In vivo precision of bootstrap algorithms applied to diffusion tensor imaging data

Purpose:

To determine the precision for in vivo applications of model and non–model‐based bootstrap algorithms for estimating the measurement uncertainty of diffusion parameters derived from diffusion tensor imaging data.

Materials and Methods:

Four different bootstrap methods were applied to diffusion datasets acquired during 10 repeated imaging sessions. Measurement uncertainty was derived in eight manually selected regions of interest and in the entire brain white matter and gray matter. The precision of the bootstrap methods was analyzed using coefficients of variation and intra‐class correlation coefficients. Comprehensive simulations were performed to validate the results.

Results:

All bootstrap algorithms showed similar precision which slightly varied in dependence of the selected region of interest. The averaged coefficient of variation in the selected regions of interest was 13.81%, 12.35%, and 17.93% with respect to the apparent diffusion coefficient, the fractional anisotropy value, and the cone of uncertainty, respectively. The repeated measurements showed a very high similarity with intraclass‐correlation coefficients larger than 0.96. The simulations confirmed most of the in vivo findings.

Conclusion:

All investigated bootstrap methods perform with a similar, high precision in deriving the measurement uncertainty of diffusion parameters. Thus, the time‐efficient model‐based bootstrap approaches should be the method of choice in clinical practice. J. Magn. Reson. Imaging 2012;36:979–986. © 2012 Wiley Periodicals, Inc.     

A study of the Repeated Actions Diary in patients suffering from obsessive compulsive disorder

The structured Repeated Action Diary (RAD) collects in vivo data on compulsions and their various characteristics. Certain compulsions (i.e., those ending because the patient feels certain that it is safe to stop) are then compared with uncertain compulsions. The compulsion profile in patients with obsessive compulsive disorder (OCD) was assessed by using the RAD. Thirty‐two patients from two sources participated in the study. Before pooling the two subgroups, we checked that they did not differ significantly with regard to demographic and clinical variables. Patients reported several categories of compulsion. The most frequently reported compulsions were washing and checking. In a given person, checking compulsions (in contrast to washing compulsions) were often produced by several different obsessions. Almost all the patients reported repeating the compulsions because of a need to feel sure. There were far more “certain” compulsions than “uncertain” compulsions. The number of repetitions was significantly lower for certain compulsions than for uncertain compulsions. The person felt greater relief from guilt and responsibility and a greater decrease in discomfort at the end of a compulsive episode for certain compulsions than for uncertain compulsions. In conclusion, the need to ritualize (prompted by uncertainty, i.e., potential danger) might explain the maintenance (or posttreatment recurrence) of OCD in many patients. The need for certainty in the completion of a compulsion may be worth considering as a therapeutic tool. The development of an approach based on the need for certainty might help to improve treatment outcomes.     

Relationships between depression,family function,physical symptoms,and illness uncertainty in female patients with chronic kidney disease

This study investigated the relationship between depression, family function, physical symptoms, and illness uncertainty in women with chronic kidney disease. Data were collected through structured questionnaire that was completed by 120 women undergoing hemodialysis. Assessment instruments consisted of the Family Adaptability, Partnership, Growth, Affection, Resolve Scale, Symptom Experience Scale, Mishel's Uncertainty in Illness Scale for Adults, and the Center for Epidemiological Studies‐Depression Scale. The higher the uncertainty about illness and physical symptoms, the higher is the level of depression, and the better the family function, the lower is the level of depression. Greater uncertainty was associated with poorer family function and worsening physical symptoms. A regression model explained 41% of the variance in depression. Significant predictors of depression were physical symptoms, living alone, illness uncertainty, and “poor” subjective health status. To improve depression of women with chronic kidney disease, nurses need to reduce physical symptoms and illness uncertainty in these patients and improve their subjective health status. In addition, the establishment of a therapeutic support system considering living arrangement will help to reduce depression in women with chronic kidney disease.     

严重烧伤患者家属疾病不确定感与其生活质量相关性研究

目的探讨严重烧伤患者家属疾病不确定感与其生活质量相关性。方法收集我院2016年1月至2019年1月收治的126名严重烧伤患者家属的资料,采用家属疾病不确定感量表(MUIS-FM)和家属生活质量量表(QOL-C)调查其疾病不确定感和生活质量并分析其相关性。结果严重烧伤患者家属疾病不确定感总平均分为(97.98±9.25)分,处于较高的不确定水平,其中不明确性总均分最高为(39.45±5.61)分。患者家属生活质量在健康状况、躯体疼痛、生理机能、生理职能、社会功能、精力、情感职能和精神健康各维度得分均处于中低等水平。采用Pearson相关性分析得出,疾病不确定感与生活质量中的健康状态、生理机能、社会功能以及精力状况均呈现负相关。结论严重烧伤患者家属存在一定不同程度的疾病不确定感,且随着不确定感增强,生活质量降低,因此医护人员应采取适当鼓励措施,以降低家属不确定感,提高其生活质量,进而提高对患者的照护效果。     

石墨炉原子吸收法快速测定尿中锰及其不确定度分析

目的:分析石墨炉原子吸收法测定尿中锰过程中不确定度的主要来源,判定分析方法建立的可行性和测量结果质量的依据。方法:采用石墨炉原子吸收法快速测定尿液中锰的浓度,同时构建数学模型,对各部分分量进行分析。结果:测定尿锰结果为30.70±1.39μg/L,美国伯乐尿金属质控品锰含量为32.8±6.5μg/L。结论:石墨炉原子吸收法快速测定尿液中锰结果令人满意。     

Influence of Parameter Values and Variances and Algorithm Architecture in ConsExpo Model on Modeled Exposures

This study evaluated the influence of parameter values and variances and model architecture on modeled exposures, and identified important data gaps that influence lack-of-knowledge-related uncertainty, using Consexpo 4.1 as an illustrative case study. Understanding the influential determinants in exposure estimates enables more informed and appropriate use of this model and the resulting exposure estimates.

