Optimization of post-label delay in single-phase arterial spin labeling (ASL) using multi-phase ASL in four-dimensional magnetic resonance angiography.

PURPOSE: To optimize the post-label delay in single-phase arterial spin labeling (SP-ASL) using multi-phase ASL in 4-dimensional magnetic resonance angiography (4D-MRA). METHODS: Ten healthy volunteers (six men, four women; age range, 24-37 years; mean, 29.1) were enrolled. 4D-MRA and SP-ASL were performed on a 3T magnetic resonance imaging (MRI) scanner. Signal intensities in four cerebral arterial territories (anterior cerebral artery, middle cerebral artery, posterior cerebral artery, and whole area) were measured using both 4D-MRA and SP-ASL, and peak time of maximum intensity through each technique was recorded. Regression analysis was used to determine the correlation between the peak times using 4D-MRA and those using SP-ASL, and the regression function obtained was used to estimate the peak time for SP-ASL (optimum post-label delay) from that obtained for 4D-MRA. RESULTS: The peak time in anterior cerebral artery territory for SP-ASL was expressed as 1.19 + 0.30 × (peak time of 4D-MRA) s, ( p = 0.017, r2 = 0.14). The peak time in middle cerebral artery territory for SP-ASL was 0.96 + 0.58 × (peak time of 4D-MRA) s, ( p < 0.001, r2 = 0.32). The peak time in posterior cerebral artery territory for SP-ASL was expressed as 0.92 + 0.58 × (peak time of 4D-MRA) s, ( p < 0.001, r2 = 0.33). The peak time in whole brain for SP-ASL was expressed as 1.04 + 0.46 × (peak time of 4D-MRA) s, ( p < 0.001, r2 = 0.25). CONCLUSION: The peak time values at 4D-MRA showed potential for use in predicting the optimum post-label delay of SP-ASL.

Framing of climate change in newspaper coverage of the East Anglia e-mail scandal.

In late 2009, a series of e-mails related to climate research were made public following the hacking into a server and the e-mail accounts of researchers at the University of East Anglia Climate Research Unit. According to some skeptics of climate change research, the content of those e-mails suggested data were being manipulated, while climate scientists said their words were taken out of context. The news coverage of this scandal provides an opportunity to consider media framing. This study has two aims: to extend previous research using a cluster analysis technique to discern frames in media texts; and to provide insight into newspaper coverage of the scandal, which is often referred to as "Climategate." This study examines the frames present in two British and two American newspapers' coverage of the issue.