13:45 | 1267.
| Quantifying microscopic anisotropy in the human heart in vivo using ultra-strong gradients Maryam Afzali1,2,3, Lars Mueller1,3, Sam Coveney1, Sarah Jones2, John Evans2, Fabrizio Fasano4,5, Erica Dall'Armellina1, Filip Szczepankiewicz6, Irvin Teh1, Derek K Jones2, and Jürgen E Schneider1 1Leeds Institute of Cardiovascular and Metabolic Medicine, University of Leeds, Leeds, United Kingdom, 2Cardiff University Brain Research Imaging Centre (CUBRIC), School of Psychology, Cardiff University, Cardiff, United Kingdom, 3These authors contributed equally to this work, University of Leeds, Leeds, United Kingdom, 4Siemens Healthcare Ltd, Camberly, United Kingdom, 5Siemens Healthcare GmbH, Erlangen, Germany, 6Medical Radiation Physics, Clinical Sciences Lund, Lund University, Lund, Sweden Keywords: DWI/DTI/DKI, Diffusion/other diffusion imaging techniques, Cardiac diffusion MRI, microscopic anisotropy, strong gradients, tensor-valued diffusion encoding, Diffusion Kurtosis imaging Motivation: Tensor-valued diffusion encoding has been shown to provide more information on tissue microstructure than conventional diffusion weighting/tensor imaging. Goal(s): Quantifying microscopic anisotropy, isotropic and anisotropic kurtosis in a human heart in vivo with a TE commonly used for DTI. Approach: We used strong gradients ($$$\mathrm{G_{max}=300\,mT/m}$$$) in combination with linear, planar, and spherical tensor encoding with up to second-order motion compensation to achieve $$$\mathrm{b_{max} = 1500\,s/mm^2}$$$ with a TE of 74 ms. Results: Estimated diffusion metrics matched the values reported in the literature while a shorter echo time was achieved due to the strong gradients used resulting in increased SNR and therefore image quality. Impact: We implemented tensor-valued diffusion encoding with ultra-strong gradients for in vivo cardiac diffusion MRI in humans. This allows us to quantify microscopic anisotropy and kurtosis. |
13:57 | 1268.
| Enabling high SNR cardiac spin echo DTI with a Cima.X MR System featuring 200 mT/m maximum gradient strength Danielle Kara1, Yuchi Liu2, Shi Chen1, Thomas Garrett1, Xiaoming Bi3, Deborah Kwon4, and Christopher T Nguyen1,4,5,6 1Cardiac Innovation Research Center, Heart Vascular and Thoracic Institute, Cleveland Clinic, Cleveland, OH, United States, 2Siemens Medical Solutions USA, Cleveland, OH, United States, 3Siemens Medical Solutions USA, Los Angeles, CA, United States, 4Cardiovascular Medicine, Heart Vascular and Thoracic Institute, Cleveland Clinic, Cleveland, OH, United States, 5Biomedical Engineering, Case Western Reserve and Cleveland Clinic, Cleveland, OH, United States, 6Imaging Institute, Cleveland Clinic, Cleveland, OH, United States Keywords: DWI/DTI/DKI, Diffusion Tensor Imaging Motivation: SNR and parameter map accuracy in cardiac DTI are limited by maximum gradient strength related to motion-compensation and diffusion encoding time, precluding evaluation of helical cardiomyocyte structure. Goal(s): Our goal was to improve SNR and cardiac DTI tissue microstructure characterization using an MR system capable of 200mT/m maximum gradient strength. Approach: DTI was performed in human and swine subjects using standard (40mT/m), performance (80mT/m), and ultra-high-performance (200mT/m) maximum gradient strengths, with zeroth, first, and second-order motion compensating gradients. Results: SNR and DTI tissue characterization were improved with ultra-high-performance gradients, however second-order motion compensation continued to be required to prevent motion artifacts. Impact: Ultra-high performance 200mT/m gradients enable high SNR
cardiac DTI with improved characterization of helical cardiomyocytes, potentially
addressing the clinical need for noninvasive cardiac microstructure evaluation.
|
14:09 | 1269.
