阑尾炎CT征象的敏感性和特异性:200例阑尾螺旋CT检查的经验

CT检查对临床怀疑阑尾炎者准确率较高,尤其是使用薄层螺旋扫描及适当的回盲肠造影,但是许多征象也可在类似阑尾炎的疾病中出现。作者旨在评价每一阑尾炎CT征象的敏感性和特异性,以明确阑尾CT的诊断价值。作者共行阑尾CT检查200例,其中阑尾炎100例,正常阑尾100例,男性89例,女性111例,年龄3～86岁。CT扫描前,全部病人均口服或灌肠对比剂,135例口服2.1％的硫酸钡混悬液,平均剂量500ml,186例用3％泛影葡     

超声弹性成像对甲状腺结节诊断的敏感性和特异性分析

目的探讨颈动脉搏动作为压力源的超声弹性成像对甲状腺结节诊断的敏感性和特异性。方法选取我院行甲状腺检查的60例患者共73个结节作为观察对象。观察常规超声和超声弹性成像诊断的敏感性和特异性。结果常规超声良性诊断为44个结节,恶性诊断为9个,其Kappa值为0.305。超声弹性成像良性诊断为52个结节,恶性诊断为13个,其Kappa值为0.696。超声弹性成像敏感度、特异度、阴性预测值显著高于常规超声(P0.05),但两者在阴性预测值上无显著差异(P0.05);在ROC曲线上,超声弹性成像下面积为0.816,常规超声面积为0.540。在超声弹性成像得分上,良性组3分例数显著高于恶性组,而4分、5分例数显著低于恶性组。结论颈动脉搏动作为压力源的超声弹性成像对甲状腺结节具有较高敏感性和特异性。     

黑麦草新品种特异性、一致性和稳定性测试指南初报

根据植物新品种特异性(Distinctness)、一致性(Uniformity)和稳定性(Stability)(简称DUS)测试的原理和技术,本文阐述了黑麦草DUS测试指南的研制目标与原则、研制过程、性状选择与确定、标准品种的选用和DUS判定标准等内容。参考国际植物新品种保护联盟的《特异性、一致性和稳定性测试指南黑麦草》(UPOV TG/4/8)、欧盟植物保护联盟的CPVO以及日本的黑麦草DUS指南,结合本次试验种植的黑麦草品种生长特性,编写完成了我国的《黑麦草DUS测试指南》。该指南的制订对促进中国植物新品种保护事业的发展,提高中国在国际植物新品种保护领域的地位,促进中国植物新品种保护事业的发展都具有重要意义。     

细粒棘球绦虫高免动物血清的特异性和敏感性分析

目的获得用于诊断细粒棘球绦虫成虫感染时特异性和敏感性高的抗血清。方法用细粒棘球绦虫成虫抗原免疫兔2只，制备高免血清，血清用饱和硫酸铵沉淀、透析、获得比较纯化的抗体，测量浓度和效价后，3μg／ml兔抗体包被，检测感染了不同犬带科绦虫的实验犬和空白犬粪样，单克隆抗体补捉抗原（1：6000），再用HRP标记的兔抗小鼠IgM（...     

MSCTA对主动脉夹层的诊断敏感性与特异性

目的探讨多层螺旋血管成像CT(MSCTA)在主动脉夹层诊断中的应用价值。方法 32例临床考虑主动脉夹层患者均经MSCTA扫描。随后采用图像后处理技术多平面重组(MPR)及曲面重组(CPR),最大密度投影(MIP)以及容积再现(VR),回顾性地分析其影像表现。结果 MSCTA各种图像后处理技术能清楚显示主动脉夹层发生部位、范围、真假腔的大小与形态、受累血管分支情况以及有无合并钙化、血栓形成等。本组MSCTA对主动脉夹层的诊断敏感性100%,特异性100%。结论 MSCTA是诊断主动脉夹层的一种无创、快速、安全、准确的检查方法,可作为主动脉夹层的首选影像检查。     

体型特异性剂量估计的概念和方法

为了降低辐射剂量并且得到临床可接受的图像,需要对CT检查的辐射剂量进行准确评估,但检查中患者受到的辐射剂量与患者体型的大小和CT扫描设备的辐射输出都是相关的,本文将对更为合理的估算患者CT检查时所受辐射剂量的体型特异性剂量估计(SSDE)方法及其局限性作一综述。     

