| 15:45 | 1010.
 | PRIME: Phase Reversed Interleaved Multi-Echo acquisition enables highly accelerated distortion-free diffusion MRI Yohan Jun1,2, Qiang Liu2,3, Jaejin Cho1,2,4, Xingwang Yong1,2,5, Shohei Fujita1,2, Susie Y Huang1,2,6, Yogesh Rathi2,3,7, and Berkin Bilgic1,2,6
1Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Boston, MA, United States, 2Department of Radiology, Harvard Medical School, Boston, MA, United States, 3Department of Psychiatry, Brigham and Women’s Hospital, Boston, MA, United States, 4Pediatric Imaging Research Center, Massachusetts General Hospital, Boston, MA, United States, 5Zhejiang University, Hangzhou, China, 6Harvard/MIT Health Sciences and Technology, Cambridge, MA, United States, 7Department of Radiology, Brigham and Women’s Hospital, Boston, MA, United States Keywords: Diffusion Acquisition, Diffusion/other diffusion imaging techniques Motivation: Current distortion-free multishot diffusion MRI (dMRI) techniques rely on interim reconstructions to estimate a fieldmap, whose quality deteriorates at high accelerations, thus precluding high-resolution imaging. Goal(s): To develop a distortion-free acquisition that reaches high accelerations with high fidelity. Approach: We propose PRIME, which incorporates a second echo acquired at lower resolution and acceleration, but with matching echo spacing as the first echo. This yields high-fidelity fieldmaps to be used in 10-fold accelerated scans. Results: PRIME enables high-quality distortion-free dMRI at Rinplane×SMS=5×2 and 1mm3 resolution without prolonging the scan thanks to utilizing the dead time in gSlider RF-encoded acquisitions. Impact: We propose a distortion-free dMRI sequence, PRIME, that reaches Rinplane×SMS=5×2 at 1mm3 resolution with high fidelity owing to its ability to estimate a high-quality fieldmap from a second echo inserted without prolonging the TR in gSlider RF-encoded acquisitions. |
| 15:57 | 1011.
 | Robust Multi-Shot Diffusion Weighted Imaging of the Abdomen with Region-Based Shot Rejection Philip Kenneth Lee1, Xuetong Zhou1,2, and Brian Andrew Hargreaves1,2,3
1Radiology, Stanford University, Stanford, CA, United States, 2Bioengineering, Stanford University, Stanford, CA, United States, 3Electrical Engineering, Stanford University, Stanford, CA, United States Keywords: Diffusion Reconstruction, Diffusion/other diffusion imaging techniques Motivation: To improve the motion robustness of multi-shot DWI in the abdomen and reduce signal dropouts and ADC overestimation caused by unresolved shot-to-shot phase. Goal(s): Demonstrate that region-based weighting of different shots improves diffusion contrast in rapidly moving abdominal organs. Approach: Shot rejection was evaluated in the pancreas. Multiple shot rejection formulations were tested, and compared using conventional monopolar, and motion-compensated diffusion encodings. Results: Shot rejection allows conventional monopolar encoding to achieve diffusion weighting and ADCs similar to the motion-compensated encoding in the pancreas. The reconstruction is linear, requires no modifications to the sequence, and is applicable to many encoding trajectories. Impact: Shot rejection may improve the consistency and robustness
of multi-shot abdominal DWI in the clinic, as well as its ability to
differentiate pathologies. This will improve repeatability of DWI studies of rapidly
moving organs, such as the pancreas and heart. |
| 16:09 | 1012.
