Cellular imaging: a bright future for 19F-CMR.

In the study entitled ‘Monocyte Imaging after Myocardial Infarction with F-fluorine MRI at 3T—A Pilot Study in explanted porcine hearts’ of this issue of the journal, Boenner and colleagues present several key innovations in the field of F-CMR. With their approach, they were able to specifically visualize and quantify macrophage infiltrations in the ischaemia-reperfused myocardium on a clinical 3T MR system. While the conventional H-proton-based CMR is well known as a most powerful tool for tissue characterization, the F-fluorine technique can boost CMR to the next level, i.e. to that of cellular tissue characterization. Conventional CMR can identify tissue characteristics such as scar vs. normal viable myocardium, necrosis, oedema, ischaemia, iron overload, intramyocardial haemorrhage,microvascular obstruction, and others. 5 However, the understanding of disease processes and the prediction of prognosis may be facilitated by characterizing the cellular composition of the tissue. F-CMR can visualize F-containing molecules, which are incorporated into specific cell types, i.e. it can detect and track F-labeled cells non-invasively in the intact body (Figure 1). As F-fluorine is not present in the human body, F-MRI can detect this label with an excellent contrast-to-noise (CNR), as this technique lacks any background signal. If the magnetic resonance (MR) scanner is acquiring the F signal at its specific resonance frequency, it can detect F-containing molecules [so-called perfluorocarbons (PFC)] similar to nuclear medicine techniques. Unlike nuclear tracers, however, the signal emanating fromthe F-PFC is notdecaying over time, andconsequently, this technique can monitor F signals of migrating cells over hours up to days without radiation.