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

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Ultrasound image segmentation: a survey

Automated breast cancer detection and classification using ultrasound images: A survey

Fiber-optic biosensors (FOBS) are optical fiber-derived devices which use optical field to measure biological species such as cells, proteins, and DNA. Because of their efficiency, accuracy, low cost, and convenience, FOBS are promising alternatives to traditional immunological methods for biomolecule measurements. Tapered fiber-optic biosensors (TFOBS) are a type of FOBS which rely on special geometries to expose the evanescent field to interact with samples. In order to amplify sensitivity and selectivity, TFOBS are often used with various optical transduction mechanisms such as changes in refractive index, absorption, fluorescence, and Surface Plasmon Resonance. In this review, the basic principles of TFOBS are summarized. Various common geometries for evanescent sensing and the influence of geometric parameters on optical principles are reviewed. Finally, a detailed account of the studies done to date for biomolecules detection using TFOBS will be provided. © 2007 Elsevier B.V. All rights reserved.

A review of fiber-optic biosensors

An ultrasonic imaging system includes an ultrasonic transducer having an image data array and a tracking array at each end of the image data array. The tracking arrays are oriented transversely to the image data array. Images from the image data array are used to reconstruct a three-dimensional representation of the target. The relative movement between respective frames of the image data is automatically estimated by a motion estimator, based on frames of data from the tracking arrays. As the transducer is rotated about the azimuthal axis of the image data array, features of the target remain within the image planes of the tracking arrays. Movements of these features in the image planes of the tracking arrays are used to estimate motion as required for the three-dimensional reconstruction. Similar techniques estimate motion within the plane of an image to create an extended field of view.

Multiple ultrasound image registration system, method and transducer

This paper presents a novel approach for speckle reduction and coherence enhancement of ultrasound images based on nonlinear coherent diffusion (NCD) model. The proposed NCD model combines three different models. According to speckle extent and image anisotropy, the NCD model changes progressively from isotropic diffusion through anisotropic coherent diffusion to, finally, mean curvature motion. This structure maximally low-pass filters those parts of the image that correspond to fully developed speckle, while substantially preserving information associated with resolved-object structures. The proposed implementation algorithm utilizes an efficient discretization scheme that allows for real-time implementation on commercial systems. The theory and implementation of the new technique are presented and verified using phantom and clinical ultrasound images. In addition, the results from previous techniques are compared with the new method to demonstrate its performance.

/pdf/real-time-speckle-reduction-and-coherence-enhancement-in-4wmyv4m5km.pdf

Real-time speckle reduction and coherence enhancement in ultrasound imaging via nonlinear anisotropic diffusion

The backscattered ultrasonic echo from tissue can be described in terms of Rayleigh distribution or K distribution. Even though both generalized K distribution and homodyned K distribution can account for some of the scattering conditions that exist in tissues, the analytical complexity involved with these distributions is significant. A much simpler generalized model based on the Nakagami distribution is proposed here. This model can describe the statistics of the envelope of the backscattered echo from an ensemble of scatterers with varying number densities, varying cross sections, and the presence or absence of regularly spaced scatterers. Computer simulations and experiments on tissue-mimicking phantoms have been undertaken to test the validity of the model. Results clearly show the versatility of the Nakagami distribution and its parameter to model the backscattered envelope from tissues. It is suggested that Nakagami distribution may be a good model for use in tissue characterization because of its simple analytical nature and ability to encompass different scattering conditions.

A general statistical model for ultrasonic backscattering from tissues

A double frequency method of measuring bubble size which has better spatial resolution than previous techniques, is described. Bubbles are insonified simultaneously by a swept, relatively low, ‘‘pumping’’ frequency near their resonance and a high ‘‘imaging’’ frequency. Theoretical expressions are derived for the sound scattered by a bubble under the influence of these two frequencies. Existence of sharp resonance behavior in the scattered sound at the sum frequency is shown both theoretically and experimentally.

Bubble size measurements using the nonlinear mixing of two frequencies

The departure of speckle magnitude from Rayleigh statistics was applied to examine insonated phantoms with both low and high concentrations of scatterers. A mathematical model, the K distribution of Jakeman, was used to characterize non-Rayleigh statistics. This model contains a parameter, α, which characterizes the clustering of the scattering sites in a medium. It is shown from phantom experiments that alpha is linearly proportional to the log-scaled scatterer concentration in a range from about 1 to 30 scatterers per sample volume.

P. Mohana Shankar

Papers

A review of fiber-optic biosensors

A general statistical model for ultrasonic backscattering from tissues

Bubble size measurements using the nonlinear mixing of two frequencies

Ultrasound speckle analysis based on the K distribution

Detection of pathogen Escherichia coli O157:H7 AT 70 cells/mL using antibody-immobilized biconical tapered fiber sensors.