| ZOOM and enhance: ZOnally magnified Oblique Multi-slice for cardiac DTI with ultra-strong gradients Lars Mueller1,2, Maryam Afzali1,2,3, Sam Coveney1, André Döring3,4, Fabrizio Fasano5,6, John Evans3, Irvin Teh1, Erica Dall'Armellina1, Filip Szczepankiewicz7, Derek K Jones3, and Jurgen E Schneider1 1Leeds Institute of Cardiovascular and Metabolic Medicine, University of Leeds, Leeds, United Kingdom, 2These Authors contributed equally to this work, Leeds, United Kingdom, 3Cardiff University Brain Research Imaging Centre (CUBRIC), School of Psychology, Cardiff University, Cardiff, United Kingdom, 4CIBM Center for Biomedical Imaging, EPFL CIBM-AIT, EPFL Lausanne, Lausanne, Switzerland, 5Siemens Healthcare Ltd, Camberly, United Kingdom, 6Siemens Healthcare GmbH, Erlangen, Germany, 7Medical Radiation Physics, Clinical Sciences Lund, Lund University, Lund, Sweden Keywords: Diffusion Acquisition, Diffusion Tensor Imaging, Cardiac diffusion MRI, strong gradients, ZOOM, reduced field of view, non co-planar rf Motivation: Cardiac diffusion tensor imaging (cDTI) with echo-planar imaging (EPI) requires long readouts to avoid aliasing artefacts if 2D-selective rf-pulses are not available. These prolong the echo time (TE) and increasing sensitivity to off-resonance artefacts. Goal(s): The reduction of the excited and refocused field of view in the phase direction to reduce TE and sensitivity to image artefacts in cDTI. Approach: We combine ZOnally-magnified Oblique Multi-slice (ZOOM) EPI (i.e. tilting the slice orientation of the refocussing rf-pulse) with ultra-strong gradients. Results: We were able to reduce TE (from ~70 ms to 59 ms) in cDTI considerably by reducing the FoV and using strong gradients. Impact: We
reduced the echo time in cDTI with ultra-strong gradients which will allow us
to use more advanced diffusion acquisitions (higher b-values and/or different
gradient waveforms) in the heart in vivo. |
14:21 | 1270.
| Axon diameter mapping in the living human brain with ultra-high gradient diffusion MRI using 500 mT/m gradient strength Yixin Ma1, Hong-Hsi Lee1, Hansol Lee1, Gabriel Ramos-Llordén1, Kowk Shing Chan1, and Susie Y. Huang1 1Martinos Center for Biomedical Imaging, Charlestown, MA, United States Keywords: Microstructure, Gradients Motivation: Noninvasive quantification of axon diameter in the living human brain offers valuable insights into the mesoscopic organization of white matter. Current methods for mapping axon diameter using diffusion MRI are limited by gradient strength. Goal(s): To evaluate the sensitivity of axon diameter mapping to small diameter axons on the Connectome 2.0 scanner (Gmax=500mT/m) compared to the original Connectome scanner (Gmax=300mT/m). Approach: The AxCaliber-SMT model was fitted to diffusion MRI data in 10 healthy subjects scanned on Connectome 2.0 and Connectome 1.0. Results: Median axon diameter in the corticospinal tract was 2.63um on Connectome 2.0 and 4.00um on Connectome 1.0. Impact: Connectome 2.0 pushes the resolution limit and signal-to-noise ratio of axonal diameter mapping, allowing for greater sensitivity toward small diameter axons at the individual level for a variety of neuroscientific and clinical applications. |
14:33 | 1271.
