基于MATLAB的锥形束CT图像去噪研究

目的:锥形束CT既是一种全新的CT成像技术,也是图像引导下放射治疗系统的关键设备。针对锥形束CT图像的低对比度,散射伪影较大的缺陷,在MATLAB平台上对CBCT去噪方法进行研究和探讨,以寻找合适的锥形束CT去噪方法。方法:首先应用不同去噪方法,如邻域平滑,中值滤波,小波去噪方法等;再应用Contourlet变换进行锥形束CT去噪,设计不同的拉普拉斯塔式滤波器和二维方向滤波器组,寻找最优的滤波器组合;Contourlet变换是一种新的图像二维表示方法,具有多分辨率,局部定位,多方向性和近邻界采样和各向异性等性质。利用Contourlet变换在处理图像几何结构方面的优点,提取图像中边缘连续特征,来区别噪声和边缘,从而增强图像边缘和细节信息,同时抑制噪声。比较常规去噪,小波去噪,Contourlet去噪和不同滤波器组合去噪效果。结果:结合头部,胸部,盆腔各10组临床图像进行去噪效果统计和分析,表明小波阈值量化法和Contourlet法在锥形束CT图像去噪上各有优势,在Contourlet法中,滤波器组合"pkva8"和"9-7"的去噪效果最好。结论:Contourlet去噪方法和小波阈值量化法都比空间邻域平滑法,中值滤波法和普通小波去噪法有优势。而Contourlet去噪方法更能有效改进CBCT图像质量,特别是胸部图像质量的改善。     

基于小波变换结合其他预处理方法的周围型早期肺癌CT图像增强研究

探讨增强早期肺癌CT图像的方法.采用小波变换增强图像细节的方法,根据图像特点,同时结合对比度自适应直方图均衡化或(和)自适应滤波去噪法,对10位早期周围型肺癌患者的50张CT图像进行增强.结果表明,处理后图像中肺内结节的边缘锐利、内部密度清晰、周围征象(如胸膜凹陷征等)清楚;各组织器官边缘清晰、层次明显,肺纹理清晰度增加.尤其是低对比度图像,处理后图像质量有较明显提高.基于小波变换结合其他预处理方法,对早期肺癌的CT图像进行增强,可为同类研究提供一定的参考.     

CT图像特征的高精度区域分割

传统CT图像分割在进行最为重要的边缘分割时,复杂空洞和非血管区域特征运用单一约束条件,缺少持续性操作过程,降低了分割精度。提出一种约束持续的CT图像特征的高精度区域分割方法,通过灰度腐蚀运算和滤波处理,获取灰度直方统计结果,据此确定种子点选取原则,实现对血管的初步分割,在此基础上采用更新均值和种子点持续分割作为约束条件,更新均值和种子点持续分割直至无满足灰度区间像素点,实现对CT图像特征的高精度区域分割。以肝脏CT图像为例的分割实验结果说明,所提方法可降低肝脏分割时产生的空洞和非血管信息的提取概率,相较于手工方法与传统方法,本研究所提方法的分割精度较高。     

双源 CT 冠状动脉三维分割算法的研究

本研究旨在从心脏双源 CT 数据中自动精确分割出冠状动脉。采用一种基于多尺度滤波和概率决策的血管自动分割算法。先基于多尺度 Hessian 矩阵增强图像中的管状结构,再利用最大后验概率基于灰度将体素分为目标和背景2类,最后用26邻域区域生长法分割出左冠状动脉。实验结果表明,可精确分割出冠状动脉并提取血管中心线。该算法避免了血管泄露问题,无伪血管,无需人工交互,是一种有效的双源 CT 冠状动脉自动提取方法。     

