Automated Contour Detection for Intravascular Ultrasound Image Sequences Based on Fast Active Contour Algorithm

INTRODUCTIONCoronary angiography has been the traditional method for assessing the coronary heart diseases inthe past several decades.It records the outline of vessels by X-rays projection technique but can onlyprovide limited information about the arterial wall morphology and geometry.Therefore it may cause cli-nicians to make mistaken estimations or diagnoses.Nowadays,intravascular ultrasound(IVUS)is be-coming wildly applied into the diagnosis of coronary heart diseases and interventi…     

A CT Image Segmentation Algorithm Based on Level Set Method

INTRODUCTION Image segmentation is one of the most important topics in medical image processing fields. In manycases, image segmentation is prerequisite. For example: In radiodiagnosis, in order to give dose protec-tion for lung organ, it is necessary to segment it frombreast CTslices. In order to give detailed informa-tion about the focus, it should be extracted from other healthy tissues. All the problems mentioned arerelative to howto express the object regions and contours accurately…     

An Alternative Derivation for Bronnikov’s Reconstruction Algorithm in X-ray Phase Contrast Tomography

In this article, we present an alternative derivation for Bronnikov’s reconstruction algorithm in X-ray phase contrast tomography with holographic measurements. A two-step method was used in the alternative derivation. The phase shift induced by the object was obtained by Fourier transform and the real part of the complex refractive index of the object was retrieved by applying the conventional filtered backprojection method. The alternative derivation provides an easier way to understand the reconstruction formula.     

The 31P–NMR Stress Test: An Approach for Detecting Myocardial Ischemia

³¹P–NMR spectroscopy has the potential to assess myocardial damage directly and noninvasively by ascertaining the relative abundances of phosphorus-containing compounds relevant to metabolism under stress conditions. Decrease in the PCr/ATP ratio during exercise is an indicator of the level of stress to which the myocardium is subject. This ratio will remain constant under mild to moderate exercise conditions in a healthy subject, but may show a precipitous decrease even under mild exercise when regions of the myocardium are ischemic. The studies examined here indicate that cardiac patients with some forms of ischemia showed a PCr/ATP ratio decrease even under light exercise, while no decrease was observed in patients whose heart disease was known to be nonischemic. Hypertension and nonstenotic chest pain in women can, in some cases, produce a decrease in PCr/ATP ratio. Only the hypertensive patients showed a significant difference in the prestress PCr/ATP ratio when compared with controls. These studies suggest that ³¹P–NMR spectroscopy before and during mild exercise in the bore of the magnet can be a useful indicator of the presence or absence of an ischemic component to myocardial disorder. © 2000 Biomedical Engineering Society. PAC00: 8764Hd, 8719Uv, 8719Xx, 8719Hh, 8719Ff     

Laplace–Dirichlet Energy Field Specification for Deformable Models. An FEM Approach to Active Contour Fitting

The construction of large scale computer models for complex biological systems requires the fitting of curves or surfaces to anatomical data sets. Algorithms recently developed to perform this task are based on the displacement of an initial model contour. There are several problems associated with this approach. Here we present improvements which eliminate the (i) sensitivity to the initial model position and shape; (ii) existence of local minima or maxima in the field used to displace the model; and (iii) presence of multiple solutions in the rules governing model displacement. Key elements of our algorithm are first that both the energy field used to displace the model and the model displacement itself are governed by partial differential equations. Secondly, we approximate the model with a polygonal contour which facilitates accurate displacement. Tests performed against cases that are known to be problematic show that our algorithm can fit complex data sets entirely automatically.     

A “Geographic Information Systems” Based Technique for the Study of Microvascular Networks

An automated system (ANET) has been developed to construct interactive maps of microvascular networks, calculate blood flow parameters, and simulate microvascular network blood flow using the geographic information systems (GIS) technology. ANET enables us to automatically collect and display topological, structural, and functional parameters and simulate blood flow in microvascular networks. The user-definable programming interface was used for the manipulation of drawings and data. Visual enhancement techniques such as color can be used to display useful information within a network. In ANET the network map becomes a graphical interface through which network information is stored and retrieved and simulations of microvascular network blood flow are carried out. We have used ANET to study the effects of ionizing radiation on normal tissue microvascular networks. Our results indicate that while vessel diameters significantly increased with age in control animals they decreased in irradiated animals. The tortuosity of irradiated vessels (16.3 ± 1.1 mean±standard error of the mean) was significantly different from control vessels (10.0 ± 1.3) only at 7 days postirradiation. Average red blood cell transit time was significantly different between control (1.6 ± 0.6 s) and irradiated (10.7 ± 5.7 s) microvascular networks at 30 days postirradiation. ANET provides an effective tool for handling the large volume of complex data that is usually obtained in microvascular network studies and for simulating blood flow in microvascular networks. © 1999 Biomedical Engineering Society. PAC99: 8764-t, 8719Tt, 0705Pj, 8750Gi     

