Simultaneously T2 And ADC Estimation From Diffusion-prepared Turbo Spin Echo MRF(DP-TES MRF)

Compared to MRI with specific-contrast weighting,quantitative parametric imaging provides higher sensitivity and better tissue specificity.Furthermore,quantitative imaging can record the evolution of disease quantitatively,making it important for clinical diagnosis and disease treatments.T1,T2 and ADC are of the most commonly used and important ones among quantitative parameters.Generally,the estimation of T1 and T2 needs quite long scan time with conventional methods.ADC estimation is fast when using EPI technique,which however suffers from inevitable image distortion and artifacts,making it hard for multi-parametric analysis.Recently,MR Fingerprinting,as a research hotspot in quantitative MRI,has been realized for simultaneous T1 and T2 mapping in a single scan within 10s.However,existing MRF techniques are only confined to T1 and T2 estimation without the consideration of ADC effect.Besides,the T2 result from commonly used FISP-MRF is less robust when compared with golden method.In this work,a novel diffusion-prepared turbo spin echo sequence combined with MRF,dubbed "DP-TSE MRF",was introduced to produce quantitative ADC maps along with T2 estimation within a single sequence,aiming to overcome the two shortcomings aforementioned of existing MRF technology.Firstly,a sequence was redesigned to simultaneously estimate ADC and T2 value.We incorporated DP and TSE modules for both diffusion and T2 sensitivity.Also,we divided the whole sequence into different parts,where the sequence parameters varied along measurements.A sliding window reconstruction and signal rearrangement methods were used in data processing.Dictionary was created based on the novel sequence parameters.The proposed method was validated in both phantom and in-vivo experiments,and the results were also compared with standard methods.In phantom experiment,the accuracy of parameter recognition with the novel method was tested among different T2 and ADC values and compared with the gold-standard methods.In the in-vivo experiment,the proposed method was investigated to detect the fiber trajectories in three orthogonal directions,and was compared with standard EPI method for ADC and FISP-MRF in T2 recognition.The results show that DP-TSE MRF provides more precise T2 estimation than FISP-MRF,and a relatively good recognition in ADC estimation.