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Whole slide imaging involves high-resolution scanning of glass slides (GSs) prepared from formalin-fixed, paraffin-embedded tissue to create digital images that can be reviewed through digital platforms. The main components of [...], * Context.--In the United States, review of digital whole slide images (WSIs) using specific systems is approved for primary diagnosis but has not been implemented for intraoperative consultation. Objective.--To evaluate the safety of review of WSIs and compare the efficiency of review of WSIs and glass slides (GSs) for intraoperative consultation. Design.--Ninety-one cases previously submitted for frozen section evaluation were randomly selected from 8 different anatomic pathology subspecialties. GSs from these cases were scanned on a Leica Aperio AT2 scanner at x 20 magnification (0.25 [micro]m/pixel). The slides were deidentified, and a short relevant clinical history was provided for each slide. Nine board-certified general pathologists who do not routinely establish primary diagnoses using WSIs reviewed the WSIs using Leica Aperio ImageScope viewing software. After a washout period of 2-3 weeks, the pathologists reviewed the corresponding GSs using a light microscope (Olympus BX43). The pathologists recorded the diagnosis and time to reach the diagnosis. Intraobserver concordance, time to diagnosis, and specificity and sensitivity compared to the original diagnosis were evaluated. Results.--The rate of intraobserver concordance between GS results and WSI results was 93.7%. Mean time to diagnosis was 1.25 minutes for GSs and 1.76 minutes for WSIs (P < .001). Specificity was 91% for GSs and 90% for WSIs; sensitivity was 92% for GSs and 92% for WSIs. Conclusions.--Time to diagnosis was longer with WSIs than with GSs, and scanning GSs and uploading the data to whole slide imaging systems takes time. However, review of WSIs appears to be a safe alternative to review of GSs. Use of WSIs allows reporting from a remote site during a public health emergency such as the COVID-19 pandemic and facilitates subspecialty histopathology services. (Arch Pathol Lab Med. 2024;148:715-721; doi: 10.5858/arpa.2023-0105-OA)

In the field of civil engineering, sounding the top layer of carriageways, i.e., the pavement layer, is classically performed using standard ground-penetrating radar (GPR), whose resolution is bandwidth dependent. The layer thickness is deduced from both the time delays of backscattered echoes and the known dielectric constant of the medium. This paper focuses on superresolution and high-resolution techniques, which serve to improve the time resolution of GPR signals, and presents a parametric technique and five subspace methods, namely, estimation of signal parameters via rotational invariance techniques (ESPRIT), multiple-signal classification (MUSIC) algorithm, Min-Norm, and their polynomial versions root-MUSIC and root-Min-Norm. The performance of these algorithms will be compared in terms of resolution power as well as root-mean-square error on the estimated thickness. The paper also presents the results of computer tests and radar measurements in the far field. Index Terms--Civil engineering, ground-penetrating radar (GPR), nondestructive testing (NDT), pavement survey, resolution, root mean square error (RMSE), time-delay estimation (TDE).

Objective: To review the reported efficacy of various imaging techniques in assessing stability of the neck in blunt trauma patients, and to present the protocol and preliminary results of a [...]

Digital image processing is formally defined as 'subjecting numerical representations of objects to a series of operations in order to obtain a desired result.' (1) More simply put, digital image [...], Digital image processing is now commonplace in radiology, nuclear medicine and sonography. This article outlines underlying principles and concepts of digital image processing. After completing this article, readers should be able to: * List the limitations of film-based imaging. * Identify major components of a digital imaging system. * Describe the history and application areas of digital image processing. * Discuss image representation and the fundamentals of digital image processing. * Outline digital image processing techniques and processing operations used in selected imaging modalities. * Explain the basic concepts and visualization tools used in 3-D and virtual reality imaging. * Recognize medical imaging informatics as a new area of specialization for radiologic technologists. This article is a Directed Reading. See the quiz at conclusion.

