In vivo quantitative mapping of human mitochondrial cardiac membrane potential: a feasibility study.
PURPOSE
Alteration in mitochondrial membrane potential (ΔΨm) is an important feature of many pathologic processes, including heart failure, cardiotoxicity, ventricular arrhythmia, and myocardial hypertrophy. We present the first in vivo, non-invasive, assessment of regional ΔΨm in the myocardium of normal human subjects.


METHODS
Thirteen healthy subjects were imaged using [18F]-triphenylphosphonium ([18F]TPP+) on a PET/MR scanner. The imaging protocol consisted of a bolus injection of 300 MBq followed by a 120-min infusion of 0.6 MBq/min. A 60 min, dynamic PET acquisition was started 1 h after bolus injection. The extracellular space fraction (fECS) was simultaneously measured using MR T1-mapping images acquired at baseline and 15 min after gadolinium injection with correction for the subject's hematocrit level. Serial venous blood samples were obtained to calculate the plasma tracer concentration. The tissue membrane potential (ΔΨT), a proxy of ΔΨm, was calculated from the myocardial tracer concentration at secular equilibrium, blood concentration, and fECS measurements using a model based on the Nernst equation.


RESULTS
In 13 healthy subjects, average tissue membrane potential (ΔΨT), representing the sum of cellular membrane potential (ΔΨc) and ΔΨm, was - 160.7 ± 3.7 mV, in excellent agreement with previous in vitro assessment.


CONCLUSION
In vivo quantification of the mitochondrial function has the potential to provide new diagnostic and prognostic information for several cardiac diseases as well as allowing therapy monitoring. This feasibility study lays the foundation for further investigations to assess these potential roles. Clinical trial identifier: NCT03265431.
['Pelletier-Galarneau|Matthieu|M|', 'Petibon|Yoann|Y|', 'Ma|Chao|C|', 'Han|Paul|P|', 'Kim|Sally Ji Who|SJW|', 'Detmer|Felicitas J|FJ|', 'Yokell|Daniel|D|', 'Guehl|Nicolas|N|', 'Normandin|Marc|M|', 'El Fakhri|Georges|G|', 'Alpert|Nathaniel M|NM|0000-0002-5487-0234']
D005240:Feasibility Studies D006801:Humans D008564:Membrane Potentials D009206:Myocardium D049268:Positron-Emission Tomography D014057:Tomography, X-Ray Computed
Mitochondrial membrane potential Tissue membrane potential Mitochondria Positron emission tomography Triphenylphosphonium