Laurent Pelissier

Importance of transducer position tracking for automated breast ultrasound: Initial assessments

Breast cancer causes the most cancer deaths in women all over the world. Given the unknown cause and invasive nature of the disease, early detection and treatment is crucial to the survival of the cancer patients. X-rays mammography is an effective screening tool for breast cancer but misses nearly half of them in women with dense breasts, in which case supplemental ultrasound (US) screening must be used. Recent development in 3D automated breast ultrasound (ABUS) provides a faster and potentially more accurate alternative to the conventional 2D hand-held US in detecting the tumors. Typically in these systems, a custom-built linear or curvilinear transducer is automatically swept over or rotated around the tissue to acquire a set of 2D images, from which a 3D high-resolution volume of the breast can be reconstructed. In this work, we study the importance of transducer position tracking in the ABUS volume reconstruction process. Our experiments show that an accurate localization of the images results in a more accurate volume reconstruction.

Microcalcification enhancement in ultrasound images from a concave Automatic Breast Ultrasound Scanner

In this paper, we have proposed a tensor-based filtering method to enhance the SNR of hyperechoic spots in human breast ultrasound images while suppressing the speckle noise. The breast images were acquired by an Automatic Breast Ultrasound Scanner (ABUS), which offers high spatial resolution and the fast full breast exam capability. The enhanced images were then gone through a pattern recognition kernel to distinguish the small hyperechoic spots against large tissue boundaries. The isolated hyperechoic spots were finally merged back to the original image. We believe the proposed method can facilitate the detection and analyzing of microcalcifications (MC) in the noisy ultrasound images. This could offer a non-invasive alternative solution for the mammography in breast cancer diagnosis.

A Flexible Research Interface for Collecting Clinical Ultrasound Images

The Sonix RP is an easy to use ultrasound imaging device that is capable of acquiring high quality images. In addition to supporting the acquisition of multiple data types such as RF, elastography, and color doppler data, the machine is an open ended system providing users with full control over imaging parameters through an investigational research interface. Since the Sonix RP is PC based and it supports open-source software development toolkits, programs can be developed and executed directly onto the device, thus eliminating the need for extra hardware that is often required for data collection and processing. Due to these advantages, many universities and research institutes have successfully used the Sonix RP to test and implement their customized solutions for different applications.

An automated breast ultrasound system for elastography

An automated breast ultrasound system (ABUS) has recently been introduced for breast screening and monitoring of cancer treatment. ABUS enables clinicians to acquire ultrasound images from the entire breast tissue in a few minutes. In this work we report the addition of tissue elasticity imaging to the ABUS system that enables the clinician to automatically acquire 3D strain volume of the breast tissue. The performance of the system is validated experimentally using a commercial breast elasticity phantom. The results show that the proposed automated system can reliably generate elasticity images of the breast tissue that can be reviewed by clinicians along side ultrasound images.

Real-time 1-D/2-D transient elastography on a standard ultrasound scanner using mechanically induced vibration

Transient elastography has been well established in the literature as a means of assessing the elasticity of soft tissue. In this technique, tissue elasticity is estimated from the study of the propagation of the transient shear waves induced by an external or internal source of vibration. Previous studies have focused mainly on custom single-element transducers and ultrafast scanners which are not available in a typical clinical setup. In this work, we report the design and implementation of a transient elastography system on a standard ultrasound scanner that enables quantitative assessment of tissue elasticity in real-time. Two new custom imaging modes are introduced that enable the system to image the axial component of the transient shear wave, in response to an externally induced vibration, in both 1-D and 2-D. Elasticity reconstruction algorithms that estimate the tissue elasticity from these transient waves are also presented. Simulation results are provided to show the advantages and limitations of the proposed system. The performance of the system is also validated experimentally using a commercial elasticity phantom.

In vivo needle visualization in ultrasound images using tensor-based filtering

In this paper, we have proposed an improved tensor-analysis based method with adaptive beam sequence and RF processing to enhance the needle visualization. In vivo study has proved that the needle CNR has been improved for more than 4 times on 30 femoral and deep interscalene blocks without introducing significant artifacts. We believe the proposed method could be useful in the real-time guidance of needle insertion.

Real-time transient elastography on standard ultrasound using mechanically induced vibration: System design and initial results

Tissue elasticity can be deduced from the study of the propagation of shear waves. Transient elastography by means of mechanical vibration has been well established in the literature as a means of assessing the elasticity of the soft tissue and shown to be useful in different clinical applications. Previous studies have focused mainly on custom single element ultrasound transducers and ultrafast ultrasound scanners. In this work, we report the design and implementation of a transient elastography system on a standard ultrasound scanner that enables quantitative assessment of tissue elasticity in real-time. We presents the actuator design as well as the proposed data acquisition schemes that enable imaging of transient shear waves both in 1D and 2D in addition to the reconstruction algorithms for estimating the Youngs modulus from these 1D and 2D wave images. The performance of the system is validated experimentally using a commercial elasticity phantom. In both 1D and 2D imaging modes, a good agreement was observed between the Youngs modulus reported by the phantom manufacturer and the Youngs modulus estimated by our system.

Adaptive Spatial Compounding for Needle Visualization

In this paper, we have proposed an adaptive tensor-analysis based spatial compounding method to enhance the needle visualization. In-vitro study has proved that the needle CNR has been improved from 0.78 to 4.58 without introducing significant artifacts. Meanwhile, no manual adjustments are needed during the procedure since the proposed method can enhance the needle with a big range of insertion angles under the same configuration. We believe the proposed method could be useful in the real-time guidance of needle insertion.

High frame rate flow imaging using plain wave transmits: A feasibility study

Ultrafast imaging using plane wave excitation has been recently introduced for high frame rate color flow imaging. In this paper, we will propose a frequency-based analysis method to estimate the average, minimum, and maximum flow velocity from the ultrafast images. The result has been compared with the traditional color flow imaging and showed high consistency. We believe the proposed high frame rate color flow imaging method will be useful when studying the complex, fast-changing flow patterns, and turbulent flow.