Here light propagation and radiation transfer of ultrafast laser pulses in heterogeneous biological tissues are simulated by use of the discrete-ordinates method (DOM). Formulations for solving the time-dependent radiation-transfer equation are deduced for three-dimensional geometries incorporating the Fresnel specularly reflecting boundary condition and characteristics of ultrafast laser pulses. The present method can treat both the incident laser intensity and the scattered radiation intensity from the walls of the targeted tissue as two components, i.e., a diffuse part and a specular part. Reflectivity at the tissue-air interface is calculated by use of Snell's law and the Fresnel equation. The high-order [S.sub.10] DOM method is found to be adequate for describing the propagation and transfer of ultrafast laser radiation in heterogeneous tissues. The time-dependent radiation field in the tissue as well as the temporal radiation intensity profiles at the boundaries can be obtained simultaneously. The absolute values of the logarithmic slope of the temporal reflectance and transmittance at various detector positions are found to converge to a constant value in a homogeneous tissue model. With the inclusion of a small inhomogeneity, such a value will change in line with the property of the embedded inhomogeneity. The orientation of heterogeneity of the tissues also substantially affects the radiation intensity at the boundaries. The effect of the Fresnel boundary in the modeling is pronounced. The simulated transmitted signals are broadened and amplified under specularly reflecting boundary condition as compared with those under diffusely reflecting boundary conditions. OCIS codes: 170.5280, 170.6920, 030.5620, 140.7090, 000.4430.

The Moderate Resolution Imaging Spectroradiometer (MODIS) aboard the Terra spacecraft contains spectral bands that allow retrieval of solar-induced phytoplankton chlorophyll fluorescence emission radiance. Concurrent airborne laser-induced (and water-Raman normalized) phytoplankton chlorophyll fluorescence data is used to successfully validate the MODIS chlorophyll fluorescence line height (FLH) retrievals within Gulf Stream, continental slope, shelf, and coastal waters of the Middle Atlantic Bight portion of the western North Atlantic Ocean for 11 March 2002. Over the entire ~480-km flight line a correlation coefficient of [r.sup.2] = 0.85 results from regression of the airborne laser data against the MODIS FLH. It is also shown that the MODIS FLH product is not influenced by blue-absorbing chromophoric dissolved organic matter absorption. These regional results strongly suggest that the FLH methodology is equally valid within similar oceanic provinces of the global oceans. OCIS codes: 010.4450, 120.0280, 280.3640, 280.3420, 300.2530, 300.6360.

Information loss may occur frequently in the imaging of living tissues by using two-photon fluorescence microscopy due to the intensive deformation of the tissue. A landmark-based optical flow interpolation scheme is proposed for image reconstruction of living aorta walls in two-photon autofluorescence image sequences. Landmarks are extracted and evaluated by an active contour-based aorta model, and are aligned and reconstructed by use of a hierarchical algorithm. The accuracy of the calculation of optical flow is improved by applying landmark-based image warping. Experimental results show that the proposed scheme outperforms commonly used optical flow interpolation techniques for the reconstruction of intensively deforming tissues. OCIS codes: 100.3020, 110.0180, 150.4620, 170.3010, 170.3880.

Holographic particle image velocimetry (HPIV) is presently the only method that can measure at high resolution all three components of the velocity in a finite volume. In systems that are based on recording one hologram, velocity components parallel to the hologram can be measured throughout the sample volume, but elongation of the particle traces in the depth direction severely limits the accuracy of the velocity component that is perpendicular to the hologram. Previous studies overcame this limitation by simultaneously recording two orthogonal holograms, which inherently required four windows and two recording systems. This paper introduces a technique that maintains the advantages of recording two orthogonal views, but requires only one window and one recording system. Furthermore, it enables a quadruple increase in the spatial resolution. This method is based on placing a mirror in the test section that reflects the object beam at an angle of 45[degrees]. Particles located in the volume in which the incident and reflected beams from the mirror overlap are illuminated twice in perpendicular directions. Both views are recorded on the same hologram. Off-axis holography with conjugate reconstruction and high-pass filtering is used for recording and analyzing the holograms. Calibration tests show that two views reduce the uncertainty in the three-dimensional (3-D) coordinates of the particle centroids to within a few microns. The velocity is still determined plane-by-plane by use of two-dimensional particle image velocimetry procedures, but the images are filtered to trim the elongated traces based on the 3-D location of the particle. Consequently, the spatial resolution is quadrupled. Sample data containing more than 200 particles/[mm.sup.3] are used for calculating the 3-D velocity distributions with interrogation volumes of 220 x 154 x 250 [micro]m, and vector spacing of 110 x 77 x 250 [micro]m. Uncertainty in velocity is addressed by examining how well the data satisfies the continuity equation. The results show significant improvements compared with previous procedures. Limitations of the technique are also discussed.

