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On the variability of single-point MPF mapping in the human brain using different Variable Flip Angle T1 mapping protocols

Lucas Soustelle^1,2, Thomas Troalen³, Andreea Hertanu^1,2, Maxime Guye^1,2, Jean-Philippe Ranjeva^1,2, Guillaume Duhamel^1,2, and Olivier M. Girard^1,2
¹Aix Marseille Univ, CNRS, CRMBM, Marseille, France, ²APHM, Hôpital Universitaire Timone, CEMEREM, Marseille, France, ³Siemens Healthcare SAS, Saint-Denis, France

Fast MPF mapping has shown great promises for the evaluation of myelin-related studies while allowing for acceptable scan times. Here we show how the input T₁ map of the single-point method inherently biases MPF values, and that T₁ should be jointly estimated in SP-quantitative MT applications.

Figure 2: Representative axial slices of T₁ (upper row) and MPF (lower row) maps from VFA protocols A to E.

Figure 1: Simulated difference (ΔT₁) between input T₁ (1000 ms) and estimated T₁ by the VFA method as a function of the pulse width for an SPGR sequence without MT effects (orange) or perfect spoiling (yellow), SPGR with MT and realistic spoiling (blue), and SPGR with CSMT pulses with MT and realistic spoiling at reference FA of 30° (purple) and 90° (green). Simulated bias related to protocols A to E are reported. SPGR-CSMT estimations were performed with a pulse duration superior to 1-ms as spectral overlapping was found suitably limited to not disrupt the on-resonance component.