Image Intensity Measurements Research Articles

Anti-Counterfeiting Tags Using Flexible Substrate with Gradient Micropatterning of Silver Nanowires.

Anti-counterfeiting technologies for small products are being developed. We present an anti-counterfeiting tag, a grayscale pattern of silver nanowires (AgNWs) on a flexible substrate. The anti-counterfeiting tag that is observable with a thermal imaging camera was fabricated using the characteristics of silver nanowires with high visible light transmittance and high infrared emissivity. AgNWs were patterned at microscale via a maskless lithography method using UV dicing tape with UV patterns. By attaching and detaching an AgNW coated glass slide and UV dicing tape irradiated with multiple levels of UV, we obtained AgNW patterns with four or more grayscales. Peel tests confirmed that the adhesive strength of the UV dicing tape varied according to the amount of UV irradiation, and electrical resistance and IR image intensity measurements confirmed that the pattern obtained using this tape has multi-level AgNW concentrations. When applied for anti-counterfeiting, the gradient-concentration AgNW micropattern could contain more information than a single-concentration micropattern. In addition, the gradient AgNW micropattern could be transferred to a flexible polymer substrate using a simple method and then attached to various surfaces for use as an anti-counterfeiting tag.

MRI Automated T1 Signal Intensity Detection of Diffuse Brain Manganese Accumulation in Cirrhosis.

Cirrhosis is associated with diffuse brain manganese deposition, which results in increased signal intensity (SI) in the brain on T1-weighted images, most often visualized in the globus pallidus. The purpose of this study was to determine if automated image intensity measurements can detect SI differences in the basal ganglia and other regions reported to have manganese deposition in patients with cirrhosis compared with controls. T1 FSPGR images were acquired on 28 patients with cirrhosis and 28 age-sex-matched controls. FreeSurfer T1 SI values were obtained for the globus pallidus, putamen, cerebral white matter, cerebral cortex, and brainstem. SI ratios were computed for globus pallidus normalized to white matter and brainstem. SI values and SI ratios were compared between groups using t-tests. Among people with cirrhosis, T1 SI was significantly increased in the globus pallidus, putamen, cerebral white matter, cerebral cortex, and brainstem (P< .001), and the globus pallidus to brainstem ratio was significantly increased (P< .001). No significant difference was seen for globus pallidus to cerebral white matter T1 SI ratio (P = .38). Automatic assessment of T1 SI allows for rapid, objective identification of widespread T1 shortening associated with manganese deposition in cirrhosis, consistent with the global deposition of neurotoxic manganese seen in pathology studies. This automated T1 assessment may have broader utility for other conditions beyond cirrhosis impacting T1 SI.

Development of a method for the Bloch image simulation of biological tissues

PurposeThe purpose of this study is to develop a method for the Bloch image simulation of biological tissues including various chemical components and T2* distribution. MethodsThe nuclear spins in the object material were modeled as a spectral intensity function Sr→ω defined by superposition of Lorentz functions with various central precession frequencies and the half width of 1/(πT2′), where 1/T2′ is a relaxation rate attributable to microscopic field inhomogeneity in a voxel. Four-dimensional numerical phantoms were created to simulate Sr→ω and used for MRI simulations of the phantoms containing water and fat protons. Single slice multiple (16) gradient-echo sequences (ΔTE = 2.2 and 1.384 ms) were used for experiments at 1.5 T and 3 T and MRI simulations to evaluate the validity of the approach. ResultsExperimentally measured image intensities of the multiple gradient-echo imaging sequences were well reproduced by the MRI simulations. The correlation coefficients between the experimentally measured image intensities and those numerically simulated were 0.9895 to 0.9992 for the 4-component phantom at 1.5 T and 0.9580 to 0.9996 for the 7-component phantom at 3 T. ConclusionT2* and chemical shift effects were successfully implemented in the MRI simulator (BlochSolver). Because this approach can be applied to other MRI simulators, the method developed in this study is useful for MRI simulation of biological tissues containing water and fat protons.

