HistoNet: A Deep Learning-Based Model of Normal Histology

We introduce HistoNet, a deep neural network trained on normal tissue. On 1690 slides with rat tissue samples from 6 preclinical toxicology studies, tissue regions were outlined and annotated by pathologists into 46 different tissue classes. From these annotated regions, we sampled small 224 × 224 pixels images (patches) at 6 different levels of magnification. Using 4 studies as training set and 2 studies as test set, we trained VGG-16, ResNet-50, and Inception-v3 networks separately at each magnification level. Among these model architectures, Inception-v3 and ResNet-50 outperformed VGG-16. Inception-v3 identified the tissue from query images, with an accuracy up to 83.4%. Most misclassifications occurred between histologically similar tissues. Investigation of the features learned by the model (embedding layer) using Uniform Manifold Approximation and Projection revealed not only coherent clusters associated with the individual tissues but also subclusters corresponding to histologically meaningful structures that had not been annotated or trained for. This suggests that the histological representation learned by HistoNet could be useful as the basis of other machine learning algorithms and data mining. Finally, we found that models trained on rat tissues can be used on non-human primate and minipig tissues with minimal retraining.

Post-Processing of Digital Radiographs in the Practice of Radiologist

The purpose: analysis of the use by radiologists techniques of post-processing of digital radiographs and the development of practical recommendations on their application.Materials and methods.The technique of post-processing was taken for analysis: negative/positive; filters/optimization of dynamic range; the intensification of the contours and smoothing; image magnification; level/window width densities, and gamma correction. Compiled questionnaire, which the doctor and the radiologist had to answer the questions of how often he uses a particular technique of digital image processing; which, in some cases, the study of what organs he uses post-processing? In total, we analyzed 18 questionnaires and their own experience in digital x-ray machines since 2003.Results.On the basis of interviews and our own experience, the author recommends that you always use the techniques of post-processing x-ray images, starting with the optimization of the dynamic range / filter, which greatly improves the quality of the picture.Conclusions.1. Doctors radiologists in the majority of cases (83%) use the methods of post-processing to analyse digital radiographs. 2. Additional option of post-processing are used most of the time (90–100%), this level and the window width, the intensification of the contours increase.3. Command path smoothing is applied in 1/3 cases (33%).4. Rarely used to optimize dynamic range and FonEqualize.5. Understanding all of the options post-processing of digital radiographs and their active use in practice of the radiologist, will improve the accuracy of x-ray, to avoid repeated shots, and as a consequence, to reduce the radiation dose of the patient.6. Recommended: start post-processing images with optimal dynamic range/filter; for detail is necessary – to change the level/window width, zoom in, sharpen the contours.

Optimisation of Magnification Levels for near Infrared Chemical Imaging of Blending of Pharmaceutical Powders

A critical parameter in the evaluation of pharmaceutical dosage forms by hyperspectral imaging is the level of magnification. If the magnification (as set by the optical objective) is inadequate to resolve the relevant features, then the value of the imaging is diminished; if the magnification level is greater than is required, then the field of view is unnecessarily reduced. The purpose of this study was to determine an optimum magnification level for the study of powder mixing. Relevant features in this system include distribution of individual components within samples and the overall content of a given sample. In the present study, three magnification levels of near infrared (NIR) chemical imaging objectives were evaluated for their effects on imaging a blend of pharmaceutical materials (powders). High, medium and low objective magnification levels were investigated by comparing the resulting blend surface images of a two-component (salicylic acid and lactose) pharmaceutical powder mixture. Multiple images from high and medium magnification were concatenated so that an equivalent field of view was obtained for all magnification levels. Univariate images, principal component analysis score images, partial least squares predicted images and spectra extracted from different intensity regions in the area images were analysed qualitatively and quantitatively for comparison. A series of images spanning a strip across the centre of the circular field were collected at each magnification level and compared with respect to surface features elucidated and area of blend surface imaged. Analyses of images indicate that the three magnification levels delineate the component distribution for this particular powder system similarly. Images obtained at the low magnification level demonstrated adequate resolution and provided the broadest view of the blend surface. It is concluded that the low optical magnification level was adequate for the system being studied and is the preferred mode for pharmaceutical powder blend image data collection for this system.

