Ultrasound Imaging• Basic Principle: sound wave pulse emitted at >20 kHZ,

some reflected, and some transmitted. • Reflection from single signal – A-scan

Reproduced from http://folk.ntnu.no/stoylen/

B-Mode Imaging

• Energy displayed as: - amplitude, as in A-mode, - brightness, as in B-mode, - motion curve, as in M-mode.

• 2D image formed with linear or angular sweep.

Reproduced from http://folk.ntnu.no/stoylen/

B-Mode 2D Imaging

• Image built line by line: i) emitting the pulse, ii) waiting for reflected echoes iii) tilt beam & emit next pulse.

• Cardiac application: 2D visualization of beating heart.

Reproduced from http://folk.ntnu.no/stoylen/

Doppler Imaging

• Idea: moving source of sound undergoes Doppler shift. 1. Moving train2. Blood flow: exploit frequency shift to estimate motion.

Reproduced from http://folk.ntnu.no/stoylen/ & Wikimedia Commons.