Clinical equivalence assessment of T2 synthesized pediatric brain magnetic resonance imaging

Background and purposeAutomated synthetic magnetic resonance imaging (MRI) provides qualitative, weighted image contrasts as well as quantitative information from one scan and is well-suited for various applications such as analysis of white matter disorders. However, the synthesized contrasts have been poorly evaluated in pediatric applications. The purpose of this study was to compare the image quality of synthetic T2 to conventional turbo spin-echo (TSE) T2 in pediatric brain MRI.Materials and methodsThis was a mono-center prospective study. Synthetic and conventional MRI acquisitions at 1.5 Tesla were performed for each patient during the same session using a prototype accelerated T2 mapping sequence package (TA_synthetic = 3:07 min, TA_conventional = 2:33 min). Image sets were blindly and randomly analyzed by pediatric neuroradiologists. Global image quality, morphologic legibility of standard structures and artifacts were assessed using a 4-point Likert scale. Inter-observer kappa agreements were calculated. The capability of the synthesized contrasts and conventional TSE T2 to discern normal and pathologic cases was evaluated.ResultsSixty patients were included. The overall diagnostic quality of the synthesized contrasts was non-inferior to conventional imaging scale (P = 0.06). There was no significant difference in the legibility of normal and pathological anatomic structures of synthetized and conventional TSE T2 (all P > 0.05) as well as for artifacts except for phase encoding (P = 0.008). Inter-observer agreement was good to almost perfect (kappa between 0.66 and 1).ConclusionsT2 synthesized contrasts, which also provides quantitative T2 information that could be useful, could be suggested as an equivalent technique in pediatric neuro-imaging, compared to conventional TSE T2.     

C/C复合材料表面等离子喷涂HA涂层在SBF中的试验

目的 探讨不同模拟体液对HA涂层体外生物学行为的影响。方法采用等离子体喷涂法,在碳／碳复合材料表面制备HA涂层,并对涂层进行了热处理。利用X射线衍射仪(X-ray diffraction)、扫描电子显微镜(Scanning electron microscopy)等检测手段,分析该涂层的物相和形貌,观察HA涂层在模拟体液中的影响。结果XRD检测结果表明,在模拟体液浸泡过程中,涂层的主要组成相的相对含量和结晶度不断发生变化。由SEM分析结果可知,在浸泡过程中,内送粉方式下制得的HA涂层的表面沉积物呈现近似网状的结构。同时,在Ringer溶液中,可以观察到HA涂层溶解痕迹。结论通过适当的热处理可以恢复HA的结构完整性,同时提高涂层的结晶度。     

尾部悬吊大鼠胸主动脉、肺动脉超微结构变化的动态观察

目的观察模拟微重力时大小循环动脉血管超微结构重塑随时间变化的差异,为微重力后立位耐力降低的机制研究积累资料。方法用透射电镜观察-30°尾部悬吊7d(TS7组)、14d(TS14组)及对照组大鼠胸主动脉、肺动脉壁超微结构的变化。结果TS7组胸主动脉内皮细胞表面出现绒毛状突起,部分线粒体空泡变性,内皮下基膜有分层,内弹力板较厚,且厚度不均匀,内弹力板下出现大量的胶原纤维;TS14组胸主动脉内皮细胞变性较明显,部分内皮细胞基质致密化,基膜复层化,内弹力板有破碎,弹力纤维增多。TS7组肺动脉部分内皮细胞突起,细胞内出现脂滴,内皮细胞基膜出现分层状改变,弹力板变薄、断裂,其下方可见收缩型平滑肌及合成型平滑肌细胞;TS14组肺动脉内皮细胞空泡变性较明显,内弹力板未见明显改变,弹力板内外均可见较多的胶原纤维和弹力纤维,内弹力板下方以收缩型平滑肌为主。结论TS7组大鼠胸主动脉和肺动脉出现损伤和增殖并存,以肺动脉较明显;TS14组肺动脉趋于形成新的稳定结构,而胸主动脉新稳定结构还未形成。模拟微重力时大小循环血管发生了结构重塑,大小循环血管重塑的时间过程不同归因于模拟微重力初期由下体转移而来的体液进入大小循环高峰期的时间差。     

模拟退火算法在图像配准中的应用

近年来 ,脑功能成像技术发展迅速 ,已在脑科学研究中占有重要地位。研究中通常需要将同一被试的多种模式成像结果或同一模式的时间序列结果结合起来分析 ,首先要解决的问题就是几幅图像的严格对齐问题 ,即所谓的图像配准。在模拟退火算法和其它工作的基础之上 ,较好的解决了图像配准中的连续变量全局优化问题 ,通过基于点的配准方法 ,实现了时间序列脑功能图像的高精度配准。     

Thyroidal handling of radioiodine in sea level residents exposed to hypobaric hypoxia

In the present investigation thyroidal accumulation of radioiodine and its release were assessed by direct testing of thyroid function using radioactive iodine, in vivo, in sea level residents intermittently exposed to hypobaric hypoxia. Thyroidal accumulation of radioiodine and its turnover were examined daily for 14 days. Twelve healthy human male volunteers were divided into three groups, with an equal number of individuals in each group. A decompression chamber was used to expose each group of subjects to hypoxic conditions at a simulated altitude of 3810 m for 8 h/day for 14 days. An oral dose of 25Ci iodine-131 was administered to each individual of the first group immediately before the initiation of intermittent hypoxia. The second group of subjects received a tracer dose at the beginning of the 4th day of the 14 days, intermittent exposure to hypoxia, while the third group received the tracer dose 1 week after the completion of the exposure. Control studies were carried out on the subjects before they were subjected to the experimental conditions. Thyroidal accumulation of¹³¹I in experimental subjects during the hypoxic state and in the post-hypoxic state was higher than in the control studies. The pattern of accumulation during exposure to hypoxia and in the post-hypoxic state showed multiple peaks of radioactive iodine uptake (PRAIU), a unique feature. The multiple PRAIU by the thyroid in experimental subjects were sharp and of short duration, reflecting an increased rate of¹³I release from the thyroid. Control subjects had a single PRAIU by the thyroid 24 h after the administration of tracer.     

