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MRI > MIDTERM- PT. 3 > Flashcards

MIDTERM- PT. 3 Flashcards

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
Q

ALL PARAMETERS ARE ____

A

CONSTANT

26
Q

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

A

LOWER
BETER

27
Q

HAS A HIGHER SIGNAL-TO-NOISE RATIO THAN A BODY COIL

A

LOCAL COIL / SURFACE COIL

28
Q

“MUSCLE”

A

PSOAS

29
Q

BANDWIDTH= ____Hz

A

50,000

30
Q

REFERS TO THE FREQUENCIES ASSOCIATED WITHER WITH RF-EXCITATION (TRANSMITTER BANDWIDTH,tBW) OR SIGNAL RECEPTION (RECEIVER BANDWIDTH, rBW) OR THE HIGHEST OR LOWEST SIGNAL

A

RF BANDWIDTH

31
Q

SIGNAL RECEPTION

A

TRANSMITTER BANDWIDTH,tBW

32
Q

THE HIGHEST OR LOWEST SIGNAL

A

RECEIVER BANDWIDTH, rBW

33
Q

IS THE RANGE OF FREQUENCIES ACCEPTED BY THE RECEIVER TO SAMPLE THE MR SIGNAL.

A

RECEIVER (OR ACQUISITION) BANDWIDTH

34
Q

rBW HAS A _____ RELATIONSHIP TO THE SIGNAL TO NOISE RATIO (SNR)

A

DIRECT RELATIONSHIP

35
Q

SNR= _____

A

1/SQUAREFOOT (rBW)

36
Q

HIGHER THE BANDWIDTHE= _____ IMAGE QUALITY

A

HIGHER

37
Q

HIGHER THE MAGNETIC FIELD STRENGTH= _____ IMAGE QUALITY

A

HIGHER

38
Q

BANDWIDTH FORMULA IS:

A

^W= FOVf / Nf

39
Q

REFERS TO THE RF EXCITATION PULSE REQUIRED FOR SLICE SELECTION IN A PULSE SEQUENCE.

A

TRANSMIT BANDWIDTH

40
Q

THE SLICE THICKNESS IS _____ TO THE BANDWIDTH OF THE RF PULSE, AND ____ TO THE APPLIED GRADIENT STRENGTH

A

PROPORTIONAL
INVERSELY PROPORTIONAL

41
Q

LOW PULSE BANDWIDTH= ___ SLICE THICKNESS

A

REDUCED

42
Q

SLICE THICKNESS IN MRI IS DETERMINED:

A
  1. THE BANDWIDTH OF THE RF (LONGER BW, LOWER SLICE THICKNESS)
  2. STEEPNESS OF THE SLOPE OF THE GRADIENT COIL (STRENGTH)
43
Q

MRI USES TECHNIQUES CALLED ______ TO ACQUIRE IMAGES WITH DIFFERENT TISSUE CONTRAST MECHANISMS.

A

PULSE SEQUENCE

44
Q

ARE SET OF PARAMETERS THAT ENABLE US TO IDENTIFY THE ANATOMY

A

PULSE SEQUENCES

45
Q

ARE A SET OF SPECIFIC INSTRUCTIONS PROGRAMMED INTO THE COMPUTER WITH AN EXPECTATION AS TO HOW THE IMAGES SHOULD APPEAR

A

PULSE SEQUENCES

46
Q

DWI; ALSO KNOWN AS __

A

DIFFUSION WEIGHTED IMAGING

47
Q

____ MOVEMENT OF _____ DUE TO RANDOM MOTION

A

DIFFUSION
MOLECULES

48
Q

USED FOR CVA (STROKE) & CNS (CENTRAL NERVOUS SYSTEM)

A

DIFFUSION WEIGHTED IMAGING

49
Q

THE COMBINATION OF ACTUAL DIFFUSION VALUES AND ___T2 SIGNAL

A

T2
DIFFUSION WEIGHTED IMAGING

50
Q

DWI: IF AN INCIDENT OCCURS LESS THAN ____ HOURS PRIOR TO THE SCAN, SWELLING DUE TO EDEMA OCCURS

A

72

51
Q

MRI: COLOR/ IMAGE
BLEEDING APPEARS _____
RUGGAE IS ____ IN THE IMAGE

A

BRIGHT
VISIBLE

52
Q

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

A

DWI

53
Q

DWI REMAINS SENSITIVE TO ____ AND _____

A

T1 RELAXATION
T2 RELAXATION

54
Q

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)

A

QUANTITATIVE

55
Q

WAS INTRODUCED TO TAKE INTO ACCOUNT THE FACT THAT THE DIFFUSION PROCESS IS COMPLEX IN BIOLOGICAL TISSUES AND REFLECTS SEVERAL DIFFERENT MECHANISMS

A

ADC (APPARENT DIFFUSION COEFFICIENT) CONCEPT

56
Q

IS THE INVERTED GREY SCALE DWI IMAGES

A

ADC (APPARENT DIFFUSION COEFFICIENT)

57
Q

ARE IMAGES REPRESENTING THE ACTUAL DIFFUSION VALUES OF THE TISSUE WITHOUT T2 EFFECTS

A

ADC MAPS

58
Q

ADC: THEY ARE THEREFORE MUCH MIRE USEFUL, AND OBJECTIVE MEASURES OF _____ CAN BE OBTAINED, HOWEVER THE ARE ______

A

DIFFUSION VALUES
MUCH LESS PRETTY TO LOOK AT

59
Q

MOST WIDELY USED. STARTS WITH 90 DEGREES PULSE AND ENDS WITH 180 DEGREES PULSE

A

SPIN ECHO

60
Q

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

A

GRADIENT ECHO
90 DEGREES

61
Q

AKA REVERSE POLARITY OF GRADIENT

A

GRADIENT ECHO SEQUENCES (GRE)

62
Q

GRE: FLIP ANGLES IS

A

LESS THAN 90 DEGREES

MRI (5 decks)

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