Clinical Cardiovascular Molecular Imaging

Abstract

Molecular imaging holds the promise of becoming a key diagnostic modality in cardiovascular medicine by allowing visualization of specific targets and pathways that precede or underlie changes in morphology, physiology, and function. As such, molecular imaging aims at detecting precursors or early stages of cardiovascular disease and at monitoring and guiding novel, increasingly specific and versatile cardiovascular therapies. Imaging of myocardial metabolism and autonomic innervation are already used in current practice, and a wide variety of other targets and probes is on the horizon. This focused review provides an overview of the opportunities and challenges that molecular imaging faces to fulfill its promises in clinical cardiovascular medicine.Key Words: molecular imaging; cardiovascular disease; myocardial metabolism; myocardial innervation The field of clinical cardiovascular imaging is changing. On the one hand, novel high-resolution techniques such as multislice CT or MRI provide ever-improving images of cardiac and coronary morphology. On the other hand, it becomes clear that the increasing variety and specificity of cardiovascular therapies require increasingly specific diagnostic information and that interrogation of morphology and pathophysiology may not suffice for this purpose (1-3).Furthermore, whereas myocardial perfusion imaging is still the mainstay of cardiovascular radionuclide applications for the diagnostic and prognostic workup of coronary artery disease, several alternative imaging methodologies for noninvasive assessment of perfusion are emerging. At the same time, nuclear imaging technology has progressed significantly toward higher sensitivity and resolution, and an increasing number of molecule-targeted radiotracers is being introduced. These developments indicate an evolution of clinical nuclear imaging beyond the assessment of myocardial perfusion, toward characterization of molecular events on the tissue level.

Biological characterization of F-18-labeled rhodamine B, a potential positron emission tomography perfusion tracer

“…Myocardial infarction is the leading cause of death in western countries, and myocardial perfusion imaging (MPI) is an important tool in the evaluation of myocardial ischemia and infarction [1, 2]. Positron emission tomography (PET) imaging offers several significant advantages over single-photon emission computed tomography (SPECT) imaging in this application including more straightforward attenuation correction, which is important in the evaluation of obese patients and women with large or dense breasts; the ability to measure myocardial blood flow, which is important in the detection of balanced ischemia; and higher spatial resolution [3–5].…”

Assessing Risk and Predicting Outcomes in Coronary Artery Disease: Physiology, Anatomy, or Biology?

“…By imaging specific molecular targets, molecular imaging allows the in vivo characterization and measurement of biologic processes at the cellular level. Thus, it can assess processes related to the basis of disease, in contradistinction to the current paradigm of imaging the end effects of these underlying molecular alterations [11]. This method merges the best of both physiological and biological approaches described above.…”

Cardiac Radionuclide Imaging to Assess Patients With Heart Failure

“…4,5 The pathophysiology is complex involving molecular processes such as abnormal myocyte recycling, myocyte energetics, ventricular structural changes and remodeling, neurohormonal factors both intrinsic and extrinsic to the heart, accelerated apoptosis, genetic mutations, and the contribution of ongoing or recurrent ischemia. [6][7][8][9] Patient evaluation involves numerous tests and procedures, which include a comprehensive history and physical examination, electrocardiogram (ECG), chest x-ray, assessment of left ventricular (LV) function most often with echocardiography but also sometimes with equilibrium radionuclide angiography (also known as radionuclide ventriculography, gated blood pool imaging, and multigated acquisition), search for potential causes and precipitants (eg, systemic problems such as hypothyroidism, valvular abnormalities, myocardial ischemia, and nonischemic insults), blood tests for humoral factors (such as norepinephrine [NE], B-type natriuretic peptide [BNP], and ST2), cardiopulmonary testing, and assessment of potential for dangerous arrhythmias.…”