Simple Imaging Technique Research Articles

Monte Carlo studies and response assessment of a new Rotational Modulation Collimator (RMC) design

A Rotational Modulation Collimator (RMC) is a simple imaging technique with applications in homeland security for detecting nuclear materials and orphan radiation sources. These compose a threat for national security and it is therefore of utmost importance to develop fast and accurate systems to locate these threats. Here we propose a new RMC design, with increased field of view (FOV), where the body of the system includes slits. Monte Carlo simulations were performed to assess the response of the new design. Image reconstruction was performed using the Maximum Likelihood Expectation Maximization (MLEM) algorithm. The proposed design results in a RMC with an extended FOV of 60°.

Front Cover: Photoluminescence intensity ratio of Eu‐conjugated lactates—A simple optical imaging technique for biomarker analysis for critical diseases (J. Biophotonics 5/2018)

Eu3+integrated photoluminescence intensity ratio (PLIR) approach for optical detection of lactates in blood serum, plasma and confocal imaging of brain tissues has very high potential for exploitation of this technique in both in vitro monitoring and in vivo bioimaging applications for the detection of biomarkers in various diseases states. This image is diagrammatic representation of fact that the overall PLIR is higher with more lactates conjugated with Eu3+ ions.Further details can be found in the article by Tarun Kakkar et al. (e201700199). image

Identification and classification of brain tumor MRI images with feature extraction using DWT and probabilistic neural network

The identification, segmentation and detection of infecting area in brain tumor MRI images are a tedious and time-consuming task. The different anatomy structure of human body can be visualized by an image processing concepts. It is very difficult to have vision about the abnormal structures of human brain using simple imaging techniques. Magnetic resonance imaging technique distinguishes and clarifies the neural architecture of human brain. MRI technique contains many imaging modalities that scans and capture the internal structure of human brain. In this study, we have concentrated on noise removal technique, extraction of gray-level co-occurrence matrix (GLCM) features, DWT-based brain tumor region growing segmentation to reduce the complexity and improve the performance. This was followed by morphological filtering which removes the noise that can be formed after segmentation. The probabilistic neural network classifier was used to train and test the performance accuracy in the detection of tumor location in brain MRI images. The experimental results achieved nearly 100% accuracy in identifying normal and abnormal tissues from brain MR images demonstrating the effectiveness of the proposed technique.

Microglial dynamics during brain development.

Microglial dynamics during brain development.

Texture analysis of breast thermograms using neighbourhood grey tone difference matrix

Breast cancer is the leading cancer in women worldwide. Early detection can reduce the mortality rate of breast cancer. Breast thermography is a non-invasive and simple imaging technique used for early detection of breast cancer. Feature extraction and selection of appropriate features play a major role in computer-aided detection of breast cancer using breast thermograms. In this article, texture features are extracted from automatically segmented breast thermograms by computing neighbourhood grey tone difference matrix (NGTDM) and run length matrix (RLM). Significance of these features in differentiating the abnormal breast from the normal breast is found by statistical test. NGTDM extracted coarseness, busyness, complexity, strength and RLM extracted long run emphasis and run percentage are found to be significant by statistical test. Extracted features are computationally less expensive and attained an average accuracy of 80%, sensitivity of 94% and specificity of 71.4% using back propagation neural network classifier.

