MB and neoplasm: The 89Zr-labeled GK1.5 N80D cDb, with its rapid blood clearance at low protein doses, yielded high-contrast PET images as early as 2–4 h p.i. In this model (non-tumor bearing C57BL/6J), 89Zr-GK1.5 N80D cDb reached higher uptake in lymphoid tissues than previously reported for the mCD4-Mb minibody (IAB46M2-18) [26].