Chaithya G R^1,2, Guillaume Daval-Frérot^1,2,3, Aurélien Massire³, Boris Mailhe⁴, Mariappan Nadar⁴, Alexandre Vignaud¹, and Philippe Ciuciu^1,2
1NeuroSpin, Joliot, CEA, Université Paris-Saclay, F-91191, Gif-sur-Yvette, France, ²Inria, Parietal, Université Paris-Saclay, F-91120, Palaiseau, France, ³Siemens Healthcare SAS, Saint-Denis, 93210, France, ⁴Siemens Healthineers, Princeton, NJ, United States

We augment the recently introduced SPARKLING algorithm and propose an improved mathematical formulation that takes the temporal dependence of the MR signal into account. This prevents the trajectories from sampling similar portions of k-space at different times, thereby reducing distortions and blurring induced by \(B_0\) inhomogenieties. Overall, these trajectories present a smooth distribution over time in k-space and Minimized Off-Resonance Effects (MORE-SPARKLING), verified both retrospectively and prospectively with scans performed in vivo at 3T on a healthy volunteer.

Marten Veldmann¹, Svenja Niesen¹, Philipp Ehses¹, and Tony Stöcker^1,2
1Deutsches Zentrum für Neurodegenerative Erkrankungen e.V. (DZNE), Bonn, Germany, ²Department of Physics & Astronomy, University of Bonn, Bonn, Germany

The 3DREAM sequence provides a fast technique for whole-brain B1 mapping, but suffers from different blurring levels in FID and STE* images. We developed a new variant of the 3DREAM sequence with a spiral readout to mitigate this problem. The spiral readout shortens the echo train duration and reduces the number of excitations after the STEAM preparation significantly. This leads to similar blurring levels in FID and STE* images and increases the effective resolution of flip angle maps. As a result, correction strategies for different blurring levels are no longer necessary.

Renata Porciuncula Baptista¹, Alexandre Vignaud¹, Chaithya G R^1,2, Guillaume Daval-Frérot^1,2, Franck Mauconduit¹, Mathieu Naudin³, Marc Lapert⁴, Remy Guillevin³, Philippe Ciuciu^1,2, Cécile Rabrait-Lerman¹, and Fawzi Boumezbeur^1
1NeuroSpin, Joliot, CEA, CNRS, University Paris-Saclay, Gif-sur-Yvette, France, ²Inria, Parietal, Université Paris-Saclay, Palaiseau, France, ³University Hospital Centre Poitiers, DACTIM-MIS, Poitiers, France, ⁴Siemens Healthcare SAS, Saint-Denis, France

Quantitative ²³Na MRI provides useful information about brain tissue homeostasis. Most sequences use deterministic non-Cartesian 3D trajectories such as TPI. However, stochastic strategies such as SPARKLING could improve the coverage of k-space. This study evaluates the advantages of SPARKLING versus TPI. From in vivo datasets at 7T, we determined that undersampled SPARKLING acquisitions outperform TPI for (8 mm)³ resolution with a birdcage coil or for (4 mm)³ with a 32-channel coil. Through extrapolation of these results, we predict that at 11.7T/32-channel, ²³Na MRI data could be acquired in 90s at (3 mm)³, which could be interesting for sodium fMRI imaging.

Harsh Kumar Agarwal¹, Shaik Ahmed¹, Rajagopalan Sundaresan¹, Sudhanya Chatterjee¹, Sajith Rajamani¹, Ashok Kumar P Reddy¹, Bhairav Mehta¹, Dattesh Shanbhag¹, and Ramesh Venkatesan^1
1GE Healthcare, Bangalore, India

MR imaging is signal starve leading to long acquisition time. Multiple averaging/excitation is most common way to boost the SNR. However, it is associated with proportionately long scan time. This abstract presents Variable Compress Sensed Excitation (vNEX) image acquisition and image reconstruction technique which subsample each signal average by compressed sensing fast MRI technique and robust image reconstruction is done to reconstruct MRI images for individual signal averages. The proposed technique is demonstrated for T2w brain MRI where SNR equivalence of 336sec scan time is shown in a 200sec vNEX MRI. Three sampling patterns were proposed and statistically compared.

Fischer Johannes¹ and Michael Bock^1
1Dept. of Radiology, Medical Physics, Medical Center University of Freiburg, Faculty of Medicine, Uni, Freiburg, Germany

Imaging sequences with sub-millisecond temporal resolution based on single point imaging (SPI) are very time inefficient. We designed and imaged a motion phantom capable of velocities up to 5.5m/s. A synchronization signal is acquired using a photoelectric barrier and combined with a sequence trigger signal. Reconstructed images show clear delineation of small structures with a spatial resolution of $$$\Delta x$$$=0.67mm and a temporal resolution of $$$\delta t$$$=246μs.
 

Valentin Fauveau¹, Adam Jacobi², Adam Bernheim², Michael Chung², Yang Yang^1,2, Thomas Benkert³, Zahi Fayad^1,2, and Li Feng^1,2
1BioMedical Engineering and Imaging Institute, Icahn School of Medicine at Mount Sinai, New York, NY, United States, ²Department of Radiology, Icahn School of Medicine at Mount Sinai, New York, NY, United States, ³MR Application Predevelopment, Siemens Healthcare GmbH, Erlangen, Germany

Spiral UTE is a relatively new MRI technique that combines ultra-short echo time acquisition with a stack-of-spirals trajectory for imaging the lung. In this work, we aimed to analyze the motion sensitivity of different reordering schemes and breath holding positions in spiral UTE MRI to determine the optimized protocol for imaging the lungs. A blind assessment was performed by three experienced chest radiologists and the results were analyzed with statistical tests. The Spiral UTE with line-in-partition reordering performed during the inspiration phase was considered the best protocol in our study.

