In Vitro and In Vivo Detection of Drug-induced Apoptosis Using Annexin V-conjugated Ultrasmall Superparamagnetic Iron Oxide (USPIO): A Pilot Study

PURPOSE: To investigate the binding potential of newly developed Annexin V-conjugated ultrasmall superparamagnetic iron oxide (V-USPIO) for detection of drug-induced apoptosis in vitro and in vivo. As a control, MRI was also obtained at 4 h after injection of USPIO without Annexin V. The ratio of tumor signal intensity (SI) on post-MRI for that on pre-MRI (Post/Pre-SI ratio) was calculated. After scanning, tumors were resected for pathological analysis to evaluate the distribution of iron and apoptotic cells. CONCLUSION: A newly developed Annexin V-USPIO could have the potential for detection of drug-induced apoptosis.