Effects of image normalization on the statistical analysis of perfusion MRI in elderly brains

Purpose

To fully understand the effects of an image processing methodology on the comparisons of regional patterns of brain perfusion over time and between subject groups.

Materials and Methods

Two brain normalization methods were compared using images of elderly controls and subjects with MCI and AD: the normalization package of statistical parametric mapping (SPM2), and a fully deformable model (FDM). The performance of these two normalization methods was quantitatively evaluated based on two criteria: (a) the alignment accuracy of five brain structures to the colin27 reference volume, and (b) impact of spatial normalization methods on the sensitivity of perfusion magnetic resonance imaging (pMRI).

Results

The delineations of all five brain structures had significantly higher overlap with expert manual tracings using FDM compared to SPM (two‐tailed, P < 0.025). When applied to the biostatistical analysis of CBF maps, a larger number of statistically significant voxels was identified from FDM compared with SPM2 regardless of the effects of the threshold and smoothing kernel.

Conclusion

The greater degree of deformation freedom associated with FDM may yield more accurate region matching and higher statistical sensitivity in identifying regions of CBF differences between elderly groups with prevalent late‐life neurodegenerative conditions. J. Magn. Reson. Imaging 2008;28:1351–1360. © 2008 Wiley‐Liss, Inc.     

SF-36问卷应用于老年人群生命质量的研究

目的：利用SF－36问卷调查社区老年人群的生命质量，探讨影响生命质量的因素。方法：面对面访谈调查生命质量及影响因素，利用Logistic逐步回归分析调查资料。结果：社区老年人群的生理健康评分较好，但心理健康较差。年龄、性别、婚姻状况和医疗费用是生理健康的主要影响因素；年龄、性别、经济收入和子女状况是心理健康的主要影响因素。结论：一些人口社会学特征影响老年人的生命质量，因此，家庭和社会应该更多地关注老年人的生活环境和医疗条件，提高老年人的健康水平。     

饮酒与脂肪肝发病关系及其影响因素的病例对照研究

目的评价饮酒、饮食、经济因素以及体重、血糖、血脂、肝炎病毒携带情况与脂肪肝危险性的关系。方法采用 1∶ 2配对研究方法 ,共调查十堰地区 81例经 B超诊断的脂肪肝病人及 16 2例对照者。通过 SAS(6 .12 )软件对资料进行条件 L ogistic回归分析。结果酒龄长、日均饮酒量大 (>5 0 g/ d)、体质指数高 (BMI≥ 2 5 )、年均醉酒次数多、血总胆固醇含量高与脂肪肝危险性增加有关联 (P<0 .0 5 ) ,蔬菜日均进食量与脂肪肝危险性降低有关联 (P<0 .0 5 )。结论十堰市居民脂肪肝的重要危险因素是日均饮酒量大 (>5 0 g/ d,OR:3.6 2 )、体质指数高 (BMI≥ 2 5 ,OR:1.811)、年均醉酒次数多(OR:1.5 6 )、血总胆固醇含量高 (OR:1.2 2 8)、酒龄长 (OR:1.0 6 6 )。而蔬菜日均进食量 (OR:0 .989)则是重要的保护因素     

Data Mining and the Implementation of a Prospective Payment System for Inpatient Rehabilitation

This paper describes the development of a new Medicare Prospective Payment System (PPS) for inpatient rehabilitation care. Congress mandated such a system in the Balanced Budget Act of 1997. To help implement this system, we assembled four years of Medicare hospitalization data, linked it to rehabilitation hospitals' information about impairment and the functional status of patients, and developed case mix groups using the CART algorithm, a common method for determining groups in health services.While CART readily produces simple and effective rules for prediction, it adheres to a restrictive functional form and its fitting algorithm does not necessarily produce a global optimum. We wanted to know how these limitations affect our results. So, we compared CART's performance with methods receiving attention in the data mining community and in the statistics literature. We estimated that the CART models explained about 90 percent of the potentially explainable variance in individual cost and they predicted annual hospital costs that were essentially identical to other methods' predictions.     

6MV X线照射人离体血细胞遗传学剂量—效应研究——常规法的微核剂量效应曲线

本文应用医用直线加速器6MV X 线照射5例健康成人离体血研究淋巴细胞微核与剂量间的关系,发现微核率及微核细胞率可各配以回归方程 Y=6.6896×10~(-3)+1.2959×10~(-2)D~2及 Y=7.3906×10~(-3)+1.0824×10~(-2)D~2,其 R~2值分别为O.9948及0.9976,有较好的拟合度,可作为预测受照剂量的模型。     

Measuring familial aggregation by using odds-ratio regression models.

