| Computer # |
| 3282.
 | 49 | M(RF)2 – Improving MRF encoding speed with tailored spatiotemporal excitation patterns Yonatan Urman1, Daniel Abraham1, and Kawin Setsompop1,2
1Electrical Engineering, Stanford University, Stanford, CA, United States, 2Radiology, Stanford University, Stanford, CA, United States Keywords: New Trajectories & Spatial Encoding Methods, Image Reconstruction, Pulse sequence design Motivation: Current Magnetic Resonance Fingerprinting techniques have shown promising results but have room for improvement in terms of acquisition speed and resolution. Goal(s): Explore the potential of a new spatiotemporal encoding dimension unique to MRF, leveraging tailored spatiotemporal excitation patterns. Approach: Employ spatially and temporally varying excitation patterns to create distinct signal evolution dictionaries at different spatial locations and reconstruct using multiple subspaces. To address computational challenges, we introduce a clustering method that reduces the number of subspaces, making the problem tractable. Results: 2D reconstruction experiments demonstrate the approach's potential and show enhanced accuracy, particularly in T2 reconstruction. Impact: We propose tailored spatiotemporal excitation encoding for Magnetic Resonance Fingerprinting. By leveraging controlled excitation patterns, we create spatially varying dictionaries that enhance the encoding capabilities, allowing for faster and higher-resolution imaging. |
| 3283.
 | 50 | Holocene Sampling: Where CAIPIRINHA meets T-Hex Maria Engel1, Lars Kasper2, and Derek Jones1
1Cardiff University Brain Research Imaging Centre, Cardiff University, Cardiff, United Kingdom, 2Toronto NeuroImaging Facility, Department of Psychology, University of Toronto, Toronto, ON, Canada Keywords: New Trajectories & Spatial Encoding Methods, Parallel Transmit & Multiband, CAIPIRINHA, SMS Motivation: For Multiband and 3D EPI (and spirals), k-space sampling patterns used to date, were either optimized heuristically (blipped-CAIPIRINHA) or only available for a discrete subset of imaging parameters (T-Hex). Goal(s): To find the optimum sampling pattern for arbitrary imaging parameters. Approach: We propose the packing density of the k-space grid in the phase-encoding plane as a metric to assess the quality of a sampling pattern, since it minimizes the noise amplification for spherical objects. Furthermore, we choose L’s and Δ’s (blipped-CAIPIRINHA nomenclature) as real-valued numbers. Results: The novel sampling patterns achieve more homogeneous k-space coverage (up to 30% higher packing density) than blipped-CAIPIRINHA. Impact: The proposed method generates
k-space sampling patterns that have potential to maximize the SNR yield per
unit time in Multiband and 3D imaging by providing the most homogeneous k-space
sampling for an arbitrary given set of imaging parameters. |
| 3284.
 | 51 | Super Resolution Using Sparse Sampling at Portable Ultra-Low Field MR Corinne Donnay1,2, Serhat V Okar3, Megan Poorman4, Daniel S Reich3, and Govind Nair5
1NINDS, NIH/Oxford, Bethesda, MD, United States, 2Nuffield Department of Clinical Neurosciences, Oxford University, Oxford, United Kingdom, 3NINDS, NIH, Bethesda, MD, United States, 4Hyperfine Inc, Guilford, CT, United States, 5NIH, Bethesda, MD, United States Keywords: New Trajectories & Spatial Encoding Methods, Low-Field MRI, Super Resolution Motivation: Ultra-low field (ULF) MRI is cost-effective and portable but has limited signal-to-noise ratio (SNR) and lower resolution. Goal(s): To develop a Fourier-based Super Resolution (FouSR) approach to enhance the resolution of ULF MRI images by combining spatial frequencies from two orthogonal ULF images. Approach: In a standard phantom and a cohort of 10 participants with multiple sclerosis (MS) we compared FouSR to ULF coronal and axial images and their average. Results: FouSR demonstrated improved image sharpness and lesion delineation without sacrificing SNR. Visual assessments of in-vivo data by an experienced MS neurologist supported the superior image quality of FouSR. Impact: The presented Fourier-based Super Resolution (FouSR) approach improves image resolution of ultra-low field MRI, providing sharper images for radiological assessment. |
| 3285.
