Assessment of ⁸⁹Zr-DFO-ICOS mAb PET imaging as a potential tool for gastrointestinal GvHD early diagnosis. (A) Heatmap visualization and hierarchical clustering of normalized ICOS PET ROI values (rows) from single transplant recipients (columns). Data shown are pooled from 2 independent experiments. (B) PCA of normalized ICOS PET ROI values. Each arrow represents the relative contribution of each ROI. (C) ROC analysis showing sensitivity against 1 − specificity for distinguishing GvHD mice from other cohorts based on PET ROI values for organs identified by the PCA analysis (spleen, mLN, and intestine) and for muscle as a negative control.