Magnetic nanoparticle-based biomolecule imaging with a scanning magnetic particle spectrometer

This study reports on a wash-free, inexpensive and sensitive approach of biomolecule imaging with magnetic nanoparticles (MNPs) via a custom-built scanning magnetic particle spectrometer (SMPS). Streptavidin-coated MNPs are used as magnetic biomarkers for the detection of Immunoglobulin G (IgG) conjugated with biotin (IgG-Biotin) while five samples with different-concentration IgG-Biotin are prepared for experiments. The measurements of the ac susceptibility indicate that the conjugation of the IgG-Biotin onto the surface of the MNPs forms cross-linking between the MNPs, thus increasing the characteristic Brownian relaxation time from 0.627 to 1.448 ms. The ratio of the 3rd to the 1st harmonics is measured on the samples with different-concentration IgG-Biotin in ac magnetic fields with a frequency ranging from about 300 Hz to 2 kHz. It shows that the measurement sensitivity of the IgG-Biotin concentration decreases from 4.62 × 10–3 to 0.39 × 10–3 nM−1 with increasing excitation frequency. Phantom images of the harmonic ratio, measured with the SMPS, indicate that unbound and bound MNPs can be easily distinguished. Furthermore, the excitation frequency dependence of the contrast-to-noise ratio of the images is discussed based on the measurement sensitivity and the standard deviation of the measured image intensity. This study demonstrates the feasibility of the SMPS for imaging biomolecules bound onto the MNPs, which is of great interest to disease diagnostics and therapy.

Diagnosis determination of chronic periapical abscess case using imaging radiography software and microbiological examination in female patients

Introduction: Diagnosis determination of chronic periapical abscess can be achieved by subjective, objective, and other examination such as radiographic and microbiological examination based on clinical finding and differences intensity at the periapical area with healthy bone suspected to be chronic abscess periapical. A microbiological examination performed to obtain the predominant bacteria that involved to determine an adequate medicament to succeed endodontic treatment. This study was aimed to compare intensity abscess lesion segmentation image reconstruction and surrounding bone for determine the diagnosis of periapical abscess more accurately and to determine the characteristic of bacteria colony from a periapical abscess tooth. Methods: The study sampling method was consecutive sampling (6 female) consisted of inclusion criteria patient with a periapical lesion in anterior maxillary that diagnosed based on clinical signs and symptoms. CBCT 3D scan of the maxillofacial region taken from of patients was measured image intensity periapical lesion and surrounding bone using semi-auto segmentation with ITK-SNAP 3.6.0. Samples from the root canals taken using three sequential sterile paper points. The samples were plated, and microorganisms were then isolated and identified by the colony characteristics. Results: There was a significant difference between the mean content of lesion intensity of (n = 6,256.710 ± 81.930 and 636.022 ± 79.981 lesion boundary. The two-tailed p-value = 0.0050, this difference was considered to be very statistically significant. The mean of group lesion minus group surrounding bone equals to 163.715. 95% confidence interval of this difference from 75.542 to 251.888. Conclusions: Demineralisation of periapical bone can be determined by voxel intensity value in CBCT 3D radiograph using semi-auto segmentation ITK SNAP, could be recommended as a quantitative interpretation for detection periapical lesion and chronic periapical abscesses is a poly-microbial disease. Keywords: Chronic periapical abscess, endodontic, microbiology, radiograph CBCT

Development of an imaging gas correlation spectrometry based mid-infrared camera for two-dimensional mapping of CO in vehicle exhausts.

