Peter J Lally¹, Matthew Grech-Sollars^2,3, Joely Smith^3,4, Ben Statton⁵, Paul M Matthews^1,6, Karla L Miller⁷, and Neal K Bangerter^4
1Department of Brain Sciences, Imperial College London, London, United Kingdom, ²Department of Surgery and Cancer, Imperial College London, London, United Kingdom, ³Department of Imaging, Imperial College Healthcare NHS Trust, London, United Kingdom, ⁴Department of Bioengineering, Imperial College London, London, United Kingdom, ⁵MRC London Institute of Medical Sciences, London, United Kingdom, ⁶UK Dementia Research Institute Centre at Imperial College, London, United Kingdom, ⁷Wellcome Centre for Integrative Neuroimaging, Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, United Kingdom

Here we describe a super-resolution 3D T₂ relaxometry approach using an unbalanced SSFP acquisition with very low flip angle RF pulses (α ≤ 1°). We then apply this to obtain 1mm isotropic T₂ maps in a reference phantom, and compare this to both the reference values and a 2D multi-echo spin echo approach. The proposed approach provides new options for high-resolution, low-SAR T₂ relaxometry experiments in a range of tissues.

Lars Bielak^1,2, Thomas Lottner¹, and Michael Bock^1,2
1Dept.of Radiology, Medical Physics, Medical Center University of Freiburg, Faculty of Medicine, University of Freiburg, Freiburg, Germany, ²German Cancer Consortium (DKTK), Partner Site Freiburg, Freiburg, Germany

A novel sequence design based on radial fast spin echo with interleaved diffusion sensitization for simultaneous ADC and T₂ mapping is presented. Additionally, a model restriction to a conventional compressed sensing reconstruction is implemented to support higher undersampling during acquisition. Simulations and phantom measurements show accurate measurement of diffusion ADC and T₂ with as few as 11 spokes per TE, and 45 different TEs.

Jeff Snyder¹ and Alan H Wilman^1
1Biomedical Engineering, University of Alberta, Edmonton, AB, Canada

A 3D FSE method using variable flip angle trains is proposed for quantification of T2 in brain.  Two images are acquired at different echo times to allow for decay curve fitting using Bloch equation and Echo Phase Graph (EPG) simulations.  Echo train lengths of 96 and 192 were investigated (total scan times of 8:12 and 2:38) in phantom and healthy subjects at 3 T, with isotropic resolutions of 0.9 and 1.3 mm³, respectively. RF was optimized to reduce blurring, sustain signal and allow T2 resolution. Comparison with previous methods was excellent, with good resolution and contrast in the 96 case.

Mei-Lan Chu¹, Tzu-Cheng Chao², Nan-kuei Chen³, and Hsiao-Wen Chung^1
1Graduate Institute of Biomedical Electronics and Bioinformatics, National Taiwan University, Taipei, Taiwan, ²Mayo Clinic, Rochester, MN, United States, ³University of Arizona, Tucson, AZ, United States

Our novel single-shot T2 mapping framework, integrating ES-GRASE acquisition and parametric  mapping, has the following advantages. First, signal contamination of high-order echoes is removed in the propose framework. Second, T₂ relaxation times can be accurately measured by incorporating parallel imaging and multi-echo-pathway signal modeling into the reconstruction procedure.

Jonathan Tamir^1,2,3, Ken-Pin Hwang⁴, Naoyuki Takei⁵, and Suchandrima Banerjee^6
1Electrical and Computer Engineering, The University of Texas at Austin, Austin, TX, United States, ²Diagnostic Medicine, Dell Medical School, The University of Texas at Austin, Austin, TX, United States, ³Oden Institute for Computational Engineering and Sciences, Austin, TX, United States, ⁴Imaging Physics, MD Anderson Cancer Center, Houston, TX, United States, ⁵MR Applications and Workflow, GE Healthcare, Hino, Tokyo, Japan, ⁶MR Applications and Workflow, GE Healthcare, Menlo Park, CA, United States

Fast, volumetric multi-contrast and quantitative imaging has a broad range of applications, but applying them in 3D remains challenging. Most volumetric approaches rely on gradient-echo-based acquisitions to achieve high scan-efficiency, even though spin-echo imaging provides higher SNR. Here we explore a hybrid acquisition that combines a fast-spin-echo acquisition block with multiple spoiled gradient-echo blocks to acquire spin- and gradient-echo images. We use a shuffled acquisition ordering together with a global subspace constraint and local low rank regularization to accelerate the scan. Following reconstruction, we fit the time series of images to quantitative parameters directly in the subspace using dictionary matching.

