Reliability of anatomic structures as landmarks in three-dimensional cephalometric analysis using CBCT

Objective:To identify anatomic structures in three dimensions and examine their reliability to be used as landmarks in a three-dimensional coordinate cephalometric analysis, using cone-beam computerized tomography (CBCT).Materials and Methods:Thirty CBCT images were randomly selected for landmark location. Forty-two anatomic landmarks, which are not included in the traditional cephalometric landmarks, were chosen based on radiographic characteristics that make them pragmatic to mark in the CBCT image slices. The principal investigator marked the full set of landmarks on the software by navigating in the X, Y, and Z axes for every image three times, with each measurement trial being at least 1 week apart. One other investigator also located the landmarks once for each image for reliability purposes. Intraclass correlation coefficients (ICCs) were used to analyze the mean differences in landmark location in all axes.Results:Intra- and interexaminer reliability for x, y, and z coordinates for all landmarks had ICC greater than 0.95 with confidence interval of 0.88–0.99. Mean measurement differences found were <1.4 mm for all landmarks in all three coordinates. Mean measurement error differences obtained in the principal investigator''s trials were primarily <0.5 mm.Conclusion:The most reliable and reproducible landmarks tested for use in CBCT are mental foramina, infraorbital foramina, inferior hamulus, dens axis, foramina transversarium of atlas, medial and lateral condyles of the mandible, superior clinoid processes, and mid-clinoid.     

Corticospinal tract modeling for neurosurgical planning by tracking through regions of peritumoral edema and crossing fibers using two-tensor unscented Kalman filter tractography

Purpose

The aim of this study was to present a tractography algorithm using a two-tensor unscented Kalman filter (UKF) to improve the modeling of the corticospinal tract (CST) by tracking through regions of peritumoral edema and crossing fibers.

Methods

Ten patients with brain tumors in the vicinity of motor cortex and evidence of significant peritumoral edema were retrospectively selected for the study. All patients underwent 3-T magnetic resonance imaging (MRI) including functional MRI (fMRI) and a diffusion-weighted data set with 31 directions. Fiber tracking was performed using both single-tensor streamline and two-tensor UKF tractography methods. A two-region-of-interest approach was used to delineate the CST. Results from the two tractography methods were compared visually and quantitatively. fMRI was applied to identify the functional fiber tracts.

Results

Single-tensor streamline tractography underestimated the extent of tracts running through the edematous areas and could only track the medial projections of the CST. In contrast, two-tensor UKF tractography tracked fanning projections of the CST despite peritumoral edema and crossing fibers. Based on visual inspection, the two-tensor UKF tractography delineated tracts that were closer to motor fMRI activations, and it was apparently more sensitive than single-tensor streamline tractography to define the tracts directed to the motor sites. The volume of the CST was significantly larger on two-tensor UKF than on single-tensor streamline tractography (\(p < 0.001\)).

Conclusion

Two-tensor UKF tractography tracks a larger volume CST than single-tensor streamline tractography in the setting of peritumoral edema and crossing fibers in brain tumor patients.

     

A Computer-Aided Decision Support System for Detection and Localization of Cutaneous Vasculature in Dermoscopy Images Via Deep Feature Learning

Vascular structures of skin are important biomarkers in diagnosis and assessment of cutaneous conditions. Presence and distribution of lesional vessels are associated with specific abnormalities. Therefore, detection and localization of cutaneous vessels provide critical information towards diagnosis and stage status of diseases. However, cutaneous vessels are highly variable in shape, size, color and architecture, which complicate the detection task. Considering the large variability of these structures, conventional vessel detection techniques lack the generalizability to detect different vessel types and require separate algorithms to be designed for each type. Furthermore, such techniques are highly dependent on precise hand-crafted features which are time-consuming and computationally inefficient. As a solution, we propose a data-driven feature learning framework based on stacked sparse auto-encoders (SSAE) for comprehensive detection of cutaneous vessels. Each training image is divided into small patches of either containing or non-containing vasculature. A multilayer SSAE is designed to learn hidden features of the data in hierarchical layers in an unsupervised manner. The high-level learned features are subsequently fed into a classifier which categorizes each patch into absence or presence of vasculature and localizes vessels within the lesion. Over a test set of 3095 patches derived from 200 images, the proposed framework demonstrated superior performance of 95.4% detection accuracy over a variety of vessel patterns; outperforming other techniques by achieving the highest positive predictive value of 94.7%. The proposed Computer-Aided Diagnosis (CAD) framework can serve as a decision support system assisting dermatologists for more accurate diagnosis, especially in teledermatology applications in remote areas.     

Reinfection risk of novel coronavirus (COVID-19): A systematic ‎review of current evidence

BACKGROUNDThere is recently a concern regarding the reinfection and reactivation of previously reCoVered coronavirus disease 2019 (CoVID-19) patients.AIMTo summarize the recent findings and reports of CoVID-19 reinfection in patients previously reCoVered from the disease.METHODSThis study was a systematic review of current evidence conducted in August 2020. The authors studied the probable reinfection risk of novel coronavirus (CoVID-19). We performed a systematic search using the keywords in online databases. The investigation adheres to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) checklist to ensure the reliability and validity of this study and results.RESULTSWe reviewed 31 studies. Eight studies described reCoVered patients with reinfection. Only one study reported reinfected patients who died. In 26 studies, there was no information about the status of the patients. Several studies indicated that reinfection is not probable and that post-infection immunity is at least temporary and short.CONCLUSIONBased on our review, we concluded that a positive polymerase chain reaction retest could be due to several reasons and should not always be considered as reinfection or reactivation of the disease. Most relevant studies in positive retest patients have shown relative and probably temporary immunity after the reCoVery of the disease.     

