| 08:15 | 1143.
 | Gradient-Free Frequency Encoded MRI Sai Abitha Srinivas1, Antonio D Glenn2, Christopher E Vaughn3, Mark A Griswold4, and William A Grissom1
1Biomedical Engineering, Case Western Reserve University, Cleveland, OH, United States, 2Computer Science, University of Washington, Seattle, WA, United States, 3Biomedical Engineering, Vanderbilt University, Nashville, TN, United States, 4Radiology, Case Western Reserve University, Cleveland, OH, United States Keywords: New Trajectories & Spatial Encoding Methods, Data Acquisition, low-field MRI, RF encoding, New spatial encoding, Bloch Siegert shift, STAR Motivation: Eliminating conventional gradients can help miniaturize and lower costs of MRI significantly. No method using RF-gradients has been able to achieve frequency encoding, the fastest encoding mechanism in MRI. Goal(s): Develop a Simultaneous-Transmit-and-Receive (STAR) system and perform RF Frequency encoding using the Bloch Siegert shift. Approach: A novel injection transformer, 2MHz/47.5mT RF coil setup and pulse sequence was developed to enable STAR to prevent the RF encoding signal from overwhelming the receiver while frequency encoding MR signal without conventional gradients. Results: The novel STAR system achieved 99.75% cancellation of RF encoding signal, enabling the first-ever acquisition of frequency encoded MR images using RF-gradients. Impact: We have demonstrated, for the first time ever, frequency encoded MRI using RF field gradients in place of conventional B0 gradients. This is a fundamental requirement to make RF encoded-MR imaging as fast as conventional gradient encoding. |
| 08:27 | 1144.
 | Efficient T2 and diffusion weighted imaging using the multiple-echo steady-state (MESS) sequence with a 3D PROPELLER acquisition Frank Zijlstra1,2,3, Maxim Zaitsev3, and Peter Thomas While1,2
1Department of Radiology and Nuclear Medicine, St. Olav's University Hospital, Trondheim, Norway, 2Department of Circulation and Medical Imaging, NTNU - Norwegian University of Science and Technology, Trondheim, Norway, 3Division of Medical Physics, Department of Diagnostic and Interventional Radiology, University Medical Center Freiburg, Faculty of Medicine, University of Freiburg, Freiburg, Germany Keywords: Pulse Sequence Design, Pulse Sequence Design, Diffusion, New Trajectories Motivation: The multiple-echo steady-state (MESS) sequence extends double-echo steady state and efficiently measures multiple images with different contrasts. Because diffusion contrasts are important in clinical imaging, this study aims to include strong diffusion weighting in the MESS sequence. Goal(s): To extend the MESS sequence to provide distortion-free, high-resolution 3D T1-, T2- and diffusion-weighted imaging. Approach: The DW-MESS sequence utilizes a 3D EPI-PROPELLER acquisition to acquire 32 echoes per repetition. An incoherent non-Cartesian k-space trajectory enables reconstruction of individual echoes. Results: The DW-MESS images show contrasts comparable to SE-EPI with anterior-posterior diffusion encoding. Artifacts are present in other diffusion directions, and require further phase corrections. Impact: This study enables stronger diffusion-weighting in DESS-type sequences in addition to T1- and T2-weighting. The incoherent k-space trajectory allows reconstruction of a B0-map and coil-sensitivities, and could allow T2* and susceptibility quantification. This provides new opportunities for efficient multi-parametric imaging. |
| 08:39 | 1145.
