Acoustic performance of mesh compression paddles for a multimodality breast imaging system.

A system incorporating automated 3-D ultrasound and digital X-ray tomosynthesis is being developed for improved breast lesion detection and characterization. The goal of this work is to develop and test candidates for a dual-modality mesh compression paddle. A Computerized Imaging Reference Systems (Norfork, VA, USA) ultrasound phantom with tilted low-contrast cylindrical objects was used.

Spatial registration of temporally separated whole breast 3D ultrasound images.

The purpose of this study was to evaluate the potential for use of image volume based registration (IVBaR) to aid in measurement of changes in the tumor during chemotherapy of breast cancer. Successful IVBaR could aid in the detection of such changes in response to neoadjuvant chemotherapy and potentially be useful for routine breast cancer screening and diagnosis. IVBaR was employed in a new method of automated estimation of tumor volume in studies following the radiologist identification of the tumor region in the prechemotherapy scan.

Breast ultrasound image improvement by pixel compounding of compression sequence.

Pixel compounding is a technique that synthesizes the information of an image sequence involving slow decorrelation of the speckle to form a detail-recovered and speckle reduced image. To avoid extra data acquisition time and patient exposure, reuse of the existing data is desirable. In the procedure of elasticity imaging, a set of B-mode images with slight changes due to deformation is produced, which provides an ideal input for the pixel compounding.

Rapid 3-D imaging of contrast flow: application in a perfused kidney phantom.

Previous studies indicate imaging of ultrasound contrast in 3-D is potentially superior to 2-D imaging for vascular characterization. A dual-beam, dynamic refill technique, which relies on volumetric contrast clearance and sequential imaging, was used to image a preserved porcine kidney perfused with contrast. A model was developed for the contrast profile across the renal artery to estimate fractional blood volume.

Suspicious breast lesions: assessment of 3D Doppler US indexes for classification in a test population and fourfold cross-validation scheme.

Purpose: To assess the diagnostic performance of various Doppler ultrasonographic (US) vascularity measures in conjunction with grayscale (GS) criteria in differentiating benign from malignant breast masses, by using histologic findings as the reference standard.

Materials And Methods: Institutional Review Board and HIPAA standards were followed. Seventy-eight women (average age, 49 years; range, 26-70 years) scheduled for breast biopsy were included.

Multi-modality 3D breast imaging with X-Ray tomosynthesis and automated ultrasound.

This study evaluated the utility of 3D automated ultrasound in conjunction with 3D digital X-Ray tomosynthesis for breast cancer detection and assessment, to better localize and characterize lesions in the breast. Tomosynthesis image volumes and automated ultrasound image volumes were acquired in the same geometry and in the same view for 27 patients. 3 MQSA certified radiologists independently reviewed the image volumes, visually correlating the images from the two modalities with in-house software.

Non-rigid registration of three-dimensional (3D) grayscale and Doppler ultrasound breast images.

The purpose of this study is to evaluate the accuracy of image volume based registration (IVBaR) of 3D ultrasound (US) image volumes of the whole breast acquired at different times. Successful IVBaR could aid in detection of tumor changes in response to neoadjuvant chemotherapy and potentially be useful for routine breast cancer screening and diagnosis. IVBaR was successful in 9 of 10 reproducibility studies, 11 of 15 image pairs collected before and after approximately 45 days of chemotherapy.

Rapid 3D imaging of contrast flow: demonstration of a dual beam technique.

Perfusion imaging in a 3D volume using ultrasound contrast agent may improve vascular characterization compared with 2D imaging. Conventional 3D acquisition requires excessive scan time. A dual transducer technique using conventional systems has been introduced that allows 3D imaging of contrast dynamics with drastically reduced scan times (LeCarpentier et al.

Automated ultrasound scanning on a dual-modality breast imaging system: coverage and motion issues and solutions.

Objective: We are developing an automated ultrasound imaging-mammography system wherein a digital mammography unit has been augmented with a motorized ultrasound transducer carriage above a special compression paddle. Challenges of this system are acquiring complete coverage of the breast and minimizing motion. We assessed these problems and investigated methods to increase coverage and stabilize the compressed breast.

Evaluating thin compression paddles for mammographically compatible ultrasound.

We are developing a combined digital mammography/3D ultrasound system to improve detection and/or characterization of breast lesions. Ultrasound scanning through a mammographic paddle could significantly reduce signal level, degrade beam focusing and create reverberations. Thus, appropriate paddle choice is essential for accurate sonographic lesion detection and assessment with this system.

Sonographic evaluation of early-stage breast cancers that undergo neoadjuvant chemotherapy.

Objective: We prospectively evaluated low-stage breast cancers treated with neoadjuvant chemotherapy using whole-volume sonography and color Doppler imaging.

Methods: Thirty-four women with breast cancer (mean maximum size, 2.4 cm) received neoadjuvant chemotherapy with doxorubicin and docetaxel.