Real-time imaging of CO in vehicle exhaust was demonstrated using a gas correlation spectrometry based mid-infrared camera for the first time. The novel gas-correlation imaging technique is used to eliminate the spectral interferences from background radiation and other major combustion products, and reduce the influences of the optical jitter and temperature variations, thereby identifying and quantifying the gas. We take several spectral factors into account for the instrument design, concentration calibration and data evaluation, including atmospheric transmission, radiation interference, as well as the spectral response of infrared camera, filter and gas cell. A calibration method based on the molecular spectroscopy and radiative transfer equation is developed to identify the numerical relationship between the CO concentration × length and the measured image intensity. Two-dimensional CO distribution of vehicle exhaust with a time resolution of 50 Hz and detection limit of 20 ppm × meter is achieved when the distance between optical equipment and engine nozzle is 3 m. The gas correlation spectrometry based mid-infrared camera shows a great potential as a future technique to monitor vehicle pollution emissions quantitatively and visually.

A new method for depth profiling reconstruction in confocal microscopy

Confocal microscopy is commonly used to reconstruct depth profiles of chemical species in multicomponent systems and to image nuclear and cellular details in human tissues via image intensity measurements of optical sections. However, the performance of this technique is reduced by inherent effects related to wave diffraction phenomena, refractive index mismatch and finite beam spot size. All these effects distort the optical wave and cause an image to be captured of a small volume around the desired illuminated focal point within the specimen rather than an image of the focal point itself. The size of this small volume increases with depth, thus causing a further loss of resolution and distortion of the profile. Recently, we proposed a theoretical model that accounts for the above wave distortion and allows for a correct reconstruction of the depth profiles for homogeneous samples. In this paper, this theoretical approach has been adapted for describing the profiles measured from non-homogeneous distributions of emitters inside the investigated samples. The intensity image is built by summing the intensities collected from each of the emitters planes belonging to the illuminated volume, weighed by the emitters concentration. The true distribution of the emitters concentration is recovered by a new approach that implements this theoretical model in a numerical algorithm based on the Maximum Entropy Method. Comparisons with experimental data and numerical simulations show that this new approach is able to recover the real unknown concentration distribution from experimental profiles with an accuracy better than 3%.

T2 relaxometry helps prognosticate seizure outcome in patients with solitary cerebral cysticercosis

ObjectiveCorrelate serial T2 relaxometry (T2R) values with long term seizure outcome in patients with solitary cerebral cysticercosis (SCC) in order to establish its usefulness as a prognostic marker in these patients. MethodsPatients with new-onset seizures due to SCC were imaged serially using a pre-determined MRI protocol at enrolment and after 3, 6, 12 and 24months. T2 relaxometry was performed using a dual echo sequence with maps generated manually from the measured image intensities at the level of the lesion. Patients were randomised to receive albendazole plus antiepileptic drugs, or only antiepileptic treatment (“controls”). At each visit, as well as four years after study initiation, patients were reviewed for seizure recurrence. Clinical and radiological outcomes were assessed by physicians blinded to treatment received. ResultsOf 123 patients recruited, 77 had at least four MRIs and >12month follow-up, and were included for analysis. Baseline clinical and demographic parameters as well as antiepileptic treatment were similar between albendazole and control groups. T2 values from the lesion were higher than normal parenchyma initially, and fell to approach normal over six months. Controls had higher T2 values from the lesion centre and wall at six months than those who received albendazole. However no difference was seen in T2 values from perilesional parenchyma between treatment and control groups, indicating lack of modulation of the development of perilesional gliosis by albendazole therapy. Patients with seizures persisting >6months after enrolment had higher perilesional T2 values than those who were seizure-free. A rise in perilesional T2 value at 12months is probably due to gliosis. A later stage of degeneration was associated with a reduced likelihood of seizure relapse. SignificanceT2 relaxometry at three and six months after seizure onset can identify patients likely to have seizures beyond six months after onset. Persistently abnormal T2 values in patients with poorer outcomes reflect the development of perilesional gliosis.

