Contemporary Cardiac SPECT Imaging-Innovations and Best Practices: An Information Statement from the American Society of Nuclear Cardiology.

This information statement from the American Society of Nuclear Cardiology highlights advances in cardiac SPECT imaging and supports the incorporation of new technology and techniques in laboratories performing nuclear cardiology procedures. The document focuses on the application of the latest imaging protocols and the utilization of newer hardware and software options to perform high quality, state-of-the-art SPECT nuclear cardiology procedures. Recommendations for best practices of cardiac SPECT imaging are discussed, highlighting what imaging laboratories should be doing as the standard of care in 2018 to achieve optimal results (based on the ASNC 2018 SPECT guideline [Dorbala et al., J Nucl Cardiol. 2018. https://doi.org/10.1007/s12350-018-1283-y ]).

Stress-only or stress/rest myocardial perfusion imaging in patients undergoing evaluation for bariatric surgery.

BACKGROUND: Bariatric surgery for management of obesity is being used with increasing frequency. Stress testing with myocardial perfusion imaging is often employed as part of the workup prior to anticipated bariatric surgery. The incidence of clinically significant abnormalities on stress MPI performed for this indication, however, has not been established. METHODS AND RESULTS: We retrospectively reviewed a series of 383 consecutive stress MPI studies performed on patients undergoing workup prior to planned bariatric surgery. The study population had a mean age 42 ± 10 years, and was 83% female, with a body mass index of 49 ± 8. The majority of patients (81%) were able to exercise using either the Bruce or Modified Bruce protocol, and 67% underwent stress-only imaging. Overall SPECT MPI findings were normal in 89% and equivocal in 6% of patients. The incidence of abnormal findings on MPI was 5% (3% mild and 2% moderate-to-severe abnormalities). At 1 year, overall survival was 99.5%, with no difference between those with and without MPI abnormalities. Similarly, the incidence of post-operative cardiac events was very low (2%), and mostly due to atrial arrhythmias or borderline elevations of troponin. CONCLUSION: In a typical pre-bariatric surgery population, the incidence of abnormal stress MPI is low. The majority of patients were able to use a stress-only strategy for assessment of perfusion. At 1 year the incidence of adverse cardiovascular outcomes is very low. Additional studies should be focused on determining whether any subgroup of such patients may benefit more from pre-operative stress testing.

Multimodal Imaging for the Diagnosis of Isolated Cardiac Sarcoidosis.

We report a case of isolated cardiac sarcoidosis (CS) diagnosed using a multimodality imaging approach. A patient presented after an out-of-hospital, ventricular fibrillation-mediated cardiac arrest. The use of echocardiography, cardiac magnetic resonance, and fluorodeoxyglucose-positron emission tomography enabled the diagnosis of isolated CS. (Level of Difficulty: Beginner.).

[18F]Fluorodeoxyglucose as a memory marker of transient myocardial ischaemia.

BACKGROUND: Experimental data have shown that glucose utilization increases during acute myocardial ischaemia, and may persist for up to 24 h. Whether fluorodeoxyglucose (FDG) uptake can be imaged as a memory marker of ischaemia in humans is unknown. METHODS: Patients with mild-to-moderate ischaemia on exercise single photon emission computed tomography (SPECT) myocardial perfusion imaging (MPI) underwent repeat exercise testing within 1-2 weeks. Positron emission tomography (PET) was performed after injection of FDG 60 min post-exercise. SPECT and PET images were assessed visually, aided by circumferential profile-based analysis modified for 'hot-spot' imaging. RESULTS: Twelve men with stress SPECT ischaemia (mean age, 69 years; nine with known coronary artery disease) were studied. The mean rate-pressure products for the first (SPECT) and second (FDG PET) exercise tests were similar (22,841+/-7321 vs. 22,680+/-7393 mmHg x bpm, P=NS). Overall, six of 12 patients studied had evidence of FDG uptake. The extent of ischaemia on SPECT was similar in FDG positive and FDG negative patients (summed difference score 10.6+/-6.9 vs. 8.0+/-1.6, P=NS). All patients with a positive FDG scan had uptake in either an ischaemic SPECT region or in a territory with known CAD by angiography. CONCLUSION: Regional myocardial uptake of FDG is enhanced even when injected 1 h post-exercise stress in a subset of patients with ischaemia on exercise SPECT MPI. The ability to image FDG uptake injected 1 h after an ischaemic episode suggests the potential utility of FDG as a memory marker of transient ischaemia.

