RESUME: Turning an SWI acquisition into a fast qMRI protocol

Abstract

Susceptibility Weighted Imaging (SWI) is a common MRI technique that exploits the magnetic susceptibility differences between the tissues to provide valuable image contrasts, both in research and clinical contexts. However, despite its increased clinical use, SWI is not intrinsically suitable for quantitation purposes. Conversely, quantitative Magnetic Resonance Imaging (qMRI) provides a way to disentangle the sources of common MR image contrasts (e.g. proton density, T1, etc.) and to measure physical parameters intrinsically related to tissue microstructure. Unfortunately, the poor signal-to-noise ratio and resolution, coupled with the long imaging time of most qMRI strategies, have hindered the integration of quantitative imaging into clinical protocols. Here we present the RElaxometry and SUsceptibility Mapping Expedient (RESUME) to show that the standard acquisition leading to a clinical SWI dataset can be easily turned into a thorough qMRI protocol at the cost of a further 50% of the SWI scan time. The R1, , proton density and magnetic susceptibility maps provided by the RESUME scheme alongside the SWI reconstruction exhibit high reproducibility and accuracy, and a submillimeter resolution is proven to be compatible with a total scan time of 7 minutes.

DCE-MRI Pharmacokinetic-Based Phenotyping of Invasive Ductal Carcinoma: A Radiomic Study for Prediction of Histological Outcomes

“…Interestingly, much more instances of R 1 features were found compared to the features from TIRM images. R 1 is a parametric map that in DCE time resolved studies is usually used as auxiliary to the computation of pharmacokinetic parameters and is seldom studied by itself, although it could give important information regarding increased vascularity, presence of edema, or necrosis [ 69 , 70 ]. Our approach, instead, dealing with this parametric map referring to explicit physiological and structural conditions without the use of contrast media, leads to the generation of more discriminative features, compared to the conventional TIRM sequence.…”

RESUME : A flexible class of multi-parameter qMRI protocols

“…A first attempt to reduce the impact on the acquisition time was suggested in [40]. The authors showed that R 1 and PD map can be derived by adding a low-FA sequence with halved repetition time.…”

“…The solution for the protocol RESUME 2 was found in [40]. The authors showed that, in a region of the space of parameters ( E 1,0 , θ 1 , θ 2 ) , the associate Eq.…”

“…For each RESUME N scheme, the magnitude images, together with the QSM derived from the phase images, were considered as a discrete version of a general multi-component image X : R 3 →R M with a bounded support Ω⊂R 3 , and thus processed via MNLM according to [40]. Therefore, the number of real datasets jointly processed for the different schemes were M = 5 for RESUME 1 and RESUME 2 , M = 6 for RESUME 3 and M = 8 for RESUME 4 .…”

“…All data processing, except the QSM (which was obtained by the free tool described in [43]), was performed using an in-house developed library for Matlab (MATLAB® Release 2020a, The MathWorks, Inc., Natick, MA, USA) partly described in previous works [52,47,44,53,38,40] on a server equipped with two Intel® Xeon® Gold 6136 CPUs and four NVIDIA® Tesla® P40 GPUs.…”