基因表达数据判别分析的随机森林方法

目的探讨随机森林算法在基因表达数据分类研究中的应用。方法通过实际基因表达数据考核其应用效果，并通过模拟试验进一步验证和研究在存在大量无差异表达基因情况下对分类产生的影响。结果随机森林算法对基因表达数据的分类具有较高的准确性，但随着基因数量的增加其判别效果呈下降的趋势，在差异表达基因之间具有相关性时，下降趋势明显减慢，能够获得较理想的分类效果。结论随机森林算法对基因表达数据的分类研究有较好的判别效果。     

应用模拟体验法开展糖尿病慢性并发症教学的探索

目前在针对临床医学专业本科生的糖尿病慢性并发症教学中,存在学生学习积极性低,对知识点的吸收、内化差,不重视糖尿病慢性并发症危害等状况。由此提出,在糖尿病慢性并发症临床见习或实习环节中引入模拟体验教学;拟通过教师引导学生穿戴糖尿病慢性并发症的模型,让学生亲身体验该病症状,以期提高学生的学习能动性、知识掌握度和吸收率,同时培养学生的同理心,提升其医学人文素养。     

基于高仿真重症医学模拟训练的非技术技能培训研究

近年来,高仿真模拟病人技术已成为临床医学教学非常重要的手段。其中非技术技能（non—technicMskills,NTS）对于医疗质量的提高有着十分重要的作用。在此,将基于科室自身教学经验,探讨NTS融人重症医学模拟训练的理论和实践,并评价实施效果。     

Driving under light and dark conditions: effects of alcohol and diazepam in young and older subjects

Objectives: Driving at night time increases accident risk due to visual conditions, fatigue and impaired performance. In addition, the use of alcohol and benzodiazepines may enhance the risks related to night-time driving. We studied these aspects of traffic safety in a simulated driving test with young and older drivers. Methods: In a double-blind, crossover, placebo-controlled study, nine young subjects, aged 22–24 years, performed simulated driving in both `light' and `dark' conditions, before and 1.5 h and 4 h after 0.8 g · kg⁻¹ ethanol (EOH) or 15 mg diazepam (DZ). Further, nine older subjects, aged 55–77 years, were similarly tested, but their EOH dose was 0.7 g · kg⁻¹ and the DZ dose was 10 mg. The tests were vigilance assessment on visual analogue scales (VAS), simulated driving under light and dark conditions for 6 min each and digit symbol substitution (DSS). Results: In the young subjects, both EOH and DZ similarly impaired DSS, with DZ causing more subjective drowsiness, clumsiness, mental slowness and poor overall performance than EOH. During simulated driving, both EOH and DZ impaired simple and complex tracking (EOH>DZ) and prolonged reaction times (EOH=DZ). Impairment of performance was practically identical under light and dark conditions. In the older subjects, objective performance on DSS was poorer (−30%) than that of the young ones, and subjective impairment was marginal. During simulated driving, the baseline levels of variables in older subjects showed definite impairment (errors +100% to +500%) when compared with young subjects. Active drugs impaired several variables (EOH>DZ), but the statistical significances were fewer than in young subjects. Increase in reaction errors reached statistical significance, especially while driving in the dark. Otherwise the driving results in light and dark were not notably different. Conclusion: Young subjects drew good baselines but were sensitive to EOH and DZ, whilst the older subjects showed poor baselines but were less sensitive to EOH and DZ. Although the baseline driving and responses to treatments were different in young and older subjects, their driving and psychomotor impairment were unaffected by light conditions. Received: 10 November 1999 / Accepted in revised form: 25 April 2000     

地面模拟失重状态对唾液分泌型免疫球蛋白A分泌率的影响

目的 探讨模拟失重对人体唾液分泌型免疫球蛋白A(SIgA)分泌率的影响.方法 14名男性被试者以头低位倾斜(-6°)模拟失重30d,地面正常男性14名作为对照,分别在实验前3、3、15、30d及后恢复第3天对受试者采集10 min唾液,并进行SIgA含量的测定并计算出SIgA分泌率.结果 试验组在地面模拟失重条件第3天唾液流量为[(7.1±0.8)ml/10 min],较受试前[(8.5±1.0)ml/10 min]及对照组的流量[(7.7±1.3)ml/10 min]有明显减少(P＜0.01),受试第15天唾液流量为(8.0±0.7)ml/10 min,也较受试前及对照组明显减少(P＜0.05);试验组受试者在受试的第3、15、30天口腔唾液SIgA浓度分别为(122±8j) ng/ml、(192±183)ng/ml和(168±183)ng/ml,SIgA的分泌率分别为(83±54) ng/min、( 14g±137) ng/min和( 135±144) ng/min,这两项指标均较受试前及对照组有明显增高(P＜0.01或P＜0.05),并以受试第3天的指标增高最为明显(P＜0.01).恢复期第3天的SIgA浓度(129±151) ng/ml及分泌率(105±124) ng/min与受试前及对照组相似(P＞0.05).对照组各时间点唾液分泌SIgA各项指标差异均无统计学意义.结论 在30d的地面模拟失重环境测试中,受试者唾液流量表现出先下降再恢复的特点,唾液SIgA的浓度和分泌率明显增加,提示口腔局部黏膜免疫水平增强,受试结束后各指标恢复到受试前水平.