The Significance of Marginal Gap and Overextension Measurement in the Evaluation of the Fit of Complete Crowns

Introduction An important criterion for the success of a crown is marginal fit. However, in the patient's mouth fit can only be evaluated by subjective methods. This study describes the correlation between objective marginal fit and its subjective evaluation by dentists and dental technicians. Materials and Methods Thirty human premolars and molars were randomly divided into six groups and prepared with a shoulder. For each of the six groups, complete crowns were made of different alloys and technologies (casting: AuAgCu, AuPdPt, PdAgAu, CoCrMo, and Ti; milling: Ti). The crowns were cemented with provisional cement. Ten dentists and 10 technicians were asked to evaluate the fit of the crowns with a new dental explorer. The crowns were then cleaned and cemented with a zinc-oxide-phosphate-cement. The marginal gap and a possible overextended margin of the crowns were examined under a special 4x light microscope with a magnification level of 560 X. The means of the gaps and the overextended margins were calculated for each group. Significances were detected by analysis of variance (ANOVA) and the post-hoctest (Bonferroni, p<0.05). Correlations between objective measuring and subjective evaluation were evaluated using the Pearson test. The influence of the measured values on the subjective evaluation was determined by regression analyses. Results Crowns made from different alloys and technologies showed partly significantly (p<0.05) different marginal gaps (mean ranging from 35ìm to 92ìm) and significantly (p<0.05) different overextended margins (mean ranging from 40ìm to 149ìm). There were significant correlations (p<0.05) between subjective findings and objective data. Significant correlations (p<0.01) were also found between the subjective findings of dentists and technicians. Compared to the marginal gap, only the overextended margin had a significant influence (p=0.00) on the subjective evaluations of the clinicians. Conclusion Crowns from different alloys and technologies showed differences in marginal fit. Marginal gap and the overextension of the crowns significantly correlated with the subjective evaluation of their fit by dentists and dental technicians. For the decision of the clinicians, whether a crown is acceptable, overextension was more important than marginal gap. Citation Boeckler AF, Stadler A, Setz JM. The Significance of Marginal Gap and Overextension Measurement in the Evaluation of the Fit of Complete Crowns. J Contemp Dent Pract 2005 November; (6)4:026-037.

The Effects of Magnification and Allowed Viewing Time on the Inspection of Printed Circuit Boards

Industrial inspectors are becoming more dependant on the stereoscopic microscope for detecting microminiature defects in electronic components. The present study investigated the effect of magnification on the detection of scratch defects in the etching of printed circuit boards. Ten subjects were tested under 3 levels of magnification (10x, 16x and 30x) with the time for each view adjusted so that the total viewing time remained constant. Results showed a significant increase in inspector sensitivity (d') at the 30x magnification level. Inspector sensitivity in the 10x and 16x conditions was not significantly different. These results suggest that improvements in inspector performance through magnification are possible without increasing inspection time.

STUDIES ON THE CORNEA

Physiological studies have demonstrated that ions, as well as large molecules such as hemoglobin or fluorescein, can diffuse across and within the cornea. Most of the substrates for corneal metabolism are obtained from aqueous humor filling the anterior chamber. In order to receive its nutrients and in order to maintain its normal conditions of hydration, the avascular cornea must transport relatively large amounts of solute and solvent across the cellular layers which cover this structure. It has been suggested in the past that there may be a morphological basis for the transport of large amounts of solvents and solutes by cells by the mechanism of pinocytosis. The use of electron-opaque markers to study fluid movements at the electron microscope magnification level was described by Wissig (29). The present study describes the fine structure of the normal rabbit cornea and the pathways of transport of colloidal particles by the cornea in vivo. Rabbit corneas were exposed in vivo to suspensions of saccharated iron oxide, thorium dioxide, or ferritin by injection of the material into the anterior chamber. In other experiments thorium dioxide or saccharated iron oxide was injected into the corneal stroma, producing a small bleb. Particles presented at the aqueous humor surface of the rabbit corneal endothelium are first attached to the cell surface and then pinocytosed. It appears that the particles are carried around the terminal bar by an intracellular pathway involving the pinocytosis of the particles and their subsequent transport in vesicles to the lateral cell margin basal to the terminal bar. Particles introduced at the basal surface of the endothelium (via blebs in the corneal stroma) are apparently carried through the endothelial cells in membrane-bounded vesicles without appearing in the intercellular space. There appears to be free diffusion of these particles through Descemet's membrane and the corneal stroma. The stromal cells take up large quantities of the particles when blebs are injected into the stroma.