Kulpanovich Alexey, Tal Assaf
Department of Chemical Physics, Weizmann Institute of Science, Rehovot, Israel.
NMR Biomed. 2018 Nov;31(11):e4001. doi: 10.1002/nbm.4001. Epub 2018 Sep 3.
Magnetic resonance fingerprinting has been proposed as a method for undersampling k-space while simultaneously yielding multiparametric tissue maps. In the context of single voxel spectroscopy, fingerprinting can provide a unified framework for parameter estimation. We demonstrate the utility of such a magnetic resonance spectroscopic fingerprinting (MRSF) framework for simultaneously quantifying metabolite concentrations, T and T relaxation times and transmit inhomogeneity for major singlets of N-acetylaspartate, creatine and choline. This is achieved by varying T , T and the flip angle of the first pulse in a PRESS sequence between successive excitations (i.e. successive T values). The need for multiparametric schemes such as MRSF for accurate medical diagnostics is demonstrated with the aid of realistic in vivo simulations; these show that certain schemes lead to substantial increases to the area under receiver operating characteristics of metabolite concentrations, when viewed as classifiers of pathologies. Numerical simulations and phantom and in vivo experiments using several different schedules of variable length demonstrate superior precision and accuracy for metabolite concentrations and longitudinal relaxation, and similar performance for the quantification of transverse relaxation.
磁共振指纹识别已被提议作为一种欠采样k空间的方法,同时生成多参数组织图谱。在单体素光谱学的背景下,指纹识别可为参数估计提供一个统一框架。我们展示了这样一个磁共振光谱指纹识别(MRSF)框架的效用,它可同时量化代谢物浓度、T1和T2弛豫时间以及N-乙酰天门冬氨酸、肌酸和胆碱主要单峰的发射不均匀性。这是通过在连续激发(即连续的T1值)之间改变PRESS序列中第一个脉冲的T1、T2和翻转角来实现的。借助逼真的体内模拟证明了诸如MRSF这样的多参数方案对于准确医学诊断的必要性;这些模拟表明,当将代谢物浓度视为病理分类器时,某些方案会导致接收器操作特征曲线下面积大幅增加。使用几种不同可变长度方案的数值模拟、体模和体内实验表明,代谢物浓度和纵向弛豫具有卓越的精度和准确性,横向弛豫量化的性能相似。