RESUME : A flexible class of multi-parameter qMRI protocols

Abstract

To introduce a class of fast 3D quantitative MRI (qMRI) schemes (RESUME N , for N = 1,…, 4) that allow for a thorough characterization of microstructural properties of brain tissues. Methods: An arbitrary multi-echo GRE acquisition optimized for quantitative susceptibility mapping (QSM) is complemented with an appropriate low flip-angle GRE sequence drawn from four possible choices. The acquired signals are processed to analytically derive the longitudinal relaxation (R 1 ) and free induction decay (R * 2 ) rates, as well as the proton density (PD) and QSM. A comprehensive modeling of the excitation and B − 1 profiles and of the RF-spoiling is included in the acquisition and processing pipeline. Results: The RESUME N maps appear homogeneous throughout the field-of-view and exhibit comparable values and high SNR across the considered range of N values. Conclusions: The introduced schemes represent a class of robust and flexible strategies to derive a thorough and fast qMRI study, suitable for a whole-brain acquisition with isotropic voxel resolution of 700 μm in less than 15 min.

Clinical correlates of R1 relaxometry and magnetic susceptibility changes in multiple sclerosis: a multi-parameter quantitative MRI study of brain iron and myelin

“…Notwithstanding the many advances witnessed in the field of tissue microstructure in MS, none of the available MR techniques is solely affected by a specific pathological aspect, which advocates for the application of multi-parameter approaches to improve our understanding of microstructural damage [25,31]. Here, we applied a multi-parameter analysis of volumetry and quantitative MRI to address the following questions: (i) what is the topography of iron and myelin changes assessed via susceptibility and relaxometry in MS?…”

“…All MRI exams were performed on the same 3T scanner (Magnetom Trio, Siemens Healthineers) and included a 3D T1-weighted sequence for volumetric analyses, a 3D T2weighted FLAIR sequence for T2-hyperintense lesions detection, and lesion load (T2-LL) quantification and two spoiled gradient echo sequences for quantitative analyses [21]. Details about acquisition parameters and a thorough description of image preprocessing [22][23][24], including the computation of R1 and QSM maps [21,25], are provided in the Supplementary Material, while a flowchart summarizing the main image processing and analysis steps is depicted in Fig. 2.…”

Technical note: MAMBA—Multi‐pAradigM voxel‐Based Analysis: A computational cookbot

“…The great variety of available statistical models, along with the opportunity to include an arbitrary amount of VB or global EVs that impact on either VB or global outcomes, can open new ways of exploring statistical relationships in radiobiology 28 and multimodal imaging 29 . Such multi‐variable VB analysis is likely to prove particularly valuable in quantitative MRI, which typically leads to the mapping of several, independent magnetic resonance parameters 30,31 …”

“…29 Such multi-variable VB analysis is likely to prove particularly valuable in quantitative MRI, which typically leads to the mapping of several, independent magnetic resonance parameters. 30,31 Clearly, the use of MAMBA requires a preprocessing phase consisting in an accurate spatial normalization step, which is not provided by our toolbox. Indeed, MAMBA is intended for general-purpose VB statistical analysis, while several and already optimized solutions exist for spatial normalization in different clinical settings, which are also standard de facto in the different communities of neuroimaging (e.g.…”

New developments in MRI: System characterization, technical advances and radiotherapy applications

“…Monti S. et al [12] introduce and investigate a class of rapid 3D quantitative MRI (qMRI) protocol for the multi-parameter characterization of brain tissue microstructure. The pulse sequence class, named RESUME N , is based on a multi-gradient echo scheme, employing low flip angles and optimized for relaxometry and quantitative susceptibility mapping (QSM).…”