Detection of familial aggregation of a disease is important for studying possible genetic and environmental factors contributing to disease etiology. Accurate quantification of familial aggregation can provide guidance for subsequent, more sophisticated genetic studies. This article presents a statistical model and method for detecting both inter- and intra-class aggregation of a binary trait with family data. The method used here is based on the logistic regression model which incorporates effects of individual covariates while measuring familial aggregation of risk as the odds ratios among classes of relatives. An estimation equation approach is presented where the joint distribution of binary traits among family members need not be fully specified. Data from a genetic epidemiologic study on liver cancer in Shanghai are analyzed for illustration, and reveal strong aggregation of risk even after adjusting for covariates. Effects of non-random sampling and ascertainment bias are also discussed.     

Bayesian spatial modeling of disease risk in relation to multivariate environmental risk fields

The relationship between exposure to environmental chemicals during pregnancy and early childhood development is an important issue that has a spatial risk component. In this context, we have examined mental retardation and developmental delay (MRDD) outcome measures for children in a Medicaid population in South Carolina and sampled measures of soil chemistry (e.g. As, Hg, etc.) on a network of sites that are misaligned to the outcome residential addresses during pregnancy. The true chemical concentration at the residential addresses is not observed directly and must be interpolated from soil samples. In this study, we have developed a Bayesian joint model that interpolates soil chemical fields and estimates the associated MRDD risk simultaneously. Having multiple spatial fields to interpolate, we have considered a low‐rank Kriging method for the interpolation that requires less computation than the Bayesian Kriging. We performed a sensitivity analysis for a bivariate smoothing, changing the number of knots and the smoothing parameter. These analyses show that a low‐rank Kriging method can be used as an alternative to a full‐rank Kriging, reducing the computational burden. However, the number of knots for the low‐rank Kriging model needs to be selected with caution as a bivariate surface estimation can be sensitive to the choice of the number of knots. Copyright © 2009 John Wiley & Sons, Ltd.     

Analysis of sex‐specific injury patterns and risk factors in young high‐level athletes

This study analyzed sex‐specific injury patterns and risk factors in young athletes (n=256) from 12 sport disciplines practicing at the national or the international level in the Grand‐Duchy of Luxembourg. Injury occurrence as a result of sport practice was analyzed retrospectively over the year 2006 using a standardized self‐administered questionnaire. Overall incidence was not different between girls and boys (1.20 and 1.21 injuries/1000 athlete‐hours, respectively), but in the context of team sport competition girls tended to be at a greater risk (rate ratio 2.05, P=0.053). Girls had a higher proportion of injuries in the ankle/foot region compared with boys (34.8% vs 16.8%). No sex‐related differences were found regarding injury severity. Multivariate logistic regression (controlling for age and practice volume) revealed that girls' team sports were associated with a greater injury risk compared with individual sports [odds ratio (OR) of 4.76], while in boys this was observed for racket sports (OR=3.31). Furthermore, physical or emotional stress tended to be a specific risk factor in girls. There was a tendency for injury outside sports to be coupled to a higher injury risk in girls and boys. Consideration of sex‐specific injury patterns and risk factors could be of importance for effective injury prevention.     

Estimation of stature from cranial sutures in a South Indian male population

The aim of this study was to investigate the possibility of estimating height from length of coronal and sagittal sutures of the skull for the positive identification of the height in forensic investigations concerned with fragmentary skeletal remains. The study was conducted on 87 male bodies subjected to medicolegal autopsy in the Department of Forensic Medicine, Kasturba Medical College, Manipal, South India and the Department of Forensic Medicine, Kasturba Medical College, Mangalore, South India. Length of coronal suture was measured from left pterion at the junction of sphenoparietal with the sphenofrontal suture, along the coronal plane, over the coronal suture to the pterion on the right side. Length of sagittal suture was measured from bregma along the sagittal plane over the sagittal suture to the lambda. The data collected were subjected to statistical methods. Significant correlation was found between height and coronal suture length in males, when compared to sagittal suture. The correlation coefficient between height and coronal suture was 0.363. The correlation coefficient between height and sagittal suture was 0.090. Linear regression equations for stature estimation were derived from coronal suture length in male population. Coronal suture length gives more accurate results in estimating stature than sagittal suture. However, in cases where identification is required by means of only skull, this method could prove useful.