Gray Value Differences Research Articles

Gamma-ray transmission evaluation using imaging plate designed for X-ray radiography

A commercial imaging plate (IP) designed for X-rays and a cesium-137 radiation exposure device were employed to evaluate gamma-ray transmission over the wide surface area of a specimen. A thin copper sheet was used as an intensifying material to enhance the sensitivity of the IP to gamma rays. The response of the copper-covered IP to the transmitted gamma ray was expressed as a two-dimensional gray-tone digital image. The relationship was experimentally determined between the transmission of copper plates with different thickness and corresponding gray values on the digital image. The gray value of the specimen was compared with the one of the copper plate exposed simultaneously on the same image to evaluate gamma-ray transmission. A two-dimensional array of stainless steel balls was fabricated as an example specimen with non-uniform thickness and many voids and its transmission was evaluated as a test. The transmission evaluated from the image agreed well with the one calculated using PHITS and the one measured with an ion chamber. The image of a thick concrete brick showed that a difference in gray values appeared between the center and edge parts. Spread of Compton scattering gamma rays was found to affect the image of a thick specimen.

Expression of CD44 in articular cartilage is associated with disease severity in knee osteoarthritis

Objectives To investigate CD44 levels in articular cartilage of knee osteoarthritis (OA) and the relationship between CD44 and severity of the disease.Methods All 50 cartilage tissues included normal and OA cartilage, and were ascribed to the following four groups on the basis of modified Mankin score: normal, mild lesions, moderate lesions and severe lesions. CD44 levels in articular cartilage were assessed by immunohistochemical methods.Results CD44 levels were detected in all four groups. The difference in average gray value of CD44 expression showed statistical significance when compared between each group (P < 0.05). In addition, CD44 expression in each group correlated with disease severity, according to the modified Mankin score (ρ = −0.848, P < 0.01).Conclusions CD44 in articular cartilage is associated with progressive knee OA joint damage.

Radiometric Correction of Multispectral Images Using Radon Transform

Satellite imagery analysis has played a key role in environmental monitoring and modeling over the past few decades. Remotely sensed multitemporal, multisensor data are often required in Earth observation applications. A common problem associated with the use of multisource image data is the gray value differences caused by non-surface factors such as different illumination, atmospheric or sensor conditions. Radiometric corrections serve to remove the effects that alter the spectral characteristics of land features, except for actual changes in ground target, becoming mandatory in multi-sensor, multi-date studies. This paper presents methodology for correction of Landsat TM images in Radon domain. We propose radiometric correction using Radon Transform based regression method. The transform domain method statistically determines correction values based on contrast between spectral properties of various homogeneous areas. TM band 1 is the band most affected by atmospheric scattering whereas TM band 5 is less affected by atmospheric scattering effect. Hence TM Band 5 is taken as the reference image. Results are assessed statistically and compared with results of popular spatial domain Regression Line Method. The application of the methods for vegetation analyses is also shown in this paper. Test results show that the method gives improved results in removal of atmospheric influence.

A New Algorithm of Eyed Typhoon Automatic Positioning Based on Single Infrared Satellite Cloud Image

According to the characteristic that the gray value difference is quite obvious in different areas of the singles infrared cloud, this paper puts forward an algorithm of the eyed typhoon's center automatic positioning. After pretreating the cloud image, we use the template to segment the airtight cloud wall area which has high gray value. In addition, the difference between gray values of the airtight cloud wall area is small. Then we do binarization processing to the image and use the method combined with the mathematical morphology and artificial intelligence to process the image in filtering smoothly. We remove the isolated interference point. Then we corrode image and adopt the seed filling algorithm to detect the candidate eye area. In the candidate eye area, the paper puts forward the discriminant function which is based on the combination of the gray information and the distance between the inspection points and the circle's center. The candidate eye area corresponded to the minimum value of the discriminant function is the center of the eyed typhoon. The experiment result shows that this algorithm has higher positioning accuracy and it can be used for meteorological service.

