Comparison between a new quantitative APT parameter APT_T1 by solving Bloch equation of multiple pool model and MTR_Rex

Motivation: Quantitative parameter is required for APT. Goal(s): Comparing a new quantitative APT parameter APT_T1 (the ratio of APT transfer rate to longitudinal relaxation rate) with MTR_RexApproach: APT_T1 was calculated by solving the Bloch equation of multiple pool model. APT_T1 was compared with MTR_Rex in numerical simulation and a clinical case. Results: MTR_asym was influenced by rNOE and differed from MTR_Rex. On the other hand, although calculation methods of APT_T1 and MTR_Rex were different, APT_T1 approximated MTR_Rex under the condition with strong CEST RF. APT_T1 and MTR_Rex can be used as complementary quantitative APT parameters. Impact: A new quantitative APT parameter APT_T1 was calculated by solving Bloch equation of multiple pool model. APT_T1 approximated MTR_Rex under the condition with strong and long CEST RF with 100% duty cycle.