Here, we evaluated [89Zr]Zr-DFO*-NCS labeled Adu-8D3 for Aβ imaging and targeting in a preclinical AD mouse model (APP/PS1 transgenic) with the aims a) to evaluate the bispecific Adu-8D3 as a candidate theranostic agent for diagnosis and therapy of AD, and b) to validate the 89Zr-immuno-PET platform as an enabling technology for the development of new antibody-based theranostics for brain exposure and target engagement. The gene discussed is PSEN1; the disease is Alzheimer disease.