE MADE WITH VARYING DESIGNS

A

RF COILS

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5
Q

ACTS AS AN ANTENNA

A

COILS

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6
Q

WHAT ARE THE 2 TYPES OF COILS:

A
  1. SHIM COILS
  2. RECEIVER COILS
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7
Q

MAKES THE MAGNETIC FIELD HOMOGENOUS

A

SHIM COILS

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8
Q

DETECTING THE RETURNING RADIO SIGNALS

A

RECEIVER COIL

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9
Q

ARE THE ANTENNA OF MRI SYSTEM
ACTS AS A TRANSMITTER/ RECEIVER

A

RF COILS

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10
Q

TYPES OF RF BODY COILS ARE:

A
  1. SURFACE COILS
  2. PAIRED SADDLE COIL
  3. HELMHORTZ PAIR COIL
  4. BIRD CAGE COIL
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11
Q

COIL: ARE SIMPLY LOOPS OF WIRE
-CIRCULAR/ RECTANGULAR
-USED FOR SMALL BODY PARTS (E.G. EYES)
-COMMONLY USED IN SPINES, SHOULDERS, TMJ’S

A

SURFACE COILS

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12
Q

COIL:
-COMMONLY USED FOR IMAGING OF THE KNEE
-PROVIDE BETTER HOMOGENEITY OF THE RF IN THE ARE OF INTEREST AND ARE USED AS VOLUME COILS UNLIKE SURFACE COILS
-ALSO USED OF THE X & Y GRADIENT COILS

A

PAIRED SADDLE COIL

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13
Q

COIL:
-USED FOR PELVIS AND SPINE & BODY STRUCTURES (HEAVY TO PENETRATE)
- CONSIST OF 2 CIRCULAR COILS PARALLEL TO EACH OTHER
-USED AS GRADIENT COILS IN MRI SCANNERS

A

HELMHORTZ PAIR COIL

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14
Q

COIL:
-MOST FREQUENTLY USED IN MRI
-COMMONLY USED IN THE HEAD
-ACTS AS A TRANSCEIVER COIL
-PROVIDES THE BEST RF HOMOGENEITY OF ALL THE RF COILS
-HAS THE APPEARANCE OF A BIRDCAGE
- THIS TYPE OF COIL IS ALSO USED OCCASIONALLY FOR IMAGING OF THE EXTREMITIES SUCH AS THE KNEES

A

BIRD CAGE COIL

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15
Q

POWER SUPPLY OF MRI:
____Kw
____VOLTAGE RIPPLE

A

2.4
5%

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16
Q

POWER SUPPLY THAT IS COMMONLY USED

A

1.5 TESLA

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17
Q

-PROVIDES RADIO FREQUENCY SHIELDING
-USES ALUMINUM OR ON CERTAIN CONDITIONS GALVANIZED STEEL TO FORM THE SHIELDED FARADAY CAGE
-SHIELDING FROM OUTSIDE INTERFERENCE

A

FARADAY CAGE

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18
Q

TO FUNCTION PROPERLY, AN MRI SCANNER NEEDS TO SIT IN A SPECIALIZED ROOM OR CHAMBER SHIELDED AGAINST A RADIO FREQUENCY (RF) INTERFACE. WITHOUT SUCH PROTECTION THE VERY WEAK RF SIGNALS THAT EMANATE FROM THE PATIENT WHEN SCANNED WOULD BE OVERWHELMED

A

FARADAY CAGE

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19
Q

USED IN MRI TO DESCRIBE RELATIVE CONTRIBUTIONS TO DETECT SIGNAL OF THE TRUE SIGNAL AND RANDOM SUPERIMPOSED SIGNALS

A

SIGNAL-TO-NOISE RATIO

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20
Q

ALSO KNOWN AS BACKGROUND NOISE

A

SUPERIMPOSED SIGNALS

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21
Q

FORMULA FOR SNR

A

MEAN SIGNAL / STANDARD DEVIATION OF BACKGROUND NOISE

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22
Q

IF THE SNR INCREASE: ___ INCREASES (7)

A

-Bo
-T2
-TR
-NEX
-PIXEL SIZE
-SLICE THICKNESS
-FOV

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23
Q

IF THE SNR INCREASE: ___ DECREASES (4)