An “imaging-biopsy” strategy for colorectal tumor reconfirmation by multipurpose paramagnetic quantum dots

Glucose transporter1 (Glut1) plays important roles in treatment of colorectal cancer (CRC) involving early-stage diagnosis, subtype, TNM stage, and therapeutic schedule. Currently, in situ marking and tracking of the tumor biomarkers via clinical imaging remains great challenges in early stage CRC diagnosis. In this study, we have developed a unique cell-targeted, paramagnetic-fluorescent double-signal molecular nanoprobe for CRC in vivo magnetic resonance imaging (MRI) diagnosis and subsequent biopsy. The unique molecular nanoprobe is composed of a fluorescent quantum dot (QD) core; a coating layer of paramagnetic DTPA-Gd coupled BSA (GdDTPA∙BSA), and a surface targeting moiety of anti-Glut1 polyclonal antibody. The engineered GdDTPA∙BSA@QDs-PcAb is 35 nm in diameter and colloidally stable under both basic and acidic conditions. It exhibits strong fluorescent intensities and high relaxivity (r₁ and r₂: 16.561 and 27.702 s⁻¹ per mM of Gd³⁺). Distribution and expression of Glut1 of CRC cells are investigated by in vitro cellular confocal fluorescent imaging and MR scanning upon treating with the ^GdDTPA∙BSA@QDs-PcAb nanoprobes. In vivo MRI shows real-time imaging of CRC tumor on nude mice after intravenously injection of the ^GdDTPA∙BSA@QDs-PcAb nanoprobes. Ex vivo biopsy is subsequently conducted for expression of Glut1 on tumor tissues. These nanoprobes are found biocompatible in vitro and in vivo. ^GdDTPA∙BSA@QDs-PcAb targeted nanoprobe is shown to be a promising agent for CRC cancer in vivo MRI diagnosis and ex vivo biopsy analysis. The “imaging-biopsy” is a viable strategy for tumor reconfirmation with improved diagnostic accuracy and biopsy in personalized treatment.     

Image panels for the special issue related to the meeting “The Nervous System of Drosophila melanogaster: From Development to Function”

These images were composed for the special issue related to the meeting “The Nervous System of Drosophila melanogaster: From Development to Function” that was held in Freiburg (Germany) from 26-29 Sept 2013.     

On the “glycogen function” of the myometrium in pregnancy

Summary Investigation was made relative to the physiological significance of the glycogen function of myometrium in pregnancy and of the mechanisms regulating it. The a mount of glycogen in the sections of myometrium lying between individual fetuses was found to be same as in those of non-gravid animals. The glycogen level in myometrium directly bordering on the fetuses was several times greater. The glycogen level in the myometrium of the uterine horn from which the fetuses were removed 3-5-15 days prior to the investigation was lower than in the myometrium of the intact horn containing fetuses. With the development of pregnancy there is a growing resistance of the myometrial glycogen during its incubation in a thermostat at 37°C. This resistance appears to be maximal near the term of pregnancy. The data obtained conforms with the results of previous investigations. It shows that in the control of the glycogen function of myometrium an improtant role is played by the impulses appearing in connection with the vital activity of the fetus and that the physiological significance of this myometrial function is assocated with the requirements of the developing fetus, and probably with its trophics.Presented by Active Member of the AMN SSSR A. I. Serebrov Translated from Byulleten Èksperimental'noi Biologii i Meditsiny Vol. 49, No. 4, pp. 101–104, April, 1960     

On the use of the outcome variable “small for gestational age” when gestational age is a potential mediator: a maternal asthma perspective

Background

The variable “small for gestational age,” frequently defined as birth weight below the 10th percentile in a gestational age and sex-normalized population, is nowadays generally perceived as a more adequate measure than birth weight or low birth weight (birth weight?<?2500 g) to capture fetal growth. However, the use of small for gestational age rather than birth weight or low birth weight as an outcome (dependent) variable may have important impacts on the interpretation of analyses aimed at estimating the causal effect of an exposure of interest on infants. We hypothesized potential differences in both types of effects estimated (direct or total) and in ability to control for confounding bias.

Methods

We first examined the use of outcome variables birth weight and small for gestational age to get insights on modeling practices within the field of maternal asthma. Using directed acyclic graph simulations where gestational age was a potential mediator, we then compared estimated exposure effects in regression models for birth weight, low birth weight, and small for gestational age. Graphs with and without confounding were considered.

Results

Our simulations showed that the variable small for gestational age captures the direct effect of exposure on birth weight, but not the indirect effect of exposure on birth weight through gestational age. Interestingly, exposure effect estimates from small for gestational age models were found unbiased whenever exposure effect estimates from birth weight models were affected by collider bias due to conditioning on gestational age in the models.

