Multi-layer Simultaneous Imaging Technology For Rapid Quantitative Magnetic Resonance Imaging

Compared to contrast-based qualitative MRI,quantitative MRI provides higher sensitivity and better specificity for clarification of in vivo pathological tissue.Quantitative MRI is important for both clinical diagnosis and basic research.Among the quantitative parameters,T1 and T2 are of the most important ones.Generally,the quantification of T1 and T2 requires two separate sequences for acquisition,and both are quite lengthy.On the other hand,MR fingerprinting,as a novel simultaneous multi-parameter mapping method,only takes limited time and achieves perfect spatial coregistration.Thus,it takes off rapidly since it was first conceived in 2013.However,conventional MRF still takes about 10-20s/slice with 60 slices in 10-20 minutes,which is not favorable especially In high resolution applications.In this work,we proposed t-a blipped SMS-MRF acquisition scheme and combined with slice-SENSE reconstruction method to accelerate MRF by 2-fold.To further accelerate SMS-MRF,we proposed a direct-spiral slice-GRAPPA reconstruction method to improve the slice unaliasing procedure and it achieves 3x acceleration at a speed of 3.8s/slice acquisition.Another important parameter in MRI is magnetic susceptibility which provides quantification of in vivo iron content,calcification,and also the vein blood saturation.Wave-CAIPI based fast acquisition and reconstruction method has been proposed and was demonstrated to provide high-quality quantitative susceptibility map in an acceleration factor with 9-15fold at minimal g-factor amplification.To achieve large TE for optimal phase contrast,we proposed to echo shift simultaneous multi-slice in 3D wave-CAIPI acquisition which sustains both speed and better contrast.