Assessment of rodent brain activity using combined [¹⁵O]H₂O-PET and BOLD-fMRI

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• 作者：Hans F. Wehrl ; Petros Martirosian ; Fritz Schick ; Gerald Reischl ; Bernd J. Pichler
• 关键词：[15O]H2O ; water labeled with the radioactive isotope [15O] ; used as a PET tracer ; AIF ; arterial input function ; BOLD ; blood oxygen level dependent effect ; CBF ; cerebral blood flow ; CBV ; cerebral blood volume ; CG ; cingulate cortex ; cl ; contralateral ; CMRO2 ; cerebral metabolic rate of oxygen consumption ; CNR ; contrast to noise ratio ; EPI ; echo planar imaging ; fMRI ; functional magnetic resonance imaging ; FWE ; family-wise error correction ; il ; ipsilateral ; OEF ; oxygen extraction fraction ; PET ; posit
• 刊名：NeuroImage
• 出版年：1 April, 2014
• 年：2014
• 卷：89
• 期：Complete
• 页码：271-279
• 全文大小：1000 K

文摘

The study of brain activation in small animals is of high interest for neurological research. In this study, we proposed a protocol to monitor brain activation in rats following whisker stimulation using the short half-life PET tracer [¹⁵O]H₂O as a marker for cerebral blood flow. This technique enables the study of baseline and activation conditions in fast succession within the same scanning session. Furthermore, we compared the results obtained from PET imaging with additional BOLD-fMRI data acquired in the same animals within the same anesthetic session in immediate succession. Although the maximum relative signal changes during brain activity observed with PET were substantially higher compared to the BOLD-fMRI results, statistical analyses showed that the number of activated voxels in PET was lower compared to the fMRI measurements. Furthermore, there was a difference in the activation centers in both the shape and location between PET and fMRI. The discrepancy in the number of activated voxels could be attributed to a lower overall contrast-to-noise ratio of the PET images compared to BOLD-fMRI, whereas the difference in the spatial location indicates a more fundamental process, involving the different physiological origins of the PET and BOLD-fMRI response. This study clearly demonstrates that [¹⁵O]H₂O-PET activation studies may be performed in small laboratory animals, and shows the complementary nature of studying brain activation using [¹⁵O]H₂O-PET and fMRI.