RT Journal Article
SR Electronic
T1 A Noninvasive Method for Quantifying Cerebral Metabolic Rate of Oxygen by Hybrid PET/MRI: Validation in a Porcine Model
JF Journal of Nuclear Medicine
JO J Nucl Med
FD Society of Nuclear Medicine
SP 1789
OP 1796
DO 10.2967/jnumed.120.260521
VO 62
IS 12
A1 Narciso, Lucas
A1 Ssali, Tracy
A1 Liu, Linshan
A1 Biernaski, Heather
A1 Butler, John
A1 Morrison, Laura
A1 Hadway, Jennifer
A1 Corsaut, Jeffrey
A1 Hicks, Justin W.
A1 Langham, Michael C.
A1 Wehrli, Felix W.
A1 Iida, Hidehiro
A1 St Lawrence, Keith
YR 2021
UL http://jnm.snmjournals.org/content/62/12/1789.abstract
AB The gold standard for imaging the cerebral metabolic rate of oxygen (CMRO2) is PET; however, it is an invasive and complex procedure that also requires correction for recirculating 15O-H2O and the blood-borne activity. We propose a noninvasive reference-based hybrid PET/MRI method that uses functional MRI techniques to calibrate 15O-O2 PET data. Here, PET/MRI of oxidative metabolism (PMROx) was validated in an animal model by comparison to PET-alone measurements. Additionally, we investigated if the MRI perfusion technique arterial spin labeling (ASL) could be used to further simplify PMROx by replacing 15O-H2O PET, and if the PMROx was sensitive to anesthetic-induced changes in metabolism. Methods: 15O-H2O and 15O-O2 PET data were acquired using a hybrid PET/MR scanner, together with simultaneous functional MRI (OxFlow and ASL), from juvenile pigs (n = 9). Animals were anesthetized with 3% isoflurane and 6 mL/kg/h propofol for the validation experiments, and arterial sampling was performed for PET-alone measurements. PMROx estimates were obtained using whole-brain (WB) CMRO2 from OxFlow and local cerebral blood flow (CBF) from either noninvasive 15O-H2O PET or ASL (PMROxASL). Changes in metabolism were investigated by increasing the propofol infusion to 20 mL/kg/h. Results: Good agreement and correlation were observed between regional CMRO2 measurements from PMROx and PET alone. No significant differences were found between OxFlow and PET-only measurements of WB oxygen extraction fraction (0.30 ± 0.09 and 0.31 ± 0.09) and CBF (54.1 ± 16.7 and 56.6 ± 21.0 mL/100 g/min), or between PMROx and PET-only CMRO2 estimates (1.89 ± 0.16 and 1.81 ± 0.10 mLO2/100 g/min). Moreover, PMROx and PMROxASL were sensitive to propofol-induced reduction in CMRO2. Conclusion: This study provides initial validation of a noninvasive PET/MRI technique that circumvents many of the complexities of PET CMRO2 imaging. PMROx does not require arterial sampling and has the potential to reduce PET imaging to 15O-O2 only; however, future validation involving human participants are required.