Microtexture Road Profiling System Using Photometric Stereo

ABSTRACT This paper presents the design and development of a stationary microtexture road profiling system using the photometric stereo (PS) technique. The structure of the developed system is simple, mainly consisting of a digital single-lens reflex (DSLR) camera with a macro lens and multiple light-emitting diodes (LEDs). The camera with the lens is oriented perpendicularly to the pavement texture and takes images each with a different LED turned on at a time. With the pavement texture images with diverse shadings, the PS technique is applied by inverting the image-forming process locally (pixel-wise) to associate the measured image intensities with the known lighting directions to estimate the gradients for each pixel-corresponding surface patch of the pavement texture. Surface normal integration (SNI) is then employed to reconstruct the three-dimensional (3D) road surface in the microtexture scale. The PS-based system has several intrinsic advantages. First, it could achieve high accuracy for surfaces with most diffuse reflection. Second, the measurement speed is fast because of its area-scanning nature. Third, the spatial resolution is high because of the usage of a high-resolution complementary metal-oxide semiconductor DSLR camera. In addition, it can be less sensitive to effects from specularities and shadows compared with most optical-based methods, since images captured under diverse lighting directions in PS provide more cues for detection purposes. Last but not least, the hardware of the system can be made compact at low cost because of its simple structure and can be adapted for direct measurement on the pavement. Parametric studies for the Lambertian-based PS technique were first investigated analytically and numerically, and these investigations yielded the design of the system having eight LEDs with the same zenith angle of 30 degrees and uniformly distributed azimuth angles in 360 degrees. Several experimental results on various types of surfaces have demonstrated that the developed system could achieve the accuracy in the order of 10 microns.

Anatomically motivated modeling of cortical laminae

Improvements in the spatial resolution of structural and functional MRI are beginning to enable analysis of intracortical structures such as heavily myelinated layers in 3D, a prerequisite for in-vivo parcellation of individual human brains. This parcellation can only be performed precisely if the profiles used in cortical analysis are anatomically meaningful. Profiles are often constructed as traverses that are perpendicular to computed laminae. In this case they are fully determined by these laminae. The aim of this study is to evaluate models for cortical laminae used so far and to establish a new model. Methods to model the laminae used so far include constructing laminae that keep a constant distance to the cortical boundaries, so-called equidistant laminae. Another way is to compute equipotentials between the cortical boundary surfaces with the Laplace equation. The Laplace profiles resulting from the gradients to the equipotentials were often-used because of their nice mathematical properties. However, the equipotentials these Laplacian profiles are constructed from and the equidistant laminae do not follow the anatomical layers observed using high resolution MRI of cadaver brain. To remedy this problem, we introduce a novel equi-volume model that derives from work by Bok (1929). He argued that cortical segments preserve their volume, while layer thickness changes to compensate cortical folding. We incorporate this preservation of volume in our new equi-volume model to generate a three-dimensional well-adapted undistorted coordinate system of the cortex. When defined by this well-adapted coordinate system, cortical depth is anatomically meaningful. We compare isocontours from these cortical depth values to locations of myelinated bands on high-resolution ex-vivo and in-vivo three-dimensional MR images. A similar comparison was performed with equipotentials computed with the Laplace equation and with equidistant isocontours. A quantitative evaluation of the equi-volume model using measured image intensities confirms that it provides a much better fit to observed cortical layering.

Quantitative Atomic Resolution Scanning Transmission Electron Microscopy

Complete understanding of atomic resolution high-angle annular dark-field (Z-contrast) images requires quantitative agreement between simulations and experiments. We show that intensity variations can be placed on an absolute scale by normalizing the measured image intensities to the incident beam. We construct fractional intensity images of a SrTiO3 single crystal for regions of different thickness up to 120 nm. Experimental images are compared directly with image simulations. Provided that spatial incoherence is taken into account in the simulations, almost perfect agreement is found between simulation and experiment.

