Statton Ben K, Smith Joely, Finnegan Mary E, Koerzdoerfer Gregor, Quest Rebecca A, Grech-Sollars Matthew
Medical Research Council, London Institute of Medical Sciences, Imperial College London, London, United Kingdom.
Department of Imaging, Imperial College Healthcare NHS Trust, London, United Kingdom.
Magn Reson Med. 2022 Mar;87(3):1446-1460. doi: 10.1002/mrm.29065. Epub 2021 Nov 9.
Before MR fingerprinting (MRF) can be adopted clinically, the derived quantitative values must be proven accurate and repeatable over a range of T and T values and temperatures. Correct assessment of accuracy and precision as well as comparison between measurements can only be performed when temperature is either controlled or corrected for. The purpose of this study was to investigate the temperature dependence of T and T MRF values and evaluate the accuracy and repeatability of temperature-corrected relaxation values derived from a B -corrected MRF-fast imaging with steady-state precession implementation using 2 different dictionary sizes.
The International Society of MR in Medicine/National Institute of Standards and Technology phantom was scanned using an MRF sequence of 2 different lengths, a variable flip angle T , and a multi-echo spin echo T at 14 temperatures ranging from 15°C to 28°C and investigated with a linear regression model. Temperature-corrected accuracy was evaluated by correlating T and T times from each MRF dictionary with reference values. Repeatability was assessed using the coefficient of variation, with measurements taken over 30 separate sessions.
There was a statistically significant fit of the model for MRF-derived T and T and temperature (p < 0.05) for all the spheres with a T > 500 ms. Both MRF methods showed a strong linear correlation with reference values for T (R = 0.996) and T (R = 0.982). MRF repeatability for T values was ≤1.4% and for T values was ≤3.4%.
MRF demonstrated relaxation times with a temperature dependence similar to that of conventional mapping methods. Temperature-corrected T and T values from both dictionaries showed adequate accuracy and excellent repeatability in this phantom study.
在磁共振指纹识别（MRF）能够在临床上得到应用之前，所获得的定量值必须在一系列T1和T2值以及温度范围内被证明是准确且可重复的。只有在温度得到控制或校正时，才能对准确性和精密度进行正确评估以及测量结果之间的比较。本研究的目的是探究T1和T2的MRF值对温度的依赖性，并评估通过使用两种不同字典大小的B1校正的稳态进动快速成像MRF所获得的温度校正弛豫值的准确性和可重复性。
使用两种不同长度的MRF序列、可变翻转角T1和多回波自旋回波T2，在15°C至28°C的14个温度下对国际医学磁共振学会/美国国家标准与技术研究院体模进行扫描，并采用线性回归模型进行研究。通过将每个MRF字典中的T1和T2时间与参考值进行关联来评估温度校正后的准确性。使用变异系数评估可重复性，测量在30个独立的时间段内进行。
对于所有T1>500 ms的球体，MRF衍生的T1和T2以及温度的模型具有统计学意义上的拟合度（p<0.05）。两种MRF方法均显示与T1（R=0.996）和T2（R=0.982）的参考值具有强线性相关性。T1值的MRF可重复性≤1.4%，T2值的MRF可重复性≤3.4%。
MRF显示出的弛豫时间对温度的依赖性与传统成像方法相似。在该体模研究中，来自两个字典的温度校正后的T1和T2值显示出足够的准确性和出色的可重复性。
