Radionuclide Imaging of Apoptosis in Malignancies: Promise and Pitfalls of 99mTc-Hynic-rh-Annexin V Imaging

Radionuclide detection of apoptosis with of 99mTc-Hynic-rh-Annexin V scintigraphy is an effective tool for in vivo visualisation and monitoring of apoptosis in various malignant tumour. Early therapy-induced increase of the tumour tracer uptake correlates with favourable outcome, whereas stable or decreased uptake correlates with stable disease or tumour progression. Therefore sequential 99mTc-Hynic-rh-Annexin V scintigraphy could be used to predict therapy outcome on a patient-to-patient basis within 48 hours after the start of treatment. However, moderate tumour-to-background ratio and therapy-induced changes in normal tissues could confound image analysis. To assure accurate interpretation of Annexin V scans, the awareness of the biophysiological and biochemical properties contributing to the tracer distribution is essential. In with manuscript we discuss the patterns of Annexin V tumour uptake and illustrate the most frequent pitfalls associated with Annexin V imaging in correlation with CT and MRI imaging.