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Abstract #1529

Pulsed Arterial Spin Labelling Perfusion Imaging at 3T: Estimating the Number of Subjects Required in Common Designs of Clinical Trials

Kevin Murphy1, Ashley D. Harris1, Ana Diukova1, Christopher John Evans1, David J. Lythgoe2, Fernando Zelaya2, Richard G. Wise1

1CUBRIC, School of Psychology, Cardiff University, Cardiff, Wales, United Kingdom; 2Kings College London, Institute of Psychiatry, Centre for Neuroimaging Sciences, DeCrespigny Park, Denmark Hill, London, United Kingdom

Pulsed ASL is likely to find a place in clinical trials and, in particular, the investigation of the action of pharmaceutical agents on neural activity. This study determines the sample sizes necessary to detect regional changes in CBF in common types of clinical trial design: between groups, a two period crossover and within-session. Power calculations suggest that comparatively small cohorts, for example, 7-15 subjects in a crossover can be used to detect a 15 % increase or decrease in CBF. Such sample sizes make feasible the use of CBF measurements in clinical trials of drugs in small cohorts.