For the atmospheric correction of ocean-color imagery obtained over Case I waters with the Sea-Viewing Wide Field-of-View Sensor (SeaWiFS) instrument the method currently used to relax the black-pixel assumption in the near infrared (NIR) relies on (1) an approximate model for the nadir NIR remote-sensing reflectance and (2) an assumption that the water-leaving radiance is isotropic over the upward hemisphere. Radiance simulations based on a comprehensive radiative-transfer model for the coupled atmosphere-ocean system and measurements of the nadir remote-sensing reflectance at 670 nm compiled in the SeaWiFS Bio-optical Algorithm Mini-Workshop (SeaBAM) database are used to assess the validity of this method. The results show that (1) it is important to improve the flexibility of the reflectance model to provide more realistic predictions of the nadir NIR water-leaving reflectance for different ocean regions and (2) the isotropic assumption should be avoided in the retrieval of ocean color, if the chlorophyll concentration is larger than approximately 6, 10, and 40 mg [m.sup.-3] when the aerosol optical depth is approximately 0.05, 0.1, and 0.3, respectively. Finally, we extend our scope to Case II ocean waters to gain insight and enhance our understanding of the NIR aspects of ocean color. The results show that the isotropic assumption is invalid in a wider range than in Case I waters owing to the enhanced water-leaving reflectance resulting from oceanic sediments in the NIR wavelengths. OCIS codes: 010.1290, 010.4450, 280.0280, 290.0290.

We demonstrate a computationally efficient procedure for determining only the semiconductor sites in a confocal reflectance image of an integrated circuit. It utilizes a one-photon optical beam-induced current (1P-OBIC) and confocal reflectance images that are generated from the same focused excitation beam. A 1P-OBIC image is a two-dimensional map of the currents induced by the beam as it is scanned across the circuit surface. A 1P-OBIC is produced by an illuminated semiconductor material if the excitation photon energy exceeds the bandgap. The 1P-OBIC image has no vertical resolution because the 1P-OBIC is linear with the excitation beam intensity. The exclusive high-contrast image of semiconductor is generated by the product of the 1P-OBIC image and the confocal image. High-contrast images of the metal sites are also obtained by the product of the complementary OBIC image and the same confocal image. OCIS codes: 180.1790, 100.2980, 110.4190.

A method for the direct observation of solute molecules interacting with a C18 stationary phase under real separation conditions in capillary electrochromatography (CEC) is investigated. The experiments were performed in a capillary electrochromatographic mode; however, the method and findings are useful both in CEC and revered-phase liquid chromatography. The distribution of solute molecules in the packed capillary is directly imaged with laser scanning confocal fluorescence microscopy. Conventional imaging techniques produce images where the C18 silica beads cannot be distinctively identified as a result of the deep depth of field. The optical sectioning capability of confocal imaging overcomes this problem to afford clearly defined images of the stationary-phase packing and the surrounding mobile phase. Fluorescein molecules are preferentially distributed in the mobile phase under reversed-phase chromatographic conditions. Nile Red and rhodamine 6G molecules prefer the environments of the porous C18 beads. Intensity distributions over time for areas within the stationary-phase beads differ from distributions of areas outside the beads in the mobile phase. Images taken at different depths into the capillary probe the internal structure of the C18 beads. While the internal structures of most beads are porous, confocal images show a small fraction (2%) of the silica beads have porous shells and nonporous cores. The capability of imaging the stationary phase distinctively from the mobile phase opens the possibilities of studying the quality of stationary phase, the structure of the column packing, and the mechanisms of separation.

The design and operation of a noncontact surface profilometry system based on the time-correlated single-photon-counting technique are described. This system has a robust optomechanical design and uses an eye-safe laser that makes it particularly suitable for operation in an uncontrolled industrial environment. The sensitivity of the photon-counting technique permits its use on a variety of target materials, and its mode of operation does not require the continual presence of an operator. The system described has been optimized for a 1-25-m standoff, has a distance repeatability of OCIS codes: 010.4450, 290.5850, 290.4020.

