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The accuracy of video signal analysis (VSA) attenuation estimates computed for B-mode images obtained after bandpass filtering of the broadband echo signals is evaluated. Unbiased attenuation estimation was provided by the narrowband VSA for frequencies lower than or at the center frequency of the broadband pulse.

An ultrasound research platform is described that allows easy access to raw radio frequency (RF) data as well as user software control over many system functions. The Ultrasonix 500RP system has provided research access to the data at multiple points in the signal processing chain and has allowed control over most imaging parameters.

A theoretical analysis of the correlation between radio-frequency (RF) echo signal data acquired from the same location but at different angles is presented. Theoretical results provide a clear understanding of angular compounding techniques used to improve the signal-to-noise ratio in ultrasonic parametric imaging and in elastography.

A phased-array transducer is translated using a precision linear stage to acquire radio frequency (RF) data from locations in a phantom at different incident angles. It is observed that the resultant scatterer-size images exhibit higher signal-to-noise ratio (SNR) with greater degrees of angular compounding.

Ultrasound elastography is developed into an imaging modality suitable for detection and diagnosis of cancers in breast, prostrate and thyroid. A new approach is described that enables the reduction of noise artifacts in elastography without significant reduction in either the contrast or spatial resolution.

Harmonic field generation through a layered liquid media is studied experimentally and theoretically. The beam patterns for transmission is computed through a layered media and these predictions are compared with measured beam profiles. Results indicate very good agreement between experimental measurements and numerical solutions.

The effects of acoustic attenuation on the statistical characteristics of ultrasonic echo signals were investigated using tissue-mimicking phantoms. To this end, samples bearing the same scatterer number density but different amounts of attenuation were interrogated with pulses from a 5 MHz focused transducer. Experimental results showed that the non-Gaussian parameter, 1/beta recorded in the focal region decreased when the attenuation in the route between the transducer and region of interest increased. This observation is in agreement with previous data indicating that beam widths of broad bandwidth transducers increase near the focal region when higher levels of tissue-like attenuation are placed in the beam path.

The frequency dependence of backscatter coefficients (BSC) depends on the concentration of the scatterer volume fraction. Continuum scattering models show that the scatterer volume fraction, when there is maximum BSC, depends on the ultrasound frequency. For a certain length of the spatial autocorrelation function, the frequency dependence of scattering is greater than the fourth-power in a dense scattering medium. Spatial autocorrelation is a function of the scatterer volume fraction.

Signals associated with a medium having randomly distributed scatterers are used to derive theoretical expressions for non-Rayleigh and non-Gaussian parameters. Transducer field and pulse frequency content influence these parameters. Experiments are conducted to prove a simple relationship between non-Gaussian and non-Rayleigh properties.

Backscatter coefficient measurements are tested for full spectrum accuracy using broadband pulses generated by a well-characterized phantom material. Multi-durational rectangular and Hamming windows are used for echo data reduction for gating function effects on solutions. Backscatter coefficients quantify ecological tissue scatterings in medical ultrasound.

In this review, we describe how technological advances in ultrasound imaging related to transducer construction and image processing fundamentally alter generation of ultrasound images to produce better quality images with higher resolution. However, carotid intima–media thickness (IMT) measurements made from images acquired on modern ultrasound systems are not comparable to historical population nomograms that were used to determine wall thickness thresholds that inform atherosclerotic cardiovascular disease risk. Because it is nearly impossible to replicate instrumentation settings that were used to create the reference carotid IMT nomograms and to place an individual's carotid IMT value in or above a clinically relevant percentile, carotid IMT measurements have a very limited role in clinical medicine, but remain a useful research tool when instrumentation, presets, image acquisition, and measurements can be standardized. In addition to new validation studies, it would be useful for the ultrasound imaging community to reach a consensus regarding technical aspects of ultrasound imaging acquisition, processing, and display for blood vessels so standard presets and imaging approaches could reliably yield the same measurements. [ABSTRACT FROM AUTHOR]