基于Contourlet阈值法的锥形束CT图像去噪研究

目的：将多尺度分析工具之一的Contourlet变换运用到锥形束CT（CBCT）图像去噪领域,并对Contourlet不同阈值去噪方法进行探讨。提出基于Contourlet变换结合半软阈值方法对锥形束CT去噪,并论证去噪效果。方法：利用Contourlet变换的多尺度多方向性以及平移不变性,对低分辨率锥形束CT图像进行拉普拉斯塔形滤波和方向滤波多层分解后得到变换系数,随后对变换系数采用不同阈值方法进行处理,最后逆序反变换得到去噪后图像。通过软阈值和硬阈值方法在Contourlet变换中的应用,提出半软阈值结合Contourlet变换方法对锥形束CT图像去噪。通过对头,胸,盆腔各10例临床锥形束CT图像的去噪,比较三种阈值去噪效果。结果：半软阈值法在胸部和盆腔部锥形束CT图像去噪中比Contourlet硬阈值去噪在PSNR上平均高出1.40 d B和3.11 d B,但在头部锥形束CT图像处理中无优势,而Contourlet软阈值去噪后的锥形束CT图像在消除噪声的同时,信号自身的能量被消弱最多。结论：本文半软阈值法在一定程度上修正了硬,软阈值函数的缺陷,结合Contourlet变换在处理图像几何结构方面的优势,为锥形束CT图像去噪提供了一个新思路。     

一种用于尿沉渣图像的自适应阈值分割新方法

我们针对复杂散焦的尿沉渣图像的精细分割,首先使用小波变换和形态学处理消除散焦影响并进行图像的粗分割,然后对粗分割得到的小波变换子图像进行自适应阈值处理,结合形态学处理完成细分割,最后再采用剥离算法处理粘连重叠成分。该方法不受散焦影响,充分利用了图像的多种信息,实验结果表明,该方法对尿沉渣图像的分割有效且令人满意。     

正交小波基函数实现图像引导放射系统中计划CT与锥形束CT图像的形变配准

计划CT图像与锥形束CT(CBCT)图像的配准是基于CBCT图像引导放射系统中实现自适应放疗的重要部分。为了提高系统中形变配准的精度和速度,提出一种基于正交小波变换的形变配准方法,此方法利用正交小波变换的多分辨率特性描述计划CT和CBCT图像的全局和局部形变,由Navier偏微分方程设计极小化能量函数来实现小波系数的能量估计。实验表明,所提出方法用于基于CBCT的图像引导放射系统时,可将日常放疗时的CBCT图像和计划CT图像进行准确且快速的配准,并且可用于放射计划系统中器官的自动分割,从而有效指导自适应治疗。     

基于Contourlet变换和PCNN的CT图像椎体解剖轮廓特征提取方法的研究

提出一种新的基于Contourlet变换和脉冲耦合神经网络(PCNN)的医学图像解剖轮廓特征提取算法。首先对原始椎体CT图像进行Contourlet变换,得到能稀疏表示图像边缘以及方向信息的子带和低频子带;然后结合PCNN对低频子带进行边缘轮廓细节提取,最后利用处理后的所有子带系数,通过Contourlet逆变换,提取出图像的边缘轮廓。实验将本算法提取的结果与Canny算子、区域生长法以及结合小波变换和PCNN的算法提取的图像边缘轮廓进行比较,结果表明新算法能够有效的实现医学图像解剖结构轮廓特征的提取。     

基于多尺度理论改进的分水岭医学图像分割算法

本文针对医学数字图像数据量大和噪声情况复杂的特点，结合多尺度分析理论，通过多小波图像分解、能量计算、分水岭变换和区域融合等步骤，克服了分水岭变换严重的过分割问题，实现了有意义的区域分割。     

基于Contourlet变换和非线性扩散的IVUS图像去噪

血管内超声(IVUS)图像的分割对于动脉粥样硬化疾病的研究和介入治疗具有重要的意义,但由于其自身存在斑点噪声,从而严重影响图像自动分割的准确性和速度.提出一种基于Contourlet变换和非线性扩散的斑点去除算法(CTND);利用自适应的对比度因子,在Contourlet域直接对IVUS图像各方向子带进行非线性扩散滤波,而不需要同态处理.实验结果表明,这种算法在保持IVUS图像强、弱边缘的同时,能有效地去除斑点噪声,并为图像外膜的提取奠定良好的基础.     

