Molecular Imaging in Ischemic Heart Disease

Abstract

Purpose of review: The purpose of this paper is to review current and new modalities to image key biological processes in ischemic heart disease and after myocardial infarction non-invasively.

Recent findings: New imaging targets have been developed to detect and quantify myocardial damage after ischemia. Although positron emission tomography (PET) has been leading the development of new probes in the past, continuous improvements of magnetic resonance imaging (MRI) together with the development of new novel MRI contrast agents opens new research avenues including the combination of both PET and MRI to obtain anatomic, functional, and molecular information simultaneously, which is not possible from a single imaging session.

Summary: This review summarizes the state of art of non-invasive molecular imaging of the myocardium during ischemia and after myocardial infarction using PET and MRI. We also describe the different contrast agents that have been developed to image the different phases of cardiac healing and the biological processes associated with each of those phases. Importantly, here we focus on imaging of inflammation as it is the key biological process that orchestrates clearance of dead cells, tissue remodeling, cardiac repair, and future outcome. We also focus on clinical translation of some of the novel contrast agents that have been tested in patients and discuss the need for larger, multi-center patient studies to fully validate the applicability of new imaging probes.

Keywords: Cardiovascular imaging; Inflammation; Ischemic heart disease; Myocardial infarction; Vascular remodeling.

Fig. 1

Summary of the healing phases and biological alterations that occur in the myocardium following an ischemic event

Fig. 2

Representative examples of targeted and non-targeted contrast agents developed to evaluate biological alterations after myocardial infarction using MRI and PET

Fig. 3

a Late gadolinium enhancement (LGE) images using gadofosveset showing contrast uptake in the infarcted area at different time points post-MI. b Trichrome images (first column) and albumin immunohistochemistry (second column) of the infarcted myocardium at different time points post-MI. Black arrow indicates the infarcted area

Fig. 4

a Co-registered ¹H and ¹⁹F short-axis images after PFC administration and macrophage immunohistochemistry (MAC-3) at different time points post-MI. b Representative short-axis images of relaxation rate (R₁) maps after ESMA administration and tropoelastin immunohistochemistry of the hearts at different times points post-MI

Fig. 5

Images from a patient acquired 3 days after acute myocardial infarction and reperfusion. Perfusion SPECT and ¹¹C-methionine PET cardiac images and associated polar maps display diffuse myocardial uptake with elevated ¹¹C-methionine accumulation in the border zone of the perfusion defect. Cardiac magnetic resonance images confirm delayed gadolinium enhancement in the infarct region, with central no-reflow area, alongside with edema in the infarct region on T2-weighted images