Term
|
Definition
| CHANGE IN FREQUENCY IN SOUND RESULTING FROM MOTION BETWEEN SOURCE (TRANSDUCER) & RECEIVER (RED BLOOD CELLS) |
|
|
Term
| POSITIVE AND NEGATIVE DOPPLER SHIFT |
|
Definition
POSITIVE SHIFT - source & receiver approaching one another
NEGATIVE SHIFT - source & receiver moving away from each other |
|
|
Term
|
Definition
DOPPLER SHIFT =
Reflected Frequency - Incident Frequency
DOPPLER SHIFT =
2 x Reflector Speed x Incident Frequency x cosine angle divided by propagation speed |
|
|
Term
| NUMBER 2 IN DOPPLER SHIFT FORMULA INDICATES: |
|
Definition
| THE NUMBER 2 REPRESENTS (1)THE RED BLOOD CELL’S INITIAL ENCOUNTER WITH THE SOUND WAVE AND (2) THE REDIRECTION OF THE WAVE BACK TO THE SOURCE |
|
|
Term
|
Definition
| Velocity of the reflector = propagation speed times Doppler frequency shift divided by 2 times operating frequency |
|
|
Term
| USE OF DOPPLER ULTRASOUND |
|
Definition
FACILITATES EXAM
PROVIDES QUALITATIVE DATA
PROVIDES QUANTITATIVE DATA
ASSESSES FLOW PATTERNS
PROVIDES INFORMATION ON FLOW DIRECTION |
|
|
Term
| COUNTINOUS WAVE ULTRASOUND |
|
Definition
2 Crystals in transducer
1 crystal continually sends
1 crystal continually listens
Able to measure high velocities
Range ambiguity |
|
|
Term
|
Definition
| ECHOES CAN COME FROM ANYWHERE ALONG THE PATH OF SOUND TRAVEL DUE TO NOT USING RANGE GATE IN CW |
|
|
Term
|
Definition
Has one crystal
Alternates between sending and receiving
Has range resolution
Subject to aliasing |
|
|
Term
|
Definition
| A DISADVANTAGE OF PW DOPPLER IS THAT IT IS SUBJECT TO ALIASING, AND THUS UNABLE TO MEASURE VERY HIGH VELOCITIES ACCURATELY. ALIASING OCCURS WHEN THE NYQUIST LIMIT IS EXCEEDED. THE NYQUIST LIMIT IS 1/2 THE PRF. |
|
|
Term
| WAYS TO ELIMINATE ALIASING |
|
Definition
Shallower sample volume
Lower frequency transducer
Adjust baseline
Increase velocity range
Use CW |
|
|
Term
| SPECTERAL WAVE FORM IS PRESENTED AS: |
|
Definition
X AXIS Represents time
Y AXIS Represents frequency shift or velocity
Z AXIS Relates to pixel brightness |
|
|
Term
|
Definition
AKA: SPECTRAL WINDOW FILLING
LAMINAR FLOW -
narrow range of velocities
NORMAL FLOW -
well circumscribed outline, narrow range of velocities, open spectral window
TURBULENT FLOW -
broad range of velocities
ABNORMAL FLOW -
irregular envelope, spectral window filling |
|
|
Term
| REASONS FOR FALSE WINDOW FILLING |
|
Definition
REASONS:
DOPPLER GAIN SET TOO HIGH
GATE TOO LARGE
GATE TOO CLOSE TO VESSEL WALL
INCORRECT (BAD) DOPPLER ANGLE |
|
|
Term
| WHAT ARE THE TWO TYPE OF ARTERIAL FLOW |
|
Definition
HIGH RESISTANCE
High systolic peak
Low diastolic flow
LOW RESISTANCE
More rounded systolic peak
Relative high level of flow in diastole |
|
|
Term
|
Definition
| THIS MATHEMATICAL FORMULA ALLOWS FOR A RATIO BETWEEN THE PEAK SYSTOLIC VELOCITY AND THE LOWEST DIASTOLIC VELOCITY TO BE OBTAINED. THIS IS KNOW AS THE RESISTIVITY INDEX OF POURCELOT (RI). |
|
|
Term
| WHAT IS THE PURPOSE OF CALCULATING RI |
|
Definition
| ). THE PURPOSE OF CALCULATING THE RI IS TO COMPARE CHANGES IN THE RESISTANCE PATTERN OF A VESSEL WITH A NORMAL VALUE FOR THE VESSEL. IF A HIGH RESISTANCE PATTERN IS SEEN IN AN AREA WHERE A LOW RESISTANCE PATTERN IS EXPECTED, STENOSIS MAY BE DEDUCED. |