In exploring the influence of parameter placement in an algorithm and of the values and variances chosen to characterize the parameters within ConsExpo, “sensitive” and “important” parameters were identified: product amount, weight fraction, exposure duration, exposure time, and ventilation rate were deemed “important,” or “always sensitive.” With this awareness, exposure assessors can strategically focus on acquiring the most robust estimates for these parameters.

ConsExpo relies predominantly on three algorithms to assess the default scenarios: inhalation vapors evaporation equation using the Langmuir mass transfer, the dermal instant application with diffusion through the skin, and the oral ingestion by direct uptake algorithm. These algorithms, which do not necessarily render health conservative estimates, account for 87, 89 and 59% of the inhalation, dermal and oral default scenario assessments,respectively, according them greater influence relative to the less frequently used algorithms.

Default data provided in ConsExpo may be useful to initiate assessments, but are insufficient for determining exposure acceptability or setting policy, as parameters defined by highly uncertain values produce biased estimates that may not be health conservative. Furthermore, this lack-of-knowledge uncertainty makes the magnitude of this bias uncertain.

Significant data gaps persist for product amount, exposure time, and exposure duration. These “important” parameters exert influence in requiring broad values and variances to account for their uncertainty. Prioritizing them for research will not only help fill a large and influential knowledge gap, but also lead to more accurate assessments and thus refine the studies informing policy decisions.     

去铁胺对促进扩张后皮瓣微循环重建的实验研究

目的：探讨去铁胺（Defemxamine,DFX）对扩张后皮瓣微循环重建的影响。方法将新西兰大耳白兔24只分成实验组和对照组,兔额部皮下植入圆柱形扩张器,制备蒂部位于耳根的矩形皮瓣,实验组分别于模型制备后即刻、第3天、第5天将DFX注射于皮瓣末端,对照组皮下注射等量的生理盐水,第7天分别进行皮瓣平均微血管数目及内径、皮瓣组织中超氧化物歧化酶（MDA）、丙二醛（SOD）含量及血管内皮生长因子（VEGF） mRNA检测。结果实验组皮瓣SOD含量、VEGF mRNA表达高于对照组（P〈0.05）,平均微血管数目多于对照组（P〈0.05）,平均微血管内径及MDA含量小于对照组（P〈0.05）。结论在扩张皮瓣的局部注射DFX,可以降低自由基水平,加快新生血管形成并促进皮瓣微循环重建。     

明胶-壳聚糖膜抑制扩张皮瓣纤维包膜的研究

目的研究明胶-壳聚糖膜对扩张皮瓣纤维包膜的影响。方法 60只Wistar大鼠,制做扩张皮瓣模型,植入明胶-壳聚糖膜,定期注水扩张,切取扩张器表面纤维包膜,制作病理切片。测量纤维包膜内毛细血管及胶原的含量。结果光镜下,包膜主要由胶原纤维沉积构成,并有少量炎性细胞浸润和毛细血管增生。实验组术后6周和12周包膜胶原面密度分别为(0.22±0.08)和(0.27±0.05)较对照组(0.37±0.07)和(0.34±0.07)减少,差异有统计学意义(t=6.03,3.20,P0.05)。实验组包膜中毛细血管面密度,术后6周为(0.13±0.18),低于对照组(0.15±0.23),差异有统计学意义(t=2.03,P0.05);术后12周时,两组包膜中毛细血管面密度差异无统计学意义(t=1.98,P0.05)。结论明胶-壳聚糖膜干预纤维包膜的形成,减少包膜中胶原含量,对纤维包膜有抑制作用,不影响皮瓣营养。     

Understanding differences in electronic health record (EHR) use: linking individual physicians’ perceptions of uncertainty and EHR use patterns in ambulatory care

Objective

Electronic health records (EHR) hold great promise for managing patient information in ways that improve healthcare delivery. Physicians differ, however, in their use of this health information technology (IT), and these differences are not well understood. The authors study the differences in individual physicians'' EHR use patterns and identify perceptions of uncertainty as an important new variable in understanding EHR use.

Design

Qualitative study using semi-structured interviews and direct observation of physicians (n=28) working in a multispecialty outpatient care organization.

Measurements

We identified physicians'' perceptions of uncertainty as an important variable in understanding differences in EHR use patterns. Drawing on theories from the medical and organizational literatures, we identified three categories of perceptions of uncertainty: reduction, absorption, and hybrid. We used an existing model of EHR use to categorize physician EHR use patterns as high, medium, and low based on degree of feature use, level of EHR-enabled communication, and frequency that EHR use patterns change.

Results

Physicians'' perceptions of uncertainty were distinctly associated with their EHR use patterns. Uncertainty reductionists tended to exhibit high levels of EHR use, uncertainty absorbers tended to exhibit low levels of EHR use, and physicians demonstrating both perspectives of uncertainty (hybrids) tended to exhibit medium levels of EHR use.

Conclusions

We find evidence linking physicians'' perceptions of uncertainty with EHR use patterns. Study findings have implications for health IT research, practice, and policy, particularly in terms of impacting health IT design and implementation efforts in ways that consider differences in physicians'' perceptions of uncertainty.