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

http://www.iacl.ece.jhu.edu/~prince/smia/2009/papers2009/NotxJACC05-CardiacFunction-Speckle-Tracking-Torsion.pdf

Measurement of ventricular torsion by two-dimensional ultrasound speckle tracking imaging

Explains set theoretic estimation, which is governed by the notion of feasibility and produces solutions whose sole property is to be consistent with all information arising from the observed data and a priori knowledge. Each piece of information is associated with a set in the solution space, and the intersection of these sets, the feasibility set, represents the acceptable solutions. The practical use of the set theoretic framework stems from the existence of efficient techniques for finding these solutions. Many scattered problems in systems science and signal processing have been approached in set theoretic terms over the past three decades. The author synthesizes a single, general framework from these various approaches, examines its fundamental philosophy, goals, and analytical techniques, and relates it to conventional methods. >

The foundations of set theoretic estimation

Publisher Summary Image recovery is a broad discipline that encompasses the large body of inverse problems, in which an image h is to be inferred from the observation of data x consisting of signals physically or mathematically related to it. Image restoration and image reconstruction are the two main sub-branches of image recovery. The term “image restoration” usually applies to the problem of estimating the original form h of a degraded image x . The following four basic elements are required to solve an image recovery problem: (1) a data formation model, (2) a priori information, (3) a recovery criterion, and (4) a solution method. The recovery criterion defines the class of images that are acceptable as solutions to the problem. It is chosen by the user on grounds that may include experience, compatibility with the available a priori knowledge, personal convictions on the best way to solve the problem, and ease of implementation. The traditional approach has been to use a criterion of optimality, which usually leads to a single best solution. An alternative approach is to use a criterion of feasibility, in which consistency with all prior information and the data defines a set of equally acceptable solutions. The solution method is a numerical algorithm that will produce a solution to the recovery problem—that is, an image that satisfies the recovery criterion. Modification can be made in two directions: in the conventional image recovery framework, one seeks to preserve the notion of an optimal solution, whereas in the set theoretic framework the emphasis is placed on feasibility.

/pdf/the-convex-feasibility-problem-in-image-recovery-8hnancgrll.pdf

The Convex Feasibility Problem in Image Recovery

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

Angle Independent Ultrasonic Detection of Blood Flow

In two-dimensional echocardiography the study of the motion of the heart, especially of the left ventricle, is of central interest Although the clinician can see this motion on real-time two-dimensional echocardiograms, its quantification can still be greatly improved This paper presents and tests a computer method to quantify the motion of the heart from digitized image sequences This method computes on every point of an image the two-dimensional velocity vector which characterizes its motion from this image to the next This approach has the following advantages: 1) border recognition algorithms are no longer needed, 2) motion is not restricted to its radial component, and 3) motion information is available on every point of the image

Computer Analysis of Heart Motion from Two-Dimensional Echocardiograms

In this paper, the theory of image restoration by projections onto closed convex sets is applied to the restoration of vector fields. A set of useful projection operators is presented together with a linear time numerical implementation. These projection operators can be used to restore from partial information the velocity or deformation fields computed between successive views of a scene. They also find applications in the restoration of vector fields of physical quantities as those encountered in mechanics, hydrodynamics, or electromagnetism. The method is compared with the variational approach and illustrated by restoring simulated vector fields.

Vector field restoration by the method convex projections

A comparative evaluation of three different approaches for detecting body surface isopotential map abnormalities in patients with myocardial infarction

A simulation study of the accuracy of the single moving dipole (SMD) cardiac representation was done using a realistic computer model of the human torso. This model included regions of different electrical conductivities such as the lungs and the intraventricular blood masses. Dipolar potential distributions generated on the surface of this model were sampled with different electrode arrangements and were subsequently contaminated with random noise. The location, magnitude, and orientation of the SMD which optimally fitted these potentials were then compared to those of the original dipole source in order to assess the errors in the SMD parameters. The SMD computations were based on a least squares estimation of a variable number of multipolar components recovered inside a torso model which was either finite and homogeneous or finite with lungs. The results showed that the SMD accuracy can be significantly improved by adding higher order multipolar components, e.g., with 120 electrodes and the absence of noise, the rms position error was 15.5 mm with eight multipoles and 0.6 mm with 24 multipoles when the same homogeneous model was used for both the simulation and the recovery. It was also shown that the addition of lungs in the recovery model permitted a higher accuracy when either the lungs, or the lungs with blood masses, were present when the dipolar potential distributions were generated; for these two cases, the rms position errors were thus 1.7 and 4 mm, respectively, using 120 electrodes and 24 multipoles in the absence of noise.

A Simulation Study of the Single Moving Dipole Representation of Cardiac Electrical Activity

In the diagnostic ultrasound community, the echographic B-scan texture is an important area of investigation since it can be analyzed to characterize the histologic state of internal tissues. In the present paper, a minicomputer based system was used to digitize B-mode images and to develop a method to measure their textural information. This method is based on the concept of local information content of spatial image proposed by Lowitz (1983, 1984). It first measures the local gray-level histogram in a small square window centered on each picture element (pixel) of a digitized B-mode image. The information derived from the local histograms is then used to characterize the tissues, to partition the B-mode image into homogeneous zones of texture, to estimate to what extent a tissue is different from another, to delimit the contours of a tissue and to measure its surface. The method is illustrated on the thyroid gland but it can be applied to the study of other organs.

Guy E. Mailloux

Papers

Computer Analysis of Heart Motion from Two-Dimensional Echocardiograms

Vector field restoration by the method convex projections

A comparative evaluation of three different approaches for detecting body surface isopotential map abnormalities in patients with myocardial infarction

A Simulation Study of the Single Moving Dipole Representation of Cardiac Electrical Activity

Local histogram information content of ultrasound B-mode echographic texture