Abstract
PURPOSE: This study leverages the echo planar time-resolved imaging (EPTI) concept in MR fingerprinting (MRF) framework for a new time-resolved MRF (TRMRF) approach, and explores its capability for fast simultaneous quantification of multiple MR parameters including T(1), T(2), T(2)*, proton density, off resonance, and B(1) (+). METHODS: The proposed TRMRF method uses the concept of EPTI to track the signal change along the EPI echo train for T(2)* weighting with a k-t Poisson-based sampling order designed for acquisition. A two-dimensional decomposition algorithm was designed for the image reconstruction, enabling fast and precise subspace modeling. The accuracy of proposed method was evaluated by a T(1)/T(2) phantom. The feasibility was demonstrated through 5 healthy volunteer brain studies. RESULTS: In the phantom studies, T(1), T(2), and T(2)* maps of TRMRF correlated strongly with gold-standard methods. The concordance correlation coefficients are 0.9999, 0.9984 and 0.9978, and R(2)s are 0.9998, 0.9971, and 0.9983. In the in vivo studies, quantitative maps were acquired with 5 healthy volunteers. TRMRF was demonstrated to have comparable results with spiral MRF and gradient-echo EPTI. TRMRF scans using 16, 10, and 6 s per slice were also evaluated to demonstrate the capability of shorter scan times. CONCLUSION: A new approach is proposed to exploit the advantage of EPTI in the MRF framework. We demonstrate in phantom and in vivo experiments that T(1), T(2), T(2)*, proton density, off resonance, and B(1) (+) can be simultaneously quantified within 6 s/slice by TRMRF.