Butanol is superior to water for performing positron emission tomography activation studies

[O-15]Butanol has been shown to be superior to [O-15]water for measuring cerebral blood flow with positron emission tomography. This work demonstrates that it is also superior for performing activation studies. Data were collected under three conditions: a visual confrontation animal-naming task, nonsense figure size discrimination, and a nonvisual darkroom control task. Time-activity curves (TAC) were obtained for regions known to be activated by the confrontation naming task to compare absolute uptake and the different kinetics of the two tracers. Also, t statistic maps were calculated from the data of 10 subjects for both tracers and compared for magnitude of change and size of activated regions. Peak uptake in the whole-brain TAC were similar for the two tracers. For all regions and conditions, the washout rate of [O-15]butanol was 41% greater than that of [O-15]water. At a threshold of 0, the [O-15]water and [O-15]butanol percent difference (nonnormalized) and t statistic (global normalization) images are nearly identical, indicating that the same property is being measured with both tracers. The [O-15]butanol parametric images displayed at a threshold of \\t\\ = 5 look similar to the [O-15]water parametric maps displayed at a threshold of \\t\\ = 4, which is consistent with the observation that t statistic values in [O-15]butanol images are generally greater. The t statistic values were equal when the [O-15]butanol parametric map was created from any subset of 6 subjects and the [[O-15]water parametric map was created from all 10 subjects. Fewer subjects need to be studied with [O-15]butanol to reach the same statistical power as an [O-15]water-based study.