- Unable to receive gadopentate contrast agent injection because of contraindications. A study subject who displays any sign of an allergic reaction to the contrast agent will be withdrawn from the dGEMRIC part of the protocol and will not receive any subsequent contrast agent injection. The subject may continue to complete the remainder fo the study, which includes MR morphometry scan, collection of blood and urine sample for biomarker assays, and completion of study questionnaires.