SONOGRAPHIC PHYSICS, INSTRUMENTATION & DOPPLER REVIEW Part 3

Transcription

1 SONOGRAPHIC PHYSICS, INSTRUMENTATION & DOPPLER REVIEW 2012 Part 3 1

2 Doppler Imaging 2

3 DOPPLER TRANSDUCER SAME FREQUENCY During Doppler operation, the reflected sound has the same frequency as the transmitted sound if the blood is stationary. 3

4 DOPPLER TRANSDUCER LOWER FREQUENCY During Doppler operation, the reflected sound has a lower frequency if the blood is moving away from the sound source. 4

5 DOPPLER TRANSDUCER HIGHER FREQUENCY During Doppler operation, the reflected sound has a higher frequency if the blood is moving toward the sound source. 5

6 DOPPLER SHIFT f 6

7 DOPPLER SHIFT FORMULA An increase in blood velocity produces an increase in the Doppler shift. An increase in the transmitted frequency produces an increase in the Doppler shift. A Doppler angle of 0º produces the maximum possible Doppler shift. A Doppler shift is not produced when the Doppler angle is 90º. 7

8 BLOOD VELOCITY FORMULA A Doppler system is capable of measuring only the Doppler shift. It calculates the blood velocity. An increase in the Doppler shift produces an increase in the calculated blood velocity. 8

9 DOPPLER RELATIONSHIPS TRANSMITTED FREQUENCY f o DOPPLER ANGLE q BLOOD VELOCITY V DOPPLER SHIFT f Increase Increase Decrease Decrease Increase Decrease Decrease Increase Increase Increase Decrease Decrease 9

10 DOPPLER CALCULATIONS Doppler shifts ( f) for V = 100 cm per second c = 1550 meters per second q cos q f o = 2.5 MHz f o = 5.0 MHz Hz 6452 Hz Hz 5588 Hz Hz 4562 Hz Hz 3226 Hz Hz 1670 Hz Hz 0 Hz 10

11 DOPPLER SHIFT EXAMPLE TRANSMITTED FREQUENCY RECEIVED FREQUENCY DOPPLER SHIFT f DIRECTION OF FLOW TO SOUND 5 MHz MHz 5 khz Away 5 MHz MHz 5 khz Toward 11

12 SPECTRAL DOPPLER FFT DISPLAY: POSITIVE DOPPLER SHIFT WITHOUT SPECTRAL BROADENING FREQUENCY SCALES FFT DISPLAY: POSITIVE DOPPLER SHIFT WITH SPECTRAL BROADENING 12

13 CW SPECTRAL DOPPLER NON-IMAGING CW B-MODE IMAGING AND CW 13

14 CW SPECTRAL DOPPLER NON-IMAGING CARDIAC CW DOPPLER TRANSDUCER 14

15 CW SPECTRAL DOPPLER CW DOPPLER DETECTING SHIFTS FROM MORE THAN ONE VESSEL 15

16 CW SPECTRAL DOPPLER B-MODE AND CW DOPPLER WITH SPECTRUM ANALYZER DISPLAY 16

17 PW SPECTRAL DOPPLER PW TRANSMITTING PW RECEIVING 17

18 PW SPECTRAL DOPPLER NON-IMAGING PW B-MODE IMAGING AND PW 18

19 PW SPECTRAL DOPPLER 19

20 PW SPECTRAL DOPPLER NORMAL SAMPLE VOLUME WITH NO SPECTRAL BROADENING LARGER THAN NORMAL SAMPLE VOLUME WITH SPECTRAL BROADENING 20

21 PW SPECTRAL DOPPLER PW TRANSDUCERS USED FOR TRANSCRANIAL DOPPLER 21

22 PW - ALIASING WRAP-AROUND 22

23 PW - ALIASING POSITIVE DOPPLER SHIFT WITH THE NYQUIST LIMIT (N.L) EXCEEDED AS A RESULT OF HIGH VELOCITY FLOW 23

24 PW - ALIASING ALIASING: NYQUIST LIMIT EXCEEDED SAME DOPPLER SHIFT BUT ALIASING ELIMINATED SCALE ADJUSTED TO INCREASE THE PULSE DOPPLER PRF AND RAISE THE NYQUIST LIMIT 24

25 PW - ALIASING ALIASING: NYQUIST LIMIT EXCEEDED SAME DOPPLER SHIFT BUT ALIASING ELIMINATED BASE LINE LOWERED TO INCREASE THE PULSE DOPPLER PRF AND RAISE THE NYQUIST LIMIT 25

26 PW - ALIASING ALIASING: NYQUIST LIMIT EXCEEDED ALIASING ELIMINATED DOPPLER ANGLE INCREASED SCALE, BASELINE, AND PRF UNCHANGED 26

27 PW - ALIASING ALIASING: NYQUIST LIMIT EXCEEDED ALIASING ELIMINATED TRANSDUCER FREQUENCY DECREASED SCALE, BASELINE, AND PRF UNCHANGED 27

28 PW - ALIASING NYQUIST LIMIT EXCEEDED 28

29 NYQUIST LIMIT NYQUIST LIMITS (PRF 2) PRF N.L. 1 khz (1000 Hz) 500 Hz 2 khz (2000 Hz) 1000 Hz 3 khz (3000 Hz) 1500 Hz 4 khz (4000 Hz) 2000 Hz 5 khz (5000 Hz) 2500 Hz 6 khz (6000 Hz) 3000 Hz 29

30 CW NO ALIASING 30

31 ANGLE-CORRECT PW - VELOCITY CORRECT: PROPER ANGLE-CORRECT VELOCITY SCALES PW - VELOCITY INCORRECT: IMPROPER ANGLE-CORRECT 31

32 WALL FILTERS WALL FILTER SETTING NORMAL WALL FILTER SETTING TOO HIGH 32

33 DOPPLER GAIN DOPPLER GAIN SETTING NORMAL DOPPLER GAIN SETTING TOO HIGH 33

34 Color-flow Imaging 34

35 COLOR-FLOW IMAGING 35

36 COLOR-FLOW IMAGING STANDARD COLOR MAP 36

37 COLOR-FLOW IMAGING ENHANCED COLOR MAP 37

38 COLOR-FLOW IMAGING STANDARD COLOR MAP 38

39 COLOR-FLOW IMAGING COLOR VARIANCE MAP 39

40 COLOR-FLOW IMAGING CAROTID 40

41 COLOR-FLOW IMAGING STANDARD COLOR MAP COLOR DOPPLER SAMPLE ANGLES 2-D, SPECTRAL DOPPLER, & COLOR-FLOW DOPPLER ECHOCARDIOGRAPHIC STUDY (Triplex) 41

42 COLOR-FLOW IMAGING COLOR-FLOW DOPPLER 42

43 COLOR-FLOW & POWER DOPPLER IMAGING COLOR-FLOW DOPPLER POWER DOPPLER 43

44 POWER DOPPLER & SPECTRAL DOPPLER 44