Independent component analysis (ICA) has shown success in blind source separation and channel equalization. Its applications to remotely sensed images have been investigated in recent years. Linear spectral mixture analysis (LSMA) has been widely used for subpixel detection and mixed pixel classification. It models an image pixel as a linear mixture of materials present in an image where the material abundance fractions are assumed to be unknown and nonrandom parameters. This paper considers an application of ICA to the LSMA, referred to as ICA-based linear spectral random mixture analysis (LSRMA), which describes an image pixel as a random source resulting from a random composition of multiple spectral signatures of distinct materials in the image. It differs from the LSMA in that the abundance fractions of the material spectral signatures in the LSRMA are now considered to be unknown but random independent signal sources. Two major advantages result from the LSRMA. First, it does not require prior knowledge of the materials to be used in the linear mixture model, as required for the LSMA. Second, and most importantly, the LSRMA models the abundance fraction of each material spectral signature as an independent random signal source so that the spectral variability of materials can be described by their corresponding abundance fractions and captured more effectively in a stochastic manner. The experimental results demonstrate that the proposed LSRMA provides an effective unsupervised technique for target detection and image classification in hyperspectral imagery. Index Terms--Hyperspectral image classification, independent component analysis (ICA), linear spectral mixture analysis (LSMA), linear spectral random mixture analysis (LSRMA).

We present what we believe to be a new digital holographic imaging method that is able to determine simultaneously the distributions of intensity, phase, and polarization state at the surface of a specimen on the basis of a single image acquisition. Two reference waves with orthogonal polarization states interfere with the object wave to create a hologram that is recorded on a CCD camera. Two wave fronts, one for each perpendicular polarization state, are numerically reconstructed in intensity and phase. Combining the intensity and the phase distributions of these two wave fronts permits the determination of all the components of the Jones vector of the object-wave front. We show that this method can be used to image and measure the distribution of the polarization state at the surface of a specimen, and the obtained results indicate that precise quantitative measurements of the polarization state can be achieved. An application of the method to image the birefringence of a stressed polymethyl methacrylate sample is presented. OCIS codes: 090.0090, 090.1760, 120.0120, 120.5410, 070.2580, 260.1440, 260.5430, 040.1520

We introduce a methodology for radiometric reconstruction, the simultaneous recovery of multiple illuminants and surface albedoes from multiple views, assuming that the geometry of the scene and of the cameras is known. We formulate the linear theory of multiple illuminants and show its similarities with the theory of geometric recovery of multiple views. Linear and nonlinear implementations are proposed, simulation results are discussed, and, finally, results on real images are presented. Index Terms--Reconstruction, multiple views, linear models, radiometric recovery, Lambertian reflection, point light sources, ambiant illumination, surface albedo.

This paper is aimed at exploring the possibility of using a microwave approach based on a genetic algorithm to detect a defect inside a known host object. Starting from the knowledge of the scattered field, the problem solution is recast as a two-step procedure. After defining a cost function depending on the geometric parameters of the crack, a minimization procedure based on a hybrid-coded genetic algorithm is applied. The influence of the noise as well as of the geometry of the defect on the crack detection and reconstruction is investigated. Moreover, the numerical effectiveness of the iterative approach is examined. Index Terms--Genetic algorithms, microwave imaging, nondestructive testing.

In this paper, we present a novel joint-source and channel image-coding scheme for noisy channel transmission. The proposed scheme consists of two innovative components: 1) intelligent bidirectional synchronization and 2) layered bit-plane error protection. The bidirectional synchronization is able to recover the coding synchronization when any single or even when two consecutive synchronization codes are corrupted by the channel noise. With synchronized partition, unequal error protection for each bit plane can be designed based on the analysis of bit-plane error sensitivity for compressed image data transmission over noisy channels. Experimental results over extensive channel simulations show that the proposed scheme outperforms the well-known approach proposed by Sherwood and Zeger [1]. Index Terms--Bidirectional synchronization, hierarchical error correction, image transmission, noisy channel.

In positron emission tomography, uncertainties in---or lack of knowledge of---depths of interaction lead to errors in the assignment of position of coincidence events. This paper examines analytically the dependence of these errors on depth of interaction. Here derived are expressions that relate rebinning errors to the uncertainties in the measurement of interaction positions including depth of interaction. The results confirm the intuitive notion that rebinning errors are minimized when depth of interaction is measured at least as well as the transverse position. Index Terms--Coincidence imaging, depth of interaction (DOI), positron emission tomography, rebinning.