Feature Extraction Based on Color Difference Algorithm for Moving Target Detection System

To improve the accuracy and robustness of the moving object detection in the image sequence, the author improves the traditional algorithm which is based on the gray-value difference. The author makes good use of the color information of images and applies the pixels in red, green, blue the three component value as its identifying information. According to the background image color composition, it adapts and adjusts the proportion of the three groups. Dynamic threshold is used to do the binarization separation of the background difference image. The simulation experiment shows, this algorithm makes full use of the color features of image and achieve the expected goal of high recognizability and good robustness.

Expression of CD44 in articular cartilage is associated with disease severity in knee osteoarthritis

To investigate CD44 levels in articular cartilage of knee osteoarthritis (OA) and the relationship between CD44 and severity of the disease. All 50 cartilage tissues included normal and OA cartilage, and were ascribed to the following four groups on the basis of modified Mankin score: normal, mild lesions, moderate lesions and severe lesions. CD44 levels in articular cartilage were assessed by immunohistochemical methods. CD44 levels were detected in all four groups. The difference in average gray value of CD44 expression showed statistical significance when compared between each group (P < 0.05). In addition, CD44 expression in each group correlated with disease severity, according to the modified Mankin score (ρ = -0.848, P < 0.01). CD44 in articular cartilage is associated with progressive knee OA joint damage.

In vitro assessment of artifacts induced by titanium dental implants in cone beam computed tomography

The objective of this study was to evaluate the geometric pattern and the intensity of artifacts around titanium implants in cone beam computed tomography (CBCT) using an in vitro model. Ten test models, each containing one 4.1-mm-diameter titanium implant, were cast from a human mandible using silicone impression material and dental stone. Each model contained an implant in one of the following single-tooth gaps: 37, 36, 34, 33, 31, 41, 43, 44, 46, and 47. For control purposes, three models without implants were produced. Each model was scanned five times using a CBCT scanner. Gray values (GV) were recorded at eight circumferential positions around the implants at 0.5mm, 1mm, and 2mm from the implant surface (GVTest ). GV were measured in the corresponding volumes of interest (VOI) in the models without implants (GVControl ). Differences of gray values (ΔGV) between GVTest and GVControl were calculated as percentages. To detect differences between GVTest and GVControl , the 95% confidence interval (CI) was computed for the values of ΔGV. Repeated measures ANOVA was used for the comparison of ΔGV at 0.5mm, 1mm, and 2mm from the implant surface. Artifacts reflected by altered GV were always present in the proximity of titanium implants, regardless of the implant position. When comparing GVTest and GVControl , increased GV were found at the buccal and lingual aspects of the implant sites, whereas regions with reduced GV were located along the long axis of the mandibular body of the test models. A significant decrease in artifact intensity was found with increasing distance from the buccal implant surface (ΔGV0.5mm : 45±10% [SD], ΔGV1mm : 28±14% [SD], ΔGV2mm : 14±7% [SD]) (P<0.001). Artifacts around titanium implants in CBCT images were distributed according to a geometrical pattern.

Research on tool wear detection based on machine vision in end milling process

This paper suggests a novel technique for the tool wear measurement based on machine vision. Tool images are captured between cutting operations using a machine vision system. The gray value difference threshold is determined from the tool image itself and the reference line is found to locate the tool in the image. The edges of the tool wear region are extracted by column scanning. A method of continuity testing is used to find the correct edge position in each wear column. To achieve a more accurate result, the sub-pixel edge detection technology is adopted to extract the edges. Finaly, the tool wear parameters can be obtained after rebuilding the top edge of the wear region and determining the bottom edge of the wear region. The measurement results gotten by the proposed method are compared with those gotten by measuring directly with a microscope. The proposed scheme is shown to be reliable and effective for the automated tool wear measurement.

Dynamic Adaptive Weight Multi-Scale and Multi-Structure Morphological Edge Detection in Anterior Chamber OCT Images

An edge detection algorithm which is applied to anterior chamber OCT images has been proposed. The algorithm firstly uses multi-structure elements to detect edge on gray level value differences on the same scale, and introduces dynamic adaptive weight to make re-fusion of pixels to gain a multi-structure element morphological edge detection image on the same scale, then confirms weight value and makes multi-scale fusion according to the noise immunity of different scale structure elements to gain the final edge detection image. The simulated results have obvious edge features,it can effectively avoid the occurrence of mutational pixels on the OCT image edge results, compared to traditional edge detection algorithms.

