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Zhuoyao Xin¹, Vishwanatha Mitnala Rao², Dong Liu³, Yanting Yang², Ye Tian², Chenghao Zhang², Andrew F. Laine², and Jia Guo^2
1Biomedical Engineering, Columbia University, New York City, NY, United States, ²Columbia University, New York City, NY, United States, ³Neuroscience, Columbia University, New York City, NY, United States

Keywords: Image Reconstruction, Multimodal

This abstract proposed a cross-modality conversion method from UTE MRI to CT images. Using the TABS and ResidualAttentionU-net model in a processing framework combining image segmentation and prediction, the skull structure can be extracted from UTE MRI with high similarity of CT based skull. Five UTE-CT image pairs of mouse brains were used in the study. And a 3D-patch based training strategy was adopted, which took the advantage of structural continuity between slices in very limited datasets. The results show that the proposed combined image segmentation and prediction framework can achieve higher accuracy in medical image synthesizing for cross-modality conversion.

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Soo Hyun Shin¹, Dina Moazamian¹, Arya Suprana^1,2, Xiaojun Chen¹, Jiyo S Athertya¹, Chun Zeng¹, Michael Carl³, Yajun Ma¹, Hyungseok Jang¹, and Jiang Du^1,2,4
1Department of Radiology, University of California, San Diego, La Jolla, CA, United States, ²Department of Bioengineering, University of California, San Diego, La Jolla, CA, United States, ³GE Helathcare, San Diego, CA, United States, ⁴Radiology Service, Veterans Affairs San Diego Healthcare System, La Jolla, CA, United States

Keywords: Relaxometry, Relaxometry

Direct imaging of semi-solid lipids, such as cell membranes and myelin, is of great interest. Yet, the short T₂ of semi-solid lipid protons hampers direct detection through conventional pulse sequences. In this study, we examined whether an ultrashort echo time (UTE) sequence can directly acquire signals from membrane lipids. Cell membranes from red blood cells were subject to D₂O exchange and freeze-drying for complete water removal. High MR signals were detected with the UTE sequence, which showed an ultrashort T₂* of ~77-252 µs and a short T₁ of 189 ms for semi-solid membrane lipids. 

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Zachary Miller¹, Luis A Torres¹, Sean Fain², and Kevin M Johnson^1
1University of Wisconsin-Madison, Madison, WI, United States, ²University of Iowa, Iowa City, IA, United States

Keywords: Image Reconstruction, Motion Correction

This work develops a method for large-scale motion compensated 4D reconstructions of fully 3D radial acquisitions at near 1mm isotropic spatial resolution and sub-second temporal resolution. We combine and extend multi-scale image reconstruction (Extreme MRI) with k-space based motion field estimation (MOTUS) to solve for a multi-scale low rank  representations of both images and motion fields. This combined approach outperforms the multi-scale low rank reconstruction without motion fields.

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Jose Borreguero¹, Fernando Galve², Jose Miguel Algarín², Jose María Benlloch², and Joseba Alonso^2
1Tesoro Imaging S.L., Valencia, Spain, ²Institute for Molecular Imaging and Instrumentation, Spanish National Research Council & Universitat Politècnica de València, Valencia, Spain

Keywords: New Trajectories & Spatial Encoding Methods, New Signal Preparation Schemes

Here we provide an MRI sequence which allows slice selection and 2D-imaging of hard tissues with T₂ as short as 275 μs within clinically acceptable scan times even at fields as low as 260 mT. Our proposed sequence combines slice selection through spin-locking, which suffers a much more benign decay (T_1ρ>>T₂), and the fastest imaging sequence (ZTE), providing a new and robust tool for slice selection of the shortest-lived tissue signals in the body. 