Conclusions

The sole consideration of the outcome small for gestational age in a study may lead to suboptimal understanding and quantification of the underlying effect of an exposure on birth weight-related measures. Instead, our results suggest that both outcome variables (low) birth weight and small for gestational age should minimally be considered in studies investigating perinatal outcomes.

     

Capturing clinical expertise: An analysis of knowledge “mining” through expert system development

This article examines the viability of expert system development as a tool for better understanding and operationalizing the complex cognitive processes underlying clinical procedural knowledge (inference, reasoning, and decision-making). Emphasis here is on the learning benefits potentially attainable through the process of probing (or mining) an expert's declarative and procedural knowledge and of representing (or modeling) this knowledge. As a basis for analysis and illustration, linkages are made to current models of memory and information processing and to experience with a specific expert system development project.     

“Nothing About Me Without Me”: An Interpretative Review of Patient Accessible Electronic Health Records

Background

Patient accessible electronic health records (PAEHRs) enable patients to access and manage personal clinical information that is made available to them by their health care providers (HCPs). It is thought that the shared management nature of medical record access improves patient outcomes and improves patient satisfaction. However, recent reviews have found that this is not the case. Furthermore, little research has focused on PAEHRs from the HCP viewpoint. HCPs include physicians, nurses, and service providers.

Objective

We provide a systematic review of reviews of the impact of giving patients record access from both a patient and HCP point of view. The review covers a broad range of outcome measures, including patient safety, patient satisfaction, privacy and security, self-efficacy, and health outcome.

Methods

A systematic search was conducted using Web of Science to identify review articles on the impact of PAEHRs. Our search was limited to English-language reviews published between January 2002 and November 2014. A total of 73 citations were retrieved from a series of Boolean search terms including “review*” with “patient access to records”. These reviews went through a novel scoring system analysis whereby we calculated how many positive outcomes were reported per every outcome measure investigated. This provided a way to quantify the impact of PAEHRs.

Results

Ten reviews covering chronic patients (eg, diabetes and hypertension) and primary care patients, as well as HCPs were found but eight were included for the analysis of outcome measures. We found mixed outcomes across both patient and HCP groups, with approximately half of the reviews showing positive changes with record access. Patients believe that record access increases their perception of control; however, outcome measures thought to create psychological concerns (such as patient anxiety as a result of seeing their medical record) are still unanswered. Nurses are more likely than physicians to gain time efficiencies by using a PAEHR system with the main concern from physicians being the security of the PAEHRs.

Conclusions

This review implements a novel scoring system, which shows there is a lack of rigorous empirical testing that separates the effect of record access from other existing disease management programs. Current research is too targeted within certain clinical groups’ needs, and although there are positive signs for the adoption of PAEHRs, there is currently insufficient evidence about the effect of PAEHRs on health outcomes for patients or HCPs.     

Fibroblast Phenotype Plasticity: Relevance for Understanding Heterogeneity in “Fibroblastic” Tumors

Cellular transformations, reflecting phenotypic plasticity, characterize embryonic life, would-repair, physiological adaptation, and neoplasia. Fibroblastic tumors show a range of cellular differentiation, which can be rationalized in terms of phenotypic plasticity of the “normal” fibroblast. In this paper, the various kinds of fibroblast transformation are discussed, and some insights provided into the molecular mechanisms involved. Comparable molecular events may take place in neoplastic fibroblasts to produce the heterogeneous tumors nevertheless identified as fibroblastic. The following transformations are discussed: histiocytic, and fibrohistiocytic tumors; adipocytic, and lipogenic tumors; myofibroblastic, and myofibroblastic tumors. A definition of the fibroblast is required. This consists of spindle-cell morphology, vimentin-staining, and abundant rough endoplasmic reticulum. Transformation to histiocytic, lipogenic and myofibroblastic phenotypes requires the development of lysosomes, lipid droplets and lamina, and peripheral myofilaments and fibronexuses respectively. These occur in non-malignant transforming (transdifferentiating) fibroblasts, and also in tumors identified as fibrohistiocytic, lipogenic and myofibroblastic. The molecular basis of the myofibroblast transformation is probably the best studied. It is driven primarily by transforming growth factor β. Investigations into the mechanisms of differentiation in normal fibrobiasts could prove fertile ground for defining comparable differentiation in tumors. In this respect, there are very few publications on the presence of growth factors in tumors or tumor-like lesions. There is, however, increasing investigation into gene expression and gene products in tumors, which bear on the differentiation process. Ultimately, our understanding of the molecular events controlling differentiation in cancer will lead to control, cure and prevention.     

