Figure 4: Molecular MR imaging of myeloperoxidase. (A) MPO-Gd enhanced MRI in EAE, where more lesions (arrows) are detected with MPO-Gd compared to DTPA-Gd. In addition, delayed enhancement confirms MPO-mediated activation. (B) MPO-Gd enhanced MRI in glioma shows low MPO activity before oncolytic virus administration (day 0). On days 1 and 3, MPO-Gd contrast increased in the peritumor area but is still present in the tumor center. On day 7, most of the enhancement in the center fades, but persistent MPO-Gd enhancement in seen in the periphery. (C) MPO-Gd enhanced MRI on day 3 after stroke correlates well with infarct on H&E staining on histology, where MPO immunostaining is present. (Modified from Chen et al. [45], Breckwoldt et al. [49], and Kleijn et al. [47] with permission.)