Analyses of spaceborne imaging radar-C (SIR-C) data and field data from the northwestern Yucatan Peninsula, Mexico, demonstrate that spaceborne multifrequency polarimetric radars are excellent tools for characterizing patterns of wetland flooding. Seasonal flooding can be detected in most types of forest and marsh in the radar backscatter magnitude and phase data of both L and C band. Field observations made in the wet and dry seasons concurrent with the space missions and chemical analyses of floodwaters confirm that flooding is the product of discharge from the Yucatan aquifer, which consists of a fresh-water lens floating on seawater. This discharge controls the distribution of wetlands. Therefore, vegetation and flooding patterns, mapped with SIR-C imagery, provide valuable information on the hydrogeology of the region. Radar-image maps of wetlands and flooding indicate that there are three major zones of groundwater discharge that correlate with structures of the buried Chicxulub crater--zone 1 with the peak ring, zone 2 with the crater rim, and zone 3 with the exterior ring. Zone 1 has sulfate-poor discharge, unlike the sulfate-rich discharge in zones 2 and 3. The highest discharge is in zone 3, where the buried crater is closest to the surface. This groundwater-discharge pattern can be explained by tidal pumping of fresh water to the surface through high permeability zones developed in the Tertiary carbonates overlying crater faults and escarpments. Keywords: Chicxulub crater, coastal environment, groundwater, radar, remote sensing, wetlands.

Byline: P. Bergamini (1), G. Bonelli (1), A. Paizis (1), L. Tommasi (2), M. Uslenghi (1), R. Falomo (3), G. Tondello (4) Keywords: high speed photometry; ICCD; MCP; photon counting Abstract: The scientific performance evaluation of a photon countingimaging system is presented. The detector is constituted by an ICCD camera with RbTe photocathode(optimized for UV radiation), and dedicated electronics for the acquisition and analysis ofthe events. For each photon event on the CCD, a real-time centroid calculation is performed, inorder to reach spatial resolution down to 25 um FWHM. The system has been tested usingthe 182 cm telescope of the Asiago Observatory.A standard stars field through U Johnson filter,and the Crab pulsar (PSR 0531+21) were observed. From the photometric data, relative magnitudes of the standard stars have been derived, showing a goodlinearity of the detector in the range of flux under consideration, as expected fromprevious laboratory measurements.The pulsar's data have been processed by FFT and epoch foldingtechniques to testthe detector's timing performances in the highest resolutionmode (4.512 ms).These observations show that a space resolved time analysis ofperiodic sources can be performed with 10.sup.-7 s accuracy. Author Affiliation: (1) Istituto di Fisica Cosmica G. Occhialini, CNR Milano, Italy (2) Istituto di Fisica Cosmica G. Occhialini, CNR Milano, Italy (3) Osservatorio Astronomico di Padova, Italy (4) Dipartimento di Elettronica e Informatica, Universita di Padova, Italy Article History: Registration Date: 07/10/2004

From its beginnings, virtual reality has been proposed as the apex of image production, completing, as many scholars and artists have argued, the search for the ultimate visual display medium. This essay examines the technology and possibilities of virtual reality by investigating these conceptual maneuvers that connect computer simulated environments to the history of mediated communication and the logic of representation. The essay examines the conceptual history of image production in mediated communication, locates contemporary discussions of virtual reality within this tradition, and offers a deconstructive critique of representation, proposing alternative visions of virtual reality and computer simulation.

The fundamental reasons that determine the tolerance of free-space optical interconnect systems to misalignment are considered. By evaluation of the overlap of single-mode optical beams in the presence of misalignment it possible to determine an optimum beam configuration. It is shown that for any level of misalignment there is an optimum beam diameter that maximizes the coupling of light through the system. Many interconnect systems are not single mode throughout, so the analysis is extended to cover multimode systems. It is shown that, in principle, any level of misalignment can be accommodated by use of multimode beams, although at the cost of reduced channel density. It is shown that the presence of misalignment will mean that the number of channels that can be supported by an interconnect reduces with the length of the interconnect. As possible candidates for passively aligned systems, three example optical systems are analyzed by use of the methods developed.

