Detection of hepatitis C virus-RNA by polymerase chain reaction in dental surgeries

The mean prevalence of anti-hepatitis C virus (HCV) in Italy is 0.87%. It reaches 2% in Campania, Southern Italy. Approximately 50% of community acquired non-A, non-B (NANB) hepatitis cannot be associated with known parenteral exposure. A recent Italian study has shown that the only demonstrable risk factor in 9% of acute C/NANB hepatitis is dental treatment. There are no data on direct contamination by HCV of dental surgeries. Possible environmental contamination by HCV-RNA was investigated in dental surgeries after treatment of anti-HCV and HCV-RNA positive patients. Thirty-five anti-HCV and HCV-RNA positive patients with chronic hepatitis underwent dental treatment and were enrolled in this study. Eight had chronic persistent hepatitis (CPH), 23 chronic active hepatitis (CAH), and 4 cirrhosis. A total of 328 samples collected from instruments and surfaces were tested after dental treatment of 35 anti-HCV positive patients. The presence of HCV-RNA was determined by polymerase chain reaction (PCR) to evaluate contamination of instruments and surfaces in dental surgeries. Twenty (6.1%) out of 328 collected samples were positive for HCV-RNA. The positive samples were from work benches (two), air turbine handpieces (one), holders (four), suction units (one), forceps (four), dental mirrors (two), and burs (six) Our data indicate that there is extensive contamination by HCV of dental surgeries after treatment of anti-HCV patients and that if sterilisation and disinfection are inadequate there is the possible risk of transmission to susceptible individuals. © 1995 Wiley-Liss, Inc.     

基于TDICCD的动态成像实验

目的延迟积分型电荷耦合器件（time delay integration and charge coupled device,TDI CCD）灵敏度高,并在低照度下具有获得高质量图像的特点,已成为齿科全景数字化成像系统开发的关键技术。在成像过程中要想得到清晰图像,必须正确使用TDI CCD。方法本文采用FCFR-USB9825B系列采集卡等搭建的动态成像装置进行实验,通过改变TDI CCD积分方向和积分时间,采集到不同图像。结果通过对比图像,发现在TDI CCD使用过程中,TDI CCD的积分方向必须与成像物体移动方向保持一致。TDI CCD积分时间与物体移动速度必须匹配,即二者的乘积等于像元尺寸。结论本实验为基于TDI CCD的全景齿科成像奠定了成像理论基础。     

纳米磁颗粒电磁探测及成像技术研究进展

近10年来,磁纳米颗粒已由最初的核磁共振造影剂发展成为集疾病诊断、靶向药物输送及磁热疗等一体化诊断平台的功能性材料。磁纳米颗粒成像(MPI)是一种通过检测注射到血管中的超顺磁性纳米颗粒的磁性来构建三维图像的计算机断层成像技术。除血管造影和干细胞跟踪,磁纳米颗粒成像在生物医学上有一系列令人激动的潜在的应用,例如实时透视、诊断和分期癌症、体内炎症成像、温度显示和功能性分子成像等。该技术试图在现有的造影剂成像技术上以更敏感、更快捷、更安全的方式得到确定体积内的示踪剂分布的图像。首先介绍磁纳米颗粒在分子成像与诊疗应用研究进展,进一步说明磁纳米颗粒的电磁探测的原理,重点从扫描仪线圈拓扑结构和图像重建两方面介绍磁颗粒的电磁成像技术的研究现状和存在的问题,最后提出未来技术重要的发展趋势。     

Part 1. Automated Change Detection and Characterization in Serial MR Studies of Brain-Tumor Patients

The goal of this study was to create an algorithm which would quantitatively compare serial magnetic resonance imaging studies of brain-tumor patients. A novel algorithm and a standard classify-subtract algorithm were constructed. The ability of both algorithms to detect and characterize changes was compared using a series of digital phantoms. The novel algorithm achieved a mean sensitivity of 0.87 (compared with 0.59 for classify-subtract) and a mean specificity of 0.98 (compared with 0.92 for classify-subtract) with regard to identification of voxels as changing or unchanging and classification of voxels into types of change. The novel algorithm achieved perfect specificity in seven of the nine experiments. The novel algorithm was additionally applied to a short series of clinical cases, where it was shown to identify visually subtle changes. Automated change detection and characterization could facilitate objective review and understanding of serial magnetic resonance imaging studies in brain-tumor patients.     

