Motion Robust MR Fingerprinting Scan to Image Neonates With Prenatal Opioid Exposure

Self Cite

PurposeFor effective optimization of MR fingerprinting (MRF) pulse sequences, estimating and minimizing errors from actual scan conditions are crucial. Although virtual‐scan simulations offer an approximation to these errors, their computational demands become expensive for high‐dimensional MRF frameworks, where interactions between more than two tissue properties are considered. This complexity makes sequence optimization impractical. We introduce a new mathematical model, the systematic error index (SEI), to address the scalability challenges for high‐dimensional MRF sequence design.MethodsBy eliminating the need to perform dictionary matching, the SEI model approximates quantification errors with low computational costs. The SEI model was validated in comparison with virtual‐scan simulations. The SEI model was further applied to optimize three high‐dimensional MRF sequences that quantify two to four tissue properties. The optimized scans were examined in simulations and healthy subjects.ResultsThe proposed SEI model closely approximated the virtual‐scan simulation outcomes while achieving hundred‐ to thousand‐times acceleration in the computational speed. In both simulation and in vivo experiments, the optimized MRF sequences yield higher measurement accuracy with fewer undersampling artifacts at shorter scan times than the heuristically designed sequences.ConclusionWe developed an efficient method for estimating real‐world errors in MRF scans with high computational efficiency. Our results illustrate that the SEI model could approximate errors both qualitatively and quantitatively. We also proved the practicality of the SEI model of optimizing sequences for high‐dimensional MRF frameworks with manageable computational power. The optimized high‐dimensional MRF scans exhibited enhanced robustness against undersampling and system imperfections with faster scan times.

Section: Introductionmentioning

confidence: 99%

Efficient pulse sequence design framework for high‐dimensional MR fingerprinting scans using systematic error index

Hu,

Qiu,

Adams

et al. 2024

Self Cite

“…The multicompartment fitting is ill-posed and typically requires additional assumptions and/or priors to obtain good results, which could create bias or artifacts. This is an open area of research, where a number of innovative reconstruction algorithms [43][44][45][46] are being developed to tackle this issue.…”

Section: Introductionmentioning

confidence: 99%

High‐resolution myelin‐water fraction and quantitative relaxation mapping using 3D ViSTa‐MR fingerprinting

Liao,

Cao,

Iyer

et al. 2023

PurposeThis study aims to develop a high‐resolution whole‐brain multi‐parametric quantitative MRI approach for simultaneous mapping of myelin‐water fraction (MWF), T1, T2, and proton‐density (PD), all within a clinically feasible scan time.MethodsWe developed 3D visualization of short transverse relaxation time component (ViSTa)‐MRF, which combined ViSTa technique with MR fingerprinting (MRF), to achieve high‐fidelity whole‐brain MWF and T1/T2/PD mapping on a clinical 3T scanner. To achieve fast acquisition and memory‐efficient reconstruction, the ViSTa‐MRF sequence leverages an optimized 3D tiny‐golden‐angle‐shuffling spiral‐projection acquisition and joint spatial–temporal subspace reconstruction with optimized preconditioning algorithm. With the proposed ViSTa‐MRF approach, high‐fidelity direct MWF mapping was achieved without a need for multicompartment fitting that could introduce bias and/or noise from additional assumptions or priors.ResultsThe in vivo results demonstrate the effectiveness of the proposed acquisition and reconstruction framework to provide fast multi‐parametric mapping with high SNR and good quality. The in vivo results of 1 mm‐ and 0.66 mm‐isotropic resolution datasets indicate that the MWF values measured by the proposed method are consistent with standard ViSTa results that are 30× slower with lower SNR. Furthermore, we applied the proposed method to enable 5‐min whole‐brain 1 mm‐iso assessment of MWF and T1/T2/PD mappings for infant brain development and for post‐mortem brain samples.ConclusionsIn this work, we have developed a 3D ViSTa‐MRF technique that enables the acquisition of whole‐brain MWF, quantitative T1, T2, and PD maps at 1 and 0.66 mm isotropic resolution in 5 and 15 min, respectively. This advancement allows for quantitative investigations of myelination changes in the brain.

Time‐resolved MR fingerprinting for T₂* signal extraction: MR fingerprinting meets echo planar time‐resolved imaging

Cui,

Liu,

Larson

et al. 2024

PurposeThis study leverages the echo planar time‐resolved imaging (EPTI) concept in MR fingerprinting (MRF) framework for a new time‐resolved MRF (TRMRF) approach, and explores its capability for fast simultaneous quantification of multiple MR parameters including T1, T2, T2*, proton density, off resonance, and B1+.MethodsThe proposed TRMRF method uses the concept of EPTI to track the signal change along the EPI echo train for T2* weighting with a k‐t Poisson‐based sampling order designed for acquisition. A two‐dimensional decomposition algorithm was designed for the image reconstruction, enabling fast and precise subspace modeling. The accuracy of proposed method was evaluated by a T1/T2 phantom. The feasibility was demonstrated through 5 healthy volunteer brain studies.ResultsIn the phantom studies, T1, T2, and T2* maps of TRMRF correlated strongly with gold‐standard methods. The concordance correlation coefficients are 0.9999, 0.9984 and 0.9978, and R2s are 0.9998, 0.9971, and 0.9983. In the in vivo studies, quantitative maps were acquired with 5 healthy volunteers. TRMRF was demonstrated to have comparable results with spiral MRF and gradient‐echo EPTI. TRMRF scans using 16, 10, and 6 s per slice were also evaluated to demonstrate the capability of shorter scan times.ConclusionA new approach is proposed to exploit the advantage of EPTI in the MRF framework. We demonstrate in phantom and in vivo experiments that T1, T2, T2*, proton density, off resonance, and B1+ can be simultaneously quantified within 6 s/slice by TRMRF.