Combination of digital mammography with semi-automated 3D breast ultrasound.

This paper describes work aimed at combining 3D ultrasound with full-field digital mammography via a semi-automatic prototype ultrasound scanning mechanism attached to the digital mammography system gantry. Initial efforts to obtain high x-ray and ultrasound image quality through a compression paddle are proving successful. Registration between the x-ray mammogram and ultrasound image volumes is quite promising when the breast is stably compressed.

Computerized characterization of breast masses on three-dimensional ultrasound volumes.

We are developing computer vision techniques for the characterization of breast masses as malignant or benign on radiologic examinations. In this study, we investigated the computerized characterization of breast masses on three-dimensional (3-D) ultrasound (US) volumetric images. We developed 2-D and 3-D active contour models for automated segmentation of the mass volumes.

Rapid elastic image registration for 3-D ultrasound.

A Subvolume-based algorithm for elastic Ultrasound REgistration (SURE) was developed and evaluated. Designed primarily to improve spatial resolution in three-dimensional compound imaging, the algorithm registers individual image volumes nonlinearly before combination into compound volumes. SURE works in one or two stages, optionally using MIAMI Fuse software first to determine a global affine registration before iteratively dividing the volume into subvolumes and computing local rigid registrations in the second stage.

Discrimination of sonographically detected breast masses using frequency shift color Doppler imaging in combination with age and gray scale criteria.

Frequency shift color Doppler imaging was assessed in conjunction with patient age and gray scale (GS) features for discriminating benign from malignant breast masses. Thirty-eight women with sonographically detected masses scheduled for biopsy were evaluated using a 6- to 13-MHz scan head, and the masses were delineated in ultrasonographic image volumes. Vascularity in and around each mass was quantified using speed-weighted pixel density (SWD).

3D spatial compounding of ultrasound images using image-based nonrigid registration.

Medical ultrasound images are often distorted enough to significantly limit resolution during compounding (i.e., summation of images from multiple views).

Treatment of metastatic cancer with tetrathiomolybdate, an anticopper, antiangiogenic agent: Phase I study.

Preclinical and in vitro studies have determined that copper is an important cofactor for angiogenesis. Tetrathiomolybdate (TM) was developed as an effective anticopper therapy for the initial treatment of Wilson's disease, an autosomal recessive disorder that leads to abnormal copper accumulation. Given the potency and uniqueness of the anticopper action of TM and its lack of toxicity, we hypothesized that TM would be a suitable agent to achieve and maintain mild copper deficiency to impair neovascularization in metastatic solid tumors.

Semiautomatic registration of volumetric ultrasound scans.

We demonstrate the ability to register easily and accurately volumetric ultrasound scans without significant data preprocessing or user intervention. Two volumetric ultrasound breast scan data sets were acquired from two different patients with breast cancer. Volumetric scan data were acquired by manually sweeping a linear array transducer mounted on a linear slider with a position encoder.

3-D color Doppler image quantification of breast masses.

In this article, new measures obtained from color Doppler images are introduced and a pilot study is described, in which these and previously published indices are evaluated for use in future work. Twenty women with breast masses observed on mammography and going to surgical biopsy were studied. Of the masses, 11 proved to be benign and 9 were malignant.

Differentiation of sinus tachycardia from ventricular tachycardia with 1:1 ventriculoatrial conduction in dual chamber implantable cardioverter defibrillators: feasibility of a criterion based on the atrioventricular interval.

Tachycardia discrimination in future implantable cardioverter defibrillators (ICDs) is likely to be enhanced by the addition of an atrial sensing/pacing lead. However, differentiation of sinus tachycardia (ST) from ventricular tachycardia (VT) with 1:1 VA conduction will remain problematic. We assessed the use of the AV interval as a potential criterion for correctly differentiating ST from VT.

Continuous wave laser ablation of tissue: analysis of thermal and mechanical events.

Thermal and mechanical events during continuous wave (CW) laser ablation of biological and phantom media were investigated. Porcine aortae, collagen fibers, and polyacrylamide control samples were subjected to argon laser irradiation while infrared and high-speed (240 images/s) video cameras were used to monitor their surfaces. Subsequent analysis of simultaneous changes in surface temperature and physical features correlated thermal and mechanical events.

Laser thermal ablation.

Continuous wave and pulsed laser ablation of tissue is described as an explosive event. A subsurface temperature maximum and superheated tissue produce high pressures that eject fragments from the tissue. Decreased water content due to dehydration and vaporization decreases thermal conductivity which reduces heat conduction.

Light and temperature distribution in laser irradiated tissue: the influence of anisotropic scattering and refractive index.

The rigorous method of discrete ordinates was used to evaluate the effects of anisotropic scattering and optical discontinuity at the boundaries on light and temperature distribution in tissue. The influence of optical parameters of tissue on its thermal response was examined by using a finite element solution of the heat conduction equation. Calculations were performed for wide ranges of scattering albedo, the anisotropy factor, as well as interface reflectivities.