Molecular imaging in heart failure patients

Abstract

This review focuses on molecular imaging using various radioligands for the tissue characterization of patients with heart failure. ¹²³I-labeled metaiodobenzylguanidine (MIBG), as a marker of adrenergic neuron function, plays an important role in risk stratification in heart failure and may be useful for predicting fatal arrhythmias that may require implantable cardioverter-defibrillator treatment. MIBG has also been used for monitoring treatment effects under various medications. Various positron emission tomography (PET) radioligands have been introduced for the quantitative assessment of presynaptic and postsynaptic neuronal function in vivo. ¹¹C-hydroxyephedrine, like MIBG, has potential for assessing the severity of heart failure. Our PET study using the β-receptor antagonist ¹¹C-CGP 12177 in patients with heart failure showed a reduction of β-receptor density, indicating downregulation, in most of the patients. More studies are needed to confirm the clinical utility of these molecular imaging modalities for the management of heart failure patients.

Keywords: Adrenergic neuronal imaging; Heart failure; Molecular imaging; Positron emission tomography; Radionuclide imaging; Receptor imaging.

Fig. 1

Schema of myocardial nerve terminals and various radioligands used to probe adrenergic functions (Color figure online)

Fig. 2

Anterior images at 4 h after ¹²³I-labeled MIBG administration in a normal control (left), a patient with moderate (middle), and a patient with severe heart failure (right). The heart-to-mediastinal count ratio (H/M) is a marker of MIBG uptake in the heart

Fig. 3

¹¹C-hydroxyephedrine (HED) PET and MIBG SPECT of a normal subject. The HED PET obtained better-quality images in the myocardium as compared to the MIBG SPECT (Color figure online)

Fig. 4

A series of short-axis slices of MIBG SPECT and HED PET images of a patient with heart failure. A moderate reduction of tracer uptake is noted, particularly in the inferior and posterolateral regions (Color figure online)

Fig. 5

Coronal slice (left) and transaxial slice (right) of PET images after the administration of ¹¹C-CGP 12177 in a patient with idiopathic dilated cardiomyopathy (Color figure online)

Fig. 6

Correlation between pretreatment β-receptor density estimated by ¹¹C-CGP 12177 PET and the improvement in left ventricular ejection fraction (ΔLVEF) after long-term β-blocker treatment in patients with idiopathic dilated cardiomyopathy