Zoe Doyle¹, Daehyun Yoon ¹, Philip Lee¹, Brian Hargreaves¹, and Kathryn Stevens^1
1Stanford University, Stanford, CA, United States

For the past decade, the development of 3D multispectral imaging (MSI) approach has facilitated the early detection of complications around metallic implants. However, the long acquisition time and need for multi-planar acquisitions make it difficult for symptomatic, elderly patients to tolerate. In this preliminary study, we evaluate the use of a fast isotropic 3D MSI technique at 3T MRI, which can potentially replace multiple sequences of orthogonal imaging planes with a single acquisition. Our results show promise for the improved visualization of various hardware complications using image reformats on arbitrary planes with diagnostically acceptable image quality.

Ekaterina A. Brui¹, Stanislas Rapacchi², David Bendahan², and Anna Andreychenko^1,3
1Department of Physics and Engineering, ITMO University, Saint Petersburg, Russian Federation, ²Aix-Marseille Universite, CNRS, Centre de Résonance Magnétique Biologique et Médicale, Marseille, France, ³Center of Diagnostics and Telemedicine Technologies, Department of Health Care of Moscow, Research and Practical Clinical, Moscow, Russian Federation

There has been previously proved that a metamaterial-based wireless coil (WLC) provided a 48-fold lower SAR in 1.5T wrist MRI in comparison to conventional RF setup. This can allow to extend the acceptable threshold of energy deposition for SAR-demanding pulse sequences. This study demonstrates that SLR-based FSE together with the WLC allowed to increase the slice selectivity while still being within the safe SAR limits. The actual energy deposition was decreased as compared to a conventional RF setup. The combination of this coil and SLR-based FSE offers an interesting alternative for investigations which require scanning in a “Low SAR” regim.

Shi Cheng¹, Kun Zhou¹, Wei Liu¹, and Dehe Weng^1
1Siemens Shenzhen Magnetic Resonance Ltd., Shenzhen, China

Spin-echo-based Dixon sequences may suffer from reduced SNR efficiency, due to dead time necessary for the readout shifts. In this abstract, an imaging method utilizing two pairs of fast-switching bipolar readout gradients and partially-opposed-phase and in-phase Dixon (CETD) is proposed to further reduce dead time. More attractively, the novel steps in joint reconstruction of the two pairs ensure the consistency of water-fat separation.

Milena Capiglioni¹, Claus Kiefer², and Roland Wiest^1
1Institute for Diagnostic and Interventional Neuroradiology, Support Center for Advanced Neuroimaging (SCAN), University of Bern, Bern, Switzerland, ²Institute for Diagnostic and Interventional Neuroradiology, Support Center for Advanced Neuroimaging (SCAN), Inselspital, Bern, Bern, Switzerland

We evaluated the performance of a new contrast based on the rotary saturation technique to observe oscillating fields induced by neuronal currents. We used Bloch simulations and phantom experiments to study and observe the double resonance effect and the influences of external factors such as field inhomogeneities and relaxation phenomena. We detected oscillating fields in the nT range using the proposed Spin lock  on/off contrast. We conclude that this technique can be used to observe oscillating neuronal fields and we propose different methods to reduce the effect of external influences on the signal.

Fabian Niess¹, Albrecht Ingo Schmid¹, Graham Kemp², Ewald Moser¹, Maxim Zaitsev¹, and Martin Meyerspeer^1
1High Field MR Center, Center for Medical Physics and Biomedical Engineering, Medical University Vienna, Vienna, Austria, ²Department of Musculoskeletal & Ageing Science, Institute of Life Course and Medical Sciences, University of Liverpool, Liverpool, United Kingdom

The purpose of this study was to develop a novel single-shot acquisition scheme to quantify the lactate doublet at 1.3 ppm in skeletal muscle at ultrahigh field of 7 T. A double quantum filtered ¹H MRS sequence was implemented using a Shinnar-Le-Roux optimised 90° pulse and adiabatic full-passage 180° pulses for slice-selective excitation and refocusing, respectively. The lactate resonance was successfully quantified in phantom (free lactate in solution) and ex vivo measurements (lactate injected into a meat specimen). Muscle fibre orientation and corresponding effects on the observed lactate resonance were in good agreement with the literature.

