MEDRADSC 2Z03 Chapter Notes - Chapter 29: Maxillary Sinus, Digital Signal Processing, Perfusion
29 Jun 2016
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Document Summary
Amplitudes of echo signals returned from tissue. Spots of varying brightness in proportion to their intensity. Sound waves -- parallel or fan-shaped beam. Time-motion trace --> records the motion of acoustic reflectors. Principle: one crystal for continuous transmission of pulses; one for the reception of reflected signals. Signal display: returning echoes are displayed acoustically, and also visually o. Frequency shifts --> calculate direction and velocity of blood flow: no info on depth or range of echo source. Principle: one crystal that functions as transmitter and receiver alternately. Signal display: echoes are recorded from designated sample volume during receiving phase: determine the depth and width, investigate blood flow. Principle: cw/ pulsed doppler combine with b-mode imaging. -> visual feedback for positioning the doppler beam and sample volume. Establish the presence or absence of vascularity. Evaluate the quantity of blood flow. Determine the time course and velocity distribution of flow. Key importance in diagnosis of vascular stenosis.
