A1 Refereed original research article in a scientific journal
A non-invasive reference-based method for imaging the cerebral metabolic rate of oxygen by PET/MR: theory and error analysis
Authors: Narciso Lucas, Ssali Tracy, Iida Hidehiro, St Lawrence Keith
Publisher: IOP PUBLISHING LTD
Publication year: 2021
Journal: Physics in Medicine and Biology
Journal name in source: PHYSICS IN MEDICINE AND BIOLOGY
Journal acronym: PHYS MED BIOL
Article number: ARTN 065009
Volume: 66
Issue: 6
Number of pages: 14
ISSN: 0031-9155
DOI: https://doi.org/10.1088/1361-6560/abe737
Self-archived copy’s web address: https://research.utu.fi/converis/portal/detail/Publication/53665737
Positron emission tomography (PET) remains the gold standard for quantitative imaging of the cerebral metabolic rate of oxygen (CMRO2); however, it is an invasive and complex procedure that requires accounting for recirculating [O-15]H2O (RW) and the cerebral blood volume (CBV). This study presents a non-invasive reference-based technique for imaging CMRO2 that was developed for PET/magnetic resonance imaging (MRI) with the goal of simplifying the PET procedure while maintaining its ability to quantify metabolism. The approach is to use whole-brain (WB) measurements of oxygen extraction fraction (OEF) and cerebral blood flow (CBF) to calibrate [O-15]O-2-PET data, thereby avoiding the need for invasive arterial sampling. Here we present the theoretical framework, along with error analyses, sensitivity to PET noise and inaccuracies in input parameters, and initial assessment on PET data acquired from healthy participants. Simulations showed that neglecting RW and CBV corrections caused errors in CMRO2 of less than 10% for changes in regional OEF of 25%. These predictions were supported by applying the reference-based approach to PET data, which resulted in remarkably similar CMRO2 images to those generated by analyzing the same data using a modeling approach that incorporated the arterial input functions and corrected for CBV contributions. Significant correlations were observed between regional CMRO2 values from the two techniques (slope = 1.00 0.04, R-2 > 0.98) with no significant differences found for integration times of 3 and 5 min. In summary, results demonstrate the feasibility of producing quantitative CMRO2 images by PET/MRI without the need for invasive blood sampling.
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