A method for obtaining phase-retardation functions, which give rise to an increase of the image focal depth, is proposed. To this end, the Wigner distribution function corresponding to a specific aperture that has an associated small depth of focus in image space is conveniently sheared in the phase-space domain to generate a new Wigner distribution function. From this new function a more uniform on-axis image irradiance can be accomplished. This approach is illustrated by comparison of the imaging performance of both the derived phase function and a previously reported logarithmic phase distribution. OCIS codes: 100.2550, 100.5070.

A method of computation of the pulse shape in an ionisation chamber with wire collectors has been developed and verified experimentally with a test chamber. Good agreement between the calculated waveforms and the acquired signals is obtained. Having proved its reliability, the same method was applied to study the dependence of the signal pulse shape and amplitude on the location of primary ionisation due to 511 keV [Gamma]-rays in the liquid xenon multiwire ionisation chamber for PET. A method of real-time amplitude correction for this effect is suggested, resulting in significant improvement of energy resolution. The simulated resolution for 511 keV [Gamma]-rays is 15%.

Byline: Kazuaki Nakayama, Kunio Miyatake, Masaaki Uematsu, Norio Tanaka, Shiro Kamakura, Satoshi Nakatani, Nobuo Yamazaki, Masakazu Yamagishi Abstract: To examine the feasibility of a tissue Doppler imaging (TDI) technique for evaluating the early contraction sites in Wolff-Parkinson-White (WPW) syndrome, we analyzed the time-sequential changes in ventricular wall motion in WPW syndrome by TDI. Fifty patients with WPW syndrome were examined by the TDI system in which the high-speed scanning technique allowed for a frame rate up to 38 frames/sec. Among 42 patients in whom the acceptable images were obtained by TDI, the early contraction, which was represented by a red or blue spot appearing on the subendocardial side at the time of the [delta] wave in the electrocardiogram, was demonstrated in 25 of 29 patients with left-sided accessory pathways. However, in 13 patients with right-sided pathways, the early contraction sites could be identified in only five patients. The TDI-determined early contraction sites were well coincided with the sites of the accessory pathways determined by the electrophysiologic examination (p < 0.01). After the successful radiofrequency catheter ablation, early contraction sites were found to disappear by TDI in all patients. These results demonstrate the feasibility of the TDI technique to evaluate the early ventricular contraction associated with the atrioventricular accessory pathways. We suggest that the TDI system is helpful to localize the accessory pathways and to evaluate the results after radiofrequency ablation, although further studies are necessary to demonstrate the advantage of TDI over conventional echocardiography and electrophysiologic study in the evaluation of the accessory pathways in WPW syndrome. (Am Heart J 1998;135:99-106.) Author Affiliation: Osaka and Tochigi, Japan Article History: Received 24 January 1997; Accepted 17 July 1997 Article Note: (footnote) [star] From the Cardiology Division of Medicine, National Cardiovascular Center, and the aDivision of Medical Engineering, Toshiba Co. Supported in part by grants from the Ministry of Heath and Welfare of Japan (Tokyo)., [star][star] Reprint requests: Kunio Miyatake, MD, Cardiology Division of Medicine, national Cardiovascular Center, 5-7-1 Fujishiro-dai, Suita, Osaka 565, Japan., a 4/1/84854

We describe a novel stereocamera for particle image velocimetry (PIV) applications that incorporates the Scheimpflug condition that the object plane, lens plane, and image plane must be collinear. We examined the governing equations for this system using a computer-based sensitivity analysis to predict the accuracy of the in-plane and out-of-plane measurement. We evaluated the performance of the Scheimpflug PIV system with a three-dimensional uniform translation test. Results indicate that the Scheimpflug PIV stereocamera performs as expected. The larger off-axis angles possible with the Scheimpflug system can provide a higher accuracy in the out-of-plane component when compared with a translation PIV stereocamera. Key words: Particle image velocimetry, Scheimpflug, stereocamera.

Shear-force imaging which is usually applied for distance regulation in scanning near-field optical microscopy was found to be an unreliable method for accurate topographic measurements. This is due to the variation of shear-force damping in various materials. Findings for the shear-force damping properties for various materials are shown. Results also indicated that there are at least two distinct shear force damping mechanisms and that damping properties are related to the islands' size on glass substrates.