Studien zur humoralen Regulation des erythropoetischen Proliferationsspeichers beim Menschen

Zusammenfassung Die Beeinflussung der Erythroblasten-Proliferation durch das Mikromilieu wurde in vitro mittels Auswertung durch Differential- und Mitosezählungen und Signifikanzberechnung vieler Versuchsreihen auch unter verschiedenen pathologischen Bedingungen getestet.Sowohl die Mitosehäufigkeit wie die Ausreifung waren positiv mit dem Erythropoetingehalt des Medium korreliert. Der Effekt wurde durch Folsäure, Ätiocholanolon und cAMP verstärkt. Cobalt stimulierte ebenso wie Testosteron und Methenolon in vitro unabhängig von der Erythropoetinkonzentration im Medium die Erythroblastenproliferation. Ein vermindertes Eisenangebot störte die endgültige Ausreifung der Erythroblasten zu Retikulozyten und bewirkte dadurch eine Ineffektivität der Erythorpoese. Anhaltspunkte für ein Erythrozyten-Chalon oder einen Erythropoetinhemmkörper ließen sich aus unserem Versuchsansatz nicht gewinnen, weil er die Transformation der pluripotenten in die erythropoetin-sensible Stammzelle nicht einschließt. Als Nebenbefund ergab sich eine Stimulation des granulozytopoetischen Proliferationsspeichers durch Serumzusatz zum Medium von Patienten nach akutem Blutverlust und bei Polycythämia vera.Unterstützt durch die Deutsche Forschungsgemeinschaft     

HLA study in Amerindian Bolivia La Paz Aymaras

Aymara people has been a relatively homogeneous group since Spanish Conquest by 1,532 CE, even if previously represented a group of various cultural defined populations who gave rise to them. They were and are established in Andean Altiplano around Titikaka Lake (Bolivia, Peru), Argentina and Chile neighborhood, speak Aymara language and have been maintained after Europeans arrival at a lower social status than Quechua (Inca) speaking people. However, both Aymara and Quechua populations acknowledge Titikaka Lake as center of their origins; both languages are also related. Specific high frequencies of HLA-A*02, -A*24 and -A*68, HLA-B*35, -B*39 and -B*48, HLA-DRB1*08:02, -DRB1*09:01, and -DRB1*14:02, and HLA-DQB1*04:02, -DQB1*03:02 and -DQB1*03:01 alleles are found in Aymaras and HLA class II haplotypes common to Andean Amerindians (DRB1*08:02-DQB1*04:02 and DRB1*04:03-DQB1*03:02), like Quechua, Aymara, Uros, Lamas and Mapuche are also found in Easter and other Pacific Islands. Giant human head stone statues at Tiwanaku (Titikaka Lake, Bolivia) are also found at Easter Island. Thus, it is possible a gene and cultural flow between Andean Amerindians and Easter and other Pacific Islands, as it was demonstrated by Thor Heyerdahl in his Kon-Tiki expedition which reached Pacific Islands sailing from El Callao Harbour (Lima, Peru).     

Lipid composition of metacestodes of Taenia taeniaeformis and lipid changes during growth

A lipid analysis was performed on developing metacestodes of Taenia taeniaeformis removed from the livers of rats at times varying from 3 to 35 weeks post infection. Lipid accounted for 7–21% of the dry weight of the parasites. The highest proportions were found at the earlier stages. The distribution was as follows; neutral lipid 27–45%; glycolipid 5–11%; and phospholipid 50–61%. The major neutral lipid was cholesterol, and minor neutral lipids were sterol esters, triglycerides, diglycerides and monoglycerides. Hydrocarbons were present throughout development, but in the highest amounts at the earlier stages. Five different glycolipids were found, all of which were identified as glycosphingolipids. An increase in the proportion of more complex glycolipids was noted as parasites grew older. Ten different phospholipids were identified, with the major components being phosphatidylcholine, phosphatidylethanolamine, and phosphatidylserine. Other phospholipids were: lysophosphatides, phosphatidylinositol, phosphatidic acid, diphosphatidylglycerol, sphingomyelin, and an unknown phospholipid component. Changes in the relative amounts of the two major phospholipids were found when the early and late stages were compared. Two lipids found throughout development were identified as glycosylated dolichol phosphates, and they comprised between 1 and 3% of the total phospholipid fraction. Nineteen fatty acids were detected, and the fatty acid distribution for each lipid class at each stage was determined. Seven major fatty acids were common to each. These were: hexadecanoic, octadecanoic, oleic, linoleic, arachidonic, docosanoic, and docosahexaenoic.     

