[Correlative imaging in cardiology. Principles and clinical application].

Technical progress has engendered a broad spectrum of methods to image cardiac structure, function, and metabolism. Frequently, the imaging tools available provide complementary information. Therefore, methods to integrate image information from different modalities into one common coordinate system are increasingly receiving attention also in cardiology. Currently available technology includes software-based image fusion as well as hardware-based registration of datasets. The latter capitalizes on so-called hybrid cameras combining detectors of different modalities in one gantry. Hardware-based image fusion is, to date, anatomically more accurate than the software-based methodology. However, the anatomic accuracy of both approaches is still far from perfect. This is, in particular, due to artifacts caused by respiratory movements also affecting the heart. The clinical potential of correlative imaging of the heart includes an improvement of accuracy in diagnosing hemodynamically significant coronary artery disease using single-photon emission computed tomography (SPECT). This is due to the possibility to correct myocardial scintigraphy for attenuation artifacts using registered X-ray computerized tomographic (CT) images. The visualization of coronary anatomy and myocardial perfusion in one imaging session using hybrid systems combining CT with positron emission tomography (PET) or SPECT is also an interesting option. Nevertheless, larger clinical trials investigating its usefulness are still missing. The possibility to match structure with radioactivity concentration is essential for approaches to image the molecular composition of atherosclerotic plaques and their stability.