 | Low-distortion Spine DWI with Ultra-high Shot and Navigator-free Reconstruction Chen Qian1, Mingyang Han1, Feiqiang Guan1, Yucheng Guo1, Zhigang Wu1, Jiangzheng Wang2, Boyu Jiang3, Ran Tao3, Liuhong Zhu4, Di Guo5, Jianjun Zhou4, and Xiaobo Qu1
1Xiamen University, Xiamen, China, 2Philips Healthcare, Beijing, China, 3United Imaging Healthcare, Shanghai, China, 4Department of Radiology, Zhongshan Hospital (Xiamen), Fudan University, Xiamen, China, 5Xiamen University of Technology, Xiamen, China Keywords: Diffusion Reconstruction, Diffusion/other diffusion imaging techniques Motivation: State-of-the-art low-rank methods recover multi-shot DWI with 2D structured matrix completion, but are hindered by long computation time (tens of minutes per image) and unsatisfactory ultra-high shot reconstruction (no more than 8-shot). Goal(s): Fast and reliable ultra-high (above 8-shot) DWI reconstruction. Approach: ODLRS: A 1D low-rank Hankel reconstruction method with self-adaptive subspace. Results: ODLRS is a novel 1D low-rank framework for multi-shot DWI reconstruction. Compared to conventional low-rank methods, ODLRS achieves 109 times accelerated reconstruction, and low-distortion spine DWI with 12 shots.S Impact: This
work achieves fast (109 times acceleration) and reliable ultra-high (10 and 12 shots)
DWI reconstruction, reducing the deformation of conventional spinal cord DWI
significantly. |
| 16:21 | 1013.
 | A Data-Driven Subspace Reconstruction for Distortion-Free Diffusion-Relaxometry Echo Planar Time-Resolved Imaging Erpeng Dai1 and Jennifer A McNab1
1Department of Radiology, Stanford University, Stanford, CA, United States Keywords: Diffusion Reconstruction, Relaxometry Motivation: The subspace-based reconstruction is an SNR-efficient approach for distortion-free diffusion-relaxometry MRI with highly under-sampled echo-planar time-resolved acquisition (EPTI), in which the needed bases can be estimated from simulations. However, the simulations may not be able to fully capture the signal evolution in complex human tissue. Goal(s): To improve the subspace-based EPTI reconstruction by estimating the bases from acquired calibration data. Approach: The efficacy of the new data-driven subspace reconstruction was evaluated with in vivo EPTI experiments. Results: High-resolution, under-sampled EPTI images are reliably reconstructed using the data-driven subspace reconstruction. Impact: Our study presents a new data-driven approach for estimating the bases for the subspace-based echo-planar time-resolved imaging (EPTI) reconstruction, which may better reflect the underlying microstructure than the numerical simulation and further facilitate studies with diffusion-relaxometry MRI. |
| 16:33 | 1014.
 | Towards Genuine Three-dimensional Diffusion Imaging with Second Order Gradient Moment Nulling Yishi Wang1, Dehe Weng2, Jieying Zhang3, Tianyi Qian3, Wenzhang Liu3, Kun Zhou2, Yanglei Wu1, Baogui Zhang3, and Qing Li3
1MR Research Collaboration Team, Siemens Healthineers Ltd., Beijing, China, 2Siemens Shenzhen Magnetic Resonance Ltd., Shenzhen, China, 3Department of Biomedical Engineering, School of Medicine, Tsinghua University, Beijing, China Keywords: Diffusion Acquisition, Pulse Sequence Design Motivation: While 3D acquisition has the advantages of achieving high resolution and signal-to-noise ratio and has been established for most sequences, diffusion imaging, has predominantly adhered to 2D acquisition or partial 3D such as multi-slab acquisition for over 50 years. Goal(s): We aim to bring diffusion imaging to the next era by implementing a genuine 3D diffusion imaging sequence. Approach: The sequence was implemented using gradient moment nulling and 3D EPI acquisition and basic reconstruction methods. Results: Whole brain 3D diffusion imaging was achieved at isotropic sub-millimeter resolution and a practical scan time. Impact: This work liberates diffusion imaging from 2D or partial 3D acquisition to true 3D acquisition. |
| 16:45 | 1015.
