Motion‐compensated b‐tensor encoding for in vivo cardiac diffusion‐weighted imaging

Motion is a major confound in diffusion‐weighted imaging (DWI) in the body, and it is a common cause of image artefacts. The effects are particularly severe in cardiac applications, due to the nonrigid cyclical deformation of the myocardium. Spin echo‐based DWI commonly employs gradient moment‐nulling techniques to desensitise the acquisition to velocity and acceleration, ie, nulling gradient moments up to the 2nd order (M2‐nulled). However, current M2‐nulled DWI scans are limited to encode diffusion along a single direction at a time. We propose a method for designing b‐tensors of arbitrary shapes, including planar, spherical, prolate and oblate tensors, while nulling gradient moments up to the 2nd order and beyond. The design strategy comprises initialising the diffusion encoding gradients in two encoding blocks about the refocusing pulse, followed by appropriate scaling and rotation, which further enables nulling undesired effects of concomitant gradients. Proof‐of‐concept assessment of in vivo mean diffusivity (MD) was performed using linear and spherical tensor encoding (LTE and STE, respectively) in the hearts of five healthy volunteers. The results of the M2‐nulled STE showed that (a) the sequence was robust to cardiac motion, and (b) MD was higher than that acquired using standard M2‐nulled LTE, where diffusion‐weighting was applied in three orthogonal directions, which may be attributed to the presence of restricted diffusion and microscopic diffusion anisotropy. Provided adequate signal‐to‐noise ratio, STE could significantly shorten estimation of MD compared with the conventional LTE approach. Importantly, our theoretical analysis and the proposed gradient waveform design may be useful in microstructure imaging beyond diffusion tensor imaging where the effects of motion must be suppressed.     

上海市农村合作医疗筹资与补偿调查分析

目的：为改革和完善上海市农村合作医疗的政策，制度，规划，计划，措施提供科学依据。方法：使用调查研究，比较研究，描述性统计及SAS统计分析等方法。结果：调查分析了上海市1997－1999年8区（县）合作医疗资金来源，数量，比例，补偿等。结论：1997年以来，上海市农村合作医疗得到了快速发展，仍存在保障水平，补偿比例，投保率低下及发展不平衡，资金使用不合理等问题。     

Myocardial perfusion SPECT reconstruction: Receiver operating characteristic comparison of CAD detection accuracy of filtered backprojection reconstruction with all of the clinical imaging information available to readers and solely stress slices iteratively reconstructed with combined compensation

BACKGROUND: Past receiver operating characteristic (ROC) studies have demonstrated that single photon emission computed tomography (SPECT) perfusion imaging by use of iterative reconstruction with combined compensation for attenuation, scatter, and detector response leads to higher area under the ROC curve (A(z)) values for detection of coronary artery disease (CAD) in comparison to the use of filtered backprojection (FBP) with no compensations. A new ROC study was conducted to investigate whether this improvement still holds for iterative reconstruction when observers have available all of the imaging information normally presented to clinical interpreters when reading FBP SPECT perfusion slices. METHODS AND RESULTS: A total of 87 patient studies including 50 patients referred for angiography and 37 patients with a lower than 5% likelihood for CAD were included in the ROC study. The images from the two methods were read by 4 cardiology fellows and 3 attending nuclear cardiologists. Presented for the FBP readings were the short-axis, horizontal long-axis, and vertical long-axis slices for both the stress and rest images; cine images of both the stress and rest projection data; cine images of selected cardiac-gated slices; the CEQUAL-generated stress and rest polar maps; and an indication of patient gender. This was compared with reading solely the iterative reconstructed stress slices with combined compensation for attenuation, scatter, and resolution. With A(z) as the criterion, a 2-way analysis of variance showed a significant improvement in detection accuracy for CAD for the 7 observers (P = .018) for iterative reconstruction with combined compensation (A(z) of 0.895 +/- 0.016) over FBP even with the additional imaging information provided to the observers when scoring the FBP slices (A(z) of 0.869 +/- 0.030). When the groups of 3 attending physicians or 4 cardiology fellows were compared separately, the iterative technique was not statistically significantly better; however, the A(z) for each of the 7 observers individually was larger for iterative reconstruction than for FBP. Compared with results from our previous studies, the additional imaging information did increase the diagnostic accuracy of FBP for CAD but not enough to undo the statistically significantly higher diagnostic accuracy of iterative reconstruction with combined compensation. CONCLUSIONS: We have determined through an ROC investigation that included two classes of observers (experienced attending physicians and cardiology fellows in training) that iterative reconstruction with combined compensation provides statistically significantly better detection accuracy (larger A(z)) for CAD than FBP reconstructions even when the FBP studies were read with all of the extra clinical nuclear imaging information normally available.     