Simple Serological Assays for Detecting Rice Tungro Viruses

An attempt was made to produce sensitive and specific polyclonal antisera against the viruses causing rice tungro disease, and to assess their potential for use in simple diagnostic tests. Using a multiple, sequential injection procedure, seven batches of polyclonal antisera against rice tungro bacilliform virus (RTBV) and rice tungro spherical virus (RTSV) were produced. These were characterized for their sensitivity and specificity using ring-interface precipitin test and double antibody sandwich (DAS) ELISA. Thirty-one weeks after the first immunization, antiserum batch B6b for RTBV showed the highest ring interface titer (DEP = 1:1920). For RTSV, batches S3, S4b and S5b all had similar titres (DEP = 1:640). In DAS-ELISA, however, significant differences among purified antisera (IgG) batches were observed only at IgG dilution of 10^-3. At that dilution, IgGB4b showed the greatest sensitivity, while IgGS3 showed greatest sensitivity for RTSV. When all IgG batches were tested against 11 tungro field isolates (dual RTBV-RTSV infections) at sample dilution of 1:10, IgGB4b and IgGB6b for RTBV and IgGS3 and IgGS6b for RTSV performed equally well. However, after cross adsorption with healthy plant extracts in a specially prepared healthy plant-Sepharose affinity column, only IgGB6b could be used specifically to detect RTBV in a simple tissue-print assay.     

Is it worthy to take full-course immunotherapy for allergic rhinitis? About efficacy biomarker of allergen immunotherapy

Nowadays, people pay more attention to biomarkers that can predict clinical efficacy of immunotherapy for allergic rhinitis. As the only recognized aetiological treatment, the efficacy of allergen immunotherapy (AIT) has been proved by many studies. However, treatment success depends on compliance and persistence greatly, which can be impaired by the lengthy duration of AIT and socioeconomic status of patients. Besides, ineffectiveness is another factor that accounts for non-adherence. If the clinical efficacy can be predicted in the early stage of immunotherapy, it can help patients choose appropriate treatment plans, increase patient compliance and optimize the allocation of medical resources. This paper mainly focuses on five candidate biomarkers, the sIgE/tIgE ratio before treatment, serum inhibitory activity for IgE, decreased basophil activation, upregulation of Tregs and tolerogenic DCs, reviews the time when potential biomarkers can predict or monitor the efficacy of AIT, discusses the reason why these indicators could serve as efficacy biomarkers and interactions among potential biomarkers.     

Neurotransmitter signaling pathways required for normal development in Xenopus laevis embryos: a pharmacological survey screen

Neurotransmitters are not only involved in brain function but are also important signaling molecules for many diverse cell types. Neurotransmitters are widely conserved, from evolutionarily ancient organisms lacking nervous systems through man. Here, results are reported from a loss‐ and gain‐of‐function survey, using pharmacological modulators of several neurotransmitter pathways to examine possible roles for these pathways in normal embryogenesis. Applying reagents targeting the glutamatergic, adrenergic and dopaminergic pathways to embryos of Xenopus laevis from gastrulation to organogenesis stages, we observed and quantified numerous malformations, including craniofacial defects, hyperpigmentation, muscle mispatterning and miscoiling of the gut. These data implicate several key neurotransmitters in new embryonic patterning roles, reveal novel earlier stages for processes involved in eye development, suggest new targets for subsequent molecular‐genetic investigation, and highlight the necessity for in‐depth toxicology studies of psychoactive compounds to which human embryos might be exposed during pregnancy.     

