Abstract
In the study of human brain functions, positron emission tomography (PET) makes significant contributions in the form of “activation studies.” Activation studies with [15O]-H2O exploit the phenomenon that activated brain regions have altered perfusion by blood. Statistical comparing of two conditions or groups on a voxel basis yields an activation map. Because blood delivery to the brain is spatially and temporally inhomogeneous, we hypothesized a strong dependency of the activation map on the time periods that are compared. We aimed to systematically chart this influence in order to optimize sensitivity and time resolution.
Methods: We dynamically scanned 11 volunteers with [15O]-H2O while they performed a motor task and a control task. We localized statistical differences between the tasks with a statistical parametric mapping on all possible permutations of consecutive frame summations.
Results: There was robust activation in the cerebellum and sensorimotor cortex and results were statistically most significant for the period 20–50 s. Intervals as short as 10 s also yielded statistically significant brain activations. The size of the activated clusters was strongly dependent on the interval that was compared and the optimal interval was different for the two locations.
Conclusion: Cluster size was indeed strongly influenced by time interval and location in interaction, but cluster significance appeared independent of location. Time periods of 10 s (20–30 or 30–40 s) were feasible, but maximal statistical power was obtained for 20–50 s durations. This knowledge allows maximization of sensitivity of [15O]-H2O PET experiments through rational experimental and statistical design.
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Abbreviations
- ANOVA:
-
Analysis of variance
- ASL:
-
Arterial spin labeling
- CBF:
-
Cerebral blood flow
- fMRI:
-
Functional MRI
- MRI:
-
Magnetic resonance imaging
- PET:
-
Positron emission tomography
- rCBF:
-
Regional CBF
- SPM:
-
Statistical parametric mapping
- SPSS:
-
Statistical package for the social sciences
- TAC:
-
Time-activity curve
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Kortekaas, R., Georgiadis, J.R. (2014). An Investigation of Statistical Power of [15O]-H2O PET Perfusion Imaging: The Influence of Delay and Time Interval. In: Dierckx, R., Otte, A., de Vries, E., van Waarde, A., Leenders, K. (eds) PET and SPECT in Neurology. Springer, Berlin, Heidelberg. https://doi.org/10.1007/978-3-642-54307-4_6
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DOI: https://doi.org/10.1007/978-3-642-54307-4_6
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