Expressions of phosphatidylinositol 3 kinase and phosphorylated Akt in condyloma acuminatum and cervical squamous cell carcinoma

Objective To investigate the roles of phosphatidylinositol 3 kinase (PI3K) and phosphorylated Akt (P-Akt) in the pathogenesis of cervical squamous cell carcinoma and condyloma acuminatum.Methods Immunohistochemistry and Western blot were used to detect the expressions of PI3K and P-Akt in tissue specimens from the lesions of 30 cases of cervical squamous cell carcinoma,30 cases of condyloma acuminatum and the prepuce of 15 normal human controls.The average optical density and gray scale values were calculated and analyzed by t test and F test respectively.Results The expressions of PI3K and P-Akt were observed in only the basal layer of the epidermis of control specimens,but in the whole epidermis of condyloma acuminatum tissue specimens.Cervical squamous cell carcinoma tissue specimens displayed a stronger expression of PI3K and P-Akt compared with the control and condyloma acuminatum tissue specimens.As immunohistochemistry revealed,the average absorbance value for PI3K and P-Akt was 0.28 ±0.05 and 0.20 ± 0.07 respectively in cervical squamous cell carcinoma tissue specimens,0.22 ± 0.04 and 0.17 ± 0.03 respectively in condyloma acuminatum tissue specimens,and 0.16 ± 0.04 and 0.10 ± 0.02 respectively in the control tissue specimens; significant differences were observed in the expressions of PI3K and P-Akt among the three groups of tissue specimens (F =44.87,20.64,respectively,both P ＜ 0.01 ).The results of Western blot were consistent with those of immunohistochemistry,and there was a significant difference in the gray scale value for PI3K and P-Akt between cervical squamous cell carcinoma,condyloma acuminatum and control tissue specimens (3.48 ± 0.48 vs.1.99 ± 0.11 vs.1.00 ± 0.03,F=354.83,P＜ 0.01; 3.33 ± 0.26 vs.1.96 ± 0.11 vs.1.00 ± 0.03,F=302.33,P＜ 0.01 ).Conclusions The PI3K/Akt signaling pathway is abnormally activated in condyloma acuminatum and cervical squamous cell carcinoma,and human papilloma virus may cause the abnormal proliferation of infected epithelium likely by affecting the upregnlated expression of PI3K/P-Akt. Key words: Carcinoma, squamous cell; Condylomata acuminata; l-Phosphatidylinositol 3-kinase; Proto-oncogene proteins c-akt

Dynamic Adaptive Weight Multi-Scale and Multi-Structure Morphological Edge Detection in Anterior Chamber OCT Images

An edge detection algorithm which is applied to anterior chamber OCT images has been proposed. The algorithm firstly uses multi-structure elements to detect edge on gray level value differences on the same scale, and introduces dynamic adaptive weight to make re-fusion of pixels to gain a multi-structure element morphological edge detection image on the same scale, then confirms weight value and makes multi-scale fusion according to the noise immunity of different scale structure elements to gain the final edge detection image. The simulated results have obvious edge features,it can effectively avoid the occurrence of mutational pixels on the OCT image edge results, compared to traditional edge detection algorithms.

Improved FCM algorithm using difference of neighborhood information

In order to overcome the shortcoming of Fuzzy C-means(FCM) that cannot deal with image noise and weaknesses of its common improved algorithms,an improved FCM algorithm using the difference of neighborhood information was proposed in this paper,which used Gaussian function to characterize the difference of space and gray value about neighborhood pixels reasonably,and to adjust the center pixel membership to achieve the purpose of noise image segmentation.The experimental results show that the proposed algorithm can effectively deal with the images with Gaussian and Pepper Salt noise,and can remove the noise while retaining more complete details of image.Its segmentation results are better than several improved FCM algorithms in the literatures.