 | 52 | POSE: POSition Encoding for accelerated MRI Albert Jang1 and Fang Liu1
1Martinos Center for Biomedical Imaging, Harvard Medical School, Charlestown, MA, United States Keywords: New Trajectories & Spatial Encoding Methods, New Trajectories & Spatial Encoding Methods Motivation: Quantitative MRI requires multiple acquisitions to sufficiently characterize a biophysical-model of interest, resulting in long scan times. Goal(s): Propose a new general strategy for accelerating MRI using subvoxel-shifting as a means of encoding. Approach: POSition Encoding (POSE) applies unique subvoxel-shifts along the acquisition parameter dimension, which is combined with a biophysical-model to generate accelerated and enhanced resolution biophysical-parameter maps. Using T1 quantification as an application, POSE was validated both numerically and experimentally. Results: Results show that POSE 1) generates quantitative maps that agree well with the reference method, 2) has robust noise performance and 3) is applicable to any biophysical-model of interest. Impact: POSE combines subvoxel-scale spatial encoding with biophysical-models to achieve enhanced resolution with acceleration. Its ease of
implementation, robust noise performance and versatility makes it an attractive framework applicable to any quantitative biophysical-model of
interest. |
| 3286.
 | 53 | Reducing ringing artifacts in dynamic pulmonary MRI with a golden-step based interleaving approach for 3D ultra-short TE acquisition Zekang Ding1,2, Huajun She1, and Yiping P. Du1
1School of Biomedical Engineering, Shanghai Jiao Tong University, Shanghai, China, 2Central Research Institute, United Imaging Healthcare, Shanghai, China Keywords: New Trajectories & Spatial Encoding Methods, Data Acquisition, Interleaved acquisition, Ringing artifacts Motivation: In 3D radial ultra-short TE based dynamic pulmonary MRI, 3D radial k-space is usually segmented into multiple interleaves for interleaved acquisition. Motion-resolved k-space data are obtained subsequently by retrospectively binning using respiratory signals. Diaphragm drifting has been commonly observed during the scan, resulting in non-uniform spherical distribution of sampling density in motion-resolved k-space and ringing artifacts in reconstructed images. Goal(s): To reduce ringing artifacts in motion-resolved images. Approach: A golden-step based interleaving approach is proposed to mitigate adversary effect of diaphragm drifting. Results: Ringing artifacts in dynamic images acquired with conventional interleaving approach are significantly reduced in that acquired with proposed interleaving approach. Impact: Using golden-step
based interleaving approach, uniform motion-resolved k-spaces can be obtained even
under severe diaphragm drifting. This proposed approach has potential to reduce
ringing artifacts in other non-Cartesian acquisitions and applications, such as
bSSFP-based free-breathing cardiac MRI and real-time MRI. |
| 3287.
 | 54 | Open SPEN using Pulseq Andreas Holl1,2, Frank Zijlstra3, Maxim Zaitsev2, Jens Groebner1, and Sebastian Littin2
1Electrical Engineering and Information Technology, South Westphalia University of Applied Sciences, Luedenscheid, Germany, 2Division of Medical Physics, Department of Diagnostic and Interventional Radiology, University Medical Center Freiburg, Faculty of Medicine, University of Freiburg, Freiburg, Germany, 3Department of Radiology and Nuclear Medicine, St. Olav's University Hospital, Trondheim, Norway Keywords: New Trajectories & Spatial Encoding Methods, Pulse Sequence Design, SPEN, open-source Motivation: SPEN is an alternative encoding method with various advantages. However, SPEN sequences are not easily accessible. Goal(s): The aim of this project is to make SPEN in the open-source framework Pulseq openly available. This enables reproducibility and availability of SPEN. Approach: The SPEN sequence was developed in MATLAB using the Pulseq framework and is openly accessible via a GitHub repository. In addition, a sequence example is developed as a guide for the use of SPEN. Results: A SPEN sequence is openly available for the vendor-independent execution on different platforms. Impact: The
implementation in Pulseq significantly increases the accessibility of SPEN. This
hopefully leads to more SPEN-related studies and to a more widespread use in
clinical applications. |
| 3288.
 | 55 | Ultra-fast radial encoding with oscillating gradients: Potential of a high performance ultrasound gradient insert Shuai Liu1, Niklas Wehkamp1, Serhat Ilbey2, Michael Bock1, and Ali Caglar Özen1
1Division of Medical Physics, Department of Diagnostic and Interventional Radiology, University Medical Center Freiburg, Faculty of Medicine, University of Freiburg, Freiburg, Germany, 2Bruker BioSpin MRI GmbH, Ettlingen, Germany Keywords: New Trajectories & Spatial Encoding Methods, New Trajectories & Spatial Encoding Methods Motivation: Radial sampling offers motion-robust, high bandwidth MRI with incoherent undersampling, but suffers from inefficient k-space sampling. 3D radial acquisitions can be accelerated using non-conventional gradient trajectories. Goal(s): To investigate the potential improvements in point spread function and acquisition time for radial encoding using oscillating gradients. Approach: Radial spokes are modified to a conical helix trajectory using external sinusoidal gradients to increase sampling efficiency. Acceleration potential and PSF were calculated using numerical simulations. Proof-of-principle phantom measurements were performed at 3T using a field camera. Results: Radial sampling with oscillating gradients improves PSF and allows for an up to 5-fold acceleration. Impact: This study
demonstrates first high-frequency conical helix spokes in 3D using high
frequency oscillating gradients. Using external ultrasound (>20kHz)
gradients, the proposed trajectory can significantly improve the PSF for both
low-resolution and high-resolution protocols while providing extremely high
acceleration factors. |
| 3289.
