Abstract:
:Attenuation measurements of various tissue mimicking phantoms and three different groups of patients were obtained using a modified commercial sector scanner. Estimates of attenuation were made using the spectral shift method with mean frequencies at different depths of a region of interest being obtained by both zero crossing and fast Fourier transform techniques. The accuracy and precision of both techniques was compared in phantoms and it was found that the FFT technique yielded less day-to-day variation (SD=3 percent) than the zero crossing technique (5 percent). For larger regions of interest, the range of variation in both techniques was more similar. Day-to-day variation in livers of normal patients was much larger than that seen in phantoms (10 to 15 percent) suggesting that in vivo measurements may be less precise due to actual daily changes in patients' livers. Attenuation estimates of phantoms were high by approximately 0.16 dB/MHz/cm compared to values obtained by transmission techniques. The attenuation values of livers in a group of 31 normal patients ranged from 0.214 dB/cm/MHz to 0.849 dB/cm/MHz with a mean of 0.627 +/- 0.126 dB/cm/MHz for the zero crossing technique while the mean value using the FFT technique was 0.86 +/- 0.168 dB/cm/MHz. A group of 26 Gauchers disease patients also showed wide variation with a mean attenuation value of 0.768 +/- 0.21 dB/cm/MHz using the FFT technique. This was significantly different than that of the normal group (p less than .05). Also, a group of 22 chronic B hepatitis patients was examined, having a mean attenuation value of 0.823 +/- 0.21 dB/cm/MHz, not significantly different from those of normal patients. Highly significant differences were found between the three groups when the power spectrum bandwidths of signals received were compared. These differences may be due to differences in the dependence of attenuation as a function of frequency between the groups and may represent a useful tissue characterization parameter.
journal_name
Ultrason Imagingjournal_title
Ultrasonic imagingauthors
Garra BS,Shawker TH,Nassi M,Russell MAdoi
10.1177/016173468400600402subject
Has Abstractpub_date
1984-10-01 00:00:00pages
396-407issue
4eissn
0161-7346issn
1096-0910journal_volume
6pub_type
杂志文章abstract::Speckle noise is known to be signal-dependent in ultrasound imaging. Hence, separating noise from signal becomes a difficult task. This paper describes a wavelet-based method for reducing speckle noise. We derive from the model of the displayed ultrasound image the optimal wavelet-domain filter in the least mean-squar...
journal_title:Ultrasonic imaging
pub_type: 杂志文章
doi:10.1177/016173460002200201
更新日期:2000-04-01 00:00:00
abstract::A Fourier transform (FT)-based technique for forming parallel receive beams has been previously employed to increase the imaging frame rate in ultrasonic imaging. However, the image quality in FT-based parallel reconstruction is degraded because differences in range focusing delays are ignored and a wide transmit beam...
journal_title:Ultrasonic imaging
pub_type: 杂志文章
doi:10.1177/016173460302500201
更新日期:2003-04-01 00:00:00
abstract::Regional anesthesia is preferred over general anesthesia for many surgical procedures; however, challenges associated with poor image guidance limit its widespread acceptance as a viable alternative. In B-mode ultrasound images, the current standard for guidance, nerves can be difficult to visualize due to their simil...
journal_title:Ultrasonic imaging
pub_type: 杂志文章
doi:10.1177/016173460903100303
更新日期:2009-07-01 00:00:00
abstract::This paper describes a method for overcoming motion artifacts in synthetic aperture imaging. The method is based on a computer simulation study on the influence of target motion on synthetic aperture techniques. A region-based motion compensation approach is used in which only the axial motion is estimated and compens...
journal_title:Ultrasonic imaging
pub_type: 杂志文章
doi:10.1177/016173460202400202
更新日期:2002-04-01 00:00:00
abstract::Time reversal of ultrasonic field allows a very efficient approach to focusing pulsed ultrasonic waves through lossless inhomogeneous media. Time reversal mirrors (TRM) are made of large transducer arrays, allowing the incident acoustic field to be sampled, time reversed and re-emitted. Time reversal processing permit...
journal_title:Ultrasonic imaging
pub_type: 杂志文章,评审
doi:10.1177/016173469601800202
更新日期:1996-04-01 00:00:00
abstract::A method has been developed for mapping density and ultrasonic speed in 1 mm thick slices of soft tissue with a resolution of about 1 mm. Tests using phantom sections have verified the accuracy and resolution of the ultrasonic speed maps. The method has been applied to breast tissues of three patients including tumors...
journal_title:Ultrasonic imaging
pub_type: 杂志文章
doi:10.1177/016173469101300105
更新日期:1991-01-01 00:00:00
abstract::Many noninvasive ultrasound techniques have been developed to explore mechanical properties of soft tissues. One of these methods, Localized Harmonic Motion Imaging (LHMI), has been proposed to be used for ultrasound surgery monitoring. In LHMI, dynamic ultrasound radiation-force stimulation induces displacements in a...
