Principles of Medical Ultrasound

1. Principles of Medical Ultrasound Pai-Chi Li Department of Electrical Engineering National Taiwan University

2. What is Medical Ultrasound? • Prevention: actions taken to avoid diseases. • Diagnosis: the process of identifying a disease by its signs, symptoms and results of various diagnostic procedures. • Treatment: care by procedures or applications that are intended to relieve illness or injury.

3. Diagnosis

4. Medical Diagnosis: Heart Attack as an Example • Heart attack: Coronary artery disease, blockage of blood supply to the myocardium.

5. Medical Diagnosis: Heart Attack as an Example • Plaque: A gradual build-up of fat (cholesterol) within the artery wall.

6. Medical Diagnosis: Heart Attack as an Example • Symptoms: • Chest pressure with stress, heart burn, nausea, vomiting, shortness of breath, heavy sweating. • Chest pain, heart attack, arrhythmias.

7. Medical Diagnosis: Heart Attack as an Example • Diagnosis: • Prehospital electrocardiography (ECG). • Continuous/serial ECG. • Exercise stress ECG. • Biochemical tests and biomarkers. • Sestamibi myocardial perfusion imaging. • Echocardiography. • Computer-based decision aids.

11. Doppler Tissue Imaging

12. Doppler Tissue Imaging Integration in time Derivation in space Integration in time

13. Doppler Tissue Imaging

14. Treatment

15. Controlled Ultrasound Tissue Erosion • Hypoplastic left heart syndrome (HLHS).

16. Ultrasound Cardiac Ablation

17. Medical Diagnosis: Heart Attack as an Example • Treatment: • Angioplasty. • Stent implantation. • Atherectomy. • Coronary bypass surgery. • Intravascular radiotherapy. • Excimer laser.

18. Medical Diagnosis: Heart Attack as an Example • Imaging: • Ultrasound.

19. Medical Diagnosis: Heart Attack as an Example • Imaging: • Optics.

20. What is Medical Ultrasound? • Wave: various propagation modes (longitudinal, shear, …etc.). • Mechanical wave: density, elastic properties, …etc. • Wave: scattering, diffraction, refraction, …etc. • Mechanical wave: heating, cavitation, …etc.

21. Bio-Effects • Heating • Cavitation

22. Ultrasound Heating • Bio-transfer equation:

23. Bio-Effects • Heating • Cavitation

24. Cavitation • Formation and behavior of gas bubbles in acoustic fields. • Transient cavitation: sudden growth and collapse of bubbles, resulting shock waves and very high temperatures.

25. Other Acoustic Phenomena • Radiation force. • Sonoluminescence. • …etc.

26. Radiation Force • An ultrasonic wave exerts a static force on an interface or in a medium where there is a decrease in power in the wave propagation direction.

27. Other Acoustic Phenomena • Radiation force. • Sonoluminescence. • …etc.

28. Sonoluminescence • Weak emission of light observable when high intensity ultrasound passing through a medium containing dissolved gases.

29. …,etc.

30. History of UltrasoundWho are the smart guys?

31. History of Ultrasound • A long time ago:

32. History of Ultrasound • A long time ago:

33. History of Ultrasound • 1822, Lake Geneva:

34. History of Ultrasound • Piezoelectric effect, Pierre Curie, 1880:

35. History of Ultrasound • 1947, Karl Dussik:

36. History of Ultrasound • 1954-1957:

37. History of Ultrasound • 1954-1957:

38. History of Ultrasound • Doppler (1842):

39. History of Ultrasound • Doppler ultrasound (1959-1960): (1966)

40. History of Ultrasound

41. History of Ultrasound

42. History of Ultrasound

43. History of Ultrasound

44. Overview of Ultrasonic Imaging