This review highlights recent advances in X-ray microcomputed tomography (microCT) as applied to materials, specifically advances made since the first materials microCT review appeared in Internati...

Recent advances in X-ray microtomography applied to materials

A sensor interface is configured to receive a sensor signal. A transmitter generates a transmit signal. A receiver receives the signal corresponding to the transmit signal. Further, a monitor interface is configured to communicate a waveform to the monitor so that measurements derived by the monitor from the waveform are generally equivalent to measurements derivable from the sensor signal.

Physiological measurement communications adapter

Micro-CT in small animal and specimen imaging

Ultrasound data is generated by a receive beamformer. Ultrasound image processing is applied to the ultrasound data for presentation of an image. Various ones of the ultrasound image processing steps may be reversed. For example, persistence processing may be reversed in order to obtain ultrasound data associated with data prior to persistence processing. This recovered data may be used to generate an image or for application of a different amount of persistence. Other processes that may be reversed to recover ultrasound data include focal and depth gain compensation, dynamic range compression, intensity or color mapping, and various filtering, such as persistence or spatial filtering.

Medical diagnostic ultrasound system and method for versatile processing

A portable therapeutic device and method of use generate longitudinally propagating ultrasound and shear waves generated by such longitudinally propagating ultrasound to provide effective healing of wounds. A transducer having an operative surface is disposed substantially adjacent to the wound to emit ultrasound to propagate in the direction of the wound to promote healing. Reflections of the ultrasound by bone tissue, by skin layers, or by internally disposed reflective media propagate toward the wound as longitudinal waves, with shear waves generated by the longitudinal waves for the healing of the wound. A focusing element is used for focusing the propagation of the ultrasound at a predetermined angle toward the wound. The operative surface of the transducer may be annularly shaped to encircle the wound to convey the ultrasound and/or reflected ultrasound thereto. A housing may be provided for positioning the transducer near a portion of the skin near the wound, and for indenting the skin to form a cavity, with the transducer disposed in the cavity to emit the ultrasound toward an internal surface of the wound. Fixture structures, such as adjustable straps, may extend about a portion of the body to position the transducer near the wound.

Ultrasonic treatment for wounds

An invention is disclosed for locating a region of interest in the calcaneus. A pair of ultrasound transducers are positioned on the medial and lateral sides of the heel, respectively. The positioning is based on a size of a portion of the body of a subject upon whom the ultrasound assessment of the calcaneus is to be made. In a presently preferred embodiment, the length of the foot from the back to the head of the first metatarsal is used in conjunction with a proportionality constant and an angle, to position the pair of transducers. The positioning so obtained facilitates (i) reproducible measurements and (ii) comparisons of the results obtained in one person with another, because relatively analogous portions of the highly heterogeneous calcanei are assessed in both. In an alternative embodiment, a single transducer is positioned similarly on the heel, operating in pulse-echo mode.

Ultrasonic bone assessment apparatus and method

Ultrasound has been proposed as a means to noninvasively assess bone and, particularly, bone strength and fracture risk. Although there has been some success in this application, there is still much that is unknown regarding the propagation of ultrasound through bone. Because strength and fracture risk are a function of both bone mineral density and architectural structure, this study was carried out to examine how architecture and density interact in ultrasound propagation. Due to the difficulties inherent in obtaining fresh bone specimens and associated architectural and density features, simulation methods were used to explore the interactions of ultrasound with bone. A sample of calcaneal trabecular bone was scanned with micro-CT and subjected to morphological image processing (erosions and dilations) operations to obtain a total of 15 three-dimensional (3-D) data sets. Fifteen two-dimensional (2-D) slices obtained from the 3-D data sets were then analyzed to evaluate their respective architectures and densities. The architecture was characterized through the fabric feature, and the density was represented in terms of the bone volume fraction. Computer simulations of ultrasonic propagation through each of the 15 2-D bone slices were carried out, and the ultrasonic velocity and mean frequency of the received waveforms were evaluated. Results demonstrate that ultrasound propagation is affected by both density and architecture, although there was not a simple linear correlation between the relative degree of structural anisotropy with the ultrasound measurements. This study elucidates further aspects of propagation of ultrasound through bone, and demonstrates as well as the power of computational methods for ultrasound research in general and tissue and bone characterization in particular.

Computational methods for ultrasonic bone assessment.

The manner in which ultrasound interacts with bone is of key interest in therapy and diagnosis alike. These may include applications directly to bone, as, for example, in treatment to accelerate the healing of bone fractures and in assessment of bone density in osteoporosis, or indirectly in diagnostic imaging of soft tissue with interest in assessing exposure levels to nearby bone. Because of the lack of analytic solutions to virtually every "practical problem" encountered clinically, ultrasound simulation has become a widely used technique for evaluating ultrasound interactions in bone. This paper provides an overview of the use of ultrasound simulation in bone. A brief description of the mathematical model used to characterize ultrasound propagation in bone is first provided. A number of simulation examples are then presented that explain how simulation may be utilized in a variety of practical configurations. The focus of this paper in terms of examples presented is on diagnostic applications in bone, and, in particular, for assessment of osteoporosis. However, the use of simulation in other areas of interest can easily be extrapolated from the examples presented. In conclusion, this paper describes the use of ultrasound simulation in bone and demonstrates the power of computational methods for ultrasound research in general and tissue and bone applications in particular.

http://www.cyberlogic.org/IEEE_2008_55(6).pdf

Ultrasound simulation in bone

The purpose of this study was to determine the relationship between three-dimensional (3D) trabecular structure and two-dimensional plain radiographic patterns. An in vitro cylinder of human calcaneal trabecular bone was three-dimensionally imaged by micro-CT using synchrotron radiation, at 33.4 μm resolution. The original 3D image was processed using 14 distinct sequences of morphologic operations, i.e., of dilations and erosions, to obtain a total of 15 3D models or images of calcaneal trabecular bone. These 15 models had distinct densities (volume fractions) and architectures. The 3D structure of each calcaneal model was assessed using mean intercept length (fabric), by averaging individual fabric measurements associated with each medial-lateral image slice, and determining the relative anisotropy, R3D, of the structure. A summated pattern or plain radiograph was also computed from the 3D image data for each calcaneal model. Each summated pattern was then locally thresholded, and the resulting two-dimensional (2D) binary image analyzed using the same fabric analysis as used for the 3D data. The anisotropy of the 2D summated pattern was denoted by Rx-ray. The volume fractions of the 15 models ranged from 0.08 to 0.19 with a mean of 0.14. The medial-lateral anisotropies, R3D, ranged from 1.38 to 2.54 with a mean of 1.88. The anisotropy of the 2D summated patterns, Rx-ray, ranged from 1.35 to 2.18 with a mean of 1.71. The linear correlation of the 3D trabecular architecture, R3D, with the radiographic trabecular architecture, Rx-ray, was 0.99 (p<0.0001). This study shows that the plain radiograph contains architectural information directly related to the underlying 3D structure. A well-controlled sequential reproducible plain radiograph may prove useful for monitoring changes in trabecular architecture in vivo and in identifying those individuals at increased risk of osteoporotic fracture.

Gangming Luo

Papers

Ultrasonic bone assessment apparatus and method

Computational methods for ultrasonic bone assessment.

Ultrasound simulation in bone

Relationship between plain radiographic patterns and three- dimensional trabecular architecture in the human calcaneus.

Finite element analysis of heel pad with insoles