图像分割在医学图像中的研究方法及应用

图像分割是指将一幅图像分解为若干互不交迭区域的集合,是图像处理与机器视觉的基本问题之一.医学图像分割是图像分割的一个重要应用领域,也是一个经典难题.本文从应用的特定角度,对近年来医学图像分割的新方法或改进算法进行综述,并简要讨论了每类分割方法的特点及应用.     

Multidetector CT colonoscopy: evaluation of the perspective-filet view virtual colon dissection technique for the detection of elevated lesions

Background The purpose of our study was to determine the usefulness of a virtual computed tomography colon dissection visualization technique for the detection of polypoid lesions in comparison with conventional virtual colonoscopy analysis and optical colonoscopy. Methods Twenty-three patients were evaluated with optical colonoscopy and computed tomography colonoscopy using 16-row MDCT on the same day. CT images were analyzed by the colon dissection workup with unfolded haustra visualization and also using the conventional virtual colonoscopy technique (axial images and endoluminal views). The CT analysis was performed by an experienced radiologist using both viewing methods in a randomized order and blinded to optical colonoscopy results. Results Optical colonoscopy revealed 35 colonic lesions; 15 < 5 mm, 18 between 5–9 mm and 2 > 9 mm. For conventional virtual colonoscopy analysis the overall sensitivity was 86.67%; for the colon dissection visualization technique, the overall sensitivity was 82.86%. The average reading time for conventional virtual colonoscopy was 15 ± 3 vs. 8 ± 2 min for the colon dissection visualization technique. Conclusions Our results showed that there is a significant reduction in the reading time using the colon dissection visualization technique without detriment to the detection rate, that is, competitive to conventional virtual colonoscopy interpretation results. There are no conflicts of interest in connection with the submitted article.     

Involvement of cathepsin B in the processing and secretion of interleukin‐1β in chromogranin A‐stimulated microglia

Cathepsin B (CB) is a cysteine lysosomal protease implicated in a number of inflammatory diseases. Although it is now evident that caspase‐1, an essential enzyme for maturation of interleukin‐1β (IL‐1β), can be activated through the inflammasome, there is still evidence suggesting the existence of lysosomal‐proinflammatory caspase pathways. In the present study, a marked induction of pro‐IL‐1β, its processing to the mature form and secretion were observed in the primary cultured microglia prepared from wild‐type mice after stimulation with chromogranin A (CGA). Although pro‐IL‐1β also markedly increased in microglia prepared from CB‐deficient mice, CB‐deficiency abrogated the pro‐IL‐1β processing. CA‐074Me, a specific inhibitor for CB, inhibited the pro‐IL‐1β maturation and its release from microglia. Furthermore, the caspase‐1 activation was also inhibited by CA‐074Me and E‐64d, a broad cysteine protease inhibitor. After treatment with CGA, CB was markedly induced at both protein and mRNA levels. The induced pro‐CB was rapidly processed to its mature form. The immunoreactivity for CB co‐localized with both that for caspase‐1 and the cleaved IL‐1β, in the acidic enlarged lysosomes. Inconsistent with these in vitro observations, the immunoreactivity for the cleaved IL‐1β was markedly observed in microglia of the hippocampus from aged wild‐type but not CB‐deficient mice. These observations strongly suggest that CB plays a key role in the pro‐IL‐1β maturationthrough the caspase‐1 activation in enlarged lysosomes ofCGA‐treated microglia. Therefore, either pharmacological or genetic inhibition of CB may provide therapeutic intervention in inflammation‐associated neurological diseases. © 2009 Wiley‐Liss, Inc.     

Functional 5‐HT1a receptor polymorphism selectively modulates error‐specific subprocesses of performance monitoring

Our study investigates the dependence of response monitoring and error detection on genetic influences modulating the serotonergic system. This was done using the event‐related potentials (ERPs) after error (Ne/ERN) and correct trials (Nc/CRN). To induce a sufficient amount of errors, a standard flanker task was used. The subjects (N = 94) were genotyped for the functional 5‐HT1A C(−1019)G polymorphism. The results show that the 5‐HT1A C(−1019)G polymorphism specifically modulates error detection. Neurophysiological modulations on error detection were paralleled by a similar modulation of response slowing after an error, reflecting the behavioral adaptation. The 5‐HT1A −1019 CC genotype group showed a larger Ne and stronger posterror slowing than the CG and GG genotype groups. More general processes of performance monitoring, as reflected in the Nc/CRN, were not affected. The finding that error‐specific processes, but not general response monitoring processes, are modulated by the 5‐HT1A C(−1019)G polymorphism is underlined by a wavelet analysis. In summary, the results suggest a specific effect of the 5‐HT1A C(−1019)G polymorphism on error monitoring, as reflected in the Ne, and suggest a neurobiological dissociation between processes of error monitoring and general response monitoring at the level of the serotonin 1A receptor system. Hum Brain Mapp, 2010. © 2009 Wiley‐Liss, Inc.     

