ERBB2 and neoplasm: The comparatively short half-life of 64Cu (t1/2 = 12.7 h) means that the radionuclide has decayed before the intact antibody achieves optimal biodistribution (ca. 4–5 days), and the small size the F(ab')2 fragments gives poor tumor-to-background tissue contrast ratios.[1], [2] In efforts to overcome these limitations in radiotracer design, Orlova et al. [28] and Kramer-Marek et al. [29] explored the potential of 124I- and 18F-labeled trastuzumab affibodies for measuring HER2/neu expression, respectively.