Effect of silver film roughness on imaging property of BaTiO3 microsphere

Due to the Abbe diffraction limit, the resolution of a traditional optical microscopy is limited to about half of the illumination wavelength. Recent studies show that super-resolution imaging through dielectric microsphere has emerged as a simple imaging technique to overcome the diffraction limit under the illumination of white light. However, for imaging through microsphere, sometimes it is needed to enhance the reflection of a sample by depositing a metallic thin film on the top of the sample. Metallic thin films with different surface roughness have different optical properties. However, the effect caused by the surface roughness of a metallic film on microsphere imaging is rarely studied. In this paper, we study the effects of silver films with different surface roughness deposited on the surfaces of samples on the imaging properties of BaTiO3 (BTG) microspheres. Silver thin films are deposited respectively at evaporation rates of 1.5-3 Å/s and 5-10 Å/s, and the surface roughness values (root mean square (RMS) values) of the obtained silver films are about 3.23 nm and 6.80 nm, respectively. Using a BTG microsphere to observe a sample with a silver film deposited on its surface, we find that the surface roughness of the silver film will affect the imaging resolution and the range of focal image position (RFIP) of the BTG microsphere. When we use a 15-μm-diameter BTG microsphere to observe a 250-nm-diameter microsphere array and 580-nm-diameter microsphere array, the RFIP of the BTG microsphere increases with the RMS of the silver film increasing from 3.23 to 6.80 nm. Moreover, a 200-nm-diameter microsphere array can also be clearly discerned. The simulation results obtained by the commercial software COMSOL show that when the surface of a microsphere array sample is deposited with a rough silver film, the electric field intensity is enhanced not only in the gaps between adjacent microspheres, but also on the silver particles due to the excitation of localized surface plasmons. We propose that the scattering effect and the local electric field intensity enhancement caused by the rough silver film allow more high-frequency information of the sample to be coupled into the BTG microsphere, and thus improving the resolution and RFIP of the microsphere. As the imaging law of microsphere imaging still needs to be explored, our research work will be helpful in further revealing the mechanism in microsphere imaging.

Photoluminescence intensity ratio of Eu-conjugated lactates-A simple optical imaging technique for biomarker analysis for critical diseases.

Instant measurement of elevated biomarkers such as lactic acid offers the most promising approaches for early treatment and prevention of many critical diseases including cardiac arrest, stroke, septic shock, trauma, liver dysfunction, as well as for monitoring lactic acid level during intense exercise. In the present study, a unique dependence of visible photoluminescence of Eu3+ ions resulting from 5 D0 to 7 FJ(J = 0,1,2,3,4) transitions, which can be exploited for rapid detection of biomarkers, both in vitro and ex vivo, has been reported. It is observed that the integrated intensity ratio of photoluminescence signals dominating at 591 and 616 nm originating from 5 D0 to 7 F2 and 5 D0 to 7 F1 transitions in Eu3+ ions can be used as a biosensing and bioimaging tool for detection of biomarkers released at disease states. The Eu3+ integrated photoluminescence intensity ratio approach reported herein for optical detection of lactates in blood serum, plasma and confocal imaging of brain tissues has very high potential for exploitation of this technique in both in vitro monitoring and in vivo bioimaging applications for the detection of biomarkers in various diseases states.

Comparison of the Slip of a PDMS Melt on Weakly Adsorbing Surfaces Measured by a New Photobleaching-Based Technique

We present an experimental method allowing to quantify slip at the wall in viscous polymer fluids, based on the observation of the evolution under simple shear flow of a photobleached pattern within a fluorescent labeled polymer melt. This straightforward method provides access to slip length at top and bottom interfaces in the 1 $\mu$m to 1 mm range and to the actual shear rate experienced by the fluid. Based on simple optical imaging and image analysis techniques, this method affords an improvement compared to previously reported methods in which the photobleached fluorescence intensity profiles before and after shear were compared and measured by scanning a photomultiplier. The present method relies on a direct determination of the displacement profile inside the polymer fluid from an analysis of the 3D evolution of the whole photobleached pattern. We demonstrate the potential of this method with measurements of the slip length for an entangled PDMS melt, as a function of the shear rate, in contact with several weakly surfaces i.e. end-tethered PDMS or polystyrene (PS) chains, a self-assembled monolayer (SAM) of trimethoxy(octadecyl)silane (OTS), and a glassy PS thin-film.

Dynamic Phosphorescent Probe for Facile and Reversible Stress Sensing.