Radiation Safety in Children With Congenital and Acquired Heart Disease: A Scientific Position Statement on Multimodality Dose Optimization From the Image Gently Alliance.

There is a need for consensus recommendations for ionizing radiation dose optimization during multimodality medical imaging in children with congenital and acquired heart disease (CAHD). These children often have complex diseases and may be exposed to a relatively high cumulative burden of ionizing radiation from medical imaging procedures, including cardiac computed tomography, nuclear cardiology studies, and fluoroscopically guided diagnostic and interventional catheterization and electrophysiology procedures. Although these imaging procedures are all essential to the care of children with CAHD and have contributed to meaningfully improved outcomes in these patients, exposure to ionizing radiation is associated with potential risks, including an increased lifetime attributable risk of cancer. The goal of these recommendations is to encourage informed imaging to achieve appropriate study quality at the lowest achievable dose. Other strategies to improve care include a patient-centered approach to imaging, emphasizing education and informed decision making and programmatic approaches to ensure appropriate dose monitoring. Looking ahead, there is a need for standardization of dose metrics across imaging modalities, so as to encourage comparative effectiveness studies across the spectrum of CAHD in children.

Noninvasive cardiac imaging in the evaluation of suspected acute coronary syndromes.

Optimal management of patients presenting with chest pain to the emergency department is a major challenge, both in terms of a diagnostic dilemma and consumption of resources. The triage of such patients can be aided vastly by the appropriate use of noninvasive imaging. Noninvasive imaging modalities such as echocardiogram, radionuclide perfusion studies, positron emission tomography, cardiac magnetic resonance imaging and computed tomography have all been demonstrated to have favorable diagnostic and prognostic value, with an enhanced sensitivity to detect acute ischemia. A normal noninvasive evaluation in the appropriate clinical setting presents a strong argument against acute ischemia as an etiology of the chest pain. Randomized trials of both rest and stress imaging in the emergency department have confirmed a reduction in unnecessary hospitalizations and cost savings without compromising the safety of the patient. Cardiac magnetic resonance and computed tomography would provide an insight into subendocardial ischemia, the detection of which has previously been difficult, using single-photon emission tomography and echocardiography. In this review, novel hot-spot imaging modalities are discussed including infarct-avid imaging agents and ischemia-avid imaging agents, thus elucidating the pathophysiology of reperfusion-induced cell death. These agents represent work in evolution and are likely to be used routinely in the future as understanding of coronary syndromes and coronary artery disease becomes clearer.

Use of radionuclide imaging in acute coronary syndromes.

The triage of patients presenting to the emergency department (ED) with acute chest pain is a diagnostic challenge. Radionuclide myocardial perfusion imaging has been shown to have favorable diagnostic and prognostic value in this setting, with an excellent early sensitivity to detect acute myocardial infarction (MI) not achieved by other testing modalities. A normal resting perfusion imaging study has been shown to have a negative predictive value of over 99% to exclude MI. Observational and randomized trials of both rest and stress imaging in the ED evaluation of patients with chest pain have demonstrated reductions in unnecessary hospitalizations and cost savings compared with routine care. Perfusion imaging has also been used in risk stratification after MI, and for measurement of infarct size to evaluate reperfusion therapies. Novel "hot spot" imaging radiopharmaceuticals that visualize infarction or ischemia are currently undergoing evaluation and hold promise for future imaging of acute coronary syndromes.