|
|
Term
|
Definition
Uses colors to represent frequency shift information relating to flow velocity and flow direction
Provides qualitative information about flow
Collects flow information from a wider field of view than spectral Doppler
Subject to aliasing |
|
|
Term
|
Definition
The number of ultrasound pulses per line of color(ENSEMBLE LENGTH)
Typically (8-30) |
|
|
Term
|
Definition
PACKET SIZE
ENSEMBLE LENGTH
COLOR SENSITIVITY
COLOR QUALITY |
|
|
Term
|
Definition
| THE LINE DENSITY IS THE NUMBER OF SCAN LINES IN THE IMAGE. + HIGHER LINE DENSITIES PRODUCE IMAGES WITH BETTER COLOR RESOLUTION. + HIGHER LINE DENSITIES PRODUCE SMALLER PIXELS. LOWER LINE DENSITIES PRODUCE LARGER PIXELS. IT TAKES MORE TIME TO WRITE MORE LINES, SO HIGHER LINE DENSITIES HAVE SLOWER FRAME RATES. |
|
|
Term
|
Definition
| + USING THIS MAP, DARKER, DULLER COLORS TOWARDS THE MIDDLE OF THE COLOR BAR REPRESENT SLOWER VELOCITIES. + BRIGHTER, LIGHTER COLORS AT THE ENDS OF THE COLOR BAR REPRESENT FASTER VELOCITIES. THE COLOR BAR IS LOCATED TO THE RIGHT OR LEFT SIDE OF THE DISPLAY SCREEN. + |
|
|
Term
|
Definition
| THE VARIANCE MAP ADDS ANOTHER COLOR TO THE DISPLAY. THIS COLOR IS USUALLY GREEN. + WHEN VARIANCE IN VELOCITIES INCREASES, THE BRIGHTNESS OF THE GREEN INCREASES. + THE COLOR GREEN SIGNIFIES A DISTURBED OR TURBULENT FLOW PATTERN. |
|
|
Term
|
Definition
MATHEMATICAL TECHNIQUE USED TO PROCESS DOPPLER FLOW FREQUENCIES IN COLOR DOPPLER
NOT AS ACCURATE AS SPECTRAL DOPPLER |
|
|
Term
| INFORMATIONS PROVIDED BY AUTOCORELATION |
|
Definition
Direction (positive or negative)
Average frequency shift
Amplitude or power
Variance |
|
|
Term
|
Definition
| . ALIASING OCCURS WHEN THE FREQUENCY OF THE DOPPLER SHIFT EXCEEDS 1/2 THE PULSE REPETITION FREQUENCY. WHEN ALIASING OCCURS THE COLORS WRAP AROUND THE COLOR BAR AND POSITIVES ARE DEPICTED AS NEGATIVES. REASONS FOR ALIASING INCLUDE HIGH VELOCITIES AND A COLOR VELOCITY SCALE SETTING THAT IS TOO LOW |
|
|
Term
| WHAT IF WE DON'T GET ANY FLOW |
|
Definition
1. MAKE SURE THE PRF OR VELOCITY RANGE SETTING IS SET TO PROPERLY DETECT ARTERIAL OR VENOUS FLOW.
+ 2. COLOR FLOW DIMINISHES AS THE ANGLE APPROACHES 90 DEGREES. CHANGE THE ANGLE OF VESSEL INSONATION.
+ 3. USING MORE DEPTH THAN NEEDED INCREASES THE PROCESSING TIME AND DECREASES THE PRF, AND THUS THE NUMBER PULSES PER SQUARE CM.
+ 4. THE COLOR BOX SHOULD BE ADJUSTED TO SAMPLE ONLY THE AREA YOU WANT TO ASSESS.
+ 5. MAKE SURE THE COLOR GAIN AND POWER SETTINGS ARE NOT TOO HIGH OR LOW.
+ 6. CHANGE PRIORITIES TO COLOR VERSUS GRAY SCALE IF NECESSARY.
+ 7. THE THUMP CONTROL REFERS TO ELECTRONIC FILTERING TO REMOVE TOO MUCH COLOR FROM THE IMAGE DUE TO THE MOVEMENT OF THE HEART OR VESSELS. PERIPHERAL VESSELS DO NOT NEED THE FILTER AS MUCH. TOO HIGH A SETTING MAY CAUSE THE VESSEL TO SHOW TOO LITTLE COLOR.
+ 8. THE WALL FILTER IS SET TO FILTER OUT LOW FREQUENCY SIGNALS. IF SET TOO HIGH IT WILL ALSO FILTER OUT LOW VELOCITY FLOW. THIS MAY BE PROBLEMATIC IN THE VEINS AND SMALL ARTERIES IN THE RENALS.