Dynamic phosphorescent copper complex incorporated into the main chain of polyurethanes produces a facile and reversible response to tensile stress. In contrast to common deformation sensors, the applied stress does not lead to bond scission, or alters the phosphor structure. The suppression of dynamics responsible for the nonradiative relaxation is found to be the major pathway governing stress response. As a result, the response of dynamic phosphor described in this work is stress specific. Compared to initial unloaded state, a nearly twofold increase of photoluminescence intensity occurs in response to a 5-35 MPa stress applied to pristine metalated polymers or their blends with various polyurethanes. Finally, the dynamic sensor proves useful for mapping stress distribution patterns and tracking dynamic phenomena in polyurethanes using simple optical imaging techniques.

Particle dynamics in avalanche flow of irregular sand particles in the slumping regime of a rotating drum

Slowly rotating drums are important due to their industrial application, but also as a simple model system for studying transient avalanche processes. A speckle visibility spectroscopy (SVS) alongside a simple imaging technique was used to measure the time-resolved avalanching of 1.3mm diameter sand particles in a 35% full rotating drum operating in the slumping regime. The major difference from spherical particle dynamics is visual observation of granular compaction in the upper part of the drum at the beginning of the avalanching process which is not present in experiments with spherical particles. The SVS measurement of avalanching shows that the fluctuation velocity, so called granular temperature, increased sharply before plateauing then decreases sharply to zero during a typical avalanche event which is different to spherical particle behavior where these transitions are more gradual. Furthermore, the granular dynamics of avalanching flow is influenced by a visually observed flowing mound down the avalanching surface so there are more characteristic peaks in the plateau region of the signal for measurement point in the lower part of the bed. Overall, the observed plastic deformation is influencing the dynamics of the system in several ways indicating the importance of considering particle shape in the study of granular flow dynamics.

Diagnosis of mitral valve cleft using real-time 3-dimensional echocardiography.

Mitral valve cleft (MVC) is the most common cause of congenital mitral insufficiency, and MVC may occur alone or in association with other congenital heart lesions. Direct suture and valvuloplasty are the major and effective treatments for mitral regurgitation (MR) caused by MVC. Therefore, it is important to determine the location and magnitude of the pathological damage due to MVC when selecting a surgical procedure for treatment. This study explored the application value of transthoracic real-time 3-dimensional (3D) echocardiography (RT-3DE) in the diagnosis of MVC. From October 2012 to June 2016, 19 consecutive patients with MVC diagnosed by 2-dimensional (2D) echocardiography in our hospital were selected for this study. Full-volume RT-3DE was performed on all patients. The 3D-imaging data were cropped and rotated in 3 views (horizontal, sagittal, and coronal) with 6 directions to observe the position and shape of the MVC and the spatial position between the cleft and its surrounding structures. The maximum longitudinal diameter and the maximum width of the cleft were measured. The origin of the mitral regurgitant jet and the severity of MR were evaluated, and these RT-3DE data were compared with the intraoperative findings. Of the 19 patients studied, 4 patients had isolated cleft mitral valve, and cleft mitral valves combined with other congenital heart lesions were detected in 15 patients. The clefts of 6 patients were located in the A2 segment, the clefts of 4 patients were located in the A1 segment, the clefts of 4 patients were located in the A3 segment, the clefts of 4 patients were located in the A2-A3 segment, and the cleft of 1 patient was located in the P2 segment. Regarding the shape of the cleft, 13 patients had V-shaped clefts, and the others had C- or S-shaped clefts. The severity of the MR at presentation was mild in 2 patients, moderate in 9 and severe in 8. Two of the patients with mild MR did not undergo surgery, while the remaining 17 patients did undergo surgery. Surgical treatment involved direct suture in 11 cases, reconstruction with ring annuloplasty in 3 cases and replacement in 3 cases. The diagnoses of MVC were confirmed by intraoperative findings. RT-3DE successfully captured full-volume 3D images of the 19 patients, which directly displayed the 3D structure of MVC with multiple views such as the position, shape, longitudinal diameter and width of the MVC, and the spatial position between the chordae tendineae surrounding the MVC and the aortic valve. The maximum longitudinal diameter of the valve leaflet cleft measured by RT-3DE and direct measurements during surgery were 12.02±2.12 and 13.01±2.45 mm, respectively, and the difference between these measurements was not statistically significant (P>0.05). Our results indicate that RT-3DE can provide more direct, accurate and abundant information. RT-3DE is a simple and fast imaging technique, and the detailed 3D images obtained can be used to confirm the diagnosis of MVC. RT-3DE is considered to be an important preoperative test that provides more comprehensive information for selecting a subsequent procedure for treatment.

