Multimodal Imaging of Zr-89 Labeled Antibody

MicroPET and microCT imaging was performed as described previously [19 (link)]. A range of ⁸⁹ZrmalDFO-GK1.5 cDb doses (2–40 µg; 0.26–5.2 MBq) were prepared in 100 µl saline and injected intravenously into mice. Mice were anesthetized with 2% isoflurane and PET and CT images were acquired 20 h post-injection. MicroPET images were acquired on an Inveon PET (Siemens) scanner for 600 sec and reconstructed using a 3D-ordered subset expectation maximization (OSEM) algorithm with 2 iterations, followed by maximum a posteriori (MAP) with 18 iterations (beta=0.1) with a zoom factor of 2.1, without attenuation correction. Whole-body CT images were acquired using the MicroCAT II (Imtek) scanner, with the x-ray source based at 70 kVp and 500 µA and an exposure time of 180 s (0.5 s per projection). A Feldkamp reconstruction algorithm was applied [21 ]. A Medical Imaging Data Examiner (AMIDE) software (http://amide.sourceforge.net) was used to view PET and CT scans. Images are displayed as 25 mm (coronal) or 2 mm (transverse) maximum intensity projections (MIP). Following the final PET/CT scan, ex vivo biodistribution was performed. Organs were removed, weighed, and counted in a Wizard 3” automatic gamma counter (Perkin Elmer) and the decay-corrected percent injected dose/gram (% ID/g) for each organ was calculated.