| Axonal Diameter Mapping as a biomarker for mTBI as detected by ultrahigh-bvalue DWI in a high performance Head-only gradient system, MAGNUS. H. Douglas Morris1, Nastaren Abad2, Chitresh Bhushan2, Luca Marinelli2, Gail Kohls1, Maureen N Hood1, James Kevin DeMarco1,3, Robert Shih1,3, Vincent B Ho1, and Thomas K F Foo2 1Radiology, Uniformed Services University of the Health Sciences, Bethesda, MD, United States, 2GE Healthcare, Niskayuna, NY, United States, 3Radiology, Walter Reed National Military Medical Center, Bethesda, MD, United States Keywords: Microstructure, Diffusion/other diffusion imaging techniques, High-performance head-only Gradient Motivation: Detect a mild traumatic brain injury with a reliable diagnostic for staging disease state and the testing therapies for treating the malady in acute and long term phase. Goal(s): Develop a MRI biomarker that can be repeated used on patients especially in the warfighter population which have more that 500,000 diagnosed mTBI over the past 30 year. Approach: Use of diffusion MRI to determine the white matter microstructural state namely the axon diameter. Results: MAGNUS SE-DWI high-B can detect changes in axon diameter and follow these changes in single subject over time. Impact: High B-value diffusion imaging (b > 30000 mm2/sec) can detect changes in mild TBI subjects that can be seen to progress through the recovery process. The high-performance gradient system, MAGNUS, (200mT/m, 500T/m/s) scanning without peripheral nerve stimulation in the subject. |
14:45 | 1272.
| Dealing with Gradient Nonlinearities for High-Performance Gradient Diffusion MRI - Application to the Human Connectome Project (HCP) Dataset M. Okan Irfanoglu1, Ahmad Beyh2,3, Anh Thai1, Carlo Pierpaoli1, and Flavio Dell'Acqua2 1QMI/NIBIB, NIBIB/NIH, Bethesda, MD, United States, 2NatBrainLab, KCL, London, United Kingdom, 3Systems Neuroscience and Psychopathology Lab, CAHBIR, Rutgers University, New Jersey, NJ, United States Keywords: Diffusion Analysis & Visualization, Diffusion/other diffusion imaging techniques, Gradient nonlinearity correction Motivation: Correction of gradient nonlinearity effects on diffusion-sensitization is important. However, not all software packages and/or diffusion models can incorporate spatially-varying bvals/bvecs information. Goal(s): Determine how significant nonlinearities are in the Human Connectome Project(HCP) dataset and investigate the feasibility of a spherical harmonics (SH)-based signal regeneration technique to directly incorporate nonlinearity effects and eliminate the need for additional information sharing. Approach: FA, MD and angular error maps from 200 subjects were compared using different formats of correction. Results: Nonlinearities are significant on HCP-dMRI data. The proposed SH-based signal regeneration approach allows the use of spatially invariant diffusion gradient tables with substantially reduced residual error. Impact: Diffusion models and software not designed to incorporate spatially-varying bvals/bvecs can now take advantage of gradient nonlinearity correction. A reprocessed version of HCP dMRI dataset will be made publicly available in this format, along with the conventional gradient deviation tensors. |
14:57 | 1273.
| UTE-Based DW-SSFP MRI for 7T Kwan-Jin Jung1 1Beckman Institute, Biomedical Imaging Center, University of Illinois at Urbana-Champaign, Urbana, IL, United States Keywords: Diffusion Acquisition, Diffusion Tensor Imaging, DW-SSFP Motivation: At 7T the conventional spin-echo EPI diffusion sequence suffers from the B1+ inhomogeneity and geometric distortion due to refocusing RF pulses and EPI readout. Goal(s): To develop a diffusion imaging sequence without refocusing RF pulses and EPI readout at 7T. Approach: Develop a 3-dimensional DW-SSFP sequence with a spiral readout to reduce the geometric distortion, to maximize the diffusion gradient time, and to reduce susceptibility effect. Results: The proposed DW-SSFP sequence was successful in reducing the B1+ inhomogeneity, the geometric distortion, and the susceptibility effect compared to the spin-echo EPI diffusion sequence using cadaveric head specimens at 7T. Impact: This sequence
enables the acquisition of high-resolution diffusion images that do not suffer
from the B1+ inhomogeneity and geometric distortion often observed at 7T. It
provides good quality fiber tracts and fractional anisotropy maps of the brain. |
15:09 | 1274.
