The emergence of ultrafast frame rates in ultrasonic imaging has been recently made possible by the development of new imaging modalities such as transient elastography. Data acquisition rates reaching more than thousands of images per second enable the real-time visualization of shear mechanical waves propagating in biological tissues, which convey information about local viscoelastic properties of tissues. The first proposed approach for reaching such ultrafast frame rates consists of transmitting plane waves into the medium. However, because the beamforming process is then restricted to the receive mode, the echographic images obtained in the ultrafast mode suffer from a low quality in terms of resolution and contrast and affect the robustness of the transient elastography mode. It is here proposed to improve the beamforming process by using a coherent recombination of compounded plane-wave transmissions to recover high-quality echographic images without degrading the high frame rate capabilities. A theoretical model is derived for the comparison between the proposed method and the conventional B-mode imaging in terms of contrast, signal-to-noise ratio, and resolution. Our model predicts that a significantly smaller number of insonifications, 10 times lower, is sufficient to reach an image quality comparable to conventional B-mode. Theoretical predictions are confirmed by in vitro experiments performed in tissue-mimicking phantoms. Such results raise the appeal of coherent compounds for use with standard imaging modes such as B-mode or color flow. Moreover, in the context of transient elastography, ultrafast frame rates can be preserved while increasing the image quality compared with flat insonifications. Improvements on the transient elastography mode are presented and discussed.

Coherent plane-wave compounding for very high frame rate ultrasonography and transient elastography

The Analysis of Variance.

This paper reviews ultrasound segmentation methods, in a broad sense, focusing on techniques developed for medical B-mode ultrasound images. First, we present a review of articles by clinical application to highlight the approaches that have been investigated and degree of validation that has been done in different clinical domains. Then, we present a classification of methodology in terms of use of prior information. We conclude by selecting ten papers which have presented original ideas that have demonstrated particular clinical usefulness or potential specific to the ultrasound segmentation problem

/pdf/ultrasound-image-segmentation-a-survey-55ssqpzk7q.pdf

Ultrasound image segmentation: a survey

Carol Mitchell, PhD, ACS, RDMS, RDCS, RVT, RT(R), FASE, Co-Chair, Peter S. Rahko, MD, FASE, Co-Chair, Lori A. Blauwet, MD, FASE, Barry Canaday, RN, MS, RDCS, RCS, FASE, Joshua A. Finstuen, MA, RT(R), RDCS, FASE, Michael C. Foster, BA, RCS, RCCS, RDCS, FASE, Kenneth Horton, ACS, RCS, FASE, Kofo O. Ogunyankin, MD, FASE, Richard A. Palma, BS, RDCS, RCS, ACS, FASE, and Eric J. Velazquez, MD, FASE,Madison, Wisconsin; Rochester, Minnesota; Klamath Falls, Oregon; Durham, North Carolina; Salt Lake City, Utah; Ikoyi, Lagos, Nigeria; and Hartford, Connecticut

Guidelines for Performing a Comprehensive Transthoracic Echocardiographic Examination in Adults: Recommendations from the American Society of Echocardiography.

Acoustic imaging balloon catheters formed by a disposable liquid-confining sheath supporting a high fidelity, flexible drive shaft which carries on its end an ultrasound transducer and includes an inflatable dilatation balloon. The shaft and transducer rotate with sufficient speed and fidelity to produce real time images on a T.V. screen. In preferred embodiments, special features that contribute to the high fidelity of the drive shaft include the particular multi-filar construction of concentric, oppositely wound, interfering coils, a pre-loaded torque condition on the coils enhancing their interfering contact, and dynamic loading of the distal end of the probe, preferably with viscous drag. The coil rotating in the presence of liquid in the sheath is used to produce a desirable pressure in the region of the transducer. Numerous selectable catheter sheaths are shown including a sheath with an integral acoustically-transparent window, sheaths with end extensions that aid in positioning, a liquid injection-producing sheath, a sheath having its window section under tension employing an axially loaded bearing, a sheath carrying a dilatation or positioning balloon over the transducer, a sheath carrying a distal rotating surgical tool and a sheath used in conjunction with a side-viewing trocar.

