基于模糊均值聚类算法的灰度不均匀脑MR图像的分割

磁共振图像经常被含有缓慢变化的灰度不均匀场所破坏,不均匀场会造成同一组织的灰度发生变化,从而影响计算机辅助诊断的准确性.传统的基于灰度信息的分割方法对具有不均匀场的磁共振图像分割效果往往并不理想.文章改进了基于灰度信息的模糊C均值(FCM)算法,将偏移场模型、代表图像空间信息的邻域控制信息和最小二乘曲面拟合方法有机结合,能同时实现图像的校正和聚类,适用于灰度不均匀脑部磁共振图像的分割,分割精度明显优于已有的基于FCM的分割方法.     

结合区域信息的分段活动轮廓模型

提出了一种结合区域信息的分段活动轮廓模型，利用边缘信息迅速找到对象的大体轮廓，然后结合区域统计信息使模型精确收敛到对象边缘。分段的层次化变形有效的利用了图像的全局和局部信息，使用仿射变换使模型的局部以同一种变换方式变形，提高模型对噪声和伪边缘的鲁棒性，同时保持模型轮廓形状的一致性。在精确匹配阶段利用区域统计信息重新定义模型的外部能量，采用自适应的搜索区域确定方法，提高了算法的效率和进入凹边缘的能力。试验表明本模型运算速度快，抗噪声和避免陷入局部极小值的能力较强，有较好的分割效果。     

一种新的舌癌图像快速自动分割方法

目的:研究一种新的舌癌图像自动分割算法以实现对舌癌肿瘤的快速准确分割。方法:通过引入一种基于局部均方差的自适应尺度算子实现演化曲线在演化过程中的自动调整,从而更高效率地向真实目标边界运动,并且克服舌癌肿瘤图像中目标边界不清和图像灰度不均匀等不良因素带来的影响。此外,为加快曲线的收敛速度,本文提出了一种新的能量项评估演化曲线轮廓内部和轮廓外部区域灰度的分布差异,以此引导曲线自适应地调整演化速度,减少完成分割任务所需的迭代次数。结果:使用本方法对22幅舌癌肿瘤MRI图像进行分割,分割结果与真实结果之间的重叠率Dice值为0.82,豪斯多夫距离HD值为1.732 mm。结论:将本文算法与其它现有的几种活动轮廓模型进行定性和定量对比分析,实验结果表明本文算法在对细节及弱边缘灰度的处理上表现更加优异,可用于舌癌肿瘤的精确分割,为临床分析提供辅助信息。     

基于高斯混合模型和马尔科夫随机场的脑MR图像分割

目的从磁共振噪声图像中分割脑组织(脑脊液、灰质、白质)。方法首先利用K均值分类自动计算三类脑组织的初始灰度分布参数,通过期望最大化算法(Expectation maximization,EM)估计高斯混合模型(Gaussian mixture model,GMM)参数。然后按照空间体素的GMM分类信息改变其相应体素的联合概率的能量函数,控制该能量函数中代表灰度信息的分量,并且自适应地调节图像灰度和空间信息的分配。结果实验结果表明该模型能够有效地分割出脑脊液,灰质和白质,并且对噪声不敏感,能消除灰度不均匀的影响。结论与同类算法相比,本算法对含有噪声污染的脑MR-T1图像分割精度较高,也表现出不错的稳定性,且算法运行时间短。     

基于对称区域生长和边缘梯度的视神经纤维的分割

在视神经横切面图像中,将每个神经纤维的内外边界进行精确分割是视神经形态分析的重要环节,提出一种基于对称区域生长和髓鞘边缘梯度的有效分割算法.该算法分两步进行,首先根据交互方式下选取的种子点,由对称区域生长算法实现轴突分割,然后在轴突轮廓模型基础上,髓鞘外轮廓在髓鞘平均边缘梯度引导下进行演化,实现自动分割.与K-均值聚类,局部阈值和水平集等其他算法的实验结果相对照显示,该算法分割获得的轴突和髓鞘轮廓与实际轮廓相吻合,其分割结果可以作为后续神经纤维形态分析的基础.     