 | Three-Dimensional Balanced Steady State Free Precession Ultra-short Echo Time MRI for Multiple Contrasts Whole Brain Imaging Xin Shen1, Eduardo Caverzasi2, Yang Yang1, Xiaoxi Liu1, Ari Green3, Roland Henry3, Uzay Emir4,5, and Peder Larson1
1Radiology and Biomedical Imaging, University of California, San Francisco, San Francisco, CA, United States, 2Department of Brain and Behavioral Sciences, University of Pavia, Pavia, Italy, 3Neurology, University of California, San Francisco, San Francisco, CA, United States, 4School of Health Science, Purdue University, West Lafayette, IN, United States, 5Weldon School of Biomedical Engineering, Purdue University, West Lafayette, IN, United States Keywords: Pulse Sequence Design, Pulse Sequence Design Motivation: Typical ultra-short echo time (UTE) sequences lack of meaningful contrast for long T2 components, and lack of straightforward method to derive images with only ultra-short T2 (uT2) components. Goal(s): To develop a novel high-resolution fast UTE MRI sequence, potentially for myelin imaging. Approach: The sequence was developed based on combining balanced steady-state free precession (bSSFP) and UTE techniques, together with a 3D rosette dual-echo k-space trajectory. Results: The sequence provides PD contrast in both echo times (TEs) and enables easy separation of uT2 components by subtraction between two TEs, which is sensitive to MS patients’ lesions. Impact: The fast and high-resolution (0.94 mm isotropic resolution under three minutes) dual-echo bSSFP UTE sequence provides both structural information (PD contrast) and uT2 components imaging for myelin quantification (by subtraction). It has great potential aiding diagnosis of multiple sclerosis patients. |
| 08:51 | 1146.
 | Ultra-Short Echo-Time Based Accelerated Four-Dimensional Rosette J-resolved Spectroscopic Imaging (4D UTE-ROS-JRESI): A pilot study Ajin Joy1, Uzay Emir2, Paul Macey3, and M. Albert Thomas1
1Radiological Sciences, University of California, Los Angeles, Los Angeles, CA, United States, 2College of Health and Human Sciences, Purdue University, West Lafayette, IN, United States, 3School of Nursing, University of California, Los Angeles, Los Angeles, CA, United States Keywords: Pulse Sequence Design, Spectroscopy, UTE, Rosette Spectroscopic Imaging, 4D JRESI Motivation: Two-dimensional spectrum resolves information-coupled metabolites along an additional spectral dimension. However, acquisition after adding the 2nd spectral encoding can increase the total acquisition time significantly. Goal(s): To achieve clinically feasible runtimes for J-resolved Spectroscopic Imaging (JRESI) using Ultra-Short Echo-Time (UTE) based sequence implementation. Approach: Implement a UTE based 4D JRESI sequence with rosette readout, which would enable shorter repetition times and use of higher undersampling factors. Results: This study demonstrated in-vivo 4D UTE-ROSE-JRESI in less than 10 minutes as compared to a semi-laser sequence with a TR of 1.5 seconds which will take 17 minutes for the same sequence. Impact: With higher incoherence
level of sampling patterns rosette based spectroscopic
imaging sequence showed the potential for highly accelerated acquisitions. Using
UTE based rosette 4D J-resolved Spectroscopic Imaging sequence allowed further
reduction in scan time with the help of shorter TR. |
| 09:03 | 1147.
 | Simultaneously multi-parameter mapping via SSFP multiple overlapping‑echo acquisition and deep learning reconstruction Weikun Chen1, Qing Lin1, Qiaoli Yao2, Liuhong Zhu2, Liangjie Lin3, Jiazheng Wang3, Zhong Chen1, Shuhui Cai1, and Congbo Cai1
1Xiamen University, Xiamen, China, 2Department of Radiology, Zhongshan Hospital(Xiamen) Fudan University, Xiamen, China, 3Clinical & Technical Solutions, Philips Healthcare, Beijing, China Keywords: Pulse Sequence Design, Quantitative Imaging, multi-parametric quantification Motivation: Multi-parametric quantitative magnetic resonance imaging provides a comprehensive and detailed characterization of tissue properties, enhancing the diagnostic accuracy and potential for scientific research. However, the long acquisition time limits its widespread application. Goal(s): To provide a method that can quickly realize multi-parametric quantitative magnetic resonance imaging. Approach: We designed a fast multi-parametric quantitative magnetic resonance imaging method which combines balanced steady-state free precession sequence with multiple overlapping echo detachment imaging technique. Results: Experimental results show that the proposed method can simultaneously obtain accurate T1, T2, T2*, proton density (PD), B0, and B1 parametric maps. Impact: The proposed method can simultaneously obtain accurate T1, T2, T2*, PD, B0, and B1 maps without distortion or artifacts, and no registration is needed. It has great potential for clinical application. |
| 09:15 | 1148.
