Ke Wang¹, Mariya Doneva², Thomas Amthor², Vera C. Keil³, Ekin Karasan¹, Fei Tan⁴, Jonathan I. Tamir^1,5, Stella X. Yu^1,6, and Michael Lustig^1
1Electrical Engineering and Computer Sciences, University of California, Berkeley, Berkeley, CA, United States, ²Philips Research, Hamburg, Germany, ³Universitätsklinikum Bonn, Bonn, Germany, ⁴Bioengineering, UC Berkeley-UCSF, San Francisco, CA, United States, ⁵Electrical and Computer Engineering, The University of Texas at Austin, Austin, TX, United States, ⁶International Computer Science Institute, University of California, Berkeley, Berkeley, CA, United States

MR Fingerprinting is an emerging attractive candidate for multi-contrast imaging since it quickly generates reliable tissue parameter maps. However, contrast-weighted images generated from parameter maps often exhibit artifacts due to model and acquisition imperfections. Instead of direct modeling, we propose a supervised method to learn the mapping from MRF data directly to synthesized contrast-weighted images, i.e., direct contrast synthesis (DCS). In-vivo experiments on both volunteers and patients show substantial improvements of our proposed method over previous DCS method and methods that derive synthetic images from parameter maps.

Adrienne E. Campbell-Washburn¹, Yun Jiang², Gregor Körzdörfer^3,4, Mathias Nittka³, and Mark A. Griswold^2
1National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD, United States, ²Department of Radiology, Case Western Reserve University, Cleveland, OH, United States, ³Siemens Healthcare GmbH, Erlangen, Germany, ⁴Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany

We assess the feasibility of T1 and T2 mapping with MR fingerprinting implemented on a high-performance 0.55T system that combines contemporary hardware and imaging methods with a lower magnetic field strength. Quantitative values correlated closely to spin-echo measurements in the NIST phantom. Brain MRF was evaluated in 12 healthy volunteers and liver MRF was evaluated in one volunteer as a proof-of-concept. At 0.55T, T1 was 539ms (white matter) and 660ms (gray matter), and T2 was 64ms (white matter) and 76ms (gray matter). The combination of MRI fingerprinting and low-field MRI systems provides an opportunity for rapid, low-cost, quantitative imaging.

Kirsten Koolstra¹, Andrew Webb¹, and Peter Börnert^1,2
1Leiden University Medical Center, Leiden, Netherlands, ²Philips Research Hamburg, Hamburg, Germany

Fast relaxation time quantification is important in dynamic muscle studies and can be achieved using Magnetic Resonance Fingerprinting (MRF). The T₂ values in muscle measured with MRF are consistently higher than those measured with the conventionally used multi-echo turbo-spin-echo (MSE) method, while T₁ values are closer to reference measurements. We hypothesize that this increase can in part be attributed to an increased sensitivity of MRF to flow compared to MSE. In this work we test the sensitivity of MRF to flow in muscle by saturating a slab at different distances above the imaging slice for variable suppression of inflowing spins.

Olivier Jaubert¹, Cristobal Arrieta^2,3, Gastao Cruz¹, Aurelien Bustin¹, Torben Schneider⁴, Georgios Georgiopoulos¹, Pier-Giorgio Masci¹, Carlos Sing-Long^3,5,6, Rene Michael Botnar¹, and Claudia Prieto^1
1Biomedical Engineering Department, School of Biomedical Engineering and Imaging Sciences, King's College London, London, United Kingdom, ²Biomedical Imaging Center, Pontificia Universidad Católica de Chile, Santiago, Chile, ³Millennium Nucleus for Cardiovascular Magnetic Resonance, Santiago, Chile, ⁴Philips Healthcare, London, United Kingdom, ⁵Instituto de Ingeniería Matemática y Computacional, Pontificia Universidad Católica de Chile, Santiago, Chile, ⁶Millennium Nucleus Center for the Discovery of Structures in Complex Data, Chile, Santiago, Chile

Quantitative T₁, T₂, T₂* and fat fraction (FF) maps are promising imaging biomarkers for the assessment of liver disease. Magnetic Resonance Fingerprinting has been recently proposed for fast T₁, T₂ and M₀ mapping of the liver, however in the presence of high iron or fat concentrations corrections using separately acquired T₂* and FF maps are needed. Here we propose a novel approach which enables simultaneous liver T₁, T₂, T₂* and FF maps from a single ~15s breath-hold scan. The proposed approach was evaluated on phantoms, 8 healthy subjects and 2 patients in comparison to conventional mapping techniques.

Yong Chen¹, Xiaopeng Zong², Dan Ma¹, Weili Lin², and Mark Griswold^1
1Radiology, Case Western Reserve University, Cleveland, OH, United States, ²Radiology, University of North Carolina at Chapel Hill, Chapel Hill, NC, United States

In this study, we developed a 3D MRF method in combination with fat navigator to improve its motion sensitivity for neuroimaging. A rapid fat navigator sampling was achieved at 3T by using the stack-of-spirals acquisition and non-Cartesian spiral GRAPPA. The improvement in motion robustness was achieved without increasing the scan time for quantitative tissue mapping. Our preliminary results demonstrate that 1) the added fat navigator sampling does not influence the accuracy of T1 and T2 quantification, and 2) the motion robustness for quantitative tissue mapping using MRF was largely improved with the proposed method.

