Inclusion Criteria:  Group 1: Healthy subjects  Must be 18 years of age or older  Must be deemed healthy at screening visit, as determined by the physician investigator or nurse practitioner, based on the following assessments at screening: physical examination, medical history and vital signs;  No known history of pre-existing cardiac or respiratory disease or malignancy Have the ability to give written informed consent.  Group 2: Myocardial Infarction  History of percutaneous coronary intervention (PCI) for acute or chronic coronary syndrome (within 3-5 days) Have the ability to give written informed consent Must be 18 years of age or older Hemodynamically stable  Group 3: Sarcoidosis  A suspected or confirmed diagnosis of intrathoracic sarcoidosis Have the ability to give written informed consent Must be 18 years of age or older  Group 4: Malignancy  Suspected or confirmed thoracic, intra-abdominal or pelvic malignancy Have the ability to give written informed consent Must be 18 years of age or older  Exclusion Criteria:  • Electrical implants, such as cardiac pacemaker or perfusion pump;  Ferromagnetic implants such as aneurysm clips, surgical clips, prostheses, artificial hearts, valves with steel parts, metal fragments, shrapnel, metallic tattoos anywhere on the body, tattoos near the eye, or steel implants ferromagnetic objects such as jewelry or metal clips in clothing; eGFR of less than 30 mL/min/1.73 m2 within the past 30 days; Pregnant or breastfeeding (a negative quantitative serum hCG pregnancy test is required for females having child-bearing potential before the subject can participate); Self-reported or documented claustrophobic reactions; Research-related radiation exposure exceeds current Radiology Department guidelines (i.e. 50 mSv in the prior 12 months); Unable to lie comfortably on a bed inside the MR-PET; BMI > 33 (limit of the PET-MRI table); Determined by the investigator(s) to be clinically unsuitable for the study (e.g. based on screening visit and/or during study procedures); Stroke within the last 3 months; Cardiac or major surgery within the last 3 months; History of abnormal heart rate including persistent tachyarrhythmia (heart rate persistently >120 bpm) or bradyarrhythmia (heart rate persistently < 50 bpm); History of atrial premature complexes with daytime pauses > 3s; Contraindications to gadolinium-based contrast agents, including an eGFR < 30 mL/min (myocardial infarction and sarcoidosis patients only). History of myeloproliferative disorder. Age >80 years.