 | 56 | An Advanced (k,T)-acquisition scheme to largely improve sensitivity and resolution for dynamic deuterium MRSI application in human brain at 7T Hannes Michel Wiesner1, Yudu Li2, Xin Li1, Xiao-Hong Zhu1, Zhi-Pei Liang2, and Wei Chen1
1CMRR, Department of Radiology, University of Minnesota, Minneapolis, MN, United States, 2Beckman Institute, University of Urbana Champaign, Urbana, IL, United States Keywords: New Trajectories & Spatial Encoding Methods, Deuterium Motivation: Further improving the spatial resolution and sensitivity of human brain deuterium MRSI (DMRSI). Goal(s): To develop an advanced (k,T)-acquisition scheme and processing pipeline to improve the SNR and resolution of dynamic DMRSI at 7T. Approach: We designed and implemented the new DMRSI pulse sequence on an FDA-approved 7T clinical scanner equipped with a 4-channel 2H-1H dual-frequency transreceiver head array coil; evaluated and compared the new (k,T)-CSI sequence and the FSW-CSI sequence performing high-resolution dynamic DMRSI. Results: The new DMRSI method significantly improves the SNR and spatial resolution and achieved better contrast between human GM, WM and CSF.
Impact: We developed an advanced DMRSI method for high-resolution and high-fidelity whole-brain DMRSI in humans at 7T. It enhances our ability to study neuroenergetics and metabolic reprograming associated with brain tumors and other neurological disorders, and provides clinical value for diagnosis. |
| 3290.
 | 57 | Compartmentalised reconstruction of cardiac 31P concentric ring MRSI at 7T Ferenc Emil Mozes1, Andrew Tyler2, Jack J. J. J. Miller1,3, William T. Clarke4, and Ladislav Valkovič1,5
1OCMR, RDM Cardiovascular Medicine, University of Oxford, Oxford, United Kingdom, 2School of Biomedical Engineering and Imaging Sciences, Faculty of Life Sciences and Medicine, King's College London, London, United Kingdom, 3The MR Research Centre and the PET Centre, Aarhus University, Aarhus, Denmark, 4Wellcome Centre for Integrative Neuroimaging, FMRIB, Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, United Kingdom, 5Department of Imaging Methods, Institute of Measurement Science, Slovak Academy of Sciences, Bratislava, Slovakia Keywords: New Trajectories & Spatial Encoding Methods, Spectroscopy, Ultra high field Motivation: Cardiac 31P MRS allows the probing of metabolism in various heart diseases, however, commonly employed 3D MRSI techniques are slow even at 7 T. Goal(s): Our work aims to evaluate the use of compartment-based localised spectroscopy using a linear algebraic model (SLAM). Approach: 31P MRSI data was collected using concentric ring trajectory acquisitions and SLAM was used to reconstruct 31P signal from the myocardium. Results: We show increased SNR and reduced uncertainty in determining the cardiac PCr signal, in addition to also reducing the repeatability of PCr/ATP ratio measurements when compared to a 2.5 minute, NUFFT-reconstructed CRT protocol. Impact: Repeatable and high-SNR 31P acquisitions will
allow the probing of cardiac energetics in patient populations that were
previously unable to attend prolonged scan sessions at ultra-high field
strengths. |
| 3291.