Inhibiting Eph kinase activity may not be “Eph”ective for cancer treatment

Abstract

Several Eph receptor tyrosine kinases (RTKs) are commonly over-expressed in epithelial and mesenchymal cancers and are recognized as promising therapeutic targets. Although normal interaction between Eph receptors and their ephrin ligands stimulates kinase activity and is generally tumor suppressive, significant Eph over-expression allows activation of ligand- and/or kinase-independent signaling pathways that promote oncogenesis. Single-agent kinase inhibitors are widely used to target RTK-driven tumors but acquired and de novo resistance to such agents is a major limitation to effective clinical use. Accumulating evidence suggests that Ephs can be inhibited by “leaky” or low-specificity kinase inhibitors targeted at other RTKs. Such off-target effects may therefore inadvertently promote ligand- and/or kinase-independent oncogenic Eph signaling, thereby providing a new mechanism by which resistance to the RTK inhibitors can emerge. We propose that combining specific, non-leaky kinase inhibitors with tumor-suppressive stimulators of Eph signaling may provide more effective treatment options for overcoming treatment-induced resistance and clinical failure.     

Molecular Identification of “Latent Precancers” for Endometrial Serous Carcinoma in Benign-Appearing Endometrium

Alteration of p53 is an early event in the development of endometrial serous carcinoma (ESC). We have recently identified a group of benign-looking endometria with p53 overexpression, designated “p53 signatures.” In this study, we investigated these p53 signatures and evaluated whether they represented “latent” precancers for ESC. The p53 signatures were specifically associated with ESC, frequently found in the benign-appearing endometrium adjacent to the ESC and only rarely in either the endometrium adjacent to endometrioid carcinomas or in non-cancerous uteri. Forty-two percent of the p53 signature samples showed at least one p53 gene mutation. There were eight ESC uteri with p53 signatures that revealed p53 gene mutations. In four (50%) of these cases, at least one identical p53 gene mutation was found in the signature glands, precancerous regions, and cancerous areas within the same uterus. We concluded that p53 gene mutations apparently precede the morphological changes in affected endometrial cells. The finding of identical p53 mutations in the p53 signatures, precancerous regions, and ESCs in a subset of the uteri provides further evidence of a probable shared lineage between these lesions and suggests that the epithelia that display these p53 signatures are likely latent ESC precancerous regions. These findings underscore the significance of the p53 signature as a target for further research in the early detection and prevention of ESC.Endometrial cancer is the most common malignancy of the female genital tract.¹ A dualistic model of endometrial carcinogenesis has been proposed since the 1980s, based on light microscopic appearance, clinical behavior, and epidemiology.^2,3 Although type I cancers, the majority of which are of the endometrioid histotype, comprise approximately 80% of all endometrial carcinomas, type II cancers, most of which are of the serous and clear cell histotypes contribute a disproportionate percentage of patient deaths for the whole group.³ The advanced stage at which many Type II carcinomas present is undoubtedly at least one factor that contributes to the comparatively unfavorable patient outcomes that has been observed in this group. The recognition of the precursors for type II endometrial cancers may therefore be of significant clinical value, both as a morphological marker that potentially portends a heightened cancer risk, and possibly, a biological target for ablation.In the last decade, progress has been greatest in molecular and histological resolution of precursors of type I carcinomas, resulting in a cohesive model of endometrial carcinogenesis encompassing both genetic and hormonal factors, revisions in the diagnostic criteria for precancers, and novel prevention strategies.⁴ In contrast, until recently, there have been relatively few comprehensive studies on the potential type II precursor lesions. Serous endometrial intraepithelial carcinoma (EIC) was previously considered the putative precancerous lesion of endometrial serous carcinoma (ESC), the prototype of type II endometrial cancer. However, serous EIC is now considered as an early form of ESC,⁵ since it is not infrequently associated with extrauterine disease.^{5,6,7,8,9,10,11,12,13} In a series of clinicopathologic studies published over the past few years, our group has shown that the spectrum of lesions to which we have applied the designation endometrial glandular dysplasia (EmGD), represent the most likely morphologically recognizable precancers for both serous and clear cell carcinoma of the endometrium.^14,15,16,17Lesions of EmGD are readily visible on routinely stained histological sections due to their increased degree of nuclear atypia relative to the background endometrium.¹⁶ Nonetheless, while studying these EmGD cases, we noticed that there were endometrial epithelia that were morphologically unremarkable but displayed diffuse and strong p53 nuclear staining. Similar staining patterns have subsequently been reported in tubal epithelia within the context of pelvic serous carcinogenesis, and have been designated the “p53 signatures.”^18,19 We hypothesized that the epithelia that constitute these p53 signatures represent a “latent form” of ESC precancer. The aims of this study are to characterize the p53 mutational status of these p53 signatures lesions, their relationship to synchronous cancers, and their frequency in non-cancerous uteri.