Is the IL-10 −819 Polymorphism Associated with Visceral Leishmaniasis?

Previous investigations demonstrated that immune responses play critical roles in the defense against visceral leishmaniasis (VL). A key regulator of immune responses is the cytokine, IL-10 and polymorphisms within its promoter which could alter its expression. Thus, the aim of this study was to examine the correlation between polymorphism at the ?819 position of the IL-10 gene and VL in a selected Iranian population. This cross-sectional study was performed on 100 patients with clinical presentation of VL and seropositive for the leishmania (group 1), 62 patients without clinical presentation but seropositive (group 2), and 128 healthy controls (group 3). The IL-10 ?819 polymorphism was evaluated using the PCR-RFLP technique. The anti-leishmania antibody titration was assessed using an immunofluorescence assay. Our results showed that the polymorphism at IL-10 ?819 (C/T) position was significantly associated with VL, and C/T genotype was significantly higher in VL patients when compared to groups 2 and 3 (p?<?0.001). However, the results demonstrated that the C and T alleles were not associated with VL (p?=?0.855). The data presented here confirm the results of previous reports that polymorphisms at the ?819 position of the IL-10 gene can influence susceptibility to VL suggesting that the C/T genotype may be considered as a risk factor for the disease.     

Catalytic C–H aerobic and oxidant-induced oxidation of alkylbenzenes (including toluene derivatives) over VO2+ immobilized on core–shell Fe3O4@SiO2 at room temperature in water

Direct C–H bond oxidation of organic materials, and producing the necessary oxygenated compounds under mild conditions, has attracted increasing interest. The selective oxidation of various alkylbenzenes was carried out by means of a new catalyst containing VO²⁺ species supported on silica-coated Fe₃O₄ nanoparticles using t-butyl hydroperoxide as an oxidant at room temperature in H₂O or solvent-free media. The chemical and structural characterization of the catalyst using several methods such as FTIR spectroscopy, XRD, FETEM, FESEM, SAED, EDX and XPS showed that VO²⁺ is covalently bonded to the silica surface. High selectivity and excellent conversion of various toluene derivatives, with less reactive aliphatic (sp³) C–H bonds, to related benzoic acids were quite noticeable. The aerobic oxygenation reaction of these alkylbenzenes was studied under the same conditions. All the results accompanied by sustainability of the inexpensive and simple magnetically separable heterogeneous catalyst proved the important criteria for commercial applications.

A highly efficient, recoverable, sustainable, economic and eco-friendly catalyst containing VO²⁺ species supported on SiO₂@Fe₃O₄ nanoparticles for selective oxidation of alkylbenzenes using TBHP or O₂ at room temperature in H₂O or solvent-free media.     

Update on the efficacy of statins in primary and secondary prevention of atrial fibrillation

Atrial fibrillation is the most common arrhythmia in adults and its prevalence is growing rapidly. It has been shown that AF is associated with increased risk of heart failure, ischemic and hemorrhagic stroke, and mortality. Hence, there is growing interest among researchers in seeking preventive and therapeutic interventions regarding AF. In recent decades, it has been suggested that statins may decrease the incidence of AF and may also decrease its recurrence after cardioversion and catheter ablation. These effects are thought to be mediated by different mechanisms such as modulating inflammation, altering the properties of transmembrane ion channels, interfering with activation of matrix metalloproteinases, and acting on endothelial function. In this article, we review and update current knowledge about the role of statins in primary and secondary prevention of AF in general and specific populations.     

Hypoxia-induced pathological angiogenesis mediates tumor cell dissemination,invasion, and metastasis in a zebrafish tumor model

Mechanisms underlying pathological angiogenesis in relation to hypoxia in tumor invasion and metastasis remain elusive. Here, we have developed a zebrafish tumor model that allows us to study the role of pathological angiogenesis under normoxia and hypoxia in arbitrating early events of the metastatic cascade at the single cell level. Under normoxia, implantation of a murine T241 fibrosarcoma into the perivitelline cavity of developing embryos of transgenic fli1:EGFP zebrafish did not result in significant dissemination, invasion, and metastasis. In marked contrast, under hypoxia substantial tumor cells disseminated from primary sites, invaded into neighboring tissues, and metastasized to distal parts of the fish body. Similarly, expression of the hypoxia-regulated angiogenic factor, vascular endothelial growth factor (VEGF) to a high level resulted in tumor cell dissemination and metastasis, which correlated with increased tumor neovascularization. Inhibition of VEGF receptor signaling pathways by sunitinib or VEGFR2 morpholinos virtually completely ablated VEGF-induced tumor cell dissemination and metastasis. To the best of our knowledge, hypoxia- and VEGF-induced pathological angiogenesis in promoting tumor dissemination, invasion, and metastasis has not been described perviously at the single cell level. Our findings also shed light on molecular mechanisms of beneficial effects of clinically available anti-VEGF drugs for cancer therapy.