基于CT图像的颅内血肿检测与分割

目的:为提高血肿分割精度,提出一种基于改进Canny算子的颅内类血肿噪声检测方法。方法:首先用区域生长算 法分割出颅脑组织,去掉颅骨等干扰信息。然后使用基于改进Canny边缘检测的方法检测颅脑边缘类血肿噪声,并与原 图像进行与运算消除该噪声。最后,通过使用OTSU适应度函数的遗传算法精准分割出颅内血肿。结果:该方法在随机 抽取的200例颅脑血肿图像中,血肿检测的准确率达到96.3%,Dice相似度达到93.5%。结论:该方法能准确、有效地检测 并分割出颅内血肿。     

基于改进的CV-RSF模型的甲状腺结节超声图像自适应分割算法

目的甲状腺结节超声图像的精确分割对甲状腺结节的良恶性诊断尤为重要。目前,对于甲状腺结节超声图像的分割,有学者提出利用主动轮廓模型分割算法,但是由于活动轮廓分割算法需要手动设置迭代次数,未实现模型的自适应性。因此,本文提出了一种基于改进的无边缘主动轮廓-局部区域可控的拟合(Chan-Vese-region scalable fitting,CV-RSF)模型的甲状腺结节超声图像自适应分割算法。方法选取南京同仁医院12例患者的甲状腺结节超声图像用于实验。首先,在无边缘主动轮廓(Chan-Vese,CV)模型中,引入一个基于梯度的边缘引导函数,根据面积变化率,自适应地获取甲状腺结节的粗分割轮廓;然后,将粗分割轮廓作为局部区域可控的拟合(region-scalable fitting,RSF)模型的初始轮廓,并根据面积变化率,自适应地获取甲状腺结节最终分割结果。将改进模型分割的结果与CV模型、RSF模型分割的结果进行比较,并分析甲状腺结节边缘清晰度对分割结果的影响。结果本文模型算法分割结果的平均迭代次数、平均面积重叠率、平均Hausdorff分别达到了134、90.34%、9.77,均优于CV模型、RSF模型的分割算法。结论该算法有效地分割出边缘清晰和不清晰的甲状腺结节超声图像,并解决手动设置迭代次数的问题,从而实现甲状腺结节的有效、准确、自动分割。     

模糊神经网络在颅脑磁共振图像分割中的应用研究

由于颅脑磁共振图像分割的效果受制于解剖结构和成像过程引起的边缘模糊和噪声，本研究结合神经网络和模糊逻辑技术，提出一种基于模糊神经网络的颅脑磁共振图像的半自动分割算法。分割实验的结果表明，在同等条件下，模糊神经网络分割算法的收敛速度比BP神经网络分割算法快三倍以上；与最大似然法、模糊c均值聚类和BP神经网络分割算法相比，FNN分割算法的抗噪声和抗模糊能力更强。     

基于改进活动窄带模型的冠状动脉CT血管造影图像分割

冠状动脉分割与狭窄分级、斑块检测等密切相关,是血管病变研究中的重要步骤。针对血管灰度不均和对比度低等问题,提出了一种基于活动窄带和符号压力函数水平集的CT血管造影冠状动脉分割方法。首先对初始轮廓做形态学膨胀和腐蚀运算,以构建活动窄带限定轮廓曲线的演化区域;其次在活动窄带区域内构造局部符号压力函数,用水平集算法使初始轮廓收敛至准确轮廓;最后利用形态学闭运算平滑曲线。通过利用活动窄带将图像区域局部化,降低了计算复杂度,克服了灰度不均匀性,促进轮廓曲线演化到细小的血管末梢和狭窄区域。实验结果表明,与传统的分割方法相比,能够更加有效准确地分割出冠状动脉,为血管病变的研究提供支持。     