+ 9. VERY, VERY SLOW FLOW CAN BE TOO LITTLE FOR DETECTION BY COLOR. SPECTRAL WAVEFORMS OR POWER DOPPLER MAY BE USED TO BE SURE THAT THERE IS NO FLOW AT ALL. + |
|
|
Term
|
Definition
AKA: COLOR DOPPLER ENERGY, ULTRASOUND ANGIO, COLOR POWER ANGIO
BASCOLOR MAPS ARE REPRESENTED BY A SINGE CONTINUOUS COLOR. + IT ESTIMATES THE POWER OF THE DOPPLER SHIFTS WITHIN A SPECIFIC REGION. + THE POWER OF THE SHIFT RELATES TO THE CONCENTRATION OF REFLECTORS (THE RED BLOOD CELLS). ED ON AMPLITUDE OF BLOOD CELL MOTION |
|
|
Term
| ADVANTAGES OF POWER DOPPLER |
|
Definition
Not angle dependant
Not subject to aliasing
Greater sensitivity to flow
Improved noise filtering |
|
|
Term
| ROCKING MOVEMENT IS USED TO |
|
Definition
| ROCKING (HEEL TOE) - banking the probe on the long axis of beam; causes vessel to head uphill or downhill in SAG; side to side in TRV |
|
|
Term
| THREE SCANNING APPROACHES IN CAROTID: |
|
Definition
ANTERIOR LATERAL
LATERAL
POSTERIOR LATERAL |
|
|
Term
|
Definition
Low resistance flow
Continuous forward flow
Has no branches in cervical region
Usually larger
Usually posterolateral |
|
|
Term
|
Definition
High resistance flow
Has branches in the cervical portion
Usually smaller
Usually anteromedial
Responds to the temporal tap |
|
|
Term
|
Definition
Elements of ICA and ECA both present
Moderate flow in diastole
Has sharp upstroke and peak
Has well defined dicrotic notch
Velocities not definitively established |
|
|
Term
|
Definition
Low resistance pattern
Substantial flow in diastole
Dicrotic notch not well seen
Broad systolic peaks
Peak systolic velocities range from 54-88 cm/sec
Peak systolic velocities of greater than 100 cm/sec abnormal |
|
|
Term
|
Definition
High resistance pattern
Relatively little flow in diastole
Sharp systolic upstroke
Diacritic notch well visualized
Peak systolic velocities range from 77cm/sec - 115 cm/sec |
|
|
Term
|
Definition
Infiltration of intima by lipid substances
Initially affects intima; later intima & media
With progressive build up there is a deposition of:
Fibrotic materials
Hemorrhagic products
Calcifications |
|
|
Term
| APPEARANCE OF INTIMAL PLAQUE |
|
Definition
ECHOGENIC
HAVE A NARROW UNIFORM WIDTH |
|
|
Term
| APPEARANCE OF INTIMAL PLAQUE |
|
Definition
ECHOGENIC
HAVE A NARROW UNIFORM WIDTH |
|
|
Term
| CHARACTERIZATION OF PLAQUE |
|
Definition
| SMOOTH PLAQUE PRESENTS LESS RISK. + PLAQUE WHICH HAS IRREGULAR BORDERS IS KNOW AS IRREGULAR OR ULCERATED. + ULCERATED PLAQUE IS DANGEROUS BECAUSE IT MAY CAUSE NARROWING OR OCCLUSION OF LUMEN, AND AGGREGATES OF PLATELETS OR PORTIONS OF THE PLAQUE MAY BREAK FREE AS EMBOLI AND BE SWEPT INTO THE BRAIN CAUSING STROKE. IF THE AREA OF ULCERATION IS 2MM OR GREATER IT IS OF MORE CONCERN. |
|
|
Term
|
Definition
| . HOLLENHORST PLAQUE REFERS TO EMBOLIC PLAQUE THAT IS SWEPT INTO THE TINY ARTERIES OF THE EYE. MOST OF THE TIME THIS IS SECONDARY TO CAROTID ARTERY BIFURCATION DISEASE. + |
|
|
Term
| CHARACTERISTICS OF NORMAL SPECTRAL WAVEFORM |
|
Definition
NARROW RANGE OF VELOCITIES IN SYSTOLE AND DIASTOLE
OPEN CLEAN SPECTRAL WINDOW
PEAK SYSTOLIC VELOCITIES DO NOT EXCEED 125 CM/SEC |
|
|
Term
| WHEN A STENOSIS IS HEMODYNAMICALLY SIGNIFICANT |
|
Definition
