Rationale:: Altered cardiac energetics is known to play an important role in the progression toward heart failure. A noninvasive method for imaging metabolic markers that could be used in longitudinal studies would be useful for understanding therapeutic approaches that target metabolism. Objective:: To demonstrate the first hyperpolarized ¹³ C metabolic magnetic resonance imaging of the human heart. Methods and Results:: Four healthy subjects underwent conventional proton cardiac magnetic resonance imaging followed by ¹³ C imaging and spectroscopic acquisition immediately after intravenous administration of a 0.1 mmol/kg dose of hyperpolarized [1- ¹³ C]pyruvate. All subjects tolerated the procedure well with no adverse effects reported ≤1 month post procedure. The [1- ¹³ C]pyruvate signal appeared within the chambers but not within the muscle. Imaging of the downstream metabolites showed ¹³ C-bicarbonate signal mainly confined to the left ventricular myocardium, whereas the [1- ¹³ C]lactate signal appeared both within the chambers and in the myocardium. The mean ¹³ C image signal:noise ratio was 115 for [1- ¹³ C]pyruvate, 56 for ¹³ C-bicarbonate, and 53 for [1- ¹³ C]lactate. Conclusions:: These results represent the first ¹³ C images of the human heart. The appearance of ¹³ C-bicarbonate signal after administration of hyperpolarized [1- ¹³ C]pyruvate was readily detected in this healthy cohort (n=4). This shows that assessment of pyruvate metabolism in vivo in humans is feasible using current technology. Clinical Trial Registration:: URL: https://www.clinicaltrials.gov . Unique identifier: NCT02648009.

Although non-invasive perfusion and viability imaging often provide the gateway to coronary revascularisation, current non-invasive imaging methods only report the surrogate markers of inducible hypoperfusion and presence or absence of myocardial scar, rather than actually visualising areas of ischaemia and/or viable myocardium. This may lead to suboptimal revascularisation decisions. Normally respiring (viable) cardiomyocytes convert pyruvate to acetyl-CoA and CO₂/bicarbonate (via pyruvate dehydrogenase), but under ischaemic conditions characteristically shift this conversion to lactate (by lactate dehydrogenase). Imaging pyruvate metabolism thus has the potential to improve upon current imaging techniques. Using the novel hyperpolarisation technique of dynamic nuclear polarisation (DNP), the magnetic resonance signal of injected [1-¹³C]pyruvate can be transiently magnified >10 000 times over that seen in conventional MR spectroscopy, allowing the characteristic metabolic signatures of ischaemia (lactate production) and viability (CO₂/bicarbonate production) to be directly imaged. As such DNP imaging of the downstream metabolism of [1-¹³C]pyruvate could surpass the diagnostic capabilities of contemporary ischaemia and viability testing. Here we review the technique, and with brief reference to the salient biochemistry, discuss its potential applications within cardiology. These include ischaemia and viability testing, and further characterisation of the altered metabolism seen at different stages during the natural history of heart failure.

Purpose: Develop and test an analytic correction method to correct the signal intensity variation caused by the inhomogeneous reception profile of an eight‐channel phased array for hyperpolarized ¹³C imaging.Theory and Methods: Fiducial markers visible in anatomical images were attached to the individual coils to provide three dimensional localization of the receive hardware with respect to the image frame of reference. The coil locations and dimensions were used to numerically model the reception profile using the Biot‐Savart Law. The accuracy of the coil sensitivity estimation was validated with images derived from a homogenous ¹³C phantom. Numerical coil sensitivity estimates were used to perform intensity correction of in vivo hyperpolarized ¹³C cardiac images in pigs.Results: In comparison to the conventional sum‐of‐squares reconstruction, improved signal uniformity was observed in the corrected images.Conclusion: The analytical intensity correction scheme was shown to improve the uniformity of multichannel image reconstruction in hyperpolarized [1‐¹³C]pyruvate and ¹³C‐bicarbonate cardiac MRI. The method is independent of the pulse sequence used for ¹³C data acquisition, simple to implement and does not require additional scan time, making it an attractive technique for multichannel hyperpolarized ¹³C MRI. Magn Reson Med 75:859–865, 2016.