Magnetic resonance fingerprinting review part 2: Technique and directions

Abstract

Magnetic resonance fingerprinting (MRF) is a general framework to quantify multiple MR‐sensitive tissue properties with a single acquisition. There have been numerous advances in MRF in the years since its inception. In this work we highlight some of the recent technical developments in MRF, focusing on sequence optimization, modifications for reconstruction and pattern matching, new methods for partial volume analysis, and applications of machine and deep learning. Level of Evidence: 2 Technical Efficacy: Stage 2 J. Magn. Reson. Imaging 2020;51:993–1007.

Magnetic resonance fingerprinting Part 1: Potential uses, current challenges, and recommendations

“…Depending on the range and step size of each property value and number of parameters and properties, dictionaries can become large and unwieldy, requiring storage space and long computation times. Overcoming these limitations is an active area of research and is discussed further in Part 2 of this review …”

“…Additionally, each map is inherently coregistered to the others, eliminating the need for post‐acquisition image registration. Many nonlinear pattern matching approaches have been explored to accelerate the matching processes, the details of which can be found in Part 2 …”

“…It is preferred for maps to be generated near instantaneously, but current MRF methods take on the order of 3 minutes to reconstruct per 2D section and in the case of 3D acquisitions, more than 2 hours or as long as 20 hours . Sequence optimization, algorithm performance metrics, and these computational limitations are an ongoing area of development and will be addressed in more detail in Part 2 of this review …”

“…Computation times and specifications should be included for the reconstruction of property maps. Metrics for this analysis are still under development and will be discussed in Part 2 . When, at last, quantitative maps are created, it is easier to compare data using the same color schemes for each property map.…”

“…These recommendations include guidelines for standardized reporting and best‐practices to enhance the validation, repeatability, and reproducibility of MRF techniques. This article serves as Part 1 of a pair of reviews, the second of which addresses recent technical advances including pulse sequence design, optimization, dictionary generation, pattern matching algorithms, and machine learning.…”