Riwei Jin¹, Zhi-pei Liang¹, and Bradley P. Sutton^1
1University of Illinois Urbana-Champaign, Champaign, IL, United States

We managed to increase the 3D coverage of dynamic speech magnetic resonance imaging to 32 slices with 96 mm full thickness, spatial resolution to 1.875×1.875×3mm and temporal resolution of 35 fps by applying sparsely sampling the temporal navigators with four k-space lines and and apply to a low-rank constraint Partial-Separability (PS) model for reconstruction. This enables visualization approaching isotropic resolution with the full vocal tract covered from side to side, enabling dynamic visualizations of complex motions that do not stay within a single imaging plane.

Sydney Nicole Williams¹, Iulius Dragonu², Patrick Liebig³, and David A. Porter^1
1Imaging Centre of Excellence, University of Glasgow, Glasgow, United Kingdom, ²Siemens Healthcare Ltd., Frimley, United Kingdom, ³Siemens Healthineers, Erlangen, Germany

For ultra-high field, parallel transmit (pTx) plays a key role in the mitigation of B₁⁺ field inhomogeneity. Slice-selective 2D imaging is particularly challenging, where common solutions such as spokes haven’t been robustly implemented in standard multi-slice acquisitions. In this abstract we use slice-by-slice shimming to combat B₁⁺ homogeneity in a multi-slice readout-segmented diffusion-weighted sequence with preliminary results shown in a human subject. Slice-by-slice shimming is compared to single-transmit and volumetric-shimming, with promising improvements in image quality.

Kyle Jeong¹, Noel Carlson², John Rose³, and Eun-Kee Jeong^4
1Utah Center for Advanced Imaging Research, University of Utah, Salt Lake City, UT, United States, ²NeuroImunology and NeuroVirology, University of Utah, Salt Lake City, UT, United States, ³Neurology, University of Utah, Salt Lake City, UT, United States, ⁴Radiology and Imaging Sciences, University of Utah, Salt Lake City, UT, United States

The signal-b curve of the Ultrahigh-b DWI (UHb-DWI) with bmax = ~ 10,000 s/mm² is sensitive to the water exchange at the myelin sheath in white-matter. Ultrahigh-b DWI is obtained using DW-stimulated-echo (DW-STE) sequence, however, a half the prepared magnetization is discarded in conventional STE imaging. Therefore, the main objective of this work has been to measure low-b DW-spin-echo and DW-stimulated-echo in a single sequence, and to correct/combine DWSE and DWSTE for ultrahigh-b DWI (UHb-DWI) of cervical spinal cord (CSC).

Yajie Wang¹, Yishi Wang², Haikun Qi³, Rui Guo⁴, Huiyu Qiao¹, Dongyue Si¹, and Huijun Chen^1
1Center for Biomedical Imaging Research, Department of Biomedical Engineering, School of Medicine, Tsinghua University, Beijing, China, ²Philips Healthcare, Beijing, China, ³School of Biomedical Engineering and Imaging Sciences, King's College London, London, United Kingdom, ⁴Department of Medicine, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, MA, United States

Previous quantitative techniques for carotid plaque T1 mapping or T1, T2 mapping have been achieved using only one scan. Besides T1 and T2 quantification, T2* mapping of the carotid plaque is also important for the detection of iron deposition, which plays an important role in plaque progression. In this study, a new quantitative technique using combined single- and multi-echo 3D golden angle radial acquisition has been proposed for simultaneous T1, T2 and T2* mapping of the carotid plaque. The quantitative accuracy and the in-vivo feasibility of the proposed sequence have been demonstrated in phantom and volunteer studies.

Serdest Demir¹, Bryan Clifford², Thorsten Feiweier³, Tom Hilbert⁴, Zahra Hosseini⁵, Augusto Lio Goncalves Filho¹, Azadeh Tabari¹, Wei-Ching Lo², Maria Gabriela Figueiro Longo¹, Michael Lev¹, Pamela Schaefer¹, Otto Rapalino¹, Kawin Setsompop⁶, Berkin Bilgic⁶, Stephen Cauley⁶, Susie Huang¹, and John Conklin^1
1Radiology, Massachusetts General Hospital, Boston, MA, United States, ²Siemens Medical Solutions, Boston, MA, United States, ³Siemens Healthcare GmbH, Erlangen, Germany, ⁴Siemens Healthcare AG, Lausanne, Switzerland, ⁵Siemens Medical Solutions, Atlanta, GA, United States, ⁶Radiology, A. A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Boston, MA, United States

EPI FLAIR images have lower tissue contrast than conventional TSE images due to the absence of significant magnetization transfer (MT) effects, which limits their acceptability to radiologists and clinicians. In this study, we developed an MT-prepared EPI FLAIR acquisition, and determined the optimal parameters of the MT-preparation module to match the tissue contrast of clinical reference TSE FLAIR images. This approach may facilitate clinical adoption of EPI FLAIR images for a variety of applications, including those where ultrafast imaging is desired (e.g., acute stroke, motion prone patients, pediatrics).
 