Phase measurement of atomic resolution image using transport of intensity equation

Since the Transport Intensity Equation (TIE) has been applied to electron microscopy only recently, there are controversial discussions in the literature regarding the theoretical concepts underlying the equation and the practical techniques to solve the equation. In this report we explored some of the issues regarding the TIE, especially bearing electron microscopy in mind, and clarified that: (i) the TIE for electrons exactly corresponds to the Schrödinger equation for high-energy electrons in free space, and thus the TIE does not assume weak scattering; (ii) the TIE can give phase information at any distance from the specimen, not limited to a new field; (iii) information transfer in the TIE for each spatial frequency g will be multiplied by g2 and thus low frequency components will be dumped more with respect to high frequency components; (vi) the intensity derivative with respect to the direction of wave propagation is well approximated by using a set of three symmetric images; and (v) a substantially larger defocus distance than expected before can be used for high-resolution electron microscopy. In the second part of this report we applied the TIE down to atomic resolution images to obtain phase information and verified the following points experimentally: (i) although low frequency components are attenuated in the TIE, all frequencies will be recovered satisfactorily except the very low frequencies; and (ii) using a reconstructed phase and the measured image intensity we can correct effectively the defects of imaging, such as spherical aberrations as well as partial coherence.

Enhancing resolution along multiple imaging dimensions using assorted pixels

Multisampled imaging is a general framework for using pixels on an image detector to simultaneously sample multiple dimensions of imaging (space, time, spectrum, brightness, polarization, etc.). The mosaic of red, green, and blue spectral filters found in most solid-state color cameras is one example of multisampled imaging. We briefly describe how multisampling can be used to explore other dimensions of imaging. Once such an image is captured, smooth reconstructions along the individual dimensions can be obtained using standard interpolation algorithms. Typically, this results in a substantial reduction of resolution (and, hence, image quality). One can extract significantly greater resolution in each dimension by noting that the light fields associated with real scenes have enormous redundancies within them, causing different dimensions to be highly correlated. Hence, multisampled images can be better interpolated using local structural models that are learned offline from a diverse set of training images. The specific type of structural models we use are based on polynomial functions of measured image intensities. They are very effective as well as computationally efficient. We demonstrate the benefits of structural interpolation using three specific applications. These are 1) traditional color imaging with a mosaic of color filters, 2) high dynamic range monochrome imaging using a mosaic of exposure filters, and 3) high dynamic range color imaging using a mosaic of overlapping color and exposure filters.

Phase Retrieval, Symmetrization Rule and Transport-of-Intensity Equation in Application to Induction Mapping of Magnetic Materials

Recent progress in the field of noninterferometric phase retrieval brings the ordinary Fresnel microscopy to a new quantitative level, suitable for recovering both the amplitude and phase of the object, based on image intensity measurements of the object. We show that this is sufficient for in-plane component mapping of magnetic induction for small magnetic elements with known geometry ranging from micro- to few nanometers size. In present paper we re-examine some conservation principles used for the transport-of-intensity (TIE) equation derived by Teaque for application to phase retrieval in light and X-ray optics. In particular, we prove that the intensity conservation law should be replaced in general case with the energy-flow conservation law. This law describes the amplitude-phase balance of the partially coherent beam on its propagation along the optical path, valid both for light and electron optics. This substitution has at least two important fundamental consequences.

Maximum-likelihood method for focus-variation image reconstruction in high resolution transmission electron microscopy

This paper deals with image reconstruction in high-resolution transmission electron microscopy (HRTEM) via focus variation. This technique aims at the reconstruction of the complex-valued electron wave at the exit plane of the specimen including correction for the aberrations of the microscope, with a focal series of HRTEM images as input. The general case with linear and non-linear contributions to the images is considered, requiring recursive optimization of the wave function, which is obtained by a non-linear least-squares fit to the measured image intensities. Based upon the pioneering work of Kirkland (1984) in this field, we discuss the following improvements. In the first place, a solution of the maximum-likelihood (MAL) equations for image reconstruction is derived in which the - for HRTEM inherent - coupling between the wave function and its complex conjugate is accounted for. Secondly, it is outlined how optimum convergence for the MAL solution is obtained. Thirdly, a computationally efficient implementation of the recursive algorithm to solve the MAL equations is presented. The algorithm is based on a factorization of the spatial coherence envelope, and on focal integration approach for the temporal coherence envelope in the transmission-cross-coefficient. The convergence behavior of this algorithm is studied using simulated focal series as input.