journal_title:Ultrasonic imaging
pub_type: 杂志文章
doi:10.1177/016173460602800203
更新日期:2006-04-01 00:00:00
abstract::In medical ultrasound imaging, two-dimensional (2-D) array transducers are desirable to implement dynamic focusing and phase aberration correction in two dimensions as well as volumetric imaging. Unfortunately, the small size of a 2-D array element results in a small clamped capacitance and a large electrical impedanc...
journal_title:Ultrasonic imaging
pub_type: 杂志文章
doi:10.1177/016173469501700202
更新日期:1995-04-01 00:00:00
abstract::Conventional ultrasonic B-mode images qualitatively describe tissue structures but are unsuitable for quantitative analyses of scatterer properties. We have recently developed an ultrasonic parametric imaging technique based on the Nakagami statistical distribution that is able to quantify scatterer concentrations. Th...
journal_title:Ultrasonic imaging
pub_type: 杂志文章
doi:10.1177/016173460803000202
更新日期:2008-04-01 00:00:00
abstract::Acoustic Radiation Force Impulse (ARFI) imaging is a method for characterizing local variations in tissue mechanical properties. In this method, a single ultrasonic transducer array is used to both apply temporally short localized radiation forces within tissue and to track the resulting displacements through time. In...
journal_title:Ultrasonic imaging
pub_type: 杂志文章
doi:10.1177/016173460202400301
更新日期:2002-07-01 00:00:00
abstract::The liver has been hypothesized to have a unique arrangement of microvasculature that presents as an arrangement of quasiperiodic scatterers to an interrogating ultrasound pulse. The mean scatterer spacing (MSS) of these quasiperiodic scatterers has been proposed as a useful quantitative ultrasound biomarker for chara...
journal_title:Ultrasonic imaging
pub_type: 杂志文章
doi:10.1177/0161734613511232
更新日期:2014-04-01 00:00:00
abstract::Coherent speckle is a source of image noise in ultrasonic B-mode imaging. The use of multiple imaging frequencies has been suggested as a technique for speckle contrast reduction. This technique involves the averaging of images whose speckle patterns have been modified by a change in the spectrum of the transmitted or...
journal_title:Ultrasonic imaging
pub_type: 杂志文章
doi:10.1177/016173468600800301
更新日期:1986-07-01 00:00:00
abstract::The microbubble contrast agent destruction/replenishment technique has been widely applied to ultrasound-based blood flow estimation. The rate of increase of the time-intensity curve (TIC) due to microbubbles flowing into the region of interest as measured from B-mode images closely reflects the flow velocity. In this...
journal_title:Ultrasonic imaging
pub_type: 杂志文章
doi:10.1177/016173460803000301
更新日期:2008-07-01 00:00:00
abstract::An autoregressive (AR) spectral estimation method was considered for the purpose of estimating scatterer size images. The variance and bias of the resulting estimates were compared with those using classical FFT periodograms for a range of input signal-to-noise ratios and echo-signal durations corresponding to various...
journal_title:Ultrasonic imaging
pub_type: 杂志文章
doi:10.1177/016173469601800102
更新日期:1996-01-01 00:00:00
abstract::Optimal transmit phasing has been proposed to increase contrast-to-tissue ratio (CTR) by relatively phasing the tissue and leakage harmonic components to cancel each other out for tissue-background suppression in harmonic imaging. Since most clinical systems are only equipped with a bipolar square-wave pulser, effecti...
journal_title:Ultrasonic imaging
pub_type: 杂志文章
doi:10.1177/016173461003200103
更新日期:2010-01-01 00:00:00
abstract::It is well-documented in literature that benign breast lesions, such as fibroadenomas, are loosely bonded to their surrounding tissue and tend to slip under a small quasi-static compression, whereas malignant lesions being firmly bonded to their surrounding tissue do not slip. Recent developments in quasi-static ultra...
journal_title:Ultrasonic imaging
pub_type: 杂志文章
doi:10.1177/0161734616686746
更新日期:2017-05-01 00:00:00
abstract::Ultrasonic waveform data from a tissue-mimicking phantom containing low contrast targets was digitized, stored and processed prior to creating and displaying ultrasonic images. Speckle reduction was performed by digital filtering of the waveform data with appropriately spaced and weighted digital filters, prior to bot...
journal_title:Ultrasonic imaging
pub_type: 杂志文章
doi:10.1177/016173468700900202
更新日期:1987-04-01 00:00:00
abstract::The theory of diffraction tomography for two-dimensional objects within the Born approximation is presented for cases where the scattered field is measured over arbitrarily shaped boundaries surrounding the object. Reconstruction algorithms are presented for both plane wave (parallel beam) and cylindrical wave (fan be...