 | Unprecedented SNR Efficiency in Prostate DWI By Combining Ultra-Strong Gradients and Spiral Readouts Malwina Molendowska1,2, Lars Müller1,3, Fabrizio Fasano4,5, Derek K Jones1, Chantal MW Tax1,6, and Maria Engel1
1Cardiff University Brain Research Imaging Centre, Cardiff University, Cardiff, United Kingdom, 2Medical Radiation Physics, Lund University, Lund, Sweden, 3Leeds Institute of Cardiovascular and Metabolic Medicine, University of Leeds, Leeds, United Kingdom, 4Siemens Healthcare Ltd, Camberly, United Kingdom, 5Siemens Healthcare GmbH, Erlangen, Germany, 6Image Sciences Institute, University Medical Center Utrecht, Utrecht, Netherlands Keywords: Diffusion Acquisition, Prostate, Field monitoring Motivation: Prostate DWI with high b-values holds promise for microstructural tissue characterization but is notoriously SNR-deprived. Goal(s): (i) To boost the SNR of prostate DWI; (ii) to reduce artefacts resulting from scanner imperfections that are exacerbated by the methods used to increase the SNR. Approach: Spirals and strong gradients (≤300mT/m) are used to attain short TEs and thus high SNR. An expanded encoding model including measured static and dynamic fields is deployed to obtain high image quality. Results: The approach is demonstrated in a healthy subject and a patient diagnosed with prostate cancer. It delivers higher SNR and improved cancerous lesion conspicuity. Impact: We provide the demonstration of prostate DWI with ultra-strong
gradients and spiral readouts. Using high b-values and short echo times
enhances lesion conspicuity and holds potential for early and non-invasive
disease detection. |
| 16:57 | 1016.
 | Improved SLIPEN (iSLIPEN) for Three-Dimensional Multi-slab Diffusion-Weighted Imaging by Partial Fourier and Prior Information Xiaorui Xu1, Shihui Chen2, Liyuan Liang2,3, Chenglang Yuan2, Hailin Xiong2, and Hing-Chiu Chang2,3
1Department of Diagnostic Radiology, The University of Hong Kong, Hong Kong, Hong Kong, 2Department of Biomedical Engineering, The Chinese University of Hong Kong, Hong Kong, Hong Kong, 3Multi-Scale Medical Robotics Center, Hong Kong, Hong Kong Keywords: DWI/DTI/DKI, Diffusion Tensor Imaging Motivation: SLIPEN is a promising technique to obtain 3D multi-slab DWI without suffering slab boundary artifacts. However, its performance is degraded when encountering limited signal SNR. Goal(s): An improved SLIPEN is desired to achieve robust perfomance regardless of limited signal SNR. Approach: Partial Fourier was applied to design an optimized sampling pattern and prior information was also incorporated into the model to improve the performance. Results: The improved SLIPEN could achieve comparable results to gold standard for in-vivo DWI images and DTI maps, with the need of only one third of gold standard data. Impact: 3D isotropic high-resolution DWI without suffering from slab boundary artifacts can be robustly achieved by our method with the use of 2D navigator, therefore benefiting the neuroscience study in evaluating crossing and kissing fibers. |
| 17:09 | 1017.
 | Accelerated multi-shell diffusion MRI with Gaussian processes estimated reconstruction of multi-band imaging Xinyu Ye1, Karla Miller1, and Wenchuan Wu1
1Wellcome Centre for Integrative Neuroimaging, FMRIB, Nuffield Department of Clinical Neurosciences, Univeristy of Oxford, Oxford, United Kingdom Keywords: Diffusion Reconstruction, Diffusion/other diffusion imaging techniques Motivation: Advanced diffusion MRI models that utilize multi-shell data provide higher specificity about tissue microstructure but require longer scan time, hindering wider application. Goal(s): To increase the acquisition speed of multi-shell diffusion MRI for rapid tissue microstructure mapping. Approach: We integrated multi-band imaging with the extended multi-shell Diffusion Acceleration with Gaussian process Estimated Reconstruction (ems-DAGER), including eddy-current corrected joint k-q reconstruction. The method was evaluated with in vivo data. Results: Simulated and in-vivo results demonstrate that ems-DAGER method can significantly improve the image quality of reconstructed dMRI data with both in-plane and slice-wise acceleration to enable advanced multi-shell diffusion analysis. Impact: Highly
accelerated dMRI with the proposed method can shorten the scan time of
multi-shell dMRI without sacrificing quality compared to conventional practice.
