Imaging metabolic processes in the human heart yields valuable insights into the mechanisms contributing to myocardial pathology and allows assessment of the efficacy of
therapies designed to treat
cardiac disease. Recent advances in
fatty acid (FA) imaging using positron emission tomography (PET) include the development of a method to assess endogenous
triglyceride metabolism and the design of new
fluorine-18 labeled tracers. Studies of patients with diabetes have shown that the heart is resistant to
insulin-mediated
glucose uptake and that metabolism of nonesterified FA is upregulated. Cardiac PET imaging has also recently shown the increase in myocardial FA uptake seen in obese patients can be reversed with
weight loss. And a pilot study of patients with
chronic kidney disease demonstrated that PET imaging can reveal myocardial metabolic alterations that parallel the decline in estimated glomerular filtration rate. Recent advances in FA imaging using single photon emission computed tomography (SPECT) have been accomplished with the tracer β-methyl-p-[(123)I]-iodophenyl-
pentadecanoic acid (
BMIPP). Two meta-analyses showed this imaging technique has a diagnostic accuracy for the detection of obstructive
coronary artery disease that compares favorably with SPECT myocardial perfusion imaging and that
BMIPP imaging yields excellent prognostic data in patients across the spectrum of
coronary artery disease. A recent multicenter study of patients presenting with
acute coronary syndromes found
BMIPP SPECT imaging has greater diagnostic sensitivity than, and enhances the negative predictive value of, clinical assessment alone. Because of their exquisite sensitivity, nuclear imaging techniques facilitate the study of physiologic processes that are the key to our understanding of cardiac metabolism in health and disease.