The Influences on Amide Proton Transfer (APT) Signal Metrics at 3T: A Simulation and In-Vitro Study

Amide Proton Transfer MRI shows clinical benefit in glioma imaging. Clinically useful APTw metrics should be sensitive to changes in amide concentration, a potential marker of tumour proliferation, and insensitive to T1 changes. To investigate sensitivity, simulations and in-vitro studies were performed over a range of amide concentrations and T1 values. In-vitro data included two varied concentration series, with and without T1-maintenance, and a constant concentration T1-vaired series. In-vitro results showed APT* had poor sensitivity, MTRrex was most sensitive to concentration and T1, AREX may overcorrect for T1, and MTRasym appears least sensitive to T1 while remaining sensitive to concentration.