Martins Otikovs¹ and Lucio Frydman^1,2
1Department of Chemical and Biological Physics, Weizmann Institute of Science, Rehovot, Israel, ²Azrieli National Center for Brain Imaging, Weizmann Institute of Science, Rehovot, Israel

Spatiotemporal encoding (SPEN) is an ultrafast imaging technique, that can serve as useful alternative to single shot and to read-out segmented (RESOLVE) spin-echo (SE) EPI methods, when trying to overcome image distortions due to magnetic field (B₀) inhomogeneities. SPEN’s reliance on adiabatic sweeps could also make it an attractive candidate for imaging at high fields, and overcoming B₁₊-related inhomogeneities. Herein we present phantom and in-vivo results acquired on a 7T human imaging system for single and multi-shot SPEN acquisitions, corroborating its robustness vs comparable single and multi-shot SE-EPI and RESOLVE acquisitions implemented on a single-Tx configuration.

Yogesh Rathi¹, Jon-Fredrik Nielsen², Maxim Zaitsev³, Lipeng Ning¹, Jr-Yuan Chiou⁴, Tae Hyung Kim⁵, William Grissom⁶, Borjan Gagoski⁷, and Berkin Bilgic^5
1Psychiatry, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, United States, ²University of Michigan, Ann Arbor, MI, United States, ³High Field MR Center, Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Vienna, Austria, ⁴Brigham and Women's Hospital, Boston, MA, United States, ⁵Athinoula A. Martinos Center for Biomedical Imaging, Harvard Medical School, Boston, MA, United States, ⁶Vanderbilt University, Nashville, TN, United States, ⁷Fetal-Neonatal Neuroimaging and Developmental Science Center, Boston Children’s Hospital, Harvard Medical School, Boston, MA, United States

Inter-scanner variability can reduce the statistical power of neuroimaging studies due to the increased variance in the data. While existing efforts employ consistent high level parameters to acquire data across scanners, we hypothesize that differences due to sequence implementation and reconstruction algorithms contribute substantially to variability in multi-center settings. We propose a unified vendor-neutral MP-RAGE protocol based on the Pulseq sequence development platform that can be used consistently across sites and vendors for reducing inter-scanner variability. Preliminary results show increased consistency of cortical thickness across sites using Pulseq protocol compared to vendor-provided sequences.

Leon Bischoff¹, Christoph Katemann², Oliver Weber², Alexander Isaak¹, Dmitrij Kravchenko¹, Narine Mesropyan¹, Christoph Endler¹, Thomas Vollbrecht¹, Claus Christian Pieper¹, Ulrike Attenberger¹, and Julian Luetkens^1
1Department of Diagnostic and Interventional Radiology, University Hospital Bonn, Bonn, Germany, ²Philips GmbH Market DACH, Hamburg, Germany

Multiparametric MRI (mpMRI) of the prostate can detect clinically significant prostate cancer in men. To accelerate the time-consuming acquisition process, we integrated a new Compressed SENSE (CS) method for T2-weighted sequences with propeller acquisition and compared it qualitatively and quantitatively to conventional SENSE accelerated T2-weighted propeller sequences. We could demonstrate that while the new CS acquisition method has less artifacts, better image sharpness and higher apparent signal-to-noise ratio (aSNR) and contrast-to-noise ratio (CNR), it reduced the acquisition time by 24%. These findings indicate a superiority over the conventional T2-sequence and could improve the diagnostic workup of patients with prostate cancer.

Sebastian Littin¹, Patrick Hucker¹, Maximilian Frederik Russe², Feng Jia¹, Philipp Amrein¹, and Maxim Zaitsev^1,3
1Department of Radiology, Medical Physics, University Freiburg, Faculty of Medicin, Freiburg, Germany, ²Department of Radiology, University Freiburg, Faculty of Medicin, Freiburg, Germany, ³Center for Medical Physics and Biomedical Engineering, High Field MR Center, Medical University of Vienna, Vienna, Austria

Imaging outside the predefined and optimized FoV may enhance accessibility for interventional MRI procedures. Here we present different measures to assess the encoding capability of gradient systems in off-center regions. Different clinically establishes sequences are compared at 0.55T and 1.5T regarding their imaging capabilities beyond the predefined target regions.

Hyungseok Jang¹, Yajun Ma¹, Dina Moazamian¹, Michael Carl², Saeed Jerban¹, Alecio F Lombardi¹, Christine B Chung^1,3, Eric Y Chang^1,3, and Jiang Du^1
1Radiology, University of California San Diego, San Diego, CA, United States, ²GE Healthcare, San Diego, CA, United States, ³Radiology Service, Veterans Affairs San Diego Healthcare System, San Diego, CA, United States

T_1ρ has been investigated as a quantitative biomarker sensitive to changes in macromolecules such as proteoglycan and collagen in musculoskeletal systems. More recently, adiabatic T_1ρ (Adiab-T_1ρ) has emerged as an alternative to conventional continuous wave T_1ρ to reduce the magic angle effect, which is a major confounding factor in accurate T_1ρ estimation. In this study, we investigated a new pulse sequence combining adiabatic T_1ρ preparation and efficient 3D fast spin echo (FSE) for more robust adiab-T_1ρ mapping in the human knee. The efficacies of RF cycling and magnetization reset were also demonstrated.