1. Echo Physics Stephen Devries, MD

3. Velocity = Frequency(transducer) x Wavelength Velocity changes with media increases through muscle (1580 m/sec) decreases through fat (1450 m/sec) markedly decreases through air (330 m/sec) Smaller wavelength Greater resolution

4. Amplitude is strength of signal (measured in log of decibels) Power is a function of amplitude Increase of 6 dB is a doubling of signal amplitude

5. Ultrasound Transducer Pizoelectric crystals, stimulated by AC, generate sound waves Pizoelectric crystals, deformed by received sound waves, produce current

6. Increasing Frequency Extends Near Field Resolution

15. Continuous Wave Doppler

17. Pulse Doppler

26. Velocity as a Hemodynamic Measurement Modified Bernoulli Equation Pressure Gradient = 4V 2

30. Several Descriptors of “Gradient”