A

-T1
-TE
-MATRIX SIZE
-BANDWIDTH

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24
Q

COMES FROM THE SURROUNDING TISSUES

A

NOISE

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25
ALL PARAMETERS ARE ____
CONSTANT
26
RF COIL: SMALLER SENSITIVE VOLUME OF COIL, THE ____ THE NOISE FROM THE ADJACENT STRUCTURES OF THE SELECTED SLICE PLANE WHICH IT CAN DETECT, AND THE ____ THE SIGNAL-TO-NOISE RATION WILL BE
LOWER BETER
27
HAS A HIGHER SIGNAL-TO-NOISE RATIO THAN A BODY COIL
LOCAL COIL / SURFACE COIL
28
"MUSCLE"
PSOAS
29
BANDWIDTH= ____Hz
50,000
30
REFERS TO THE FREQUENCIES ASSOCIATED WITHER WITH RF-EXCITATION (TRANSMITTER BANDWIDTH,tBW) OR SIGNAL RECEPTION (RECEIVER BANDWIDTH, rBW) OR THE HIGHEST OR LOWEST SIGNAL
RF BANDWIDTH
31
SIGNAL RECEPTION
TRANSMITTER BANDWIDTH,tBW
32
THE HIGHEST OR LOWEST SIGNAL
RECEIVER BANDWIDTH, rBW
33
IS THE RANGE OF FREQUENCIES ACCEPTED BY THE RECEIVER TO SAMPLE THE MR SIGNAL.
RECEIVER (OR ACQUISITION) BANDWIDTH
34
rBW HAS A _____ RELATIONSHIP TO THE SIGNAL TO NOISE RATIO (SNR)
DIRECT RELATIONSHIP
35
SNR= _____
1/SQUAREFOOT (rBW)
36
HIGHER THE BANDWIDTHE= _____ IMAGE QUALITY
HIGHER
37
HIGHER THE MAGNETIC FIELD STRENGTH= _____ IMAGE QUALITY
HIGHER
38
BANDWIDTH FORMULA IS:
^W= FOVf / Nf
39
REFERS TO THE RF EXCITATION PULSE REQUIRED FOR SLICE SELECTION IN A PULSE SEQUENCE.
TRANSMIT BANDWIDTH
40
THE SLICE THICKNESS IS _____ TO THE BANDWIDTH OF THE RF PULSE, AND ____ TO THE APPLIED GRADIENT STRENGTH
PROPORTIONAL INVERSELY PROPORTIONAL
41
LOW PULSE BANDWIDTH= ___ SLICE THICKNESS
REDUCED
42
SLICE THICKNESS IN MRI IS DETERMINED:
1. THE BANDWIDTH OF THE RF (LONGER BW, LOWER SLICE THICKNESS) 2. STEEPNESS OF THE SLOPE OF THE GRADIENT COIL (STRENGTH)
43
MRI USES TECHNIQUES CALLED ______ TO ACQUIRE IMAGES WITH DIFFERENT TISSUE CONTRAST MECHANISMS.
PULSE SEQUENCE
44
ARE SET OF PARAMETERS THAT ENABLE US TO IDENTIFY THE ANATOMY
PULSE SEQUENCES
45
ARE A SET OF SPECIFIC INSTRUCTIONS PROGRAMMED INTO THE COMPUTER WITH AN EXPECTATION AS TO HOW THE IMAGES SHOULD APPEAR
PULSE SEQUENCES
46
DWI; ALSO KNOWN AS __
DIFFUSION WEIGHTED IMAGING
47
____ MOVEMENT OF _____ DUE TO RANDOM MOTION
DIFFUSION MOLECULES
48
USED FOR CVA (STROKE) & CNS (CENTRAL NERVOUS SYSTEM)
DIFFUSION WEIGHTED IMAGING
49
THE COMBINATION OF ACTUAL DIFFUSION VALUES AND ___T2 SIGNAL
T2 DIFFUSION WEIGHTED IMAGING
50
DWI: IF AN INCIDENT OCCURS LESS THAN ____ HOURS PRIOR TO THE SCAN, SWELLING DUE TO EDEMA OCCURS
72
51
MRI: COLOR/ IMAGE BLEEDING APPEARS _____ RUGGAE IS ____ IN THE IMAGE
BRIGHT VISIBLE
52
IS MOST APPLICABLE WHEN THE TISSUE OF INTEREST IS DOMINATED BY ISOTROPIC WATER MOVEMENT (E.G. GREY MATTER IN THE CEREBRAL CORTEX AND MAJOR BRAIN NUCLEI, OR IN THE BODY
DWI
53
DWI REMAINS SENSITIVE TO ____ AND _____
T1 RELAXATION T2 RELAXATION
54
TO ENTANGLE DIFFUSION AND RELATION EFFECTS ON THE IMAGE CONTRAST, ONE MAY OBTAIN ______ IMAGES OF THE DIFFUSION COEFFICIENT, OR MORE EXACTLY THE APPARENT DIFFUSION COEFFICIENT (ADC)
QUANTITATIVE
55
WAS INTRODUCED TO TAKE INTO ACCOUNT THE FACT THAT THE DIFFUSION PROCESS IS COMPLEX IN BIOLOGICAL TISSUES AND REFLECTS SEVERAL DIFFERENT MECHANISMS
ADC (APPARENT DIFFUSION COEFFICIENT) CONCEPT
56
IS THE INVERTED GREY SCALE DWI IMAGES
ADC (APPARENT DIFFUSION COEFFICIENT)
57
ARE IMAGES REPRESENTING THE ACTUAL DIFFUSION VALUES OF THE TISSUE WITHOUT T2 EFFECTS
ADC MAPS
58
ADC: THEY ARE THEREFORE MUCH MIRE USEFUL, AND OBJECTIVE MEASURES OF _____ CAN BE OBTAINED, HOWEVER THE ARE ______
DIFFUSION VALUES MUCH LESS PRETTY TO LOOK AT
59
MOST WIDELY USED. STARTS WITH 90 DEGREES PULSE AND ENDS WITH 180 DEGREES PULSE
SPIN ECHO
60
A GRADIENT TO REFOCUS THE SPINS. -ARE MORE SUSCEPTIBLE TO BLOOD FLOW. THEY UTILIZE FLIP ANGLE LESSER THAT _____ DEGREES IN ADDITION TO TR AND TE
GRADIENT ECHO 90 DEGREES
61
AKA REVERSE POLARITY OF GRADIENT
GRADIENT ECHO SEQUENCES (GRE)
62
GRE: FLIP ANGLES IS
LESS THAN 90 DEGREES

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