白内障超声乳化术后角膜地形图和屈光状态的观察

目的　观察白内障超声乳化人工晶状体植入术后 ,患者角膜地形图和屈光状态的变化。方法　对2 0 0 0年～ 2 0 0 1年行白内障超声乳化的 136例 (15 1只眼 )患者术前、术后随访一年的资料进行回顾性分析。结果　术后 1、3、6、12月术眼的球镜、散光、角膜地形图曲率和散光 sim k值统计结果无明显差异 ;术后 1～ 12月视力和屈光状态稳定 (方差分析 P >0 .0 5 )。术后 6月平均视力为 0 .5 9± 0 .2 3,矫正视力为 0 .82± 0 .19,术后 6月 ,球镜为 (-0 .2 4± 0 .88) D,散光为 (- 0 .5 6± 1.0 1) D,在± 1.0 D之内球镜和散光眼分别为 84.0 %和 6 4.0 % ,≥ 0 .5和≥ 0 .8的视力分别为 70 .0 %和 2 8.0 % ,≥ 0 .5和≥ 0 .8的矫正视力分别为 94.0 %和 72 .0 %。≥ 0 .5和≥ 0 .8裸眼视力和矫正视力的平均百分率分别由 6 1.96 %和 2 3.49%提高到配镜矫正后的 92 .35 %和 6 3.0 9%。结论　超声乳化术后角膜形态和屈光状态保持良好的稳定性 ,患者可以达到良好的视力。由于植入的人工晶状体无调节功能和测量误差 ,目前部分患者需要配戴较低度数的眼镜矫正远或近视力 ,达到更好的视觉效果。     

热分析中系列相关反应的补偿效应研究

根据热分析谱图峰顶的数学特征与Ｃｏａｔｓ－Ｒｅｄｆｅｒｎ方程，推得在一定实验条件下，在系列相关反应中，若峰顶温度相接近，则各反应的表观活化能Ｅ与指前因子Ａ之间存在着有动力学意义的补偿效应，即ｌｎＡ＝ａＥ＋ｂ。并经系列含水硫酸盐脱水反应实验验证。     

Injured worker helplessness: Critical relationships and systems level approach for intervention

An appropriate paradigm for explaining the evident problems of motivating the workers' compensation claimant toward occupational recovery may be found in the learned helplessness model. This article examines the critical relationships in the workers' compensation system and the potential for development of the injured worker helplessness within that system. The author offers the learned helplessness model as an alternative framework through which injured worker behavior can be explained and understood. It is suggested that the non-contingent rewards and the uncontrollable dynamics characteristic of workers' compensation systems lead to claimants' learning helplessness. Finally, a total quality managed disability prevention system is offered as the organization's best approach to reducing the likelihood of learned helplessness.     

Clinical and laboratory investigations of the relationship of accommodation and convergence function with refractive error

Studies of the relationship of clinical and laboratory measures of accommodation and convergence function with refractive error are reviewed. There are inconsistencies in results from study to study presumably due, in part, to methodological differences. However, some basic trends can be outlined. In studies in young adults, accommodation in darkness (dark focus), optical reflex accommodation, and proximally induced accommodation are less in myopes than in emmetropes and hyperopes. It also appears that nearpoint esophoria is associated with higher rates of myopia progression in children. Implications for myopia etiology are discussed.     

Health status,work limitations,and return-to-work trajectories in injured workers with musculoskeletal disorders

BACKGROUND: The purpose of this study was to describe the health status and work limitations in injured workers with musculoskeletal disorders at 1 month post-injury, stratified by return-to-work status, and to document their return-to-work trajectories 6 months post-injury. METHODS: A sample of 632 workers with a back or upper extremity musculoskeletal disorder, who filed a Workplace Safety and Insurance Board lost-time claim injury, participated in this prospective study. Participants were assessed at baseline (1 month post-injury) and at 6 months follow-up. RESULTS: One month post-injury, poor physical health, high levels of depressive symptoms and high work limitations are prevalent in workers, including in those with a sustained first return to work. Workers with a sustained first return to work report a better health status and fewer work limitations than those who experienced a recurrence of work absence or who never returned to work. Six months post-injury, the rate of recurrence of work absence in the trajectories of injured workers who have made at least one return to work attempt is high (38%), including the rate for workers with an initial sustained first return to work (27%). CONCLUSIONS: There are return-to-work status specific health outcomes in injured workers. A sustained first return to work is not equivalent to a complete recovery from musculoskeletal disorders.