Gray Value Differences to Dentin of Root Posts Radiographed with Digital Intraoral Systems and Conventional X-ray Films

This study compared the gray value differences to dentin of titanium and FRC root posts in anterior and posterior teeth radiographed with digital intraoral systems and conventional x-ray film. Radiographic images (n=5) of titanium or fiber-reinforced composite (FRC) root posts placed in extracted teeth were taken with six digital intraoral radiographic devices and conventional x-ray film (control group). Gray value differences were evaluated between the root posts and root dentin. Statistical analyses of the results were performed with three-way and one-way ANOVA with Bonferroni-Dunn's multiple comparisons post-hoc analyses (α=0.05). Significantly higher gray value differences of titanium and FRC posts were found in anterior teeth but not in molars for XIOS, Sidexis and Visualix digital intraoral systems, but not for RVG, DenOptix and VistaScan (FRC posts). Except for DenOptix with incisors and molars and VistaScan with molars, conventional x-ray films showed significantly lower gray value differences of titanium posts in incisors and molars compared to the corresponding digital radiographs.

Leaf Vein Extraction Based on Gray-scale Morphology

Leaf features play an important role in plant species identification and plant taxonomy. The type of the leaf vein is an important morphological feature of the leaf in botany. Leaf vein should be extracted from the leaf in the image before discriminating its type. In this paper a new method of leaf vein extraction has been proposed based on gray-scale morphology. Firstly, the color image of the plant leaf is transformed to the gray image according to the hue and intensity information. Secondly, the gray-scale morphology processing is applied to the image to eliminate the color overlap in the whole leaf vein and the whole background. Thirdly, the linear intensity adjustment is adopted to enlarge the gray value difference between the leaf vein and its background. Fourthly, calculate a threshold with OSTU method to segment the leaf vein from its background. Finally, the leaf vein can be got after some processing on details. Experiments have been conducted with several images. The results show the effectiveness of the method. The idea of the method is also applicable to other linear objects extraction. Index Terms—leaf vein; gray-scale morphology; image segmentation; linear object

In Vivo Volumetric Intravascular Ultrasound Visualization of Early/Inflammatory Arterial Atheroma Using Targeted Echogenic Immunoliposomes

This study aimed to demonstrate three-dimensional (3D) visualization of early/inflammatory arterial atheroma using intravascular ultrasound (IVUS) and targeted echogenic immunoliposomes (ELIP). IVUS can be used as a molecular imaging modality with the use of targeted contrast agents for atheroma detection. Three-dimensional reconstruction of 2-dimensional IVUS images may provide improved atheroma visualization. Atheroma were induced in arteries of Yucatan miniswine (n = 5) by endothelial cell denudation followed by a 4-week high cholesterol diet. The contralateral arteries were left intact and served as controls. Anti-intercellular adhesion molecule-1 (ICAM-1) and generic gammaglobulin (IgG) conjugated ELIP were prepared. Arteries were imaged using IVUS before and after ELIP injection. Images were digitized, manually traced, segmented, and placed in tomographic sequence for 3D visualization. Atheroma brightness enhancement was compared and reported as mean gray scale values. Plaque volume was quantified both from IVUS and histologic images. Anti-ICAM-1 ELIP highlighting of the atheroma in all arterial segments was different compared with baseline (P < 0.05). There was no difference in the mean gray scale values with IgG-ELIP. Arterial 3D IVUS images allowed visualization of the entire plaque distribution. The highlighted plaque/atheroma volume with anti-ICAM-1 ELIP was greater than baseline (P < 0.01). This study demonstrates specific highlighting of early/inflammatory atheroma in vivo using anti-ICAM-1 ELIP. Three-dimensional IVUS reconstruction provides good visualization of plaque distribution in the arterial wall. This novel methodology may help to detect and diagnose pathophysiologic development of all stages of atheroma formation in vivo and quantitate plaque volume for serial and long-term atherosclerotic treatment studies.