颈动脉的血流动力学:应用MRI计算流体动力学方法观察应用氨氯地平和赖诺普利病人的特异性变化

目的评估联合应用MRI和流体动力学计算(CFD)是否能够显示降压效果相似的两种降压药——氨氯地平(钙离子通道拮抗剂)和赖诺普利(血管紧张素转换酶抑制剂)引     

先天性心脏病心室间隔缺损大小的计算和部位判断的研究(电子计算机聚类和逐步回归分析)

先天性心脏病心室间缺损(简称室缺)病人,术前缺损大小的计算一直应用Corlin根据Torrceli有关水力学的公式计算方法。这个公式由于麻烦且准确率低,常常不被临床医生所采用。电子计算机的日益广泛应用,给医学临床研究带来了方便。本文使用电子计算机技术,运用聚类(Clustering)和多因素逐步回归分析(Multiple StepwisRegression Analysis)的统计方法,利用术前右心导管术,超声心动图和X胸部照片检查的资料,分别推导出计算非紫绀性室缺病人缺损大小和缺损部位判断的偏归方程(Partial Regression Equation)。     

胶质母细胞瘤病人假性进展:在独立测试背景下应用基于像素的容积加权多参数聚类方法分析MR成像数据

<正>摘要目的在独立测试背景下,验证基于像素的容积加权多参数聚类(VVMC)方法处理MR成像数据能否鉴别胶质母细胞瘤病人假性进展及早期进展(ETP)。材料与方法本研     

Aortic dissection: sensitivity and specificity of MR imaging

Gated transverse magnetic resonance (MR) images of 54 patients (35 male, 19 female; aged 16-90 years) with suspected or known aortic dissection were reviewed by three cardiac radiologists without knowledge of clinical details. The reviewers independently determined the presence or absence and the type of aortic dissection. A confidence level was assigned for each diagnosis, and receiver operating characteristic curves were generated. The reviewer with extensive MR experience correctly identified 96% of the proved aortic dissections and all of the normal cases; the reviewer with moderate experience identified 96% and 84%, respectively; and the reviewer with minimal experience, 78% and 94%. The sensitivity at a specificity level of 90% was determined for each reviewer (100%, 96%, and 83%, respectively). MR imaging is highly sensitive and specific in the diagnosis of aortic dissection but does require considerable experience because of the need to recognize flow artifacts.     

Methods for calculating internal mechanical work: comparison using elite runners

Two methods for calculating internal work—the absolute work method, based on changes in mechanical energy, and the absolute power method, based on the powers produced by the joint moments of force—were compared. The results from both methods were normalized to body mass and running speed to obtain the ‘internal biomechanical cost’ (IBC). The IBCs of normal running for eight runners were compared to their IBCs for four inefficient running styles. The absolute power method was able to detect the inefficient runs significantly more often than the absolute work method (χ²=3.22, P<0.05). In addition, the absolute power method showed less variability quantifying both internal and external work. In conclusion, the absolute power method was judged the superior technique for quantifying mechanical energy costs of running.     

CT of small-bowel obstruction in children: sensitivity and specificity.

OBJECTIVE.:The aim of this study was to determine the sensitivity, specificity, and accuracy of CT in the diagnosis of small-bowel obstruction in children. MATERIALS AND METHODS: The CT scans of 30 children with surgically proven small-bowel obstruction, 22 children with ileus, and 29 children who served as controls were retrospectively reviewed by two of four interpreters who were unaware of the children's final diagnoses. Causes of obstruction in the patients included 19 adhesions, six cases of volvulus, five intussusceptions, four strictures, and two cases each of internal hernia and abscess. Eight obstructions had multiple causes. The CT scans were evaluated for the presence of small-bowel obstruction using a scale with five degrees of confidence. In cases of discrepancy of more than one level of certainty, a third interpreter was consulted. Criteria for small-bowel obstruction included a discrepancy in caliber between the proximal dilated and the more distal small bowels or generalized small-bowel dilatation (>2.5 cm) in the presence of a collapsed colon. An interpreter's rating that an obstruction was either present or probable was considered a positive finding; a rating indicating that the interpreter was not sure whether an obstruction was present or believed that an obstruction was not probable or saw normal anatomic structures was considered a negative finding for small-bowel obstruction. The cause and level of obstruction also were recorded. RESULTS: There were 26 true-positive (87%) and four false-negative (13%) interpretations for small-bowel obstruction. Among the interpretations of scans of patients with ileus, 68% were true-negative and 32% were false-positive interpretations for small-bowel obstruction. Among the control group, there were no false-positive readings. Sensitivity of CT was 87%, specificity was 86%, and accuracy was 86%. In the scans of children 2 years and younger, CT had a sensitivity of 100% and specificity of 0%. Of the patients with surgically confirmed levels of obstruction, the correct level of obstruction was described by both interpreters in 12 (86%) of 14 scans. The causes of obstruction were correctly identified in 14 (47%) of 30 scans. CONCLUSION: CT is both sensitive and specific for use in diagnosing small-bowel obstruction in children, especially in children older than 2 years.     

