Synopsis

Keywords: Contrast mechanisms: Relaxometry, Image acquisition: Multiparametric

Quantitative MRI plays an increasingly significant role in clinical and research studies. Recent advancements in accelerated imaging techniques have made quantitative MRI both feasible and accessible within clinically practical timeframes. In this presentation, we will explore several cutting-edge time-resolved multiparametric mapping techniques, such as Magnetic Resonance Fingerprinting (MRF), Echo-planar Time-resolved Imaging (EPTI), and Magnetic Resonance Multitasking. These methods can furnish invaluable insights into various tissue properties, including longitudinal and transversal relaxation times (T₁ and T₂), transverse magnetization influenced by field inhomogeneity (T₂*), proton density (PD), myelin-water fraction (MWF), mean diffusivity (MD), and fractional anisotropy (FA).

Introduction

Quantitative MRI is a powerful tool for the characterization of tissues and understanding the microstructural and macrostructural changes in brain, liver, heart, and other organs. In recent years, several time-resolved multi-parametric mapping techniques have been proposed, providing valuable information about tissue properties. In this presentation, we will explore several cutting-edge multi-parametric mapping techniques:

Magnetic resonance fingerprinting (MRF)¹
MRF is a rapid quantitative imaging technique that simultaneously estimates multiple tissue parameters and has garnered significant interest as a diagnostic tool in various diseases. Additionally, MRF, which originally only measured relaxometry parameters, can be combined with other imaging techniques, such as diffusion tensor parameters, T₂*, myelin-water fraction and velocity parameters, to provide more detailed and complementary information about tissue microstructure and function.

Echo-planar time-resolved imaging (EPTI)²
EPTI is an efficient distortion- and blurring-free multi-shot echo planar imaging (EPI) technique for time-resolved multiple-contrast and/or quantitative imaging. While traditional EPI can quickly generate 2D images in single-shot acquisition, it often suffer from geometric distortions and T₂* blurring. EPTI addresses these issues by employing accelerated spatio-temporal sampling with B₀-informed subspace reconstruction. This method allows for the generation of hundreds of time-resolved, distortion- and blurring-free images using a small number of EPTI shots, facilitate quantitative map fittings at sub-millisecond intervals.

MR Multitasking³
MR Multitasking framework captures the physiological and bulk motion by frequently acquiring the center k-space area, which forms the training data. The contrast dynamics and motion information are extracted from the training data. The images containing the combination of all the contrasts and all motion states are reconstructed by exploiting the high image correlation along and across the multiple dynamic dimensions using low-rank tensor structure. This continuous-acquisition approach captures motion, relaxation and other dynamics to efficiently perform quantitative MRI without the use of ECG triggering or breath holds.

Acknowledgements

No acknowledgement found.