Effect of diabetes mellitus and insulin therapy on bone density around osseointegrated dental implants: a digital subtraction radiography study in rats

To evaluate the effect of diabetes mellitus (DM) and insulin therapy on bone density around osseointegrated dental implants by digital subtraction radiography (DSR). Forty implants were placed in tibiae of 40 adult rats. After a healing period of 2 months, the animals were divided into four groups of 10 animals each: a 2-month control group, sacrificed at time (A), a diabetic group (D), an insulin-treated group (I) and a 4-month control group (C). During 2 months, group I received subcutaneous doses of insulin, whereas groups C and D received only saline. The animals in groups D, I and C were thereafter sacrificed. The glucose plasma levels (GPLs) were monitored throughout the experiment. Film radiographs were taken at implant surgery and on the day of sacrifice. The radiographs were digitized, and bone density in regions of osseointegration (OR) around the implants was evaluated by quantitative DSR between baseline and final images. Differences in shades of gray among the groups were assessed using ANOVA. GPLs were within normal range for groups A, C and I and higher for group D. There was a significant difference in mean gray shade values in the OR of subtraction images between groups D (122+/-7) and I (136+/-5) (P<0.05) while there were no significant differences between control groups A (128+/-13) and C (134+/-10) and the insulin group I. DM impaired bone density around osseointegrated dental implant. Further, insulin therapy maintained bone density in diabetic rats.

Anatomical Organization of the Blind's Brain: Combined VBM and DTI Analysis.

Purpose: To explore the whole brain grey and white matter organization in a large cohort of congenital blindness (CB) individuals compared to normal-sight (NS) controls using Diffusion Tensor Imaging (DTI) and tractography (DTT). Materials and Methods: Thirteen CB and thirteen NS were scanned in this experiment. T1WI, T2WI, and DTI (61 directions; b=1200 s/mm) were acquired on a Siemens 3T scanner. T1 and T2 images were segmented using the VBM5 toolbox in SPM5. DARTEL was used for high dimensional inter-subject registration. The diffusion tensor was fitted using the RESTORE algorithm. VBM5 was used for voxel-based analysis for comparing the group differences of gray matter, white matter and FA values. Probabilistic tractography (20 streamlines) implemented in FSL was used to generate anatomical connectivity maps (ACM) using a brain mask as seed ROI. DTIstudio was used for DTT to display the fiber tracts related to the visual pathway, in which two regions of interest (ROI) were defined on the coronal plain for both sides: one covered the whole occipital lobe at middle level of occipital lobe and the other covered the inferior fronto-occipital fasciculus (IFO) at the level through middle corpus callosum. Results: All structures belonging to the visual system showed significant volume reductions. All components of the retino-geniculo-striate system including optic nerve, chiasm, lateral geniculate nucleus, optic radiations and visual cortex were reduced. Especially, the volume of the bilateral superior colliculi was decreased (see Fig.1). In the Non-visual areas changes were observed in the posterior hippocampus and parts of the frontal and temporal lobes. All structures belonging to the visual system showed significant reductions of anatomical connectivity (see Fig.2). Most of the NS, 11 of 13, showed the fiber tracts going through the both ROIs. On the contrary, only 2 of 13 CB demonstrated the similar fiber tracts (see Fig.3). Conclusion: We show for the first time large reductions in the midbrain visual structures. The tractography results of CB were consistent with our VBM results. Our VBM data however did not confirm the enlargement of the fronto-occipital and the supra-longitudinal fasciculi previously reported. Fig.1 Group Comparison for the White Matter between the subjects with NS and CB, FDR correction with p<0.005. All structures belonging to the visual system showed significant volume reductions, including optic chiasm, lateral geniculate bodies and primary and secondary visual area (green arrowheads). Especially, the volume reduction was found in both superior colliculi (blue arrow).

