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Purpose: To develop and evaluate a method for rapid estimation of multiparametric T , T , proton density, and inversion efficiency maps from 3D-quantification using an interleaved Look-Locker acquisition sequence with T preparation pulse (3D-QALAS) measurements using self-supervised learning (SSL) without the need for an external dictionary.
Methods: An SSL-based QALAS mapping method (SSL-QALAS) was developed for rapid and dictionary-free estimation of multiparametric maps from 3D-QALAS measurements. The accuracy of the reconstructed quantitative maps using dictionary matching and SSL-QALAS was evaluated by comparing the estimated T and T values with those obtained from the reference methods on an International Society for Magnetic Resonance in Medicine/National Institute of Standards and Technology phantom. The SSL-QALAS and the dictionary-matching methods were also compared in vivo, and generalizability was evaluated by comparing the scan-specific, pre-trained, and transfer learning models.
Results: Phantom experiments showed that both the dictionary-matching and SSL-QALAS methods produced T and T estimates that had a strong linear agreement with the reference values in the International Society for Magnetic Resonance in Medicine/National Institute of Standards and Technology phantom. Further, SSL-QALAS showed similar performance with dictionary matching in reconstructing the T , T , proton density, and inversion efficiency maps on in vivo data. Rapid reconstruction of multiparametric maps was enabled by inferring the data using a pre-trained SSL-QALAS model within 10 s. Fast scan-specific tuning was also demonstrated by fine-tuning the pre-trained model with the target subject's data within 15 min.
Conclusion: The proposed SSL-QALAS method enabled rapid reconstruction of multiparametric maps from 3D-QALAS measurements without an external dictionary or labeled ground-truth training data.
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http://dx.doi.org/10.1002/mrm.29786 | DOI Listing |
Magn Reson Med
September 2025
Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Boston, Massachusetts, USA.
Purpose: To address the unmet need for a cross-platform, multiparametric relaxometry technique to facilitate data harmonization across different sites.
Methods: A simultaneous T and T mapping technique, 3D quantification using an interleaved Look-Locker acquisition sequence with a T preparation pulse (3D-QALAS), was implemented using the open-source vendor-agnostic Pulseq platform. The technique was tested on four 3 T scanners from two vendors across two sites, evaluating cross-scanner, cross-software version, cross-site, and cross-vendor variability.
Quant Imaging Med Surg
May 2025
Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins University School of Medicine, Baltimore, MD, USA.
Background: Relaxometry, specifically T and T mapping, has become an essential technique for assessing the properties of biological tissues related to various physiological and pathological conditions. Many techniques are being used to estimate T and T relaxation times, ranging from the traditional inversion or saturation recovery and spin-echo sequences to more advanced methods. Choosing the appropriate method for a specific application is critical since the precision and accuracy of T and T measurements are influenced by a variety of factors including the pulse sequence and its parameters, the inherent properties of the tissue being examined, the magnetic resonance imaging (MRI) hardware, and the image reconstruction.
View Article and Find Full Text PDFMagn Reson Med Sci
April 2025
Department of Radiology, University of Wisconsin-Madison, Madison, WI, USA.
Multiparametric quantitative MRI (MP-qMRI) methods, which measure multiple relaxation times simultaneously, are becoming into practical tools, but the relationship between different MP-qMRI methods has not been clarified. In particular, since 2D multidynamic multiple-echo (2D-MDME) was provided by multiple major MRI vendors, many patient studies have been reported, but its relationship with 3D-QALAS (3D-QuAntification using an interleaved Look-Locker Acquisition Sequence with T preparation pulse), which is expected to be its 3D version successor, is unknown. In this study, we implemented 2D-MDME and 3D-QALAS on an originally designed 1.
View Article and Find Full Text PDFbioRxiv
August 2024
Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins University School of Medicine, Baltimore, MD, USA.
Purpose: Relaxometry, specifically and mapping, has become an essential technique for assessing the properties of biological tissues related to various physiological and pathological conditions. Many techniques are being used to estimate and relaxation times, ranging from the traditional inversion or saturation recovery and spin-echo sequences to more advanced methods. Choosing the appropriate method for a specific application is critical since the precision and accuracy of and measurements are influenced by a variety of factors including the pulse sequence and its parameters, the inherent properties of the tissue being examined, the MRI hardware, and the image reconstruction.
View Article and Find Full Text PDFMagn Reson Med
May 2024
Department of Radiology, Juntendo University, Tokyo, Japan.