Uncombable Hair (cheveux incoiffables, pili trianguli et canaliculi) Syndrome: Brief Review and Role of Scanning Electron Microscopy in Diagnosis

Uncombable hair syndrome was first described some 3 decades ago as "cheveux incoiffables" and is also known as spun-glass hair and pili trianguli et canaliculi. Both inherited (autosomal dominant and recessive with variable levels of penetrance) and sporadic forms of uncombable hair syndrome have been described, both being characterized by scalp hair that is impossible to comb due to the haphazard arrangement of the hair bundles. A characteristic morphologic feature of hair in this syndrome is a triangular to reniform to heart shape on cross-sections, and a groove, canal or flattening along the entire length of the hair in at least 50%of hairs examined by scanning electron microscopy. Most individuals are affected early in childhood and the hair takeson a spun-glassappearance with the hair becoming dry, curly, glossy, lighter in color, and progressively uncombable. Only the scalp hair is affected. Several conditions are associated with uncombable hair, such as ectodermal dysplasia, retinal dysplasia/ pigmentary dystrophy, juvenile cataract, digit abnormalities, tooth enamel anomalies, oligodontia, and phalangoepiphyseal dysplasia. Other syndromes with hair abnormalities may also mimic uncombable hair syndrome clinically and these include, Rapp-Hodgkin ectodermal dysplasia; loose anagen hair syndrome; ectodermal dysplasia, ectrodatyly, cleft lip/ palate (EEC) syndrome; and familial tricho-odonto-onchyial ectodermal dysplasia with syndactyly. Unlike other conditions with an uncombable hair component, uncombable hair syndrome alone (cheveux incoiffables, pili trianguli etcanaliculi) is not associated with physical, neurologic, or mental abnormalities. In most cases of uncombable hair syndrome, the hair is grossly abnormal in infancy and early childhood, but may have improved manageability later in life. Scanning electron microscopy of hair samples provides definitive evidence for diagnosis of clinically suspected uncombable hair syndrome and eliminates other hair abnormalities from the differential diagnosis.     

A comparative study of cholinergic systems of the neocortex and hippocampus in rats with low and high resistance to hypoxia

Synaptic structures in the neocortex and hippocampus of the intact brain were compared between rats with low and high resistance to hypobaric hypoxia. Activities of choline acetyltransferase, acetylcholinesterase, Na,K-ATPase, and the portion of protein in the light and heavy synaptosome fractions and subfractions were measured. A discrepancy in cholinergic metabolism molecular mechanisms between high and low resistance animals have been found in the heavy somatosoma fraction from the neocortex. Activities of choline acetyltransferase, acetylcholinesterase, and Na,K-ATPase in the synaptolemmal subfraction of low resistant rats were much lower than in high resistant rats. This implies a less effective synaptic transmission in proper cholinergic neurons in the low resistance animals and, therefore, specifically changed neuron functioning in the circulation control. No differences in the cholinergic components of either neocortical light synaptosome fraction or hippocampal light and heavy synaptosome fractions were found between low and high resistance rats. Translated fromByulleten' Eksperimental'noi Biologii I Meditsiny, Vol. 125, No. 5, pp. 521–525, May, 1998     

BSACI guideline for the diagnosis and management of cow's milk allergy

This guideline advises on the management of patients with cow's milk allergy. Cow's milk allergy presents in the first year of life with estimated population prevalence between 2% and 3%. The clinical manifestations of cow's milk allergy are very variable in type and severity making it the most difficult food allergy to diagnose. A careful age‐ and disease‐specific history with relevant allergy tests including detection of milk‐specific IgE (by skin prick test or serum assay), diagnostic elimination diet, and oral challenge will aid in diagnosis in most cases. Treatment is advice on cow's milk avoidance and suitable substitute milks. Cow's milk allergy often resolves. Reintroduction can be achieved by the graded exposure, either at home or supervised in hospital depending on severity, using a milk ladder. Where cow's milk allergy persists, novel treatment options may include oral tolerance induction, although most authors do not currently recommend it for routine clinical practice. Cow's milk allergy must be distinguished from primary lactose intolerance. This guideline was prepared by the Standards of Care Committee (SOCC) of the British Society for Allergy and Clinical Immunology (BSACI) and is intended for clinicians in secondary and tertiary care. The recommendations are evidence based, but where evidence is lacking the panel of experts in the committee reached consensus. Grades of recommendation are shown throughout. The document encompasses epidemiology, natural history, clinical presentations, diagnosis, and treatment.