Clinical use of nuclear cardiology in the assessment of heart failure

Abstract

A nuclear cardiology test is the most commonly performed non-invasive cardiac imaging test in patients with heart failure, and it plays a pivotal role in their assessment and management. Quantitative gated single positron emission computed tomography (QGS) is used to assess quantitatively cardiac volume, left ventricular ejection fraction (LVEF), stroke volume, and cardiac diastolic function. Resting and stress myocardial perfusion imaging, with exercise or pharmacologic stress, plays a fundamental role in distinguishing ischemic from non-ischemic etiology of heart failure, and in demonstrating myocardial viability. Diastolic heart failure also termed as heart failure with a preserved LVEF is readily identified by nuclear cardiology techniques and can accurately be estimated by peak filling rate (PFR) and time to PFR. Movement of the left ventricle can also be readily assessed by QGS, with newer techniques such as three-dimensional, wall thickening evaluation aiding its assessment. Myocardial perfusion imaging is also commonly used to identify candidates for implantable cardiac defibrillator and cardiac resynchronization therapies. Neurotransmitter imaging using (123)I-metaiodobenzylguanidine offers prognostic information in patients with heart failure. Metabolism and function in the heart are closely related, and energy substrate metabolism is a potential target of medical therapies to improve cardiac function in patients with heart failure. Cardiac metabolic imaging using (123)I-15-(p-iodophenyl)3-R, S-methylpentadecacoic acid is a commonly used tracer in clinical studies to diagnose metabolic heart failure. Nuclear cardiology tests, including neurotransmitter imaging and metabolic imaging, are now easily preformed with new tracers to refine heart failure diagnosis. Nuclear cardiology studies contribute significantly to guiding management decisions for identifying cardiac risk in patients with heart failure.

Keywords: Diastolic function; Metaiodobenzylguanidine; Prognosis; Quantitative gated single photon emission computed tomography; β-methyl-p-iodophenyl-pentadecanoic acid.

Figure 1

Single photon emission computed tomography image of exercise ²⁰¹Tl scintigraphy in a 70-year-old man. The stress image (upper panel) shows decreased perfusion in the infero-lateral region. There is a redistribution of the tracer in the rest image (lower panel), which indicates exercise-induced myocardial ischemia in the infero-lateral region of the left ventricle.

Figure 2

Post-stress left ventricular dysfunction detected by quantitative gated single positron emission computed tomography analysis. Transient ischemic dilatation was observed in a patient with multi-vessel disease. ESV: End-systolic volume; EDV: End-diastolic volume; EF: Ejection fraction.

Figure 3

A patient with heart failure had ¹²³I-MIBG imaging and was treated with β-blockers. After treatment, ¹²³I-MIBG H/M ratio and washout rate (WR) were improved.

Figure 4

Scintigraphic features of Takotsubo cardiomyopathy are depicted. Bull’s eye maps of ^99mTc-sestamibi (MIBI), ¹²³I-MIBG and ¹²³I-β-methyl-p-iodophenyl-pentadecanoic acid (BMIPP) are shown. Both ¹²³I-MIBG and ¹²³I-BMIPP images show reduced uptake in the apical segment of the myocardium, which are typical features of the disease.

Figure 5

Fusion image reveals that the ischemic area in the basal antero-lateral region shown by single photon emission computed tomography image is perfused by small vessels or has no corresponding artery assessed as imaging artifacts. Thus, the fusion image has increased diagnostic confidence for the detection of the culprit lesion in patients with coronary artery bypass grafting.