Acoustic imaging catheter and the like

The recent introduction of tissue harmonic imaging could resolve the problems related to ultrasound in technically difficult patients by providing a marked improvement in image quality. Tissue harmonics are generated during the transmit phase of the pulse-echo cycle, that is, while the transmitted pulse propagates through tissue. Tissue harmonic images are formed by utilizing the harmonic signals that are generated by tissue and by filtering out the fundamental echo signals that are generated by the transmitted acoustic energy. To achieve this, two processes could be used; one by using filters for fundamental and harmonic imaging and the second using two simultaneous pulses with a 180 degrees difference in phase. The introduction of harmonics allows increased penetration without a loss of detail, by obtaining a clearer image at depth with significantly less compromise to the image quality caused by the use of lower frequencies. This imaging mode could be used in different organs with a heightening of low-contrast lesions through artefact reduction, as well as by the induced greater intrinsic contrast sensitivity of the harmonic imaging mode.

Clinical use of ultrasound tissue harmonic imaging

Compound Scanning with an Electrically Steered Beam

Many Doppler imaging studies have been performed in recent years in a large number of ocular disorders because of improvements in the Doppler equipment used for detecting and measuring the low blood-flow velocities that are a requisite for the quantitative evaluation of blood flow in the orbital vessels. The ophthalmic artery, central retinal artery and vein, posterior ciliary arteries, and the superior ophthalmic vein can be easily identified using color Doppler sonography. The changes in local blood flow in these vessels assessed by spectral analysis pulsed Doppler sonography have been used to characterize and to obtain new insights into different nontumoral vascular disorders including carotid artery stenosis, central retinal vein occlusion, giant cell arteritis, glaucoma, diabetes, fistulas, and tumoral processes of the eye and orbit. Our experience has confirmed the important role of Doppler sonography in the assessment of subclinical changes in the vascular bed, in the understanding of different processes, for following up after specific treatments, and for determining the long-term prognosis of these various conditions.

Color Doppler imaging of orbital vessels: personal experience and literature review.

The standard conditions of spirometry (i.e., wearing a noseclip and breathing through a mouthpiece and a pneumotachograph) are likely to alter the ventilatory pattern. We used “time-motion” mode (M-mode) sonography to assess the changes in diaphragm kinetics induced by spirometry dunng quiet breathing. An M-mode sonographic study of the nght diaphragm was performed before and dunng standard spirometry in eight patients without respiratory disease (age 34 to 68 yr). During spirometry, the diaphragm inspiratory amplitude (DIA) increased from 1.34 ± 0.18 cm to 1.80 ± 0.18 cm (P = 0.007), whereas the diaphragmatic mspiratory time (T1 diaph) increased from 1.27 ± 0.15 to 1.53 ± 0.23 sec, (P = 0.015), without change in diaphragmatic total time interval (Ttot diaph). Therefore, the diaphragm duty cycle (T1 diaph /Ttot diaph) increased from 38% ± 1% to 44% ± 4% (P = 0.023). The diaphragm inspiratory (DIV) and expiratory (DEV) motion velocity increased (P = 0.007). M-mode sonography enabled us to demonstrate that the weanng of a nose clip and breathing through a mouthpiece and a pneumotachograph induce measurable changes in diaphragm kinetics.

https://link.springer.com/content/pdf/10.1007%2FBF03013389.pdf

Non-invasive quantification of diaphragm kinetics using m-mode sonography

The endoscopic probe, more especially for medical use, comprises a tubular member insertable in a cavity to be explored, having a flexible part ending in an endmost section able to be orientated by means of mechanical control means disposed inside the flexible section. The section carries optical illumination and image return means and an ultrasonic electro-acoustic translater. This translator comprises a fixed curved linear array of piezoelectric elements, the convexity of the curve being directed outwardly. The array is associated with an electronic circuit for energizing the elements according to a sectorial sweep sequence in an angular field overlapping with the field of view of the optical means.

Léandre Pourcelot

Papers

Clinical use of ultrasound tissue harmonic imaging

Compound Scanning with an Electrically Steered Beam

Color Doppler imaging of orbital vessels: personal experience and literature review.

Non-invasive quantification of diaphragm kinetics using m-mode sonography

Ultrasonic sweep echography and display endoscopic probe