Differential effects of semantic processing on memory encoding

Deeper semantic processing of words leads to enhanced memory encoding (depth of processing effect). The left inferior prefrontal cortex (LIPC) and the left hippocampus are known to be involved in this effect. We tested the hypothesis that different semantic encoding processes contribute qualitatively differently to memory encoding. In a memory experiment using functional magnetic resonance imaging, we compared three different encoding tasks: a nonsemantic alphabetical, an animacy decision, and a size comparison tasks. Recognition memory was tested subsequently. We hypothesized that the size comparison task would activate brain areas involved in the processing of object features and that this would be associated with successful memory encoding. Results showed that the size comparison task led to significantly better memory encoding than the two other tasks. As with the animacy decision task, it led to stronger activation of the LIPC and left hippocampus than the nonsemantic task. Both regions also had stronger activations for later remembered than for nonremembered words. The size comparison task additionally led to stronger activation in the left anterior fusiform gyrus, which was also associated with successful memory encoding. We conclude that different types of semantic processing affect memory encoding based on distinguishable brain processes. Hum Brain Mapp, 2010. © 2010 Wiley‐Liss, Inc.     

Measuring the Complexity of Atrial Fibrillation Electrograms

AF Electrogram Complexity. Introduction: Complex fractionated atrial electrograms (CFAE) have been identified as targets for atrial fibrillation (AF) ablation. Robust automatic algorithms to objectively classify these signals would be useful. The aim of this study was to evaluate Shannon's entropy (ShEn) and the Kolmogorov‐Smirnov (K‐S) test as a measure of signal complexity and to compare these measures with fractional intervals (FI) in distinguishing CFAE from non‐CFAE signals. Methods and Results: Electrogram recordings of 5 seconds obtained from multiple atrial sites in 13 patients (11 M, 58 ± 10 years old) undergoing AF ablation were visually examined by 4 independent reviewers. Electrograms were classified as CFAE if they met Nademanee criteria. Agreement of 3 or more reviewers was considered consensus and the resulting classification was used as the gold standard. A total of 297 recordings were examined. Of these, 107 were consensus CFAE, 111 were non‐CFAE, and 79 were equivocal or noninterpretable. FIs less than 120 ms identified CFAEs with sensitivity of 87% and specificity of 79%. ShEn, with optimal parameters using receiver‐operator characteristic curves, resulted in a sensitivity of 87% and specificity of 81% in identifying CFAE. The K‐S test resulted in an optimal sensitivity of 100% and specificity of 95% in classifying uninterpretable electrogram from all other electrograms. Conclusions: ShEn showed comparable results to FI in distinguishing CFAE from non‐CFAE without requiring user input for threshold levels. Thus, measuring electrogram complexity using ShEn may have utility in objectively and automatically identifying CFAE sites for AF ablation. (J Cardiovasc Electrophysiol, Vol. 21, pp. 649‐655, June 2010)     

数字化模板测量在选择髋关节假体中的应用

目的 探讨采用数字化模板测量方法选择人工髋关节假体的应用效果.方法 选取2005年1月至2007年2月的122例患者(132髋),男68例,女54例;年龄35～82岁,平均62.4岁.应用医院数字化影像网络系统和数字化模板在计算机上进行全髋关节置换术前模板测量.由手术医生组和影像科医生组分别进行数字化模板测量,预测手术中所需假体型号的大小,并与手术中实际应用的假体型号进行比较.结果 手术医生组髋臼假体型号与股骨假体型号手术前后测量差异无统计学意义(Z=0.4531,P=0.6505;Z=0.5452,P=0.5856).手术医生组术前预测髋臼假体型号与股骨假体型号同术中应用的假体型号之间存在相关性(r=0.9361,P=0.0068;r=0.9435,P=0.0087).影像科医生组髋臼假体型号与股骨假体型号手术前后测量比较差异无统计学意义(Z=0.6834,P=0.4934;Z=0.1027,P=0.8990).影像科医生组术前预测髋臼假体型号、股骨假体型号同术中应用髋臼假体型号、股骨假体型号之间存在相关性(r=0.9214,P=0.0051;r=0.9357,P=0.0072).应用数字化模板测量选择的假体型号与术中实际应用假体型号相比较,髋臼假体的准确率达71.59%,股骨假体准确率达78.04%.结论 应用数字化模板测量进行术前设计,选择人工全髋关节置换的假体具有较高的准确率和可信度.     

刺五加根及根茎中紫丁香苷、刺五加苷E的提取工艺

目的:优选刺五加的最佳提取工艺。方法:采用正交设计法,以HPLC测定提取物中紫丁香苷、刺五加苷E的含量。结果:最佳提取工艺为10倍量的80%乙醇回流提取3次,每次2h。结论:该提取工艺稳定,设计合理,重现性好,可为生产实践提供理论依据。     

炮制对藏药南寒水石钙溶出率的影响

目的:通过测定各产地藏药南寒水石不同炮制品钙溶出率,揭示炮制对南寒水石钙溶出率的影响。方法:运用EDTA滴定法测定青海、西藏、甘肃、四川四省区产地藏药南寒水石生品、水淬品、酒淬品、酸酪淬品水煎液钙溶出率。结果:各种炮制方法均能显著提高藏药南寒水石水煎液钙溶出率,除黄南浪加和甘南合作美其乡的样品外,其余各产地南寒水石炮制品水煎液钙溶出率大小顺序均为酸酪淬品>酒淬品>水淬品。结论:通过测定和比较各产地藏药南寒水石不同炮制品的钙溶出率,为评价各产地南寒水石的品质、阐明南寒水石炮制机理和规范其炮制工艺提供了基础数据。