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Sheng Chen¹, Zhixing Wang¹, Yekaterina K. Gilbo², Helen L. Sporkin¹, Samuel W. Fielden³, Steven P. Allen⁴, John P. Mugler III⁵, G. Wilson Miller⁵, and Craig H. Meyer^1,5
1Biomedical Engineering, University of Virginia, Charlottesville, VA, United States, ²Netflix, Los Gatos, CA, United States, ³U.S. Food and Drug Administration, Silver Spring, MD, United States, ⁴Brigham Young University, Provo, UT, United States, ⁵Radiology and Medical Imaging, University of Virginia, Charlottesville, VA, United States

Keywords: Sparse & Low-Rank Models, Image Reconstruction, UTE, Spiral, Focused Ultrasound

Unintended heating of the skull and nearby brain tissue during MR-guided Focused Ultrasound (MRgFUS) treatment is not standardly monitored. A method for addressing this issue, which combines variable flip angle (VFA) T1 mapping and proton resonance frequency (PRF) shift thermometry based on a dual-echo 3D spiral ultra-short echo time (UTE) acquisition, was accelerated with a low-rank plus sparse model in image reconstruction and validated using retrospectively undersampled data in vitro.

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Stefan Sommer^1,2,3, Constantin von Deuster^1,2,3, Tom Hilbert^3,4,5, and Daniel Nanz^2
1Siemens Healthineers International AG, Zurich, Switzerland, ²Swiss Center for Musculoskeletal Imaging (SCMI), Balgrist Campus, Zurich, Switzerland, ³Advanced Clinical Imaging Technology (ACIT), Siemens Healthineers International AG, Lausanne, Switzerland, ⁴Department of Radiology, Lausanne University Hospital and University of Lausanne, Lausanne, Switzerland, ⁵LTS5, École Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland

Keywords: Data Acquisition, Pulse Sequence Design, DESS, UTE, UTE-DESS, DW-DESS, DW-UTE-DESS, ZTE

The quality of echo-planar diffusion images can suffer from severe distortions and signal dropouts, especially in regions with high susceptibility gradients and rapidly decaying (short T2*) signal. To overcome these problems, we implemented a diffusion sensitive UTE-DESS sequence. The acquisition along six distinct diffusion directions allows for fitting of a diffusion tensor. We show the feasibility of Diffusion tensor imaging with Ultra-short echo time Double Echo steady state (DUDE) at 3T and present preliminary results in the brain of a healthy volunteer.

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Hanna Frantz¹, Patrick Metze¹, and Volker Rasche^1
1Ulm University Hospital, Ulm, Germany

Keywords: New Trajectories & Spatial Encoding Methods, Lung, Function

Lung MRI is a steadily evolving field of research, especially concerning the evaluation of chronic lung diseases such as cystic fibrosis or COPD. The major limitation of lung MRI is the ultrashort T₂^* relaxation time of lung parenchyma, which demands ultrashort echo time sequences. Sufficient SNR values in the parenchyma are crucial for clinical evaluations and the assessment of physiological parameters. This abstract presents an adapted rosette trajectory for UTE imaging, yielding higher SNR per unit time in comparison to radial UTE sampling approaches.

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Serhat Ilbey¹, Antonia Susnjar², Uzay Emir^2,3, Michael Bock¹, and Ali Caglar Özen^1
1Division of Medical Physics, Department of Radiology, University Medical Center Freiburg, Freiburg, Germany, ²Weldon School of Biomedical Engineering, Purdue University, West Lafayette, IN, United States, ³School of Health Science Department, Purdue University, West Lafayette, IN, United States

Keywords: New Trajectories & Spatial Encoding Methods, New Trajectories & Spatial Encoding Methods

A multi-contrast multi-resolution UTE sequence was developed with a dual-echo acquisition between 1-1 binomial water excitation pulses and a conventional UTE readout. This acquisition scheme provides 3 images with different echoes, flip angles, spatial resolution, and contrast (water excitation). T₂^* was quantified in the whole brain in TA<15min, and UTE images of the brain were reconstructed with 0.5mm isotropic resolution without additional scan time.

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Peter Latta¹, Vladimir Juras², Zenon Starcuk³, Martin Kojan¹, Ivan Rektor¹, Pavol Szomolanyi², and Siegfried Trattnig^2
1Masaryk University, Brno, Czech Republic, ²Medical University of Vienna, Vienna, Austria, ³Institute of Scientific Instruments, Czech Academy of Sciences, Brno, Czech Republic

Keywords: Tendon/Ligament, Skeletal, Achilles tendon, Bi-exponential . T2*

We investigated tri‑component analysis of 2D-UTE in-vivo measurements on a clinical 3T scanner and tested its ability to eliminate the effect of fat suppression on short T₂* values in Achilles tendons. We found that fat-suppressed acquisition with two-component analysis provides ratios of short-T₂* to long-T₂* component intensities that are substantially lower (by a factor 0.95 to 0.55) than those resulting from fat-unsuppressed acquisition and tri-component fitting. Hence it seems that the combination of 2D-UTE acquisition with tri-component analysis might contribute to further improvement of T₂* estimation accuracy. 