 | 58 | Improved fat suppression of cervical spine T2 weighted TSE images using enhanced slice-selective gradient reversal (enhanced LIPO) Daichi Murayama1, Masami Yoneyama2, Takayuki Sakai3, Iain Ball4, and Shigehiro Ochi3
1Radiology, Eastern Chiba Medical Center, Chiba, Japan, 2Philips Japan, Tokyo, Japan, 3Eastern Chiba Medical Center, Chiba, Japan, 4Philips Australia & New Zealand, North Ryde, Australia Keywords: New Trajectories & Spatial Encoding Methods, Artifacts, fat suppresstion Motivation: CHESS and its derivative SPIR hybrid techniques are nonuniform fat suppression occurs farther away from the isocenter of B0. These effects are common in the cervical spine and other cervical regions. Goal(s): We hypothesized that using LIPO-Only (LION) technique can be extended for T2-TSE with further optimization to increase the robustness of fat suppression. Approach: CR was calculated with ROIs placed on the spinal cord and vertebral intravital fat where fat suppression failure is most likely to occur. SNR were calculated with ROIs placed in spinal cord. Results: Combining T2-TSE with enhanced LION improves the robustness of fat suppression. Impact: These results suggested that enhanced LION T2-TSE improved the robustness of fat suppression and possible to maintain SNR equivalent to the conventional SPAIR T2-TSE. Further investigation is needed to improve the SNR with enhanced LIPO TSE. |
| 3292.
 | 59 | Fast and Motion-Robust Non-Contrast MR Angiography using Centric ky–kz Trajectory. Vadim Malis1, Won C Bae1,2, Diana Vucevic 1, Yoshimori Kassai3, Albert Hsiao1, Katsumi Nakamura4, and Mitsue Miyazaki1
1Radiology, UC San Diego, La Jolla, CA, United States, 2VA San Diego Healthcare System, San Diego, CA, United States, 3Canon Medical, Ōtawara-shi, Japan, 4Radiology, Kyoritsu Tobata Hospital, Fukuoka, Japan Keywords: New Trajectories & Spatial Encoding Methods, Blood vessels, FBI, Non-contrast Motivation: The purpose of this study is to develop a fast, motion-robust fresh blood imaging (FBI) technique using a centric ky–kz k-space trajectory (cFBI) and an exponential refocusing flip angle (eFA) scheme. Goal(s): Investigate scan time reduction and image quality of cFBI and compare it with the standard FBI technique. Approach: Advancement of the cFBI sequences with eFA and optimized cardiac trigger delays on a 3-T MR imager, aiming to reduce the scan time and maintaining the image quality. Results: cFBI outperforms standard FBI in scan time reduction with good image quality with less motion-related artifacts and Nyquist N/2 artifacts. Impact: A two-fold reduction in scan time is achieved with the non-contrast FBI technique, while still maintaining image quality and reducing motion and N/2 artifacts. |
| 3293.
 | 60 | Conical readouts in free-running 3D bSSFP imaging Martin Nicoletti1, Christopher William Roy1, Jérôme Yerli1, Robin Ferincz1, Bastien Milani2, Matthias Stuber1, and Cyril Tous1
1Lausanne University Hospital (CHUV) and University of Lausanne (UNIL), Lausanne, Switzerland, 2IHU Liryc Bordeaux, Bordeaux, France Keywords: New Trajectories & Spatial Encoding Methods, New Trajectories & Spatial Encoding Methods Motivation: The 3D radial golden angle phyllotaxis pattern integrated into the Free Running framework, supports 5D imaging of the heart during free breathing and without the need for an ECG or navigators. However, it inherently oversample low k-space frequencies with sparser coverage at the periphery of k-space. Goal(s): Our proposed approach relies on the same phyllotaxis pattern but substitutes the radial readout with spiral sections, enhancing high-frequency sampling, and reduces the overall number of radial readouts needed. Approach: We formulated the cone equations to account for un-aliasing and hardware limitations and validated our method by simulating bSSFP acquisition. Results: We obtained improved image quality. Impact: 3D spirals span a broader extent of k-space compared to radial readouts and allow for a higher sampling density at the periphery of k-space. This may help support higher spatial resolution, reduced noise, and improved image quality. |
| 3294.
 | 61 | Rapid gradient-recalled echo line scanning with crisp line profiles for human MRI at 7 Tesla Martijn A Cloos1, Shota Hodono1, Mukund Balasubramanian2, and Jonathan R Polimeni2,3,4
1Australian Institute for Bioengineering and Nanotechnology, University of Queensland, St Lucia, Australia, 2Department of Radiology, Harvard Medical School, Boston, MA, United States, 33Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Charlestown, MA, United States, 4Harvard-MIT Division of Health Sciences and Technology, Massachusetts Institute of Technology, Cambridge, MA, United States Keywords: New Signal Preparation Schemes, Pulse Sequence Design, Line Scanning Motivation: Line-scanning trades coverage for speed and resolution in a single direction, suitable for the study of mesoscale structure and functional dynamics across cortical depth. However, at ultra high-field strength, the sampling rate is constrained by the specific absorption rate. Goal(s): Facilitate Rapid gradient-recalled echo line scanning with crisp line profiles for human MRI at 7 Tesla. Approach: A new line-scan Tip-Down Tip-Up based preparation module. Results: Using the proposed preparation module, it is possible to perform gradient-recalled echo line scanning experiments with short TR and crisp line profiles. Impact: Using the proposed preparation module, it is possible to perform gradient-recalled echo line scanning experiments with short TR and crisp line profiles. Such advances can be used to study functional dynamics across cortical depth with high sampling rates. |
| 3295.
