Simultaneous PET/MRI Imaging During Mouse Cerebral Hypoxia-ischemia

Abstract

Dynamic changes in tissue water diffusion and glucose metabolism occur during and after hypoxia in cerebral hypoxia-ischemia reflecting a bioenergetics disturbance in affected cells. Diffusion weighted magnetic resonance imaging (MRI) identifies regions that are damaged, potentially irreversibly, by hypoxia-ischemia. Alterations in glucose utilization in the affected tissue may be detectable by positron emission tomography (PET) imaging of 2-deoxy-2-( 18 F)fluoro-ᴅ-glucose ([ 18 F]FDG) uptake. Due to the rapid and variable nature of injury in this animal model, acquisition of both modes of data must be performed simultaneously in order to meaningfully correlate PET and MRI data. In addition, interanimal variability in the hypoxic-ischemic injury due to vascular differences limits the ability to analyze multi-modal data and observe changes to a group-wise approach if data is not acquired simultaneously in individual subjects. The method presented here allows one to acquire both diffusion-weighted MRI and [ 18 F]FDG uptake data in the same animal before, during, and after the hypoxic challenge in order to interrogate immediate physiological changes. Video LinkThe video component of this article can be found at

Optimization of a depth of interaction encoding PET block detector for a PET/MRI insert

“…Preclinical MRI, especially, is becoming a fundamental tool used to supplement PET data with additional morphological and functional information. Key use cases for combined PET/MRI include quantitative and dynamic studies that utilize synchronous acquisition of the two modalities, requiring improved detection sensitivity for PET imaging (Wehrl et al 2013, Ouyang et al 2014, Ouyang et al 2015). The wide availability of commercial MR compatible photodetectors, specifically SiPMs, has improved the feasibility of developing MR compatible PET systems, contributing to their increasing popularity and use (Roncali and Cherry 2011).…”

“…One promising application driving the development of simultaneous PET/MRI as a research tool is measurement of multiple functional aspects of a single transient process in vivo (Wehrl et al 2013, Ouyang et al 2015, Ko et al 2016b). Measurement of transient processes often requires that the target biology be imaged dynamically to extract meaningful information.…”