Gastao Cruz¹, Haikun Qi¹, Olivier Jaubert¹, Aurelien Bustin¹, Thomas Kuestner¹, Torben Schneider², René M. Botnar¹, and Claudia Prieto^1
1Biomedical Engineering Department, School of Biomedical Engineering and Imaging Sciences, King's College London, London, United Kingdom, ²Philips Healthcare, Guildford, United Kingdom

Cardiac Magnetic Resonance Fingerprinting (cMRF) has been proposed for simultaneous myocardial T1 and T2 mapping. This approach uses ECG-triggering to synchronize data acquisition to a small mid-diastolic window, reducing cardiac motion artefacts but also limiting the amount of acquired data per heartbeat. This low scan efficiency can limit the spatial resolution achievable in a breath-held scan. Here we introduce a novel approach for contrast-resolved motion-corrected reconstruction, that combines the generalized matrix description formulism for non-rigid motion correction with low-rank compression of temporally varying contrast. This approach enables longer acquisition windows and higher scan efficiency in cMRF, correcting for cardiac motion.

Ding Xia^1,2, Zidan Yu^1,2,3, Riccardo Lattanzi^1,2,3, and Martijn A Cloos^1,2
1Center for Advanced Imaging Innovation and Research, Department of Radiology, New York University School of Medicine, New York, NY, United States, ²Center for Biomedical Imaging, Department of Radiology, New York University School of Medicine, New York, NY, United States, ³Sackler Institute of Graduate Biomedical Sciences, New York University School of Medicine, New York, NY, United States

We evaluated the ability of three reported MR fingerprinting methods to mitigate the effect of B₁⁺ inhomogeneity at 7T. Results from each method were compared with gold standard results. All methods provided relatively accurate T1 quantification. We show that T2 cannot be accurately quantified at 7T without accounting for B₁⁺ in the MR fingerprinting dictionary. The Inversion-Recovery-FISP-FLASH (IRFF) method provided the most accurate T2 values. We conclude that the use of both FISP and FLASH segments best encodes B₁⁺ into the fingerprint.

Lixian Zou^1,2, Huihui Ye³, Shi Su¹, Haifeng Wang¹, Dong Liang^1,4, Xin Liu¹, and Hairong Zheng^1
1Shenzhen Institutes of Advanced Technology,Chinese Academy of Sciences, Shenzhen, China, ²Shenzhen College of Advanced Technology, University of Chinese Academy of Sciences, Shenzhen, China, ³State Key Laboratory of Modern Optical Instrumentation, College of Optical Science and Engineering, Zhejiang University, Zhejiang, China, ⁴Research Center for Medical AI, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen, China

MRF is a time-efficient technique to simultaneously measure of multiple parameters through pattern recognition. The completeness of dictionary to describe the signal evolution process in NMR system is very important to acquire the accurate T₁ and T₂ values. A new dictionary, generated by using fractional Bloch equations and B₁ correction, is proposed to improve the MRF-FISP accuracy. In this work, we compared the accuracy of relaxation values with three dictionary models through phantom and in-vivo experiments. Results illustrated that dictionary generated through fractional Bloch equation with B₁ correction is the best to approach T₁ and T₂ standards.

Qing Li^1,2, Xiaozhi Cao¹, Huihui Ye^1,3, Zihan Zhou¹, Hongjian He¹, and Jianhui Zhong^1
1Center for Brain Imaging Science and Technology, Key Laboratory for Biomedical Engineering of Ministry of Education, College of Biomedical Engineering and Instrumental Science, Zhejiang University, Hangzhou, China, ²Siemens Healthcare Ltd., Shanghai, China, ³State Key Laboratory of Modern Optical Instrumentation, College of Optical Science and Engineering, Zhejiang University, Hangzhou, China

In this study, we used a 3D ultrashort-echo-time MR Fingerprinting (UTE-MRF) method to generate distortion-free quantitative T1, T2, and proton density maps with an isotropic resolution of 0.8 x 0.8 x 0.8 mm³.

Guido Buonincontri^1,2, Jan W Kurzawski^2,3, Joshua Kaggie⁴, Tomasz Matys⁴, Ferdia Gallagher⁴, Matteo Cencini^2,5, Graziella Donatelli^2,6, Paolo Cecchi⁶, Mirco Cosottini^2,6,7, Nicola Martini⁸, Francesca Frijia⁹, Domenico Montanaro⁹, Pedro A Gómez^2,10, Rolf F Schulte¹¹, Alessandra Retico³, and Michela Tosetti^1,2
1IRCCS Stella Maris, Pisa, Italy, ²Imago7 Foundation, Pisa, Italy, ³Istituto Nazionale di Fisica Nucleare, Pisa, Italy, ⁴Department of Radiology, University of Cambridge, Cambridge, United Kingdom, ⁵University of Pisa, Department of Physics, Pisa, Italy, ⁶U.O. Neuroradiologia, Azienda Ospedaliera Universitaria Pisana (AOUP), Pisa, Italy, ⁷University of Pisa, Department of Translational Research and New Technologies in Medicine and Surgery, Pisa, Italy, ⁸Fondazione Toscana Gabriele Monasterio, Pisa, Italy, ⁹U.O.C. Risonanza Magnetica Specialistica e Neuroradiologia, Fondazione CNR/Regione Toscana G. Monasterio, Pisa, Italy, ¹⁰Technical University of Munich, Munich, Germany, ¹¹GE Healthcare, Munich, Germany

Three-dimensional magnetic resonance fingerprinting with spiral projection k-space trajectory offers fully-quantitative estimations at a high spatial resolution. To assess the repeatability and reproducibility of the estimations, we acquired test/re-test data in the human brain at 1.5T and 3.0T in a travelling head study involving a total of 12 subjects and 8 different MR scanners. Our approach estimated voxel-wise performance in the CNS: variability was assessed using coefficients-of-variation, bias using a GLM analysis. Solid matter repeatability CVs were under 2% for nPD/T1, and 5% for T2, while reproducibility biases were under 10% in solid matter compartments for T1/T2.