The document discusses the history and physics of ultrasound imaging and echocardiography. It covers how ultrasound interacts with tissues through reflection, scattering, attenuation and absorption. It describes the basic principles of ultrasound including frequency, wavelength, velocity and acoustic impedance. It also summarizes how ultrasound images are formed using piezoelectric transducers and discusses the different imaging modes and applications of Doppler imaging in cardiology.

1. Physics of Echocardiography Dr. Anil Kumar H.R Junior Consultant Department of Anaesthesiology Narayana Hrudayalaya

5. As sound propagates through a medium the particles of the medium vibrate Air at equilibrium, in the absence of a sound wave Compressions and rarefactions that constitute a sound wave

6. Compressions and rarefactions which constitute the sound wave can be represented as “Sine wave” Amplitude - maximal compression of particles above the baseline Wavelength - distance between the two nearest points of equal pressure and density

8. Sound velocity in different materials Material Velocity ( m/s) Air 330 Water 1497 Metal 3000 - 6000 Fat 1440 Blood 1570 Soft tissue 1540

16. How is ultrasound imaging done? “ From sound to image”

17. Pierre Curie (1859-1906), Nobel Prize in Physics, 1903 Jacques Curie (1856-1941) PIEZOELECTRIC EFFECT

19. Construction of a Transducer Backing Material Electrodes Piezoelectric crystal

20. Electronic Phased Array which uses the principle of Electronic Delay Phased Array Transducers

21. Electronic Focusing Electronic beam steering

22. Characteristics of ULTRASOUND BEAM

23. Length of near field = ( radius) 2 / wavelength of emitted ultrasound

25. Schematic representation of the recording and display of the 2-D image

26. Our TEE Work Station..

31. The Trade off ..

34. A – mode shows the Amplitude of reflected energy at certain depth B- Brightness mode shows the energy as the brightness of the point M- Motion mode the reflector is moving so if the depth is shown in a time plot, the motion will be seen as a curve A B C

37. M-mode beam through Mitral Valve M-Mode Imaging

39. 2-D imaging by steering the transducer over an area that needs to be imaged

40. Mechanical Steering of the Transducer

41. Electronic Phased Array Transducers for 2-D imaging Linear Array Curvilinear Array

42. A single ‘FRAME’ being formed from one full sweep of beams A ‘CINE LOOP’ from multiple FRAMES

45. Comparison between 2-D and Doppler So, both are complementary to each other 2-D Doppler Ultrasound target Tissue Blood Goal of diagnosis Anatomy Physiology Type of information Structural Functional

46. Christian Andreas Doppler (1803 – 1853) DOPPLER EFFECT

48. OBSERVER 2 Long wavelength Low frequency OBSERVER 1 Small wavelength High frequency

49. Doppler Frequency Shift - Higher returned frequency if RBCs are moving towards the and lower if the cells are moving away Doppler principle as applied in Echo..

51. Doppler Equation

55. Importance of being parallel to flow when detecting flow through the aortic valve

56. Velocity is directly proportional to frequency shift and for clinical use it is usual to discuss velocity rather than frequency shift ( although either is correct) V   f d / cos  V = c f d / 2 f o cos  V   f d

60. CWD at LVOT in Deep TG Aortic Long axis view

62. 1/2 PV 2 Pressure Kinetic Energy Potential Energy P = 4V 2 Bernoulli Equation Balancing Kinetic and Potential energy This goes down.. As this goes up..

64. Transducer alternately transmits and receives the ultrasound data to a sample volume. Also known as Range-gated Doppler.

65. PWD at LVOT in Deep TG aortic long axis view

68. Full spectral display of a high velocity profile fully recorded by CW Doppler PW display is aliased, or cut off, and the top is placed at the bottom

72. Multigated, PW Doppler in which blood flow velocities are sampled at many locations along many lines covering the entire imaging sector

73. Echo data is processed through two channels that ultimately combine the image with the color flow data in the final display.

75. CFM v/s Angiography CFM Angiography Records velocity not flow; So in MR, CFM jet area consists of both atrial and ventricular blood – Billiard Ball Effect Records flow Larger regurgitant orifice area there will be smaller jet area Larger regurgitant orifice area there will be larger jet area