Magnetic resonance fingerprinting using echo‐planar imaging: Joint quantification of T 1 1 and T 2 ? T 2 ? T 2 ? T T 2 2 ? ? relaxation times

摘要

Purpose To develop an implementation of the magnetic resonance fingerprinting (MRF) paradigm for quantitative imaging using echo‐planar imaging (EPI) for simultaneous assessment of T 1 and T 2 ? . Methods The proposed MRF method (MRF‐EPI) is based on the acquisition of 160 gradient‐spoiled EPI images with rapid, parallel‐imaging accelerated, Cartesian readout and a measurement time of 10 s per slice. Contrast variation is induced using an initial inversion pulse, and varying the flip angles, echo times, and repetition times throughout the sequence. Joint quantification of T 1 and T 2 ? is performed using dictionary matching with integrated B 1 + correction. The quantification accuracy of the method was validated in phantom scans and in vivo in 6 healthy subjects. Results Joint T 1 and T 2 ? parameter maps acquired with MRF‐EPI in phantoms are in good agreement with reference measurements, showing deviations under 5% and 4% for T 1 and T 2 ? , respectively. In vivo baseline images were visually free of artifacts. In vivo relaxation times are in good agreement with gold‐standard techniques (deviation T 1 : 4?±?2%, T 2 ? : 4?±?5%). The visual quality was comparable to the in vivo gold standard, despite substantially shortened scan times. Conclusion The proposed MRF‐EPI method provides fast and accurate T 1 and T 2 ? quantification. This approach offers a rapid supplement to the non‐Cartesian MRF portfolio, with potentially increased usability and robustness. Magn Reson Med 78:1724–1733, 2017. ? 2016 International Society for Magnetic Resonance in Medicine.