Reading protocol for dynamic contrast-enhanced MR images of the breast: sensitivity and specificity analysis

PURPOSE: To prospectively determine sensitivity and specificity of breast magnetic resonance (MR) imaging in a screening and symptomatic population by using independent double reading, with histologic or cytologic results or a minimum 18-month follow-up as the standard. MATERIALS AND METHODS: Informed consent and ethical approval were obtained. Reader performance was analyzed in 44 radiologists at 18 centers from 1541 examinations, including 1441 screening examinations in 638 high-risk women aged 24-51 years (mean, 40.5 years) and 100 examinations in symptomatic women aged 23-81 years (mean, 49.2 years). A screening protocol of dynamic T1-weighted three-dimensional imaging and 0.2 mmol/kg gadolinium-based intravenous contrast agent was used. Logistic and Poisson regressions were used to analyze reader performance in relation to experience. Correlation between readers was determined with kappa statistics. Sensitivity and specificity were analyzed according to reader, field strength, machine type, and histologic results. RESULTS: The proportion of studies with lesions analyzed reduced significantly with reader experience (odds ratio, 0.84 per 6 months; P < .001), and number of regions per lesion analyzed also diminished (incidence rate ratio, 0.98 per 6 months; P = .047). The two readers for each study agreed 87% of the time, with a moderately good kappa statistic of 0.52 (95% confidence interval [CI]: 0.45, 0.58). By taking the reading with the highest score (most likely to be malignant) from each double-read study, sensitivity was 91% (95% CI: 83%, 96%) and specificity was 81% (95% CI: 79%, 83%). Single readings had 7% lower sensitivity (95% CI: 4%, 11%) and 7% higher specificity (95% CI: 6%, 7%). Sensitivity did not differ between MR imager manufacturers or between 1.0- and 1.5-T field strength, but there were significant differences in specificity for machine type (P = .001) and for field strength adjusted for manufacturer (P = .001). Specificity, but not sensitivity, was higher in women younger than 50 years (P = .02). CONCLUSION: Independent double reading by 44 radiologists blinded to mammography results showed sensitivity and specificity acceptable for screening; sensitivity was higher when two readings were used, at the cost of specificity. Interreader correlation was moderately good, and evidence of learning was seen. Equipment manufacturer, field strength, and age affected specificity but not sensitivity.     

Diffusion-weighted and fluid-attenuated inversion recovery imaging in Creutzfeldt-Jakob disease: high sensitivity and specificity for diagnosis

BACKGROUND AND PURPOSE: Abnormalities on diffusion-weighted images (DWIs) and fluid-attenuated inversion recovery (FLAIR) images are reported in Creutzfeldt-Jakob disease (CJD). To our knowledge, no large study has been conducted to determine the sensitivity and specificity of DWI and FLAIR imaging for diagnosing CJD. METHODS: Two neuroradiologists, blinded to diagnosis, retrospectively evaluated DWI and FLAIR images from 40 patients with probable or definite CJD and 53 control subjects with other forms of dementia and rated the likelihood of CJD on the basis of the imaging findings. RESULTS: DWI and FLAIR imaging was 91% sensitive, 95% specific, and 94% accurate for CJD. Interrater reliability was high (kappa = 0.93). Sensitivity was higher for DWI than FLAIR imaging. Abnormalities involved cortex and deep gray matter (striatum and/or thalamus) in 68% of patients with CJD, cortex alone in 24%, and deep gray matter alone in 5%. The most typical and specific patterns were corresponding hyperintensity on both FLAIR images and DWIs confined to the gray matter in the cortex, striatum, medial and/or posterior thalamus, or a combination of these areas. Narrow-window soft-copy review of artifact-free DWIs and FLAIR images and recognition of the normal variation in cortical signal intensity proved critical for successful differentiation of CJD from other dementias. CONCLUSION: Because specific patterns of abnormality on DWI and FLAIR images are highly sensitive and specific for CJD, these sequences should be performed whenever CJD is suspected.