Upper airway imaging and its role in preoperative airway evaluation

Ultrasonography (USG) is well-known as a fast, safe, and noninvasive technique. Its application for imaging of the airway is now gaining momentum. The upper airway has a complex anatomy, and its assessment forms a vital part of every preanesthetic evaluation. Ultrasound (US) imaging can help in upper airway assessment in the preoperative period. There are various approaches to upper airway USG. The technique has its own advantages, disadvantages, and limitations. This simple yet challenging imaging technique is all set to become an important part of routine preoperative airway evaluation. This article reviews the various approaches to upper airway US imaging, interpretation of the images, limitations, and disadvantages of the technique and its varied clinical applications in the preoperative period. The scientific material presented here was hand searched from textbooks and journals, electronically from PubMed, and Google scholar using text words.

Radionuclide Shuntography for the Evaluation of Ventriculo-Peritoneal Shunt in Children with Hydrocephalus

Background: Radionuclide shuntography is a safe, simple and non-invasive functional imaging technique for determining ventriculo-peritoneal (V-P) shunts tube patency with minimal radiation exposure. This is particularly useful in children with hydrocephalus in whom V-P shunt is inserted to divert CSF drainage. V-P shunts are, in many cases, permanent treatment option for children with hydrocephalus and radionuclide shuntography is becoming a very popular technique because of the increasing numbers and survival of children with shunt-treated hydrocephalus. Objective: The aim of this study is to document the usefulness of shuntography in the evaluation of V-P shunt in patients with hydrocephalus. Materials and Methods: All shuntograms performed in our institution from 2008 to 2015 were included in this study. Radionuclide shuntography was performed with Tc-99m DPTA injected into the shunt reservoir and images acquired using a dual headed MEDISO camera. A normal shuntogram is considered as free flow of radiotracer (Tc-99m DTPA) from site of injection to the distal end of shunt tube and spillage into the peritoneum. Results: A total of 56 children were studied comprising of 32 males and 24 females with age ranges of 5month to 11years. Different patterns of results were found, normal functioning shunt tube, partial block shunt tube due to infection or inflammatory debris and total blocked shunt tube due to mechanical defects. Conclusion: About 52% of our patients had partial blockage of their shunt tube. Patients who are diagnosed with a partial tube blockage will require only flushing of the tube and antibiotics treatment, while mechanically blocked tube will require shunt revision. This distinction is critical considering the cost of replacement of V-P shunt tube and the manpower time for surgery. There was no mortality or morbidity associated with radionuclide shuntography in our patients.

Introduction. December 2015 at a glance.

Much is dedicated to cardiovascular imaging in heart failure (HF) in this issue. Ferre et al. review the role of cardiopulmonary ultrasound in the diagnosis and early management of acute HF. A stepped approach is shown where the role of simple imaging techniques for the diagnosis of pulmonary and systemic venous congestion, the estimate of the left ventricular filling pressure and the differentiation of the clinical presentations of HF is shown.1 In a research by Ikonomidis et al., impaired left ventricular twisting and untwisting has been related with reduced coronary flow reserve, vascular dysfunction and markers of increased collagen synthesis in patients with hypertensive heart disease.2 A large space is once again dedicated to biomarkers. Much has been written regarding the heterogeneity among the patients with HF and preserved ejection fraction.3 In this issue of the journal, D'Elia et al. discuss the role of new biomarkers for phenotyping these patients and differentiate pathogenetic mechanisms.4 Other studies regard the independent prognostic role of high sensitivity troponin T measurements and their changes in patients with acute HF,5 the use of biomarkers to select the HF patients at low risk of events,6 the selection of the patients more likely to benefit from natriuretic peptides guided therapy7 and a new, and first, marker of muscle wasting.8 With respect of treatment, a simple treatment of sleep disordered breathing, based on a lateral sleep position, is shown to be effective in patients with HF, above all when obstructive sleep apnea is their main complaint.9 The implications of these findings and their comparison with the results of the large randomized trial SERVE-HF are discussed in an accompanying editorial.10 Finally, the design of an innovative trial comparing usual care with the use of the HFA website, heartfailurematters.org, and with an interactive platform including a link to this website, is shown.11 Enjoy reading!