 | High SNR rapid T1-weighted MP-RAGE and MP-FISP using a 3D stack-of-spirals trajectory at 0.55 T Nam G. Lee1, Bilal Tasdelen2, and Krishna S. Nayak1,2
1Department of Biomedical Engineering, University of Southern California, Los Angeles, CA, United States, 2Ming Hsieh Department of Electrical and Computer Engineering, University of Southern California, Los Angeles, CA, United States Keywords: Pulse Sequence Design, Low-Field MRI, structural brain imaging Motivation: Acquiring High SNR T1-weighted MP-RAGE at low field strengths, such as 0.55T, often requires multiple averages due to reduced equilibrium polarization (~30 min for 3 averages). Goal(s): Provide high SNR MP-RAGE (and MP-FISP) within a reasonable scan time (~15 min) using an SNR-efficient readout while mitigating spatial blurring caused by static off-resonance and concomitant fields. Approach: MP-RAGE and MP-FISP sequences with a stack-of-spirals trajectory were implemented with the Pulseq framework. Spatial blurring was mitigated using the MaxGIRF framework implemented in BART. Results: Spiral MP-RAGE achieves comparable image quality and higher SNR relative to Cartesian MP-RAGE given only half of the scan time. Impact: This work demonstrates the feasibility of acquiring high SNR T1-weighted
structural brain imaging at 0.55T within a reasonable scan time (~15 min). This
opens opportunities for structural neuroimaging and harmonized multi-site
studies via code sharing with open-source frameworks. |
| 09:27 | 1149.
 | pTx Pulseq in hybrid sequences Universal Pulses, made Truly Universal Thomas Roos1, Kyung Min Nam1, Edwin Versteeg1, Mark Gosselink1, Hans Hoogduin1, Dennis Klomp1, Jeroen Siero1, and Jannie Wijnen1
1Department of Radiology, High Field MRI group, University Medical Center Utrecht, Utrecht, Netherlands Keywords: Pulse Sequence Design, Parallel Transmit & Multiband Motivation: Advancing MRI sequence development by integrating parallel transmit capabilities with the open-source and widely-used Pulseq framework. Goal(s): To integrate pTx capabilities into the Pulseq framework, facilitating the design of universal pTx pulses that enhance imaging homogeneity and quality. Approach: Development of 'pTx-Pulseq' as a backwards-compatible extension, validated through single-channel control and complex sequence operation, culminating in a hybrid sequence that enhances a native MP-RAGE with Pulseq flexibility. Results: Effective control of pTx channels using pTx-Pulseq, yielding uniform imaging results and demonstrating the potential of hybrid sequencing for improved MRI applications. Impact: 'pTx-Pulseq' empowers researchers to universally and easily harness pTx technology, allowing for the creation of truly universally pTx pulses that reduce the burden of B1+ inhomogeneity and elevate the quality of high-field MRI. |
| 09:39 | 1150.
