This is an open label, nonrandomized, dose-escalation trial of a fixed dose of MVT-2163 and varying antibody masses of MVT-5873. The study is designed to identify an optimal dose (total antibody mass) and optimal timing, for tumor imaging using PET scanning. This trial will include a dose escalation and an expansion phase. During the dose escalation portion of the study, a determination of the optimal time to perform PET imaging will be made. Following the identification of the "optimal" dose and timing, an 10 additional subjects will be imaged using the best dose and timing.