1. Departments of Chemistry and Medical Physics & Applied Radiation Sciences, McMaster University, 1280 Main St. West, Hamilton, ON, Canada L8S 4M1, Pfizer Inc., 235 East 42nd Street 3/58, New York, New York 10017, Department of Medicine, McMaster University, 1200 Main St. West, Hamilton, ON, Canada L8M 3Z5, and Department of Radiology, Hamilton Health Sciences, 1200 Main St. West, Hamilton, ON, Canada L8M 3Z5