A method of acoustic remote palpation, capable imaging local variations in the mechanical properties tissue, is under investigation. In this method, focused ultrasound used to apply localized (on order 2 mm3) radiation force within and resulting tissue displacements are mapped using ultrasonic correlation based methods. The inversely proportional stiffness thus a stiffer region exhibits smaller than more compliant region. paper, feasibility palpation demonstrated experimentally breast...

Delay estimation is used in ultrasonic imaging to estimate blood or soft tissue motion, measure echo arrival time differences for phase aberration correction, and displacement elasticity measurements. In each of these applications delay performed using speckle signals which are at least partially decorrelated relative one another. estimates utilize such data subject large errors known as false peaks smaller magnitude jitter. While can sometimes be removed through nonlinear processing, jitter...

A simple algorithm for angle independent motion imaging is described. This method requires only one absolute difference operation per pixel, compared to eight operations normalized cross correlation. Quantitative studies using speckle-generating targets translated by fixed amounts both axially and laterally indicate that the technique tracks moving speckle as accurately Color flow images generated from clinical blood liver data highlight success of tracking large small motions in two...

Conventional ultrasound images are formed by delay-and-sum beamforming of the backscattered echoes received individual elements transducer aperture. Although beamformer is well suited for image formation, it corrupted speckle noise and challenged acoustic clutter phase aberration. We propose an alternative method imaging utilizing short-lag spatial coherence (SLSC) echoes. Compared with matched B-mode images, SLSC demonstrate superior SNR contrast-to-noise ratio in simulated experimental...

We present a new technique for blood velocity imaging based on tracking the motion of speckle pattern produced by blood. Unlike Doppler determinations, these are angle independent. Initial in vivo experiments yield promising results.

Time-delay estimators, such as normalized cross correlation and phase-shift estimation, form the computational basis for elastography, blood flow measurements, acoustic radiation force impulse (ARFI) imaging. This paper examines performance of these algorithms small displacements (less than half ultrasound pulse wavelength). The effects noise, bandwidth, stationary echoes, kernel size, downsampling, interpolation, quadrature demodulation on accuracy time delay estimates are measured in terms...

Medical ultrasonic images are degraded by tissues with inhomogeneous acoustic velocities. The resulting phase aberration raises the off-peak response of imaging system’s point spread function (PSF), decreasing dynamic range. In extreme cases, multiple a single target displayed. Phase may become limiting factor to image quality as frequency and aperture size increased in order improve spatial resolution. A method is proposed correct for unknown aberration, which uses speckle brightness...

In order to design improved spatial compounding ultra- sound scanning systems it is necessary determine the correlation of speckle patterns as a function aperture translation. We have con- ducted experiments measuring with lateral ap- erture translation for linear phased array pulse-echo ultrasonic im- aging systems. Results are presented variable frequency, range, transducer length, focus error, and reflecting material. Tests were on two commercially availahle one research imaging sys- tem....

A full-wave equation that describes nonlinear propagation in a heterogeneous attenuating medium is solved numerically with finite differences the time domain (FDTD). Three-dimensional solutions of are verified water tank measurements commercial diagnostic ultrasound transducer and shown to be excellent agreement terms fundamental harmonic acoustic fields power spectrum at focus. The linear components algorithm also independently. In nonattenuating regime match results from Field II, well...

The use of ultrasonic methods to track the tissue deformation generated by acoustic radiation force is subject jitter and displacement underestimation errors, with being primarily caused lateral elevation shearing within point spread function (PSF) beam. Models have been developed using finite element Field II, a linear field simulation package, study impact focal configuration, tracking frequency, material properties on accuracy ultrasonically excitations. These models demonstrate that...

The utility of acoustic radiation force impulse (ARFI) imaging for real-time visualization abdominal malignancies was investigated. Nine patients presenting with suspicious masses in the liver ( n = 7) or kidney 2) underwent combined sonography/ARFI imaging. Images were acquired a total 12 tumors nine patients. In all cases, boundary definition ARFI images improved equivalent to B-mode images. Displacement contrast superior echo each tumor. mean suspected hepatocellular carcinomas (HCCs) 2.9...

The design, fabrication and evaluation of two-dimensional transducer arrays are described for medical ultrasound imaging. A 4 × 32, 2.8 MHz array was developed to use new signal processing techniques improved B-scan imaging including elevation focusing, phase correction synthetic aperture Laboratory measurements from typical elements showed 50 Ω dB, − dB pulse-echo angular response 62°. Simulations beam plots have shown grating lobes 20 below the main lobe at ±7° in direction. complete 2-D...

Acoustic Radiation Force Impulse (ARFI) imaging is a method for characterizing local variations in tissue mechanical properties. In this method, single ultrasonic transducer array used to both apply temporally short localized radiation forces within and track the resulting displacements through time. an ongoing study of response force excitation, ARFI datasets have been obtained ex vivo tissues under various focal configurations. The goal paper report observations discuss implications these...

Radiation force-based techniques have been developed by several groups for imaging the mechanical properties of tissue. Acoustic radiation force impulse (ARFI) is one such method that uses commercially available scanners to generate localized forces in The response tissue determined using conventional B-mode pulses track micron-scale displacements Current research ARFI focused on producing real-time images arid related properties. Obstacles a ARFl modality include data acquisition,...

A common framework is presented to classify several phase correction techniques. subset of these techniques are evaluated through simulations which utilize 2-D aberration profiles measured in the breast. The compared based on their ability reduce errors, stability, and sensitivity noise missing elements transducer array. Significant differences observed measures performance when size location aperture area used generate a reference signal varied. Techniques that small region more susceptible...

Coherent speckle is a source of image noise in ultrasonic B-mode imaging. The use multiple imaging frequencies has been suggested as technique for contrast reduction. This involves the averaging images whose patterns have modified by change spectrum transmitted or received acoustical pulse. We measured rate this pattern function center frequency data used to quantitatively describe trade-off resolution loss versus reduction encountered when compounding employed and derive optimal method...

Acoustic radiation force impulse imaging has been used clinically to study the dynamic response of lesions relative their background material focused, impulsive acoustic excitations through generation displacement field images. Dynamic data are typically displayed as a set parametric images, including immediately after excitation, maximum displacement, time peak and recovery from displacement. To date, however, no definitive trends have established between these images tissues' mechanical...

An online adaptive phased-array ultrasonic imaging system capable of markedly improving the detectability targets viewed through inhomogeneous media is described. phase correction technique implemented on a research scanner The theoretical basis for this presented by describing relationship between magnitude aberrations and regional brightness speckle pointlike targets. currently generates corrected image in approximately 0.1 s utilizes no prior knowledge aberrating or target. algorithm uses...