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Sam Sedaghat¹, James V Luck², Annette von Drygalski³, Scott T Ball⁴, Soo Hyun Shin¹, Eddie Fu¹, Eric Y Chang^1,5, Jiang Du^1,5,6, and Hyungseok Jang^1
1Department of Radiology, University of California San Diego, San Diego, CA, United States, ²Department of Orthopaedic Surgery, University of California Los Angeles, Los Angeles, CA, United States, ³Department of Medicine, University of California San Diego, San Diego, CA, United States, ⁴Department of Orthopaedic Surgery, University of California San Diego, San Diego, CA, United States, ⁵Radiology Service, Veterans Affairs San Diego Healthcare System, San Diego, CA, United States, ⁶Department of Bioengineering, University of California San Diego, San Diego, CA, United States

Keywords: MSK, Hematologic

We investigated the quantitative capability of the UTE-QSM technique in the assessment of hemosiderin compared to histology. UTE-QSM and histology were performed in knee synovium tissues from hemophilia patients to visualize hemosiderin. The susceptibility maps from UTE-QSM showed a visually high similarity to the corresponding histological findings for all tissues. There was a significant difference in tissues with low and high iron load (p<0.001) in UTE-QSM. The susceptibility values on UTE-QSM showed a significant strong positive correlation to the blue signal in histology (R=0.908; p<0.001). We showed that UTE-QSM has excellent performance for detecting and quantifying hemosiderin in HA. 
 

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Misung Han¹, Peder EZ Larson^1,2, Thomas M Link¹, Drew A Lansdown³, Brian T Feeley³, and Sharmila Majumdar^1,2
1Radiology and Biomedical Imaging, University of California, San Francisco, San Francisco, CA, United States, ²UCSF-UC Berkely Graduate Program in Bioengineering, University of California, San Francisco, San Francisco, CA, United States, ³Department of Orthopaedic Surgery, San Francisco, CA, United States

Keywords: Tendon/Ligament, Quantitative Imaging

Rotator cuff tears are a common source of pain and disability. Surgical treatment is normally considered for patients who fail in non-operative management, but a failure of tendon healing after surgery can be dependent on tendon quality. In this work, we applied two ultrashort-echo time (UTE) quantification imaging methods, UTE T₂* quantification as well as UTE magnetization transfer (MT) quantification, on healthy subjects and patients with rotator cuff tears, and evaluated their ability to assess tendon degeneration. Significant difference was observed for quantified T₂* and MT parameters over segmented supraspinatus tendon between the healthy control and patient groups.

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Saeed Jerban¹, Yajun Ma¹, Qingbo Tang², Eddie Fu², Nikolaus Szeverenyi¹, Hyungseok Jang¹, Christine B Chung¹, Jiang Du¹, and Eric Y Chang^1,2
1Radiology, University of California, San Diego, San Diego, CA, United States, ²Radiology Service, Veterans Affairs San Diego Healthcare System, San Diego, La Jolla, CA, USA, San Diego, CA, United States

Keywords: Muscle, Magnetization transfer, Collagen Content; Fat Content

Magnetization transfer (MT) MR imaging can indirectly characterize the spatial distribution of the relative contents of the macromolecular and water proton pools (MMF) of skeletal muscles. Fat presence in muscle has always been a source of concern in MMF calculation where some studies have reported significant underestimation of MMF for muscles with a considerable fat fraction (FF). We investigated the impact of FF on MMF in muscle/fat phantoms using an ultrashort echo time (UTE) MT model after T1 compensation. MMF demonstrated a relatively robust value with under 5% and 20% changes for FF increases up to 30 and 45%, respectively.