Intravital two-photon microscopy: focus on speed and time resolved imaging modalities

Summary: Initially used mainly in the neurosciences, two-photon microscopy has become a powerful tool for the analysis of immunological processes. Here, we describe currently available two-photon microscopy techniques with a focus on novel approaches that allow very high image acquisition rates compared with state-of-the-art systems. This improvement is achieved through a parallelization of the excitation process: multiple beams scan the sample simultaneously, and the fluorescence is collected with sensitive charge-coupled device (CCD)-based line or field detectors. The new technique's performance is compared with conventional single beam laser-scanning systems that detect signals by means of photomultipliers. We also discuss the use of time- and polarization-resolved fluorescence detection, especially fluorescence lifetime imaging (FLIM), which goes beyond simple detection of cells and tissue structures and allows insight into cellular physiology. We focus on the analysis of endogenous fluorophores such as NAD(P)H as a way to analyze the redox status in cells with subcellular resolution. Here, high-speed imaging setups in combination with novel ways of data analysis allow the generation of FLIM data sets almost in real time. The implications of this technology for the analysis of immune reactions and other cellular processes are discussed.     

Third molar impaction and agenesis: influence on anterior crowding

Background Third molar influence on anterior crowding is controversial, but they are assumed to play a major role in compromising dental arch space.

Aim To evaluate the relationship among impaction, agenesis and crowding in black South African males.

Subjects and method Mandibles and maxillae of 535 black South African males in the Raymond A. Dart Collection of Human Skeletons, University of the Witwatersrand were examined for anterior crowding and third molar agenesis and impaction. Dental crowding was determined using Little’s irregularity index.

Results Individuals with impaction showed more moderate-to-extreme crowding than those with agenesis. Bilateral third molar presence was more frequently associated with ideal-to-minimal crowding. Weak positive but significant correlations between crowding and impaction were found (mandible, ρ?=?0.154, p?=?0.000; maxilla ρ?=?0.130, p?=?0.000). The direction was the opposite for bilateral presence of molars (mandible, ρ = ?0.135, p?=?0.02; maxilla, ρ = ?0.111, p?=?0.010). Odds of mandibular crowding were greatest in individuals with impaction (OR = 3.22, CI = 1.716–6.05, p?Conclusion Third molar impaction plays a role in anterior crowding. Third molar presence was not associated with anterior crowding, while agenesis did not explain absence of crowding.     

Interobserver error involved in independent attempts to measure cusp base areas of Pan M1s

Cusp base areas measured from digitized images increase the amount of detailed quantitative information one can collect from post-canine crown morphology. Although this method is gaining wide usage for taxonomic analyses of extant and extinct hominoids, the techniques for digitizing images and taking measurements differ between researchers. The aim of this study was to investigate interobserver error in order to help assess the reliability of cusp base area measurement within extant and extinct hominoid taxa. Two of the authors measured individual cusp base areas and total cusp base area of 23 maxillary first molars (M(1)) of Pan. From these, relative cusp base areas were calculated. No statistically significant interobserver differences were found for either absolute or relative cusp base areas. On average the hypocone and paracone showed the least interobserver error (< 1%) whereas the protocone and metacone showed the most (2.6-4.5%). We suggest that the larger measurement error in the metacone/protocone is due primarily to either weakly defined fissure patterns and/or the presence of accessory occlusal features. Overall, levels of interobserver error are similar to those found for intraobserver error. The results of our study suggest that if certain prescribed standards are employed then cusp and crown base areas measured by different individuals can be pooled into a single database.     

