Conventional ultrasound images are formed by delay-and-sum beamforming of the backscattered echoes received by individual elements of the transducer aperture. Although the delay-and-sum beamformer is well suited for ultrasound image formation, it is corrupted by speckle noise and challenged by acoustic clutter and phase aberration. We propose an alternative method of imaging utilizing the short-lag spatial coherence (SLSC) of the backscattered echoes. Compared with matched B-mode images, SLSC images demonstrate superior SNR and contrast-to-noise ratio in simulated and experimental speckle-generating phantom targets, but are shown to be challenged by limited point target conspicuity. Matched B-mode and SLSC images of a human thyroid are presented. The challenges and opportunities of real-time implementation of SLSC imaging are discussed.

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Short-lag spatial coherence of backscattered echoes: imaging characteristics

The experimental test of novel ultrasound (US) investigation methods can be made difficult by the lack of flexibility of commercial US machines. In the best options, these only provide beamformed radiofrequency or demodulated echo-signals for acquisition by an external PC. More flexibility is achieved in high-level research platforms, but these are typically characterized by high cost and large size. This paper presents a powerful but portable US system, specifically developed for research purposes. The system design has been based on high-level commercial integrated circuits to obtain the maximum flexibility and wide data access with minimum of electronics. Preliminary applications involving nonstandard imaging transmit/receive strategies and simultaneous B-mode and multigate spectral Doppler mode are discussed.

ULA-OP: an advanced open platform for ultrasound research

REVIEW: Ultrasound imaging

http://www.brl.uiuc.edu/Publications/2015/ClinGastroHepatol.pdf

Noninvasive Diagnosis of Nonalcoholic Fatty Liver Disease and Quantification of Liver Fat Using a New Quantitative Ultrasound Technique

Ultrasound image segmentation deals with delineating the boundaries of structures, as a step towards semi-automated or fully automated measurement of dimensions or for characterizing tissue...

Ultrasound image segmentation and tissue characterization.

Under a contract with the National Cancer Institute, we have developed a research interface to an ultrasound system. This ultrasound research interface (URI) is an optional feature providing several basic capabilities not normally available on a clinical scanner. The URI can store high-quality beamformed radio-frequency data to file for off-line processing. Also, through an integrated user interface, the user is provided additional control over the B-mode receive aperture and color flow ensemble size. A third major capability is the ability to record and playback macro files. In this paper, we describe the URI and illustrate its use on three research examples: elastography, computed tomography, and spatial compounding

An ultrasound research interface for a clinical system

Errata - An ultrasound research interface for a clinical system

The capability of ultrasound transmission tomography to reconstruct acoustic parameters of proven histological relevance like acoustic speed and attenuation has been established over the past few decades by several researchers. The approach taken so far was a fully custom designed transmission tomography system which is a considerably multifaceted venture. The outcome of the earlier research proved the feasibility of the concept but fell short of the clinical requirements due to its inadequate spatial resolution and reconstruction accuracy on one hand and its experimental nature on the other hand. The major consideration behind the novel approach presented here is to make use of a commercially available ultrasound system and to supplement it with an add-on module, the latter being designed to extend the function of the former to realize a transmission ultrasound mode. The ultrasound transmission data of an object, when acquired from multiple directions, allows spatially resolved tomographic reconstruction of parameters like acoustic speed and acoustic attenuation. The use of a standard ultrasound system makes the acquisition of transmission as well as echo data of the whole object possible; the latter allows a further processing for three dimensional rendering of the echosonographic image, compounding and tissue characterization based on multiple parameters.

A new approach towards ultrasonic transmission tomography with a standard ultrasound system

A system for the computerized differentiation of parotid gland tumors is proposed. The parotid gland is the largest of the salivary glands. It is found in the subcutaneous tissue of the face, overlying the mandibular ramus and anterior and inferior to the external ear. The classification system is based on a multifeature tissue characterization approach, using fuzzy inference systems as higher-order classifiers. Baseband ultrasonic echo data were acquired during conventional ultrasound imaging examinations using standard ultrasound equipment. Several tissue-describing parameters were calculated within numerous small regions of interest to evaluate spectral and textural tissue properties. The parameters were processed by an adaptive network-based fuzzy inference system, using the results of conventional histology after parotidectomy as the “gold standard.” The results of the classification are presented as a numerical score indicating the probability of a certain tumor or alteration for each parotid gland. The score can be presented to the physician during examination of the patient to improve the differentiation between various types of parotid gland tumors. The system was evaluated on n = 23 cases of patients undergoing radical parotidectomy. The receiver operating characteristic curve area is AROC = 0.95 ± 0.07 when using fourfold cross-validation over cases and differentiating between various benign parotid gland tumors and monomorphic adenoma. (E-mail: Ulrich@Scheipers.org )

Sonohistology for the computerized differentiation of parotid gland tumors

A high precision mechanical add-on module was realized to implement a transmission tomography system around a commercial analog ultrasound system. The modular nature of the add-on lets it be used, however, more universally. Without enormous effort the module could be programmed to be coupled to a fully digital high end commercial ultrasound system. A Siemens Antares was used for this work, which allows the acquisition of RF data of high quality B-scans and tissue harmonic imaging (THI) over the Axius Direct Ultrasound Research Interface (URI). This possibility was exploited to explore some more intricate processing options for image compounding in addition to the conventional spatial compounding approach. Several compounding schemes were implemented. One of the two new strategies for compounding consists of calculation of a compound image from the THI data, as the latter is known to possess a better contrast and lateral resolution. While the RF data acquired from various transducer positions provides all the essential input for monostatic synthetic aperture focusing (SAFT), the other strategy was to implement SAFT imaging. The effect of inhomogeneous speed of sound was studies carefully and two different schemes were implemented to overcome the problems of image registration arising from it. The algorithms were tested on polypropylene fiber phantoms in water and ethylene glycol. While the monostatic synthetic aperture reconstruction technique was found to be best in enhancing signal to noise ratio, the speckle reduction was notably better for the THI compounding scheme than that of the conventional compounding strategy. The resulting spatial resolution of the compound images was comparable for the latter two cases and the former technique outperformed the other ones in this respect.

M. Ashfaq

Papers

An ultrasound research interface for a clinical system

Errata - An ultrasound research interface for a clinical system

A new approach towards ultrasonic transmission tomography with a standard ultrasound system

Sonohistology for the computerized differentiation of parotid gland tumors

Spatial compounding with tissue harmonic images and monostatic synthetic aperture reconstruction