In 2010, Hindryckx et al. used [18F]FDG to monitor the common used dextrose sodium sulphate (DSS)-induced mouse model of IBD.289 However, the physiological uptake of [18F]FDG in the gut is highly variable, limiting its application in IBD.290 In 2018, Freise et al. developed [89Zr]Zr-DFO-GK1.5 cDb, a fragment of an anti-mouse CD4 antibody derived from the GK1.5 hybridoma. The gene discussed is CD4; the disease is inflammatory bowel disease.