Arterial input function in MRI and PET. BJC Cancer Frontier Fund; Washington University Institute of Clinical and Translational Sciences. Quantitative perfusion studies by PET can be limited by difficulties obtaining reliable sampling using arterial lines, which can be painful to patients, and significantly complicate PET experiments. Similarly, quantitative MRI perfusion studies have been challenged by variability of biology and instrumentation: universal scaling coefficients for quantitation have been elusive. This research describes a novel model of cerebral perfusion that incorporates coupled information from PET water studies as well as MRI bolus-tracking. The model predicts PET AIFs that have excellent agreement with independently sampled PET tracer from radial artery cannulation and could be a useful adjunct to perfusion studies on the new generation of PET/MRI scanners. P.I.: Joshua S. Shimony.