| High-resolution whole brain multi-shell diffusion MRI at 5.0 Tesla Fan Liu1, Diwei Shi2, Xin Shao1, Sisi Li1, Qiyuan Tian1, and Hua Guo1 1Center for Biomedical Imaging Research, Department of Biomedical Engineering, School of Medicine, Tsinghua University, Beijing, China, 2Center for Nano and Micro Mechanics, Department of Engineering Mechanics, Tsinghua University, Beijing, China Keywords: DWI/DTI/DKI, Diffusion Tensor Imaging Motivation: In neuroscientific researches, 3T DWI provides limited resolution while 7T DWI suffers from challenges such as shorter relaxation time and increased field inhomogeneity. Goal(s): To evaluate the performance of 5T in high-resolution whole brain multi-shell DWI. Approach: 1.1 mm-isotropic whole brain DWI with 2 shells was acquired using multi-band single-shot 2D EPI on 5T. DTI metrics and MSMT-CSD model were computed. The nearly identical acquisition parameters and data processing were applied to the same subject on 3T. Results: 5T DWI resolved brain structural connectivity more accurately than 3T. Better FA contrast was observed at 5T, demonstrating higher SNR achieved at 5T. Impact: The feasibility of simultaneously achieving high spatial resolution and adequate q-space sampling in practical acquisition time at 5T demonstrated its potential as a new tool in DWI-based neuroscientific studies. |
15:21 | 1275.
| DTI at four directions: an application at ultra-low field Joshua Mawuli Ametepe1, James Gholam1, Álvaro Planchuelo-Gómez2, Francesco Padormo3, Leandro Beltrachini4, Mara Cercignani1, and Derek Kenton Jones1 1School of Psychology, Cardiff University, Cardiff, United Kingdom, 2University of Valladolid, Valladolid, Spain, 3Hyperfine Inc., Guilford, CT, United States, 4School of Physics and Astronomy, Cardiff University, Cardiff, United Kingdom Keywords: DWI/DTI/DKI, Low-Field MRI, Tetrahedral Encoding Motivation: The project aimed to tackle extended DTI scan durations, worsened by low SNR at low fields, striving to boost efficiency while preserving results' accuracy at lower SNR levels. Goal(s): The study sought to create an ML-based approach to shorten DT-MRI scans while ensuring reliable tensor estimation despite low SNR challenges at ULF. Approach: ML models, trained on synthetic data, predicted diffusivities and principal eigenvectors from four diffusion-weighted images, factoring in simulated noise and gradient rotations for noise and motion. Results: The models estimated diffusivities and fibre orientations with fewer data, showing promise for ULF tractography. Suggesting shorter DTI scans are possible at ULF. Impact: Our results are relevant to clinicians and researchers using
low-field MRI, potentially enabling faster DT-MRI scans, opening avenues for efficient
DTI in challenging settings, and making fibre mapping more accessible with
reduced acquisition scan times. |
15:33 | 1276.
| Diffusion Tensor Imaging at 0.05 T Ye Ding1,2, Linfang Xiao1,2, Shi Su1,2, Jiahao Hu1,2, Yujiao Zhao1,2, and Ed X. Wu1,2 1Laboratory of Biomedical Imaging and Signal Processing, The University of Hong Kong, Hong Kong, China, 2Department of Electrical and Electronic Engineering, The University of Hong Kong, Hong Kong, China Keywords: DWI/DTI/DKI, Diffusion Tensor Imaging Motivation: The employment of DTI in ULF MRI systems demonstrates considerable potential for examining microstructural variations in neuropathology and therapy. Although confronted with the inherent obstacle of low SNR at ULF, incorporating DTI yields an array of benefits. These advantages involve heightened accessibility, diminished costs, and superior patient care, while simultaneously extending the range of application possibilities for this crucial imaging modality throughout diverse healthcare contexts. Goal(s): The implementation of DTI on an ULF MRI scanner. Approach: DTI protocol was successfully implemented at 0.05 T. Results: This study demonstrated the successful implementation of DTI protocol on an ULF MRI system. Impact: This study explored the potential of a 0.05 T MRI system to increase MRI accessibility. Successful DTI implementation demonstrated the scanner's capacity to examine microstructural changes, highlighting its promising application in this field. |