Spectral Doppler refers to the combination of either continuous wave Doppler or pulsed Doppler with a spectral display. Spectral Doppler provides a quantitative analysis of the velocity and direction of blood flow.
The Fourier spectrum analyzer performs a fast Fourier transformation on the Doppler signal. The amplitudes of the resulting spectra are encoded as brightness. In the 2D spectral display, the frequency shift is depicted in the vertical and the time in the horizontal axis. The range of blood velocities in the volume produces a corresponding range of frequency shifts.

See also Acceleration Index and Triplex Exam.

Ultrasound biomicroscopy utilizes high frequency (10 - 50 MHz) diagnostic ultrasound to examine living tissue at a microscopic level and allows to image the skin with extremely high resolution to a depth of 2-3 centimeters. Ultrasound biomicroscopy images provide detailed anatomical information that can lead to better and more accurate treatments and avoid a biopsy.
Ultrasound biomicroscopy improves also the spatial resolution of US images of the anterior segment of the eye. US biomicroscopy of the eye operates in the 50 MHz range with a possible axial resolution on the order of 30 μm. In this frequency range, tissue penetration of only approximately 5 mm is attainable. Both continuous wave Doppler and high-frequency pulsed Doppler can be used.

See also Ultrasound Imaging Procedures, A-Scan, B-Scan and C-Scan.

Ultrasound imaging is excellent for diagnosing cysts and other fluids in soft tissue. For ultrasound imaging or ultrasonography, different modes are used to examine the arterial/venous system, heart, pancreas, urinary system, ovaries, spinal cord, joints and more.
Power levels, frequencies used, amplification, and beamforming determine the clarity of the image. These things are controlled by the sonographer, interacting with the properties of the ultrasound machine.

Various imaging modes:

From GE Healthcare.;
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From GE Healthcare.;
'The incredible Vivid i system establishes a completely new level of cardiovascular performance that gives clinicians the freedom to get diagnostic results outside of the echo lab.'