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

[¹⁵O]Butanol has been shown to be superior to [¹⁵O]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 [¹⁵O]butanol was 41% greater than that of [¹⁵O] water. At a threshold of 0, the [¹⁵O] water and [¹⁵O]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 [¹⁵O]butanol parametric images displayed at a threshold of |t| = 5 look similar to the [¹⁵O] water parametric maps displayed at a threshold of |t| = 4, which is consistent with the observation that t statistic values in [¹⁵O]butanol images are generally greater. The t statistic values were equal when the [¹⁵O]butanol parametric map was created from any subset of 6 subjects and the [¹⁵O]water parametric map was created from all 10 subjects. Fewer subjects need to be studied with [¹⁵O]butanol to reach the same statistical power as an [¹⁵O]water-based study.