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Dantian Zhu¹, Yijie Fang¹, Wenhao Wu¹, Shaolin Li¹, Long Qian², and Yajun Ma^3
1Department of Radiology,Fifth Affiliated Hospital, Sun Yat-Sen University, Zhuhai, China, ²MR Research, GE Healthcare, Beijing, China, ³University of California, San Diego, Department of Radiology, San Diego, CA, United States

Keywords: Cartilage, Cartilage

To assess the detection of changes in the knee cartilage of amateur marathon runners before and after long-distance running. We recruited 23 amateur marathon runners prospectively. MRI scans using UTE-MT and UTE-T2* sequences. UTE-MTR and UTE-T2* were measured for knee cartilage. The UTE-MTR values in lateral tibial plateau, central medial femoral condyle, and medial tibial plateau showed a significant decrease at 2 days post-race compared to the other two time points (P < 0.05). But no significant UTE-T2* changes were found for any cartilage subregions. UTE-MTR is a promising method for the detection of dynamic changes in knee cartilage.

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Saeed Jerban^1,2,3, Dina Moazamian¹, Sheronda Statum¹, Hyungseok Jang^1,2, Eric Y Chang^1,2, Jiang Du^1,2, Christine B Chung^1,2, and Yajun Ma^1
1Department of Radiology, University of California, San Diego, La Jolla, CA, USA, San Diego, CA, United States, ²Radiology Service, Veterans Affairs San Diego Healthcare System, San Diego, La Jolla, CA, USA, San Diego, CA, United States, ³Department of Orthopedic Surgery, University of California, San Diego, La Jolla, CA, USA, San Diego, CA, United States

Keywords: Skeletal, Magnetization transfer, Intervertebral disc

Quantitative ultrashort echo time (UTE) MRI can be used for quantitative assessment of intervertebral discs (IVDs). It is hypothesized that the investigation of quantitative UTE MRI properties of IVD under mechanical loading may highlight the affected regions of IVD by diseases and injuries. We investigated the feasibility of using UTE-T1, UTE-Adiab-T1ρ, and UTE-MT measures for detecting the IVD deformation under loading. T1 and T1 ρ decreased in IVDs under loading while MMF from UTE-MT modeling as an index for collagen content increased by loading. This study highlights the potential of UTE-MRI to detect subvoxel deformations in IVDs caused by loading.

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James H Holmes¹, Vincent A Magnota¹, Mathews Jacob², Yan Chen², Joshua Hanson³, Paul A DiCamillo¹, and Curtis A Corum^3
1Radiology, University of Iowa, Iowa City, IA, United States, ²Electrical and Computer Engineering, University of Iowa, Iowa City, IA, United States, ³Champaign Imaging, LLC, Shoreview, MN, United States

Keywords: Neuro, Pulse Sequence Design, silent imaging

In this work, we present progress in developing a ZTE-based silent and motion-robust neuroimaging protocol using intermittent magnetization preparation for generation of standard imaging contrasts including T1w and T2w. 

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Yupeng Cao¹, Jun Zhao¹, Weinan Tang², Wentao Liu¹, and Dong Han^1
1National Center for Nanoscience and Technology, Beijing, China, ²Wandong Medical Inc, Beijing, China, Beijing, China

Keywords: New Trajectories & Spatial Encoding Methods, Lung

Single breath-hold high-resolution lung imaging is challenging due to the short T₂^* and scan efficiency. The stack-of-spirals UTE enables fast lung imaging in a single breath hold. However, fast scanning of stack-of-spirals results in a long readout time, introducing adverse effects of the short T₂^* of the lung. Herein, we proposed a density-controllable spiral trajectory (DCST) design method to design a short readout time trajectory concurrently satisfying the criteria of optimal compressed sensing (CS), reducing the adverse effect of the short T₂^*. The short readout time trajectory combined with CS-UTE improves the single breath-hold high-resolution lung imaging.