journal_title:Ultrasonic imaging
pub_type: 杂志文章
doi:10.1177/016173468400600207
更新日期:1984-04-01 00:00:00
abstract::The amplitude and frequency contents of a received ultrasound pulse depends on the spatial pressure amplitude distribution of the sound field, as produced by the transducer in the medium, and on the position and orientation of the reflecting surface in this field. Often, the geometry of the reflecting surface and the ...
journal_title:Ultrasonic imaging
pub_type: 杂志文章
doi:10.1177/016173469001200405
更新日期:1990-10-01 00:00:00
abstract::It may be possible to diagnose and monitor scarring, inflammation and edema in transplant kidney using reconstructive ultrasound elasticity imaging. Kidney elasticity is expected to change dramatically with scar, and to a lesser degree, with acute inflammation and edema. The hypothesis that changes in kidney elasticit...
journal_title:Ultrasonic imaging
pub_type: 杂志文章
doi:10.1177/016173460002200303
更新日期:2000-07-01 00:00:00
abstract::Breast ultrasound (BUS) imaging has become a crucial modality, especially for providing a complementary view when other modalities (i.e., mammography) are not conclusive in the task of assessing lesions. The specificity in cancer detection using BUS imaging is low. These false-positive findings often lead to an increa...
journal_title:Ultrasonic imaging
pub_type: 杂志文章
doi:10.1177/0161734615589287
更新日期:2016-05-01 00:00:00
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journal_title:Ultrasonic imaging
pub_type: 杂志文章
doi:10.1177/0161734618815070
更新日期:2019-03-01 00:00:00
abstract::An algorithm for deconvolution of medical ultrasound images is presented. The procedure involves estimation of the basic one-dimensional ultrasound pulse, determining the ratio of the covariance of the noise to the covariance of the reflection signal, and finally deconvolution of the rf signal from the transducer. Usi...
journal_title:Ultrasonic imaging
pub_type: 杂志文章
doi:10.1177/016173469301500204
更新日期:1993-04-01 00:00:00
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journal_title:Ultrasonic imaging
pub_type: 杂志文章
doi:10.1177/016173469001200302
更新日期:1990-07-01 00:00:00
abstract::Accurate tracking of tissue motion is critically important for several ultrasound elastography methods. In this study, we investigate the feasibility of using three published convolution neural network (CNN) models built for optical flow (hereafter referred to as CNN-based tracking) by the computer vision community fo...
journal_title:Ultrasonic imaging
pub_type: 杂志文章
doi:10.1177/0161734620902527
更新日期:2020-03-01 00:00:00
abstract::Two-dimensional echocardiography (2-D echo) imaging is a more attractive clinical tool than other modalities that either involve radiation exposure or are too slow to image heart motion in real-time. Computer-aided analysis of left ventricular(LV) wall motion provides quantitative parameters for diagnosis. This study ...
journal_title:Ultrasonic imaging
pub_type: 杂志文章
doi:10.1177/016173469701900204
更新日期:1997-04-01 00:00:00
abstract::Sidelobe contribution from off-axis targets degrades image quality in a coherent array imaging system. In ultrasound imaging, focusing errors resulting from sound-velocity inhomogeneities in human tissue--also known as phase aberrations reduce the coherence of the received signals and elevate the sidelobe level. This ...
journal_title:Ultrasonic imaging
pub_type: 杂志文章
doi:10.1177/016173460502700205
更新日期:2005-04-01 00:00:00
abstract::In recent years, adaptive minimum-variance (MV) beamforming has been successfully applied to medical ultrasound imaging, resulting in simultaneous improvement in imaging resolution and contrast. MV has high resolution and hence can provide accurate estimates of the target locations. However, the MV amplitude estimates...
journal_title:Ultrasonic imaging
pub_type: 杂志文章
doi:10.1177/0161734615600167
更新日期:2016-07-01 00:00:00
abstract::This paper presents a new beamforming technique, in which ultrasound waves are focused at the display pixels on the Cartesian coordinates, rather than sampling points located on the uniformly-separated scanlines on either the polar or Cartesian coordinates. Consequently, this method does not require a digital scan con...
journal_title:Ultrasonic imaging
pub_type: 杂志文章
doi:10.1177/016173460102300101
更新日期:2001-01-01 00:00:00
abstract::Tracking large deformations in tissue using ultrasound can enable the reconstruction of nonlinear elastic parameters, but poses a challenge to displacement estimation algorithms. Such large deformations have to be broken up into steps, each of which contributes an estimation error to the final accumulated displacement...
journal_title:Ultrasonic imaging
pub_type: 杂志文章
doi:10.1177/0161734613479246
更新日期:2013-04-01 00:00:00