 | 62 | Deep Learning based Phase Correction with Noise and Artifacts Removal for MERGE Daming Shen1, Xinzeng Wang2, Patricia Lan3, and Wei Sun1
1GE Healthcare, Waukesha, WI, United States, 2GE Healthcare, Houston, TX, United States, 3GE Healthcare, Menlo Park, CA, United States Keywords: New Signal Preparation Schemes, Data Processing Motivation: Multiple Echo Recombined Gradient Echo (MERGE) images are inherently complex-valued, and motion, field inhomogeneities, etc. could cause echo-to-echo background phase variations. Filter-based phase correction often results in signal cancellation. Goal(s): To remove echo-to-echo phase variations for complex echo combination and improve the in-plane resolution and SNR of complex combined image Approach: We used a deep-learning-based phase correction to improve complex echo combination and apply AIR Recon DL to further improve the in-plane resolution and SNR Results: Deep learning based phase correction minimized signal cancellation and enabled robust complex echo combination With AIR Recon DL, MERGE images showed improved resolution and SNR. Impact: With improved image quality, it could improve the visualization, segmentation and measurement of tissue of interest, improving diagnosis, treatment response monitoring, etc. |
| 3296.
 | 63 | Rapid ∆B0 Field Mapping for Real-Time Shimming of Human Brain Nutandev Bikkamane Jayadev1, Yulin Chang1, Andre van der Kouwe2,3, Jason Stockmann2,3, Robert Frost2,3, Nicolas Arango4, and Ovidiu C Andronesi2,3
1Siemens Medical Solutions, USA, Inc.,, Malvern, PA, United States, 2Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Charlestown, MA, USA, Charlestown, MA, United States, 3Department of Radiology, Harvard Medical School, Boston, MA, United States, 4Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, Cambridge, MA, United States Keywords: Parallel Imaging, Motion Correction, fast B0 field mapping, EPI navigator, shimming Motivation: High-quality MRI demands accurate ∆B0 field mapping. Traditional field mapping methods cannot address motion-induced susceptibility changes during acquisition. A rapid navigator can achieve real-time motion correction with accurate shim and frequency updates. Goal(s): Develop a rapid navigator to achieve accurate field maps for real time motion correction applications. Approach: We developed GRAPPA accelerated dual-echo EPI-vNavs of rapid ∆B0 field mapping. We compared field mapping and shim current accuracy of vNavs at different resolutions and accelerations to 3D-GRE in scanner-based 2SH and multi-coil shimming. Results: The field maps generated with accelerated vNavs closely matched 3D-GRE field maps and accurately determined shim currents. Impact: Accelerated dual-echo EPI vNavs provide rapid, accurate field
mapping, reducing feedback delays. This research provides valuable insights
into impact of acceleration and resolution in vNav-based field mapping, to
benefit various MRI applications in mitigating susceptibility artifacts arising
from motion-induced changes. |
| 3297.
 | 64 | MR Imaging of tumor vascular normalization: DCE and IVIM Jing Yu1, Yong jun Cheng2, Peng Wu2, and Bo Gao1
1Department of Radiology, Affiliated Hospital of Guizhou Medical University, Guiyang, China, 2Philips Healthcare, Shanghai, China Keywords: Parallel Imaging, Cancer Motivation: The prognosis for patients with advanced nasopharyngeal carcinoma is often poor. Although anti-angiogenic therapy can enhance the effectiveness of chemo-radiotherapy, drug resistance remains a challenging issue. Accurately monitoring the time window for vascular normalization is crucial. Goal(s): The objective of this study was to assess the value of DCE-MRI and IVIM-MRI in dynamically monitoring tumor vascular normalization. Approach: By applying different antiangiogenic therapies to preclinical models, this study evaluated the effectiveness of DCE and IVIM in monitoring tumor vascular normalization (TVN). Results: Preliminary results suggest that IVIM-MRI can potentially replace DCE-MRI in monitoring tumor vascular normalization. Impact: This study holds profound implications for the clinical application of anti-angiogenesis therapy. It provides valuable insights into the effectiveness of combination therapies and offers a deeper understanding of vascular normalization indicators. These findings could potentially improve treatment strategies. |