In general, the failing human heart is characterized by a selective reduction in β1- adrenoceptors (β1-ARs) without change in β2-AR density. Medical imaging techniques, either single photon emission computed tomography (SPECT) or positron emission tomography (PET) with appropriate radioligands, offer the possibility of assessing β- adrenoceptor density non-invasively in humans. To date, neither a SPECT nor a PET ...