Whole-Body Diffusion Imaging Applying Simultaneous Multi-Slice Excitation.

PURPOSE: The purpose of this study was to examine the feasibility of a fast protocol for whole-body diffusion-weighted imaging (WB-DWI) using a slice-accelerated echo-planar sequence, which, when using comparable image acquisition parameters, noticeably reduces measurement time compared to a conventional WB-DWI protocol. MATERIALS AND METHODS: A single-shot echo-planar imaging sequence capable of simultaneous slice excitation and acquisition was optimized for WB-DWI on a 3 T MR scanner, with a comparable conventional WB-DWI protocol serving as the reference standard. Eight healthy individuals and one oncologic patient underwent WB-DWI. Quantitative analysis was carried out by measuring the apparent diffusion coefficient (ADC) and its coefficient of variation (CV) in different organs. Image quality was assessed qualitatively by two independent radiologists using a 4-point Likert scale. RESULTS: Using our proposed protocol, the scan time of the WB-DWI measurement was reduced by up to 25.9 %. Both protocols, the slice-accelerated protocol and the conventional protocol, showed comparable image quality without statistically significant differences in the reader scores. Similarly, no significant differences of the ADC values of parenchymal organs were found, whereas ADC values of brain tissue were slightly higher in the slice-accelerated protocol. CONCLUSION: It was demonstrated that slice-accelerated DWI can be applied to WB-DWI protocols with the potential to greatly reduce the required measurement time, thereby substantially increasing clinical applicability. KEY POINTS: •Whole-body diffusion-weighted imaging (WB-DWI) using simultaneous multi-slice and blipped-CAIPIRINHA reduces the measurement time strongly without having a significant impact on image quality. •The reduction in measurement time might strongly contribute to the clinical applicability of WB-DWI. •However, further refinement of the slice-accelerated EPI sequence, and the WB-DWI protocol applying this sequence type seems necessary; and the value of such WB-DWI protocols for assessment of systemic oncological diseases needs to be investigated in further clinical studies.

Economics of youth drug use, addiction and gateway effects.

The use of illicit drugs by American youth rose dramatically during the 1990s. Reducing these trends is an important policy objective. However, for policies to be effective it is important to understand the key causal links that lead to substance use and abuse. Policy makers must understand whether attempts to reduce the demand for one drug have impacts on the current and future use of other drugs. This paper overviews an economic approach to modeling drug use, addiction and gateway effects, emphasizing the potential of this method for identifying causal links in consumption. The paper demonstrates how this multi-substance theory of drug use leads to empirical specifications that can identify the impact of consumption of one drug on the contemporaneous and future consumption of other drugs. This is followed by a discussion of what types of data would be needed to estimate these effects.

Self-insurance and worksite alcohol programs: an econometric analysis.

OBJECTIVE: The worksite is an important point of access for alcohol treatment and prevention, but not all firms are likely to find offering alcohol programs profitable. This study attempts to identify at a conceptual and empirical level factors that are important determinants of the profitability of worksite alcohol programs. A central question considered in the empirical analysis is whether firms' decisions about worksite alcohol programs are related to how employee group health insurance is provided. METHOD: The data used are from the 1992 National Survey of Worksite Health Promotion Activities (N = 1,389-1,412). The econometric analysis focuses on measures of whether the surveyed firms offer Employee Assistance Programs (EAPs), individual counseling, group classes and resource materials regarding alcohol and other substance abuse. RESULTS: Holding other factors constant, the probability that a self-insured firm offers an EAP is estimated to be 59%, compared to 51% for a firm that purchases market group health insurance for its employees. Unionized worksites and larger worksites are also found to be more likely to offer worksite alcohol programs, compared to nonunionized smaller worksites. Worksites with younger work-forces are less likely than those with older employees to offer alcohol programs. CONCLUSIONS: The empirical results are consistent with the conceptual framework from labor economics, since self-insurance is expected to increase firms' demand for worksite alcohol programs while large worksite is expected to reduce the average program cost. The role of union status and workforce age suggests it is important to consider workers' preferences for the programs as fringe benefits. The results also suggest that the national trend towards self-insurance may be leading to more prevention and treatment of worker alcohol-related problems.

Should you eat breakfast? Estimates from health production functions.

This paper uses an econometric specification based on the health production function approach to examine the importance of lifestyles for adult health. The approach treats health practices such as eating breakfast, smoking, and exercise as inputs into the production of good health; several output measures are explored. The econometric models estimated with data from the 1985 Health Interview Survey show broad agreement with conventional wisdom about the importance of healthy lifestyles. This paper also investigates the role schooling plays in the production of good health. Schooling is found to be related to good health even after controlling for differences in observable health inputs. However, lack of support for a plausible specification of the productive efficiency hypothesis casts some doubt on the interpretation that schooling increases the efficiency of the household production of health.

Do drunk drivers pay their way? A note on optimal penalties for drunk driving.

This paper uses a simple framework to describe optimal penalties for drunk driving, and reviews available data to judge current policies against this standard. The analysis suggests that policies should be designed so that the penalties paid by drunk drivers equal the value of the increased risks drunk drivers impose on others. Current penalties appear to be too lenient, implying that current levels of drunk driving are too high.