Hyungseok Jang¹, Yajun Ma¹, Michael Carl², Saeed Jerban¹, Roland Lee¹, Eric Y Chang^1,3, Jody Corey-Bloom¹, and Jiang Du^1
1University of California, San Diego, San Diego, CA, United States, ²GE Healthcare, San Diego, CA, United States, ³Veterans Affairs San Diego Healthcare System, San Diego, CA, United States

It is challenging to directly image myelin due to its extremely short T₂* (<300µs at 3T). Adiabatic Inversion Recovery prepared Ultrashort Echo Time (IR-UTE) imaging has been proposed for direct myelin imaging in human brain. More recently, Short Repetition Time Adiabatic Inversion Recovery (STAIR) has been proposed as a novel contrast mechanism for myelin imaging with improved suppression of long T₂ signal. In this study, we explored feasibility of STAIR based Zero Echo Time (STAIR-ZTE) combined with an amplitude- and phase-modulated RF pulse and interleaved Water- and Fat-Suppressed Proton Projection MRI (WASPI) for myelin imaging in human brain.

Alecio F. Lombardi^1,2, Zhao Wei¹, Hyungseok Jang¹, Saeed Jerban¹, Lillian Gong¹, Jiang Du¹, Eric Y. Chang^1,2, and Ya-Jun Ma^1
1Radiology, University of California, San Diego, CA, United States, ²Radiology Service, Veterans Affairs, San Diego, CA, United States

To overcome the limitations of imaging short T2/T2* tissues with conventional MRI and increase contrast between the osteochondral junction and adjacent tissues, we developed a 3D dual adiabatic inversion recovery prepared ultrashort echo times cones (3D DIR-UTE-Cones) sequence for volumetric imaging at a 3T scanner. We expected the proposed DIR-UTE-Cones sequence to generate higher OCJ contrast than the IR-FS-UTE Cones, especially in between OCJ and fat.

Lumeng Cui¹, Emily J. McWalter^1,2, Gerald R. Moran³, and Niranjan Venugopal^4
1Division of Biomedical Engineering, University of Saskatchewan, Saskatoon, SK, Canada, ²Department of Mechanical Engineering, University of Saskatchewan, Saskatoon, SK, Canada, ³Research Collaboration Manager, Siemens Healthcare Limited, Oakville, ON, Canada, ⁴Department of Radiology, University of Manitoba, Winnipeg, MB, Canada

Ultrashort echo time (UTE) pulse sequences can capture the signal from short T2 tissues. Many UTE techniques have been developed for achieving an ultrashort TE (less than 0.1 ms) or enhancing the short T2 contrast. However, these approaches have not been extensively compared head-to-head due to the lack of a flexible UTE sequence that integrates the different approaches. Therefore, in this work, we developed a versatile UTE sequence that can directly compare UTE approaches and provide options for researchers to choose the appropriate UTE that fit the particular application.

Jinil Park¹ and Jang-Yeon Park^2,3
1Biomedical Institute for Convergence at SKKU, Sungkyunkwan University, Suwon, Korea, Republic of, ²Department of Biomedical engineering, Sungkyunkwan University, Suwon, Korea, Republic of, ³Department of Intelligent Precision Healthcare Convergence, Sungkyunkwan University, Suwon, Korea, Republic of

Non-Cartesian radial sampling can preserve the spatial resolution without aliasing when under-sampling, but makes streak artifacts and internal structure identification difficult.Because C-UTE uses non-selective rectangular pulses to acquire projection data containing information about the entire object, setting the ROI smaller than the object further increases the under-sampling problem. the recently developed VS-UTE uses selective SINC pulses, and it's a method to minimize under-sampling problems. In this study, we demonstrate the ability of VS-UTE to maintain image quality when the number of projection views is under-sampled or when the imaging volume is chosen smaller than the imaging target.