Comparing Performance of the CADstream and the DynaCAD Breast MRI CAD Systems

Computer-aided diagnosis (CAD) systems are software programs that use algorithms to find patterns associated with breast cancer on breast magnetic resonance imaging (MRI). The most commonly used CAD systems in the USA are CADstream (CS) (Merge Healthcare Inc., Chicago, IL) and DynaCAD for Breast (DC) (Invivo, Gainesville, FL). Our primary objective in this study was to compare the CS and DC breast MRI CAD systems for diagnostic accuracy and postprocessed image quality. Our secondary objective was to compare the evaluation times of radiologists using each system. Three radiologists evaluated 30 biopsy-proven malignant lesions and 29 benign lesions on CS and DC and rated the lesions’ malignancy status using the Breast Imaging Reporting and Data System. Image quality was ranked on a 0–5 scale, and mean reading times were also recorded. CS detected 70 % of the malignant and 32 % of the benign lesions while DC detected 81 % of the malignant lesions and 34 % of the benign lesions. Analysis of the area under the receiver operating characteristic curve revealed that the difference in diagnostic performance was not statistically significant. On image quality scores, CS had significantly higher volume rendering (VR) (p < 0.0001) and motion correction (MC) scores (p < 0.0001). There were no statistically significant differences in the remaining image quality scores. Differences in evaluation times between DC and CS were also not statistically significant. We conclude that both CS and DC perform similarly in aiding detection of breast cancer on MRI. MRI CAD selection will likely be based on other factors, such as user interface and image quality preferences, including MC and VR.     

Efficacy of bisphosphonates in detection of early enamel caries using NIR fluorescence imaging and inhibition of caries progression

NIR fluorescence imaging using bisphosphonate-Indocyanine green has been indicated for early interproximal caries detection. This study assessed diagnostic accuracy of caries detection by NIR fluorescence imaging with OsteoSense 750^® (OS750) in vitro and ex vivo, and to analyze the therapeutic efficacy of a bisphosphonate (Etidronate) in inhibiting enamel caries progression in vitro.Methods: Four experiments were conducted using extracted human teeth; 1) to calculate the infiltration rate of OS750 into interproximal white spot lesions using fluorescence microscope, 2) to assess diagnostic accuracy of interproximal natural white spot lesions using desktop NIR fluorescence imaging device in vitro setting, 3) to assess diagnostic accuracy of artificially created deeper enamel carious lesion (0.5 mm~1.0 mm) using NIR fluorescence image through the head-mount display in ex vivo setting, 4) to compare the progression on the enamel caries lesions treated by Etidronate, NaF and distilled-water. Diagnostic accuracy was analyzed using sensitivity, specificity and receiver operating curves (ROC). The caries progression was calculated with micro-CT and was statistically analyzed using a two-way ANOVA and the Tukey HDS post-hoc test.Results: 1) The infiltration rate of OS750 was 101.83% ± 8.66 (Min: 90.10%, Max: 133.94%). 2) The average of sensitivity and specificity in vitro setting experiments were 86.7% ± 4.4% and 70% ± 11%, respectively. The average of area under the ROC curves (AUC) was 0.883 ± 0.059 indicating excellent performance. 3) The mean sensitivity and specificity in ex vivo setting was 82.97% ± 15% and 76.78% ± 13.27% respectively. 4) The carious lesion volume treated by Etidronate was significantly smaller at post treatment-1 (p<0.05) and treatment-2 (p<0.01) than the control. There was no significant difference in lesion volume in the Etidronate and NaF group at the time point of post treatment-1.Conclusion: This study suggests that bisphosphonates contribute to both early diagnosis of enamel caries and inhibition of caries progression.     

Automatic Detection of the Nipple in Screen-Film and Full-field Digital Mammograms Using a Novel Hessian-Based Method

