Hyperpolarized 13C Pyruvate-MRI and FDG-PET in a Single Exam for the Prognosis of Ischemic Cardiomyopathy

schemic cardiomyopathy (ICM), characterized by compromised blood flow to the heart muscle, demands innovative solutions to accurately assess myocardial viability and metabolic function. While myocardial viability assessment is a widely practiced concept for selecting patients for revascularization, current imaging techniques often require separate sessions and lack holistic functional data.

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This project introduces a novel hybrid multimodal imaging method designed to holistically understand the interplay between metabolism and perfusion in ischemic cardiomyopathy. To achieve this, the study deliberately partitions imaging objectives:

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Myocardial Viability: SPECT MPI and 18F-FDG PET will be used together to assess myocardial viability. FDG-PET exploits the preferential uptake of glucose by metabolically active cells to identify viable myocardial tissue within ischemic regions.

Myocardial Metabolism: HP-13C-MRI provides additional, distinct insights into myocardial metabolism. By tracking the conversion of hyperpolarized 13C-pyruvate into metabolic intermediates like bicarbonate and lactate, this technique allows for the real-time quantification of alterations in cardiac substrate utilization and oxidative metabolism.

The study will enroll a total of 15 human subjects divided into two primary groups:

Healthy Participants (n=6): Individuals with normal left ventricular ejection fraction (LVEF > 0.50) to establish baseline imaging parameters.

ICM Participants (n=9): Patients with advanced ischemic cardiomyopathy and low LVEF (≤ 40%) scheduled for standard-of-care CABG surgery.

Due to current technical constraints regarding multi-nuclear support on hybrid PET-MRI scanners, the imaging modalities will be acquired on separate days within a 3-month period. The ICM cohort will be evaluated at two critical time points: preoperatively before CABG surgery, and longitudinally at one follow-up point 3-6 months post-surgery. Ultimately, this multimodal approach seeks to provide a non-invasive, highly accurate evaluation of disease severity, progression, and postoperative myocardial response to surgical revascularization.

Study Objectives

Primary Objective:

To evaluate myocardial metabolism, viability, and mechanical function in preoperative ICM patients with low LVEF (≤ 40%) scheduled for Coronary Artery Bypass Graft (CABG) using a combined assessment of HP-13C-MRI, FDG-PET, and SPECT MPI. This aims to correlate metabolic and viability data with clinical indicators, providing insights into abnormal cardiac metabolism.

Secondary Objectives:

Secondary Objective 1: To establish baseline metabolic, viability, and mechanical function parameters in healthy subjects with normal LVEF (> 0.50) using the combined HP-13C-MRI, FDG-PET, and SPECT MPI approach, serving as a comparative foundation.

Secondary Objective 2: To longitudinally assess changes in myocardial metabolism, viability, and mechanical function in the ICM patient cohort at 3-6 months post-surgical revascularization (CABG). This aims to elucidate the impact of surgical revascularization on postoperative myocardial changes.

Study Population Description The study population will consist of 12 to 15 human subjects divided into two main groups. The first group includes 6 healthy individuals with a normal left ventricular ejection fraction (LVEF > 0.50). The second group comprises 9 patients with advanced ischemic cardiomyopathy (ICM) and a low LVEF (< 0.40) who are scheduled for standard-of-care Coronary Artery Bypass Graft (CABG) surgery. The study team will aim to recruit a mixed-sex, age-matched population with equal numbers for all metabolic imaging studies.

Ischemic Cardiomyopathy (ICM) Patient Cohort

Inclusion criteria

Male or Female, age 18-80 years. Patient scheduled for Coronary Artery Bypass Surgery as standard of care therapy per clinical guidelines.

Presence of 1 or more stenotic coronary artery vessels. Left Ventricular Ejection Fraction (LVEF) ≤ 40%, or clinical indication for myocardial viability assessment.

Able to tolerate FDG PET/MRI protocol and preparation (e.g., fasting state, glucose regulation).

Medication use within 24 hours of the scan is allowed and will be reported. Negative pregnancy test for females of childbearing age (on the day of scanning).

No known contraindications to 3T MRI, SPECT MPI, or FDG PET.

Exclusion criteria

Male or female, age < 18 or > 80 years of age. Patients not scheduled for CABG or those without confirmed coronary artery disease (CAD).

History of prior myocardial infarction with transmural scar > 50% (based on prior imaging or clinical history).

Patient not eligible for 3T MRI (Any condition or device precluding safe MRI e.g., pacemakers, defibrillators, metal implants), SPECT (significant arrhythmias or hemodynamic instability), or FDG-PET (e.g., severely impaired glucose metabolism).

Positive pregnancy test or females currently breastfeeding (on the day of scanning).

Severe renal impairment (GFR < 30 mL/min) or contraindication to FDG PET tracer.

History of uncontrolled diabetes mellitus (HbA1c > 9%) or inability to achieve stable glucose levels for FDG PET preparation.

Healthy Volunteer Cohort

Inclusion criteria

Male or Female, age 18-80 years. No history of coronary artery disease or diabetes. Eligible for 3T MRI, SPECT, and FDG-PET. Negative pregnancy test for females of childbearing age (on the day of scanning).

Exclusion criteria

History of coronary artery disease, diabetes, or other medical conditions deemed exclusionary by the study team.

Positive pregnancy test or females currently breastfeeding (on the day of scanning).

Contraindications to MRI (e.g., metallic implants, claustrophobia), SPECT MPI, or FDG-PET.