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Investigating Cardiac Metabolism in the Isolated Perfused Mouse Heart with Hyperpolarized [1-13C]Pyruvate and 13C/31P NMR Spectroscopy
Published on: April 21, 2023
Metabolic MRI with hyperpolarized [1-13C]pyruvate separates benign oligemia from infarcting penumbra in porcine
Nikolaj Bøgh1, Rie B Olin2, Esben Ss Hansen1
1The MR Research Center, Department of Clinical Medicine, Aarhus University, Aarhus, Denmark.
Abstract:
Acute ischemic stroke patients benefit from reperfusion in a short time-window after debut. Later treatment may be indicated if viable brain tissue is demonstrated and this outweighs the inherent risks of late reperfusion. Magnetic resonance imaging (MRI) with hyperpolarized [1-13C]pyruvate is an emerging technology that directly images metabolism. Here, we investigated its potential to detect viable tissue in ischemic stroke. Stroke was induced in pigs by intracerebral injection of endothelin 1. During ischemia, the rate constant of pyruvate-to-lactate conversion, kPL, was 52% larger in penumbra and 85% larger in the infarct compared to the contralateral hemisphere (P = 0.0001). Within the penumbra, the kPL was 50% higher in the regions that later infarcted compared to non-progressing regions (P = 0.026). After reperfusion, measures of pyruvate-to-lactate conversion were slightly decreased in the infarct compared to contralateral. In addition to metabolic imaging, we used hyperpolarized pyruvate for perfusion-weighted imaging. This was consistent with conventional imaging for assessment of infarct size and blood flow. Lastly, we confirmed the translatability of simultaneous assessment of metabolism and perfusion with hyperpolarized MRI in healthy volunteers. In conclusion, hyperpolarized [1-13C]pyruvate may aid penumbral characterization and increase access to reperfusion therapy for late presenting patients.
Insights
Hyperpolarized [1-13C]pyruvate MRI detects viable brain tissue in ischemic stroke, potentially enabling reperfusion therapy for late-presenting patients. This advanced imaging technique assesses metabolism and perfusion, aiding in treatment decisions.
Area of Science:
- Neuroimaging
- Metabolic imaging
- Stroke research
Background:
- Acute ischemic stroke requires timely reperfusion therapy within a narrow time window.
- Identifying viable brain tissue is crucial for considering late reperfusion, balancing benefits against risks.
- Magnetic resonance imaging (MRI) with hyperpolarized [1-13C]pyruvate offers direct metabolic imaging, an emerging technology for stroke assessment.
Purpose of the Study:
- To investigate the potential of hyperpolarized [1-13C]pyruvate MRI to detect viable brain tissue in ischemic stroke.
- To assess metabolic changes (pyruvate-to-lactate conversion) in ischemic penumbra and infarct zones.
- To evaluate the simultaneous assessment of metabolism and perfusion using hyperpolarized MRI for stroke diagnosis and treatment.
Main Methods:
- Stroke was induced in pigs using intracerebral injection of endothelin 1.
- Hyperpolarized [1-13C]pyruvate MRI was used to measure the rate constant of pyruvate-to-lactate conversion (kPL) during ischemia and after reperfusion.
- Perfusion-weighted imaging was performed using hyperpolarized pyruvate, and results were compared with conventional imaging.
- The translatability of the technique was confirmed in healthy volunteers.
Main Results:
- During ischemia, kPL was significantly higher in the penumbra (52%) and infarct (85%) compared to the contralateral hemisphere (P=0.0001).
- Within the penumbra, regions that later infarcted showed a 50% higher kPL than non-progressing regions (P=0.026).
- After reperfusion, pyruvate-to-lactate conversion decreased slightly in the infarct.
- Hyperpolarized pyruvate perfusion imaging results were consistent with conventional methods for infarct size and blood flow assessment.
Conclusions:
- Hyperpolarized [1-13C]pyruvate MRI can characterize the ischemic penumbra by detecting metabolic activity.
- This technique may help identify patients who could benefit from late reperfusion therapy.
- Simultaneous assessment of metabolism and perfusion with hyperpolarized MRI is translatable to clinical settings, potentially improving stroke management.
