[Molecular imaging of apoptosis and necrosis -- basic principles of cell biology and use in oncology]

Soon molecular imaging techniques will play a prominent role in basic scientific research and clinical approaches. In particular, important aspects of medicine such as apoptosis and gene- and stem-cell therapy will play a pivotal role in radiology too. This review presents the basic principles of apoptosis, recent results and future perspectives of apoptosis imaging. Apoptosis or programmed cell death is a precisely regulated, complex cascade of molecular events to eliminate individual cells. Disturbances may lead to diseases like malignancies and neurodegenerative diseases that are of clinical relevance. Several therapeutic strategies in oncology are based on apoptosis induction; conversely, resistance to therapy is indicative of decreased apoptosis induction. Whereas up to now the clinician had to depend exclusively on biopsy specimens to detect apoptosis, the feasibility of non-invasive imaging of this cell-biological phenomenon in vivo opens up new horizons in future. This review focuses on different modifications of this imaging technique, with and without the use of molecular probes (e. g. annexin V, synaptotagmin I), in vitro and in vivo using the various detector systems (like MRI, flow cytometry) currently available. Future perspectives are also addressed.