Multiple gradient echo propeller (MGREP) MRI: Technical development and potential applications

The PROPELLER (Periodically Rotated Overlapping Parallel Lines with Enhanced Reconstruction) magnetic resonance imaging (MRI) technique has inherent advantages over other fast imaging methods, including robust motion correction, reduced image distortion, and resistance to off-resonance effects. These features make PROPELLER highly desirable for T2*-sensitive imaging, high-resolution diffusion imaging, and many other applications. However, PROPELLER has been predominantly implemented as a fast spin-echo (FSE) technique, which is insensitive to T2* contrast, and requires time-inefficient signal averaging to achieve adequate signal-to-noise ratio (SNR) for many applications. These issues presently constrain the potential clinical utility of FSE-based PROPELLER. ^ In this research, our aim was to extend and enhance the potential applications of PROPELLER MRI by developing a novel multiple gradient echo PROPELLER (MGREP) technique that can overcome the aforementioned limitations. The MGREP pulse sequence was designed to acquire multiple gradient-echo images simultaneously, without any increase in total scan time or RF energy deposition relative to FSE-based PROPELLER. A new parameter was also introduced for direct user-control over gradient echo spacing, to allow variable sensitivity to T2* contrast. In parallel to pulse sequence development, an improved algorithm for motion correction was also developed and evaluated against the established method through extensive simulations. The potential advantages of MGREP over FSE-based PROPELLER were illustrated via three specific applications: (1) quantitative T2* measurement, (2) time-efficient signal averaging, and (3) high-resolution diffusion imaging. Relative to the FSE-PROPELLER method, the MGREP sequence was found to yield quantitative T2* values, increase SNR by ∼40% without any increase in acquisition time or RF energy deposition, and noticeably improve image quality in high-resolution diffusion maps. In addition, the new motion algorithm was found to improve the performance considerably in motion-artifact reduction. ^ Overall, this work demonstrated a number of enhancements and extensions to existing PROPELLER techniques. The new technical capabilities of PROPELLER imaging, developed in this thesis research, are expected to serve as the foundation for further expanding the scope of PROPELLER applications. ^

Behavioral journalism newsletters to increase employee participation in a free worksite wellness center

Background. Providing an worksite fitness center for employees is an effective setting to increase an adult’s levels of physical activity, demonstrably reducing health care costs and elevating employee productivity. Increasing compliance and adherence among employees to consistently utilize an onsite facility remains a challenge.^ Purpose. To illustrate if two electronic behavioral journalism newsletters can increase employee participation in a free worksite wellness center.^ Design. A randomized control trial was implemented. ^ Setting. A large petroleum-producing corporation located in Houston, Texas Subjects.70 full or part time employees that had checked into visited the wellness center during September, October, and November 2009. ^ Intervention. Two behavioral journalism newsletters were created based on authentic community member role model interviews. Newsletters were distributed to intervention group participants via company email. Intervention and control group participant’s visits to the wellness center were monitored via a key card check in system at the facility for two weeks following the newsletter intervention.^ Analysis. Count variable statistics were used to identify rate differences between the intervention and control group wellness center visits. A binomial test for equality of proportions was used to identify differences between participants that had at least one visit to the wellness center compared with those with none.^ Results. Both intervention and control groups had a baseline of zero wellness center visits. The control group had a mean visit rate 0.441 and the intervention group had 0.857. A 0.416, almost one half more visits were found among the intervention group.^ Conclusion. This study indicates that behavioral journalism newsletters featuring a role model from within the worksite population can be a cost effective communication method to improve participation in an onsite wellness center. ^