RSF模型的优化及其在MRI脑肿瘤分割中的应用

磁共振成像(MRI)具有图像模糊,灰度不均等特点,其分割问题一直都是研究的热点和难点。可变区域拟合(RSF)能量模型是一种较新的区域活动轮廓模型,可用于灰度不均匀图像的分割。然而,RSF模型设定的水平集函数(LSF)不适合初始轮廓内外灰度分布不同的环境,应用于整体灰度环境复杂的脑肿瘤MRI图像时,通常得不到理想的分割结果。构建新的LSF,并辅以mean shift平滑算法可使其更适用于肿瘤图像的分割,使新模型具有更好的收敛性和目标指向性。利用优化后的模型进行一系列实验,其结果表明:该算法鲁棒性强,可以快速、准确地分割出MRI图像中的脑肿瘤,具有显著的临床意义。     

Schizophrenia in a North Swedish geographical isolate, 1900–1977. Epidemiology, genetics and biochemistry

Over 200 schizophrenic patients belonging to three major and interrelated pedigree complexes have been investigated over the past 30 years in a North Swedish geographically isolated population, presently numbering about 6,000. An intensive investigation of a number of biochemical correlates and genetic markers in a few selected families belonging to one of the major pedigrees has indicated new strategies for the current research program.
Schizophrenia, as defined operationally, is significantly associated with decreased activities of two enzymes (1) blood platelet monoamine oxidase, (2) plasma dopamine-β-hydroxylase, and (3) with the genetic marker Gc² (group specific antigen). Both enzymes are subject to genetic variation. A positive score for linkage between schizophrenia and low plasma DBH activity has been calculated, but, so far, available data are insufficient for discrimination between linkage and partial contribution of genetically controlled low plasma DBH to the pathogenesis of the disease. Alternatively, both mechanisms could be involved.
As a model for continued research, schizophrenia is explained as based on a double dominant-recessive genotype (Aabb), representing a vulnerability which in about 50 % of cases develops into clinical schizophrenia. It is suggested that the dominant mutation (A) operates on or affects MAO activity, and that the recessive genotype (bb) is instrumental in low variates of DBH activity and very likely such variates within the normal range of physiological variation. Moreover, it is suggested that the combined effects of MAO- and DBH-reduced efficiency on the metabolism of e.g. dopamine could be an essential pathogenic mechanism for the schizophrenic illness which is segregating in this population.     

The dominant diseases of modernized societies as omega-3 essential fatty acid deficiency syndrome: Substrate beriberi

About 1900, modern food selection and processing caused widespread $\text{epidemics}$ of the B vitamin deficiency diseases of beriberi and pellagra which, for genetic reasons, often expressed as different diseases ranging from bowel and heart disease to dermatoses and psychoses. But the B vitamins merely help convert essential fatty acids (EFA) into the prostaglandin (PG) tissue regulators and it now turns out that, through hydrogenation, milling and selection of w3-poor southern foods, we have also been systematically depleting, by as much as 90%, a newly discovered trace Nordic EFA (w3) of special importance to primates and sole precursor of the PG3(4) series, even as a concurrent fiber deficiency increases body demand for EFA. Since substrate EFA is processed by many B vitamin catalysts, an EFA deficiency will mimic a $\text{panh}$ypovitaminosis B, i.e., a mixture of $\text{substrate}$ beriberi and $\text{substrate}$ pellagra resembling vitamin beriberi and pellagra but exhibiting as even more diverse $\text{endemic}$ disease. This would consitute a second stage of the Modern Malnutrition and explain why some workers now hold the dominant diseases of modermized societies to be new, nutritionally based, pellagraform yet lipid-related and to range, once again, from heart disease to psychosis. It is an assumption that our dominant diseases are unrelated to each other or are merely revealed by our diagnostic acumen and therapeutic success; and that hydrogenating millions of tons of food oils annually, to destroy the rancidity producing w3-EFA, is safe for $\text{primates}$. Extensive beriberiform disease is reported here in 32 typical cases taken from medical practice which responds strikingly to linseed oil supplements (60% w3-EFA) in confirmation of identical results in Capuchins.     

The universal muscular chain reaction,muscle spasm,Torsions, ruptures and extravasations. Chameleons of pathology and some manifestations of simple muscular disorders

Most bodily functions require the coordinated actions of complementary and supplementary paired muscle groups. Where this essential muscular cooperation is lacking, hollow organs may burst and others become literally screwed up, giving rise to many similar spastic diseases such as Torticollis, Twisted ovarian cyst, Torsion of the Testis, Volvulus of the intestines, Varicose Veins, Megacolon, Aortamegaly, Scoliosis, Erb's Palsy, Peyronie's Disease, Main-en-Griffe, Undescended Foot (Pes Cavus), Talipes, Strabismus. Spasm is “panenepidemic” and unclassified examples of Torsion Dystonia and Dyskinesia really are as common as debt and taxes.     

