Abstract One factor that impedes the uptake of T 1 and T 2 maps as quantitative imaging biomarkers in clinical radiotherapy is the large bias and disparity in acquired values across different centers and scanners. In this study, it is shown that the T 1 fitting method results in a large dependence of the acquired T 1 on the applied flip angles. A modification of the signal equation is suggested that reduces this variability.The use of mono-exponential fitting in T 2 mapping is responsible for a large bias that is dependent on the echo time spacing in a multi-spin-echo pulse sequence. A bi-exponential fit provides 3 parametric maps with distinct physiological features and results in more reliable and reproducible T 2 maps. QA phantoms that exhibit mono-exponential decay are unable to pick up or assess the impact of non-mono-exponential T 2 decay in tissue. Numerical simulations have been applied to determine the optimum range of imaging parameters to minimize the stochastic and systematic uncertainty in T 1 and T 2 maps.
Deene et al. (Fri,) studied this question.