Automatic detection of the nipple in mammograms is an important step in computerized systems that combine multiview information for accurate detection and diagnosis of breast cancer. Locating the nipple is a difficult task owing to variations in image quality, presence of noise, and distortion and displacement of the breast tissue due to compression. In this work, we propose a novel Hessian-based method to locate automatically the nipple in screen-film and full-field digital mammograms (FFDMs). The method includes detection of a plausible nipple/retroareolar area in a mammogram using geometrical constraints, analysis of the gradient vector field by mean and Gaussian curvature measurements, and local shape-based conditions. The proposed procedure was tested on 566 mammographic images consisting of 372 randomly selected scanned films from two public databases (mini-MIAS and DDSM), and 194 digital mammograms acquired with a GE Senographe 2000D FFDM system. A radiologist independently marked the centers of the nipples for evaluation of the results. The average error obtained was 6.7 mm (22 pixels) with reference to the center of the nipple as identified by the radiologist. Only two out of the 566 detected nipples (0.35 %) had an error larger than 50 mm. The method was also directly compared with two other techniques for the detection of the nipple. The results indicate that the proposed method outperforms other algorithms presented in the literature and can be used to identify accurately the nipple on various types of mammographic images.     

System level analysis of motor-related neural activities in larval Drosophila

The way in which the central nervous system (CNS) governs animal movement is complex and difficult to solve solely by the analyses of muscle movement patterns. We tackle this problem by observing the activity of a large population of neurons in the CNS of larval Drosophila. We focused on two major behaviors of the larvae – forward and backward locomotion – and analyzed the neuronal activity related to these behaviors during the fictive locomotion that occurs spontaneously in the isolated CNS. We expressed a genetically-encoded calcium indicator, GCaMP and a nuclear marker in all neurons and then used digitally scanned light-sheet microscopy to record (at a fast frame rate) neural activities in the entire ventral nerve cord (VNC). We developed image processing tools that automatically detected the cell position based on the nuclear staining and allocate the activity signals to each detected cell. We also applied a machine learning-based method that we recently developed to assign motor status in each time frame. Our experimental procedures and computational pipeline enabled systematic identification of neurons that showed characteristic motor activities in larval Drosophila. We found cells whose activity was biased toward forward locomotion and others biased toward backward locomotion. In particular, we identified neurons near the boundary of the subesophageal zone (SEZ) and thoracic neuromeres, which were strongly active during an early phase of backward but not forward fictive locomotion.     

Biplane Correlation Imaging: A Feasibility Study Based on Phantom and Human Data

The objective of this study was to implement and evaluate the performance of a biplane correlation imaging (BCI) technique aimed to reduce the effect of anatomic noise and improve the detection of lung nodules in chest radiographs. Seventy-one low-dose posterior–anterior images were acquired from an anthropomorphic chest phantom with 0.28° angular separations over a range of ±10° along the vertical axis within an 11 s interval. Similar data were acquired from 19 human subjects with institutional review board approval and informed consent. The data were incorporated into a computer-aided detection (CAD) algorithm in which suspect lesions were identified by examining the geometrical correlation of the detected signals that remained relatively constant against variable anatomic backgrounds. The data were analyzed to determine the effect of angular separation, and the overall sensitivity and false-positives for lung nodule detection. The best performance was achieved for angular separations of the projection pairs greater than 5°. Within that range, the technique provided an order of magnitude decrease in the number of false-positive reports when compared with CAD analysis of single-view images. Overall, the technique yielded ~1.1 false-positive per patient with an average sensitivity of 75%. The results indicated that the incorporation of angular information can offer a reduction in the number of false-positives without a notable reduction in sensitivity. The findings suggest that the BCI technique has the potential for clinical implementation as a cost-effective technique to improve the detection of subtle lung nodules with lowered rate of false-positives.     

红外热成像技术在乳腺癌检测中的应用进展

乳腺癌作为全球女性中最常见的恶性肿瘤, 近年来,发病率逐年增高。人们期待寻找新一代检查方法,能进一步提高乳腺癌检出率,早期控制疾病进程,从而提高乳腺癌患者的生存率。红外热成像技术是一种常见的物理技术,在军事、工业、医疗等多个领域均有应用,我国近十几年来才开始将该项技术应用到医学领域中。由于该技术具有操作简单、非接触、无辐射、无创伤等优点,在医学领域中有广泛的应用前景。本文主要对该物理技术在乳腺疾病检测中的应用及该技术的临床诊断价值做简要概述。     

Neural sources involved in auditory target detection and novelty processing: an event-related fMRI study