Sunglitter radiance modulation by internal waves

Quantitative sunglitter radiance modulations at the ocean surface due to internal waves were calculated applying a simple first order theory. The results have been compared with the image data of internal wave signatures northeast of Nantucket Shoals off the coast of Massachusetts, U.S.A., taken by the Earth Terrain Camera (ETC) during the Skylab mission. The maximum magnitudes of sunglitter radiance modulations predicted by the theory are comparable to the satellite image data. The extreme values of calculated modulations depend only weakly on the wavelength of the internal wave signature. This is consistent with the analysed ETC data. On the other hand, the shapes of simulated and measured image intensity transects across an internal wave packet are different. This may possibly be explained by the assumed idealized sinusoidal type of thermocline used in the calculations. The theory predicts that sunglint signatures of internal waves are advected relative to positions of extreme slope regions of the thermocline due to currents.

Void distribution and susceptibility differences in ceramic materials using MRI

Magnetic Resonance Imaging (MRI) is applied to porous ceramic materials to study structural properties. In ceramics, processing differences create inhomogeneous binder distribution in the materials which can cause the formation of regions with differing densities and voids. These defects can be observed with MRI using solvent permeation. Fractional porosity obtained by using image intensity measurements and weight gain due to solvent permeation can be correlated. Dark regions in the image are due to defects such as closed voids, pockets of binder, or agglomerates. Defects such as voids or agglomerates usually have different magnetic susceptibilities. This difference causes artifacts in the image. By exploiting the increase in signal loss using a gradient-echo sequence, apparent enhancement of voids in ceramics is achieved.

Differential algorithm for the determination of shape from shading using a point light source

This paper presents a linear algorithm for recovering shape information of Lambertian surfaces from the shading information inherent in a single 2D image. The local orientation of a planar Lambertian surface patch is determined from a single video image when both camera and a light source are near to the surface. A simple linear relationship is derived between the ratios of the measured image intensities and their first partial derivatives and the components of the surface normal vector. An advantage of the formulation is that the resulting equations are independent of the intensity strength of the illuminating source as well as the surface reflection coefficient (albedo). Results for noisy synthetic images as well as real images are presented.

On the simulation of coherent clutter textures with arbitrary spectra

An important stage in the simulation of coherent clutter textures is the ability to deduce the surface cross-section autocorrelation function (ACF) from the measured image intensity ACF. Previously this inversion process has been derived exactly for a few simple models. In this paper an approach is proposed which allows arbitrary surface spectra to be reconstructed approximately. The validity of the method is demonstrated by comparing an example of sonar clutter with simulated textures based on the best simple model alone or on this more general method.

Nuclear magnetic resonance imaging of experimentally induced liver disease

Experimental animal models of hepatitis, fatty liver, and hepatic iron overload were evaluated using a 3.5-kGauss nuclear magnetic resonance (NMR) imaging system. Increases in image intensity measurements and in T2 relaxation times equalled the sensitivity of histologic findings for the detection of early stages of hepatitis. A significant shift in T1 relaxation times characterized the early stages of hepatic necrosis. Liver triglyceride content correlated significantly with increases in NMR intensity measurements (p less than 0.01); however, changes in liver water content had a much greater influence on intensity, T1, and T2. Thus, it may be possible to distinguish hepatitis from benign fatty liver. Liver iron content correlated with decreases in NMR intensity measurements (p less than 0.001), and iron levels as low as 1.2 mg/g were detected. NMR may more specifically identify hepatocellular iron overload than do other techniques that do not distinguish hepatocellular from reticuloendothelial iron.