'Very sore nights and days': the child's experience of illness in early modern England, c.1580-1720

Sick children were ubiquitous in early modern England, and yet they have received very little attention from historians. Taking the elusive perspective of the child, this article explores the physical, emotional, and spiritual experience of illness in England between approximately 1580 and 1720. What was it like being ill and suffering pain? How did the young respond emotionally to the anticipation of death? It is argued that children’s experiences were characterised by profound ambivalence: illness could be terrifying and distressing, but also a source of emotional and spiritual fulfilment and joy. This interpretation challenges the common assumption amongst medical historians that the experiences of early modern patients were utterly miserable. It also sheds light on children’s emotional feelings for their parents, a subject often overlooked in the historiography of childhood. The primary sources used in this article include diaries, autobiographies, letters, the biographies of pious children, printed possession cases, doctors’ casebooks, and theological treatises concerning the afterlife.     

Guidelines for the Validation and Use of Immunoassays for Determination of Introduced Proteins in Biotechnology Enhanced Crops and Derived Food Ingredients

Recent advancements in agricultural biotechnology have created a need for analytical techniques to determine introduced proteins in crops enhanced through modern biotechnology techniques. These proteins are expressed in plant tissues and may be present in food ingredients. Immunoassays are ideally suited for protein detection and may be used as both quantitative and threshold methods. Microplate ELISA and lateral flow devices are two of the most commonly used immunoassay formats for agricultural biotechnology applications. This paper provides general background information and a discussion of criteria for the validation and application of immunochemical methods to the analysis of proteins introduced into plants and food ingredients using biotechnology methods. It is the result of a collaborative effort of members of the Analytical Environmental Immunochemical Consortium. This collaborative effort represents the combined expertise of several organizations to reach consensus on establishing guidelines for the validation and use of immunoassays. Further, the paper offers developers and users a consistent approach to adopting the technology as well as aid in producing accurate and meaningful results.     

Ultracryotomy: development and application (with examples from the yeast cytology) (author's transl)

The preparation steps usually necessary for obtaining ultrathin frozen sections of biological material (chemical prefixation, enclosing, cryoprotective treatment, freezing, sectioning, and post-staining the sections for transmission electron microscopy) are submitted to a critical analysis. The application of cryo-ultramicrotomy, in particularly for cytochemical purposes, is reviewed. Fundamental considerations of chemical prefixation and poststaining are supported by examples from yeast cytology. Furthermore, the efficiency of the cryo-ultramicrotomy (electron optical resolution of ultrastructural details) is demonstrated on yeast cells and protoplasts.     