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Matthew Willmering¹, Guruprasad Krishnamoorthy^2,3, Joseph Plummer^1,4, Abdullah Bdaiwi¹, Laura Walkup^1,4,5, Zackary Cleveland^1,4,5, James Pipe³, and Jason Woods^1,4,5
1Cincinnati Children’s Hospital Medical Center, Cincinnati, OH, United States, ²Philips Healthcare, Rochester, MN, United States, ³Mayo Clinic, Rochester, MN, United States, ⁴University of Cincinnati, Cincinnati, OH, United States, ⁵University of Cincinnati Medical Center, Cincinnati, OH, United States

Keywords: Data Acquisition, Data Acquisition

FLORET UTE MRI has been used for many applications including lung, brain, musculoskeletal, and multinuclear imaging. The appeal of the pulse sequence comes from its high SNR and sampling efficiencies. With recent improvements minimizing artifacts, high-quality FLORET images are obtained routinely. However, acquisition of multiple echoes has not been investigated. Here, we determined the feasibility and optimal pulse-sequence design of multi-echo FLORET. Collecting echoes independently, but interleaved, produces the highest quality images, especially for ≥3 echoes. Furthermore, additional echoes provide improvements to image quality and add clinically useful contrast like T₂*.

Hui Feng¹, Li Yang¹, Chen Zhang², Hui Liu¹, Ning Zhang¹, and Gaofeng Shi^1
1The Fourth Hospital of Hebei Medical University, Shijiazhuang, China, ²Siemens Healthineers, Beijing, China

Keywords: Visualization, Lung

The PETRA technique had high sensitivity for the detection of subsolid pulmonary nodules and can accurately assess their diameter and morphologic characteristics.

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Kwan-Jin Jung¹, Ryan Larsen², Laurie Rund², and Andrew Steelman^3,4,5
1Biomedical Imaging Center, Beckman Institute, University of Illinois at Urbana-Champaign, Urbana, IL, United States, ²Department of Animal Sciences, University of Illinois at Urbana-Champaign, Urbana, IL, United States, ³Neuroscience Program, 2325/21, University of Illinois at Urbana-Champaign, Urbana, IL, United States, ⁴Carl R. Woese Institute for Genomic Biology, University of Illinois at Urbana-Champaign, Urbana, IL, United States, ⁵Division of Nutritional Sciences, University of Illinois at Urbana-Champaign, Urbana, IL, United States

Keywords: Relaxometry, Neuro, Myelin, Piglet

Myelin content was measured from the fast T1 relaxation component using bi-exponential T1 relaxation regression. The data was collected using UTE with variable flip angles to detect short T2 signal of myelin and to avoid magnetic susceptibility corruption by T2*-based myelin contrast methods. The estimated myelin content was influenced  by CSF, which was suppressed by use of the slow T1 relaxation time. The estimated myelin content was higher in white matter  than other brain regions. However, the myelin content was increased in the anterior pole and low in motor areas in this in-vivo piglet data.

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Gehua Tong¹, Andreia S. Gaspar², Rita G. Nunes², Jon-Fredrik Nielsen³, John Thomas Vaughan, Jr.^1,4, and Sairam Geethanath^4,5
1Biomedical Engineering, Columbia University, New York, NY, United States, ²Institute for Systems and Robotics (ISR-Lisboa)/LaRSyS, Department of Bioengineering, Instituto Superior Técnico, Universidade de Lisboa, Lisbon, Portugal, ³Biomedical Engineering, University of Michigan, Ann Arbor, MI, United States, ⁴Columbia Magnetic Resonance Research Center, Columbia University, New York, NY, United States, ⁵Accessible MR Laboratory, BioMedical Engineering and Imaging Institute, Dept. of Diagnostic, Molecular and Interventional Radiology, Icahn School of Medicine at Mt. Sinai, New York, NY, United States

Keywords: Validation, Pulse Sequence Design

We validated five open-source PyPulseq minimal TE sequences (half/full pulse 2D/3D UTEs and COncurrent Dephasing and Excitation (CODE)) at three sites with different scanner models. The ISMRM/NIST T₂ array and a porcine muscle and bone sample were imaged. SNR, contrast-to-noise ratio (CNR), and T₂ contrast curves were calculated and compared. We found that the sequences were able to recover more SNR from bone tissue compared to vendor GRE (an additional 50% - 1060% for 3T and 34% - 474% for 1.5T) and higher signal for short-T₂ spheres but intersite differences existed that were consistent with field strengths.