Enhanced phase-sensitive SSFP reconstruction for fat-water separation in phased-array acquisitions

Purpose: To propose and assess a method to improve the reliability of phase-sensitive fat–water separation for phased-array balanced steady-state free precession (bSSFP) acquisitions. Phase-sensitive steady-state free precession (PS-SSFP) is an efficient fat–water separation technique that detects the phase difference between neighboring bands in the bSSFP magnetization profile. However, large spatial variations in the sensitivity profiles of phased-array coils can lead to noisy phase estimates away from the coil centers, compromising tissue classification. Materials and Methods: We first perform region-growing phase correction in individual coil images via unsupervised selection of a fat-voxel seed near the peak of each coil's sensitivity profile. We then use an optimal linear combination of phase-corrected images to segregate fat and water signals. The proposed method was demonstrated on noncontrast-enhanced SSFP angiograms of the thigh, lower leg, and foot acquired at 1.5T using an 8-channel coil. Individual coil PS-SSFP with a common seed selection for all coils, individual coil PS-SSFP with coil-wise seed selection, PS-SSFP after coil combination, and IDEAL reconstructions were also performed. Water images reconstructed via PS-SSFP methods were compared in terms of the level of fat suppression and the similarity to reference IDEAL images (signed-rank test). Results: While tissue misclassification was broadly evident across regular PS-SSFP images, the proposed method achieved significantly higher levels of fat suppression (P < 0.005) and increased similarity to reference IDEAL images (P < 0.005). Conclusion: The proposed method enhances fat–water separation in phased-array acquisitions by producing improved phase estimates across the imaging volume. J. Magn. Reson. Imaging 2016;44:148–157. © 2015 Wiley Periodicals, Inc

Scenario-driven roadmapping for technology foresight

This paper presents a novel method for using scenarios for technology foresight. Technology foresight is a well-established discipline, practised with popular foresight methods such as roadmapping and scenario planning. Applying each foresight method reveals limitations in practice, some of which can be addressed by combining methods. Following calls for combining foresight methods, and past attempts to integrate scenario planning and technology roadmapping, we propose a novel method for their combination. The resulting method — ‘scenario-driven roadmapping’ differs in: i) using scenario planning first to identify plausible images of the general environment and then using the scenarios for technology roadmapping; and ii) taking advantage of ‘flex points’ – critical developments which would signal transitions along particular pathways – to create a ‘radar’ to support effective monitoring of the environment over time. This new combined method takes advantage of the strengths of both methods, while addressing their limitations. A case study vignette centred on the work of a special interest group for Radio Frequency IDentification (RFID) technology adoption in the English National Health Service is presented to illustrate and reflect upon the use in practice of the ‘scenario-driven roadmapping’ method. Participants were able to develop a detailed technology roadmap with clear ‘flex points’ helping to connect present circumstances with pathways towards future scenarios. We report on how participants engaged with the scenario-driven method and outcomes achieved were recorded

Age- and region-specific hepatitis B prevalence in Turkey estimated using generalized linear mixed models: a systematic review

Toy M, Önder FO, Wörmann T, et al. Age- and region-specific hepatitis B prevalence in Turkey estimated using generalized linear mixed models: a systematic review. BMC infectious diseases. 2011;11(1): 337.BACKGROUND: To provide a clear picture of the current hepatitis B situation, the authors performed a systematic review to estimate the age- and region-specific prevalence of chronic hepatitis B (CHB) in Turkey. METHODS: A total of 339 studies with original data on the prevalence of hepatitis B surface antigen (HBsAg) in Turkey and published between 1999 and 2009 were identified through a search of electronic databases, by reviewing citations, and by writing to authors. After a critical assessment, the authors included 129 studies, divided into categories: 'age-specific'; 'region-specific'; and 'specific population group'. To account for the differences among the studies, a generalized linear mixed model was used to estimate the overall prevalence across all age groups and regions. For specific population groups, the authors calculated the weighted mean prevalence. RESULTS: The estimated overall population prevalence was 4.57, 95% confidence interval (CI): 3.58, 5.76, and the estimated total number of CHB cases was about 3.3 million. The outcomes of the age-specific groups varied from 2.84, (95% CI: 2.60, 3.10) for the 0-14-year olds to 6.36 (95% CI: 5.83, 6.90) in the 25-34-year-old group. CONCLUSION: There are large age-group and regional differences in CHB prevalence in Turkey, where CHB remains a serious health problem