The Imaging Biomarker Ontology describes radiological measurements that characterize biological processes (such as anisotropic water diffusion in a particular tissue region) of imaged subjects (such as neuro-imaging observations) and help clinicians, particularly in the assessment of therapeutic responses and the early prediction of pathologies. IBO reuses several OBO ontologies namely BFO, IAO, PATO, GO, FMA, and OGMS.