 | 3D/4D Ultrashort Echo Time Balanced-SSFP MR Lung Images Reconstructed Using XD-GRASP-Pro William J Garrison1, Zachary Miller2, John P Mugler III1,2, Jing Cai3, and G Wilson Miller1,2,4
1Biomedical Engineering, University of Virginia, Charlottesville, VA, United States, 2Radiology and Medical Imaging, University of Virginia, Charlottesville, VA, United States, 3Health Technology and Informatics, Hong Kong Polytechnic University, Kowloon, Hong Kong, 4Physics, University of Virginia, Charlottesville, VA, United States Keywords: Image Reconstruction, Sparse & Low-Rank Models Motivation: Obtaining high-quality images of the lung using proton MRI is challenging due to breathing motion and the short T2* and low proton density of lung parenchyma. Goal(s): Our goal was to demonstrate a free-breathing proton lung MRI approach that maximizes parenchyma and vessel signal in the lungs. Approach: This method combines a 3D ultra-short echo time (UTE) balanced steady-state free precession (bSSFP) pulse sequence with a GRASP-Pro-based reconstruction algorithm applied to respiratory phase-binned data. Results: Image quality was markedly better for SSFP images than for spoiled images, and end-of-exhalation frames reconstructed from 4D images compared favorably with respiratory-triggered images. Impact: A UTE bSSFP radial pulse sequence combined with
temporally-constrained reconstruction produces high-signal, high-resolution
lung images at end-of-exhalation collected during free breathing. While
non-end-of-exhalation reconstruction was less effective, a similar reconstruction
algorithm that incorporates motion fields could improve results. |
| 09:51 | 1151.
 | Motion-insensitive heavily T2-weighted phase-based imaging using readout alternation technique Daiki Tamada1, Tabassum A Kennedy1, and Scott B Reeder1,2,3,4,5
1Department of Radiology, University of Wisconsin-Madison, Madison, WI, United States, 2Department of Medical Physics, University of Wisconsin-Madison, Madison, WI, United States, 3Department of Biomedical Engineering, University of Wisconsin-Madison, Madison, WI, United States, 4Department of Medicine, University of Wisconsin-Madison, Madison, WI, United States, 5Department of Emergency, University of Wisconsin-Madison, Madison, WI, United States Keywords: Pulse Sequence Design, Motion Correction Motivation: Heavily T2-weighted (T2W) imaging plays a central role in many fluid-sensitive applications. Drawbacks of T2W conventional methods include relatively long acquisition times and motion sensitivity. Goal(s): The goal of this study is to evaluate the feasibility of a novel approach using Heavily T2weighted Phase-Based (HT2WPB) imaging with readout alternation (ROA) to achieve motion-insensitive imaging. Approach: Phantom and in vivo experiments where used to demonstrate the feasibility of heavily T2W using HT2WPB with ROA. Results: Results from this work showed that PBT2W with ROA enabled heavily T2-weighted contrast for improved visibility of fluid containing anatomical structures with reduced motion sensitivity. Impact: The use of heavily T2-weighted phase-based imaging with ROA in MR imaging is a promising method to improve visibility of fluid-containing anatomical structures. This technique has the potential to enhance diagnostic accuracy for the evaluation of various pathologies. |
| 10:03 | 1152.
 | Automated Sequence Design using Neural Architecture Search: Reliability and Reproducibility Rokgi Hong1, Hongjun An1, Sooyeon Ji1, and Jongho Lee1
1Department of Electrical and Computer Engineering, Seoul National University, Seoul, Korea, Republic of Keywords: Pulse Sequence Design, Pulse Sequence Design, Machine Learning/Artificial Intelligence Motivation: An automated sequence design framework utilizing neural architecture search was proposed, and successfully designed optimal sequences for given properties and target objectives without any prior knowledge of MR physics.
Goal(s): We aimed to explore the reliability and reproducibility of this method. Approach: The reliability of the method was evaluated by adjusting the weights of the desired objectives for sequence design. The reproducibility was tested through multiple runs of the design process. Results: Our method exhibited reasonable reliability within a certain range of loss weights. Also, it demonstrated reasonable reproducibility in designing SE sequences; however, it exhibited less robustness when designing IR sequences. Impact: Our previous work, an automated sequence design
framework utilizing neural architecture search, is further explored. Our
methodology successfully designed sequences with reasonable reliability and
reproducibility, despite designing without prior knowledge of MR physics. |