We used event-related functional magnetic resonance imaging (erfMRI) techniques to examine the cerebral sites involved with target detection and novelty processing of auditory stimuli. Consistent with the results from a recent erfMRI study in the visual modality, target processing was associated with activation bilaterally in the anterior superior temporal gyrus, inferior and middle frontal gyrus, inferior and superior parietal lobules, anterior and posterior cingulate, thalamus, caudate, and the amygdala/hippocampal complex. Analyses of the novel stimuli revealed activation bilaterally in the inferior frontal gyrus, insula, inferior parietal lobule, and in the inferior, middle, and superior temporal gyri. These data suggest that the scalp recorded event-related potentials (e.g., N2 and P3) elicited during similar tasks reflect an ensemble of neural generators located in spatially remote cortical areas.     

磁共振联合磁敏感加权成像评估急性脑梗死的临床价值

目的:探讨磁共振成像（MRI）联合磁敏感加权成像（SWI）评估急性脑梗死预后的临床价值。方法:采用随机数字表法将100例急性脑梗死患者分为观察组（n=50）和对照组（n=50）。对照组行MRI检查,观察组行MRI联合SWI检查。比较两组患者的疾病检出率、脑微出血检出情况。结果:观察组疾病检出率显著高于对照组（96.0% vs 78.0%, P<0.05）;观察组脑微出血检出率显著高于对照组（64.0% vs 12.0%, P<0.05）;观察组的出血检出面积为（972.83±110.54） mm2,显著高于对照组的（532.71±110.53） mm2（P<0.05）。观察组脑梗死面积诊断评分显著小于对照组（P<0.05）。入院15 d后,观察组神经功能缺损程度评分明显低于对照组（P<0.05）;观察组神经功能缺损程度稳定率及好转率显著高于对照组（P<0.05）。结论:MRI联合SWI检查对急性脑梗死疾病的检出率明显较高,能够准确预测脑微出血,有助于制定正确的临床治疗方案,改善急性脑梗死患者的预后。     

Part 2. Automated Change Detection and Characterization Applied to Serial MR of Brain Tumors may Detect Progression Earlier than Human Experts

An algorithm was developed which compares serial MRI brain examinations of brain tumor patients and judges them as either “stable” or “progressing”. A set of 88 serial MR cases were obtained, consisting of cases which were stable and remained stable for at least 8 months, cases which were stable but progressed in less than 8 months, and cases which were progressing. The algorithm was run and its output was compared to the original clinical interpretation. Of the exam pairs which were judged stable and which remained stable at least 8 months after the later examination, the algorithm diagnosed 45/46 as stable. For exam pairs judged to be progressing, the algorithm judged 15/17 to be progressing. Of the exam pairs which were judged stable, but which went on to progress less than 8 months after the later of the pair, 16/25 were judged by the algorithm to be progressing.     

Light and electron microscopic analysis of the somata and parent axons innervating the rat upper molar and lower incisor pulp

The morphology of intradental nerve fibers of permanent teeth and of continuously growing rodent incisors has been studied in detail but little information is available on the parent axons that give rise to these fibers. Here we examined the axons and somata of trigeminal neurons that innervate the rat upper molar and lower incisor pulp using tracing with horseradish peroxidase and light and electron microscopic analysis. The majority (∼80%) of the parent axons in the proximal root of the trigeminal ganglion that innervated either molar or incisor pulp were small myelinated fibers (<20 μm² cross-sectional area). The remaining ∼20% of the fibers were almost exclusively large myelinated for the molar pulp and unmyelinated for the incisor pulp. The majority of neuronal somata in the trigeminal ganglion that innervated either molar (48%) or incisor pulp (62%) were medium in size (300–600 μm² cross-sectional area). Large somata (>600 μm²) constituted 34% and 20% of the trigeminal neurons innervating molar and incisor pulp, respectively, while small somata (<300 μm²) constituted 17% of the molar and 18% of the incisor neurons. The present study revealed that the morphology of parent axons of dental primary sensory neurons may differ from that of their intradental branches, and also suggests that the nerve fiber function may be carried out differently in the molar and incisor pulp in the rat.