| A HEMODYNAMICALLY SIGNIFICANT STENOSIS IS ONE IN WHICH THE LUMEN OF THE VESSEL IS DECREASED BY 50-60%. AT THIS POINT THE VOLUME OF FLOW WHICH IS DELIVERED TO THE BRAIN IS DIMINISHED. CORRESPONDING CHANGES IN VELOCITIES AND WAVEFORM PATTERNS ARE EVIDENT AS WELL. LOTS OF ATTENTION IS GIVEN TO THE 50-60% LEVELS OF STENOSIS BECAUSE SURGICAL TREATMENT IS CONSIDERED AT THIS POINT |
|
|
Term
| WHICH ONE? % DIAMETER REDUCTION OR % AREA REDUCTION |
|
Definition
| ALTHOUGH AREA REDUCTION IS MORE ACCURATE IN DETERMINING THE DEGREE OF STENOSIS WITH ECCENTRIC PLAQUE, DIAMETER REDUCTION IS THE METHOD USED IN ULTRASOUND ASSESSMENT. + A 50% DIAMETER REDUCTION CORRELATES WITH A 75% AREA REDUCTION. + AT THE 50-60% DIAMETER REDUCTION LEVELS THE PEAK SYSTOLIC AND END DIASTOLIC VELOCITIES INCREASE, AND SPECTRAL BROADENING OCCURS. |
|
|
Term
| HOW IS FLOW IN PRESTENOTIC LOCATION |
|
Definition
Proximal to stenosis
Peak systolic velocities normal
Maybe a resistive flow pattern in diastole |
|
|
Term
|
Definition
Peak systolic velocities increase
End diastolic velocities increase
Spectral broadening occurs |
|
|
Term
| FLOW IN POST STENOTIC SITE |
|
Definition
Peak systolic velocities decrease
End diastolic velocities decrease
Turbulent flow is present |
|
|
Term
| WHICH SITE TO SAMPLE PRE, AT OR POST |
|
Definition
| SAMPLING MUST OCCUR PRE-STENOTICALLY, AT THE STENOSIS, AND POST-STENOTICALLY! |
|
|
Term
|
Definition
NORMAL peak systolic velocity less than 125 cm/sec
MILD (1-15%) velocities in diastole slightly increased, peak systolic does not exceed 125 cm/sec, open sonic window |
|
|
Term
|
Definition
| MODERATE (16-49%) peak systolic velocities do not exceed 125 cm/sec, spectral broadening may or may not be present ; ICA/CCA ratio less than 1.5 |
|
|
Term
| MODERATLY SEVERE STENOSIS |
|
Definition
| MODERATELY SEVERE (49-80%) peak systolic velocities greater than 125 cm/sec, end diastolic velocities increase but not higher than 105 cm/sec, spectral broadening and window filling; ICA/CCA ratio is 2.0 or greater |
|
|
Term
|
Definition
| SEVERE (80-99%) peak systolic velocities 250 cm/sec or greater, end diastolic velocities exceed 110 cm/sec, marked spectral broadening and window filling; ICA/CCA ratio is 5.6 or greater |
|
|
Term
| WHAT TO DO IN SEARCH FOR STRING SIGN(LITTLE FLOW WITH NEAR TOTAL OCCLUTION |
|
Definition
LOWER PRF (VELOCITY SCALE)
LOWER WALL FILTER
TURN UP DOPPLER GAIN
INCREASE SAMPLE SIZE
GO DISTAL IN ICA (may detect flow distal to severe stenosis proving there is flow)
USE POWER DOPPLER |
|
|
Term
|
Definition
NO FLOW VISUALIZED
LUMEN IS FILLED WITH ECHOES
WALLS ARE NOT PULSATILE
BLUNTED DOPPLER IN CCA
NO DIASTOLIC FLOW IN CCA
DRUMBEAT DOPPLER IN PROX ICA (flow may reverse) |
|
|
Term
| CCA FLOW WITH PROXIMAL STENOSIS |
|
Definition
Dampened systolic component
Forward flow in diastole with increase in diastolic flow
Decrease in pulsatility |
|
|
Term
| CCA WAVEFORM WITH DISTAL STENOSIS (SEVERE) |
|
Definition
Blunted systolic portion
Diastolic component absent or decreased
Distal obstruction is apparent in diastolic component |
|
|
Term
| INDIRECT CEREBROVASCULAR TESTING |
|
Definition
OPHTHALMIC ARTERY FIRST BRANCH OF ICA
ALTERED HEMODYNAMICS IN THE OPHTHALMIC, ITS BRANCHES, AND ECA BRANCHES REFLECT PROXIMAL DISEASE |
|
|