Orbital angular momentum in electron diffraction and its use to determine chiral crystal symmetries

In this work we present an alternative way to look at electron diffraction in a transmission electron microscope. In stead of writing the scattering amplitude in Fourier space as a set of plane waves, we use the cylindrical Fourier transform to describe the scattering amplitude in a basis of orbital angular momentum (OAM) eigenstates. We show how working in this framework can be very convenient when investigating e.g. rotation and screw axis symmetries. For the latter we find selection rules on the OAM-coefficients that unambiguously reveal the handedness of the screw axis. Detecting the OAM-coefficients of the scattering amplitude thus offers the possibility to detect the handedness of crystals without the need for dynamical simulations, the thickness of the sample nor the exact crystal structure. We propose an experimental setup to measure the OAM-components where an image of the crystal is taken after inserting a spiral phase plate in the diffraction plane and perform mulsti-slice simulations on $\alpha$-quartz to demonstrate how the method indeed reveals the chirality. Experimental feasibility of the technique is discussed together with its main advantages with respect to chirality determination of screw axes. The method shows how the use of a spiral phase plate can be extended from a simple phase imaging technique to a tool to measure the local OAM-decomposition of an electron wave, widening the field of interest well beyond chiral space group determination.

Portable IR Laser System for Real-Time Display of Alive People in Fire Scenes

An innovative approach is shown that can allow search-and-rescue personnel to find survivors trapped in fire scenarios through active laser scanning. This new but simple imaging technique permits to see live people through a flame wall by portable system suitable for on-field applications. Combining IR laser raster scanning with a bandpass frequency filter and an IR camera, we show that a direct useful signature of a scattered human target can be detected while discarding the flame emission. Several experiments are reported also by using a cheap, light-weight and low-resolution camera to demonstrate that the proposed approach allows real-time operation by portable light-weight device, thus being useful in the hands of firefighters.

A versatile toolbox for posttranscriptional chemical labeling and imaging of RNA.

Cellular RNA labeling strategies based on bioorthogonal chemical reactions are much less developed in comparison to glycan, protein and DNA due to its inherent instability and lack of effective methods to introduce bioorthogonal reactive functionalities (e.g. azide) into RNA. Here we report the development of a simple and modular posttranscriptional chemical labeling and imaging technique for RNA by using a novel toolbox comprised of azide-modified UTP analogs. These analogs facilitate the enzymatic incorporation of azide groups into RNA, which can be posttranscriptionally labeled with a variety of probes by click and Staudinger reactions. Importantly, we show for the first time the specific incorporation of azide groups into cellular RNA by endogenous RNA polymerases, which enabled the imaging of newly transcribing RNA in fixed and in live cells by click reactions. This labeling method is practical and provides a new platform to study RNA in vitro and in cells.

Overcoming the diffraction limit of imaging nanoplasmonic arrays by microspheres and microfibers.

