Description

Positron emission tomography (PET) scans use positron-emitting radionuclide tracers, which simultaneously emit 2 high-energy photons in opposite directions. These photons can be simultaneously detected (referred to as coincidence detection) by a PET scanner, comprising multiple stationary detectors that encircle the thorax. Compared with single photon emission computed tomography (SPECT) scans, coincidence detection offers a greater spatial resolution. PET has been investigated as an option to diagnose and evaluate patients with cardiac conditions such as coronary artery disease, left ventricular dysfunction, and cardiac sarcoidosis.

Summary of evidence - Intro

For individuals with suspected coronary artery disease and an indeterminate SPECT scan who receive cardiac PET perfusion imaging, the evidence includes several systematic reviews and meta-analyses. Relevant outcomes are test accuracy, disease-specific survival, morbid events, and resource utilization. Meta-analyses of studies in which PET results were compared with results from coronary angiography and fractional flow reserve have shown that PET is comparable in diagnostic accuracy to these referent standards. In meta-analyses of studies that included clinical outcomes such as mortality and adverse cardiac events, results have shown that PET is a useful prognostic tool. Meta-analyses have also found PET to have greater sensitivity or specificity compared to SPECT, which provides further evidence to support the use of PET when SPECT is indeterminate. The evidence is sufficient to determine that the technology results in an improvement in the net health outcome.

For individuals with left ventricular dysfunction who are potential candidates for revascularization who receive cardiac PET scanning to assess myocardial viability, the evidence includes a large randomized controlled trial with long-term follow-up and several small trials comparing SPECT with PET. Relevant outcomes are test accuracy, disease-specific survival, and morbid events. In the large controlled trial, patients with left ventricular dysfunction were randomized to care from physicians who would make management decisions based on PET images or to care from physicians who would make management decisions without PET images. Physicians who would make management decisions without PET images were permitted to administer other tests for myocardial viability, although details were not available as to which tests were performed, if any. At 1- and 5-year follow-ups, patients who received care indicated by the PET images were at a decreased risk for cardiac death, myocardial infarction, and recurrent hospital stays compared with patients who did not. One trial comparing SPECT with PET showed that both modalities were useful in managing patients considering revascularization; however, this trial was small and may have been underpowered to detect a difference in outcomes. Evidence-based recommendations from specialty societies have concluded that PET scanning is at least as good as, and likely superior, to SPECT scanning for this purpose. The evidence is sufficient to determine that the technology results in an improvement in the net health outcome.

For individuals with coronary artery disease who require myocardial blood flow quantification for cardiac event risk stratification who receive quantitative cardiac PET perfusion imaging, the evidence includes observational studies and meta-analyses of those observational studies. Relevant outcomes are disease-specific survival and morbid events. Studies evaluating PET-derived quantitative myocardial blood flow and myocardial flow reserve have found that impaired myocardial flow reserve is significantly associated with an increase in all-cause mortality and can assist in identifying patients who may receive a survival benefit with early revascularization compared to medical therapy. The benefits observed in these single-center studies may be difficult to generalize due to differences in protocols, methodologies, and thresholds for intervention among institutions. These methods are considered to be in a developmental stage for clinical use. Large, prospective clinical trials are needed to better define the potential utility of myocardial blood flow quantification. The evidence is insufficient to determine that the technology results in an improvement in the net health outcome.

For individuals with suspected cardiac sarcoidosis who cannot undergo magnetic resonance imaging (MRI), the evidence includes nonrandomized studies and meta-analyses of observational studies. Relevant outcomes are disease-specific survival, test accuracy, and morbid events. Currently, there is no criterion standard for diagnosing cardiac sarcoidosis. A combination of clinical evaluations and results from imaging techniques, usually MRI, are used during the clinician's assessment. Meta-analyses have found moderate sensitivity and specificity of fluorine 18-labeled fluorodeoxyglucose PET or PET/computed tomography for diagnosis of cardiac sarcoidosis. Two small studies have evaluated variations in PET techniques such as using a radiolabeled somatostatin receptor ligand and adding a simultaneous cardiac MRI. Reported results were positive in these small studies, showing concordance between MRI and PET, but larger samples are needed to confirm the usefulness of these changes. While MRI is the technique most often used to evaluate cardiac sarcoidosis, for patients who are unable to undergo MRI (eg, patients with a metal implant), evidence supports PET scanning as the preferred test. The evidence is sufficient to determine that the technology results in an improvement in the net health outcome.

Cardiac positron emission tomography (PET) scanning may be considered medically necessary to assess myocardial perfusion and thus diagnose coronary artery disease in individuals with indeterminate single photon emission computed tomography (SPECT) scan; or in individuals for whom SPECT could be reasonably expected to be suboptimal in quality on the basis of body habitus.

Cardiac PET scanning may be considered medically necessary to assess myocardial viability in individuals with severe left ventricular dysfunction as a technique to determine candidacy for a revascularization procedure. (See the Background section regarding the relative effectiveness of PET and SPECT scanning.)

Cardiac PET scanning is investigational for quantification of myocardial blood flow for cardiac event risk stratification in individuals diagnosed with coronary artery disease.

Cardiac PET scanning may be considered medically necessary for diagnosing cardiac sarcoidosis in individuals who are unable to undergo magnetic resonance imaging. Examples of individuals who are unable to undergo magnetic resonance imaging include, but are not limited to, individuals with pacemakers, automatic implanted cardioverter defibrillators, or other metal implants