Hypo- und Hypermagnesämie aus kardiologischer Sicht

Zusammenfassung Eine Reihe pathologischer Zustände bedingen Magnesiummangel. Zustände mit Hypermagnesämie sind ebenfalls bekannt, doch wesentlich seltener. Für den Kardiologen beachtenswert ist, daß unter Therapie mit bestimmten Diuretica bei Herzinsuffizienz, bei Herzinfarkt, Kardiomyopathie, Digitalisintoxikation und bestimmten Herzrhythmusstörungen Hypomagnesämie beobachtet wurde. Leider kann in der klinischen Routine nur ein extracelluläres Magnesiumdefizit durch Serumbestimmungen gemessen werden; über Magnesiummangel einzelner Organe kann nichts ausgesagt werden. Hinweise für Magnesiummangel geben aber neben der Messung des Serumspiegels Anamnese, klinischer Befund, bestimmte EKG-Veränderungen wie auch evtl. Hypokalämie, ein Zustand, bei dem sich oft — besonders bei Aldosteronismus — parallele Veränderungen zeigten.Tierexperimente deuten darauf hin, daß infarktähnliche Läsionen unter Magnesiummangel entstehen, doch ob Herzinfarkt beim Menschen durch Magnesiummangel ausgelöst werden kann, ist noch ungeklärt. In Leichenherzen zeigte sich im Infarktgebiet neben Calciumakkumulation signifikanter Magnesiumverlust, wobei unklar blieb, ob sich Ursache oder Folge des Infarktes widerspiegelten. Falls ein ursächlicher Zusammenhang besteht, ist er im Myokardstoffwechsel selbst zu suchen, wie bei der Alkoholkardiomyopathie, wo myokardialer Magnesiummangel zumindest als pathogenetischer Teilfaktor anerkannt wird. Andererseits versucht man aber auch Beziehungen zwischen Atherosklerose, Blutgerinnung und Hypomagnesämie herzustellen, in der Meinung, daß Magnesiummangel auch über den coronaren Pathomechanismus des Herzinfarktes wirken könnte. Sicher scheint, daß gewisse EKG-Veränderungen und Herzrhythmusstörungen durch einen irritierten Magnesiumhaushalt bedingt sein können, da sie bei Gabe bzw. Entzug von Magnesium verschwinden. Daß Magnesiummangel die Glykosidtoleranz verringert, wird tierexperimentell bestätigt. Unter Hypomagnesämie bewirkt Acetylstrophanthidin eher und länger Rhythmusstörungen als ohne, außerdem lassen diese sich durch Magnesiumgaben eliminieren. Da in gewissen Fällen spontane und digitalisinduzierte Herzrythmusstörungen durch Magnesiuminjektionen beseitigt wurden, scheint Magnesium als Therapeuticum angebracht. Einsatz verschiedener Magnesiumsalze bei Angina pectoris, degenerativen Herzerkrankungen und Herzinsuffizienz ohne geprüften und offensichtlich gestörten Magnesiumhaushalt ist fragwürdig, weil keine eindeutigen klinischen Erfolgsbeweise vorliegen. Immerhin mag es aber larvierte, durch Serumbestimmungen nicht erfaßbare Mangelzustände geben. Allgemein erscheint es aus kardiologischer Sicht ratsam, den Magnesiumhaushalt zu überwachen und in entsprechenden Fällen auszugleichen, um möglichen Myokardläsionen oder fatalen Herzrhythmusstörungen entgegenzuwirken.     

HLA in North Colombia Chimila Amerindians

HLA-A,-B,-C,-DRB1 and -DQB1 alleles have been studied in Chimila Amerindians from Sabana de San Angel (North Colombian Coast) by using high resolution molecular typing. A frequent extended haplotype was found:HLA-A*24:02-B*51:10-C*15:02-BRB1*04:07-DQB1*03:02 (28.7%) which has also been described in Amerinndian Mayos Mexican population (Mexico, California Gulf, Pacific Ocean). Other haplotypes had already been found in Amerindians from Mexico (Pacific and Atlantic Coast), Peru (highlands and Amazon Basin), Bolivia and North USA. A geographic pattern according to HLA allele or haplotype frequencies is lacking in Amerindians, as already known. Also, five new extended haplotypes were found in Chimila Amerindians. Their HLA-A*24:02 high frequencies characteristic is shared with aboriginal populations of Taiwan; also, HLA-C*01:02 high frequencies are found in New Zealand Maoris, New Caledonians and Kimberly Aborigines from Australia. Finally, this study may show a model of evolutionary factors acting and rising one HLA allele frequency (-A*24:02), but not in others that belong to the same or different HLA loci.     

The case for allele‐specific recognition by the TCR

There is a sharp difference in how one views TCR structure–function–behaviour dependent on whether its recognition of major histocompatibility complex‐encoded restriction elements (R) is germline selected or somatically generated. The generally accepted or Standard model is built on the assumption that recognition of R is by the V regions of the αβ TCR, which is not driven by allele specificity, whereas the competing model posits that recognition of R is allele‐specific. The establishing of allele‐specific recognition of R by the TCR would rule out the Standard model and clear the road to a consideration of a competing construct, the Tritope model. Here, the case for allele‐specific recognition (germline selected) is detailed making it obvious that the Standard model is untenable.