This may facilitate a wider application of advanced dMRI models in basic and
clinical neuroscience. |
| 17:21 | 1018.
 | Self-navigated 3D multi-slab EPI for SNR-efficient high-resolution diffusion MRI Ziyu Li1, Karla L. Miller1, Xi Chen1,2,3, Mark Chiew1,4,5, and Wenchuan Wu1
1Wellcome Centre for Integrative Neuroimaging, FMRIB, Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, United Kingdom, 2Biomedical Imaging Research Institute, Cedars-Sinai Medical Center, Los Angeles, CA, United States, 3Department of Radiological Sciences, David Geffen School of Medicine at UCLA, Los Angeles, CA, United States, 4Physical Sciences, Sunnybrook Research Institute, Toronto, ON, Canada, 5Department of Medical Biophysics, University of Toronto, Toronto, ON, Canada Keywords: Diffusion Acquisition, Sparse & Low-Rank Models, 3D multi-slab imaging, Navigator, Diffusion acquisition, Diffusion reconstruction Motivation: 3D multi-slab EPI achieves superior SNR efficiency for high-resolution diffusion MRI but requires navigators for phase correction, which increase scan time and SAR. Goal(s): To eliminate the requirement for navigators in 3D multi-slab diffusion MRI. Approach: 3D imaging is intrinsically highly segmented, making self-navigation challenging. Our optimized multi-shot sampling facilitates self-navigation by ensuring each shot intersects with kz=0 plane. The overall sampling pattern’s overlap and gaps are also minimized. A structured low-rank reconstruction is leveraged to reconstruct 2D phase maps from these intersections for phase correction. Results: Compared to navigated imaging our self-navigated method achieves comparable image quality with 31.4% shorter scan time. Impact: By removing the need for navigation, our method enables 3D multi-slab diffusion MRI to efficiently achieve TRs with near-optimal SNR efficiency. This approach may permit wider adoption of high-resolution diffusion MRI for basic and clinical neuroscience. |
| 17:33 | 1019.
 | Slice-POCS-ICE: a navigator-free reconstruction for SMS-accelerated multi-shot spiral-based diffusion-weighted imaging Guangqi Li1, Yuancheng Jiang1, Yajing Zhang2, and Hua Guo1
1Center for Biomedical Imaging Research, Department of Biomedical Engineering, School of Medicine, Tsinghua University, Beijing, China, 2MR R&D, Philips Health Technology (Suzhou), Suzhou, China Keywords: Diffusion Acquisition, Diffusion/other diffusion imaging techniques, Spiral diffusion imaging Motivation: Simultaneous multi-slice (SMS) technique can further enhance the acquisition efficiency of spiral-based diffusion imaging. Goal(s): Our goal was to achieve SMS-accelerated navigator-free multi-shot spiral-based diffusion imaging. Approach: RF pulse phase encoding strategy was optimized to introduce the CAIPI phase modulation. Furthermore, we proposed the slice-POCS-ICE algorithm to simultaneously perform CAIPI phase demodulation, inter-shot phase error correction, and diffusion image reconstruction. The proposed algorithm was tested on simulated and in-vivo data. Results: Our proposed slice-POCS-ICE algorithm can simultaneously accomplish CAIPI phase demodulation and remove the shot-to-shot phase variations, for SMS-accelerated multi-shot navigator-free spiral-based DWI. The proposed slice-POCS-ICE has a stable convergence behavior. Impact: The
proposed slice-POCS-ICE reconstruction algorithm can successfully reconstruct
multi-shot diffusion images from SMS-accelerated navigator-free spiral acquisitions
with optimized CAIPI phase modulation, which may be valuable for speeding up
multi-shot spiral-based DWI acquisitions, to facilitate both neuroscience
research and clinical diagnosis. |