Protection against Human Immunodeficiency Virus Type 1 Tat Neurotoxicity by Ginkgo biloba Extract EGb 761 Involving Glial Fibrillary Acidic Protein

Human immunodeficiency virus (HIV)-1 Tat protein is an important pathogenic factor in HIV-associated neuropathogenesis. Despite recent progress, the molecular mechanisms underlying Tat neurotoxicity are still not completely understood. However, few therapeutics have been developed to specifically target HIV infection in the brain. Recent development of an inducible brain-specific Tat transgenic mouse model has made it possible to define the mechanisms of Tat neurotoxicity and evaluate anti-neuroAIDS therapeutic candidates in the context of a whole organism. Herein, we demonstrate that administration of EGb 761, a standardized formulation of Ginkgo biloba extract, markedly protected Tat transgenic mice from Tat-induced developmental retardation, inflammation, death, astrocytosis, and neuron loss. EGb 761 directly down-regulated glial fibrillary acidic protein (GFAP) expression at both protein and mRNA levels. This down-regulation was, at least in part, attributable to direct effects of EGb 761 on the interactions of the AP1 and NF-kappaB transcription factors with the GFAP promoter. Most strikingly, Tat-induced neuropathological phenotypes including macrophage/microglia activation, central nervous system infiltration of T lymphocytes, and oxidative stress were significantly alleviated in GFAP-null/Tat transgenic mice. Taken together, these results provide the first evidence to support the potential for clinical use of EGb 761 to treat HIV-associated neurological diseases. Moreover, these findings suggest for the first time that GFAP activation is directly involved in Tat neurotoxicity, supporting the notion that astrocyte activation or astrocytosis may directly contribute to HIV-associated neurological disorders.

Corpus Luteum Morphology and Vascularization Assessed by Transvaginal Two-dimensional and Three-dimensional Ultrasound

Abstract Background Our aim was to describe the corpus luteum morphology by two-dimensional ultrasound correlated by its vascularization and volume by 3D ultrasound and study the possible relationship between serum progesterone levels and the corpus luteum morphology. Methods Thirty-eight women were included in an intrauterine insemination program (IUI) in Santa Cristina University's Hospital. All the patients were evaluated in mesoluteal phase, the day +7 after hCG administration, by two-dimensional and three-dimensional ultrasound. The volume and vascular indices of the corpus luteum were calculated off-line using virtual organ computer-aided analysis (VOCALTM) software. Results Four different morphologies were described in the corpus luteum: echo-positive, echo-negative or sonoluscent, mixed echogenicity or nonvisible. Corpus luteum with mixed echogenicity was the most frequent one with 37.5% (12 cases). The corpus luteum vascular indices change in each morphology type, but there was statistically significant association just in vascularization index between echo-negative and mixed echogenicity corpus luteum morphologies, with p = 0.034. The rest of vascular indices do not change in each morphology corpus luteum types. There was statistically significant difference in mean gray value between echo-negative and mixed echogenicity morphologies, with p = 0.007. There were no statistically significant correlations between the corpus luteum morphology and the corpus luteum volume of any of the different types. There either was no statistically significant correlation between the corpus luteum morphology and progesterone serum levels on day +7 postovulation. Conclusions The mixed echogenicity corpus luteum morphology has more vessels and more cell mass than echo-negative ones. Progesterone serum levels in mid-luteal phase has no influence in corpus luteum morphology and vascularization.

Multigrid based total variation image registration

We consider the image registration problem to find a reasonable displacement field, such that a transformed template image becomes similar to a so-called reference image. The minimization of the similarity measure (exemplarily based on the gray-value difference) yields a nonlinear ill-posed inverse problem. The necessary regularization is done by replacing the ill-conditioned Hessian by a multidimensional total variation $$(\mathcal{TV})$$ norm. This allows steep gradients and discontinuities in the displacement field in contrast to the common approach by elastic regularization which leads to globally smooth displacement fields. We propose and investigate a multigrid algorithm as inner iteration for $$\mathcal{TV}$$ registration. As we use Neumann boundary conditions which lead to singular systems, a special treatment before and during the FAS multigrid algorithm is required, e.g. the introduction and solution of an augmented system. We describe the necessary modifications for the multigrid algorithm and present convergence results as well as first registration experiments demonstrating the capabilities of the proposed approach.