Super-resolution microscopy by microspheres emerged as a simple and broadband imaging technique; however, the mechanisms of imaging are debated in the literature. Furthermore, the resolution values were estimated based on semi-quantitative criteria. The primary goals of this work are threefold: i) to quantify the spatial resolution provided by this method, ii) to compare the resolution of nanoplasmonic structures formed by different metals, and iii) to understand the imaging provided by microfibers. To this end, arrays of Au and Al nanoplasmonic dimers with very similar geometry were imaged using confocal laser scanning microscopy at λ = 405 nm through high-index (n~1.9-2.2) liquid-immersed BaTiO3 microspheres and through etched silica microfibers. We developed a treatment of super-resolved images in label-free microscopy based on using point-spread functions with subdiffraction-limited widths. It is applicable to objects with arbitrary shapes and can be viewed as an integral form of the super-resolution quantification widely accepted in fluorescent microscopy. In the case of imaging through microspheres, the resolution ~λ/6-λ/7 is demonstrated for Au and Al nanoplasmonic arrays. In the case of imaging through microfibers, the resolution ~λ/6 with magnification M~2.1 is demonstrated in the direction perpendicular to the fiber with hundreds of times larger field-of-view in comparison to microspheres.

Adaptive remodeling of the biliary architecture underlies liver homeostasis.

Serving as the center for metabolism and detoxification, the liver is inherently susceptible to a wide variety of damage imposed by toxins or chemicals. Induction of cell populations with biliary epithelial phenotypes, which include progenitor-like cells and are referred to as liver progenitor cells, is often observed in histopathological examination of various liver diseases in both human patients and animal models and has been implicated in regeneration. However, the tissue dynamics underlying this phenomenon remains largely unclear. We have developed a simple imaging technique to reveal the global and fine-scale architecture of the biliary tract spreading in the mouse liver. Using this novel method, we show that the emergence and expansion of liver progenitor cells actually reflect structural transformation of the intrahepatic biliary tree in mouse liver injury models. The biliary branches expanded their area gradually and contiguously along with the course of chronic injury. Relevant regulatory signals known to be involved in liver progenitor cell regulation, including fibroblast growth factor 7 and tumor necrosis factor-like weak inducer of apoptosis, can modulate the dynamics of the biliary epithelium in different ways. Importantly, the structural transformations of the biliary tree were diverse and corresponded well with the parenchymal injury patterns. That is, when chronic hepatocyte damage was induced in the pericentral area, the biliary branches exhibited an extended structure from the periportal area with apparent tropism toward the distant injured area. The hepatobiliary system possesses a unique and unprecedented structural flexibility and can remodel dynamically and adaptively in response to various injury conditions; this type of tissue plasticity should constitute an essential component to maintain liver homeostasis.

Rapid resistivity imaging for marine controlled-source electromagnetic surveys with two transmitter polarizations: An application to the North Alex mud volcano, West Nile Delta

To image the internal resistivity structure of the North Alex mud volcano offshore Egypt, the marine electromagnetics group at the Helmholtz Centre for Ocean Research Kiel (GEOMAR) developed and conducted a novel transient marine controlled-source electromagnetic experiment. The system, which was specifically developed to image the mud volcano, is also generally suitable for surveys of other small seafloor targets, such as gas-hydrate reservoirs, fluid-flow features, and submarine massive-sulfide deposits. An electric bipole antenna is set down by a remotely operated vehicle on the seafloor sequentially in two perpendicular polarizations at each transmission station. Two orthogonal horizontal electric field components are recorded on the seabed by an array of independently deployed nodal receivers (RXs). With two transmitter polarizations, the unique acquisition geometry of the system provides a very rich data set. However, for this geometric setup, conventional marine electromagnetic interpretation schemes (such as normalized magnitude variation with offset plots) have been difficult to implement. We have developed a simple imaging technique, which can be used for a first-step mapping of seafloor apparent resistivity with the GEOMAR system. Images can be produced in just a few minutes on a regular laptop computer, and the robustness of the approach was demonstrated using two synthetic data sets from simple seafloor models. The method was then applied to the real data acquired at the North Alex mud volcano in 2008. Results found increased apparent sediment resistivities of up to 4 Ωm near the center of the mud volcano occurring at source-RX offsets greater than 500 m, which mapped to apparent depths of greater than 150 m. This may be caused by large quantities of free gas or freshwater in the sediment pore space.