ISMRM 23rd Annual Meeting & Exhibition • 30 May - 05 June 2015 • Toronto, Ontario, Canada

Electronic Poster Session • Ultra-High Field
3140 -3163 UHF Applications: General
3188 -3211 UHF Acquisitions: Neuro

Note: The videos below are only the slides from each presentation. They do not have audio.

Monday 1 June 2015
Exhibition Hall 14:15 - 15:15

  Computer #  
73 Simultaneous in vivo 1H/23Na-imaging of superficial lymph nodes using 7 Tesla-MRI
Martin T. Freitag1, Nadia Benkhedah2, Pedram Yazdanbakhsh3, Titus Lanz3, Moritz Berger2, Mathies Breithaupt2, Jessica Hassel4, Heinz-Peter Schlemmer1, Mark E Ladd2, and Armin M. Nagel2
1Department of Radiology, German Cancer Research Center, Heidelberg, Baden-Wuerttemberg, Germany, 2Medical Physics in Radiology, German Cancer Research Center, Heidelberg, Baden-Wuerttemberg, Germany, 3Rapid Biomedical, Rimpar, Bayern, Germany, 4Department of Dermatology, National Center for Tumor Diseases, Heidelberg, Baden-Wuerttemberg, Germany

There is substantial interest to develop diagnostic procedures for lymph node (LN) staging that feature a high spatial resolution combined with functional imaging techniques because conventional tomographic methods are limited to correctly assess the nodal involvement. 23Na-imaging could be a novel approach for the characterization of often hypervascularized lymph node metastases because sodium is accumulated in malignant cells and blood vessels. By using a double-resonant 1H/23Na-Coil, 5 patients with pathological LNs were examined at 7 Tesla. Here, the first in vivo images of human lymph nodes are demonstrated using simultaneous 1H/23Na-imaging where pathological LNs revealed a higher relative sodium signal.

3141.   74 Successful 2-Spoke pTX RF Pulse excitation using a single-channel transmit 7T console retrofitted with a 16-channel B1 Shimming unit
Sebastian Schmitter1, Xiaoping Wu1, Edward John Auerbach1, Lance DelaBarre1, Gregor Adriany1, Kamil Ugurbil1, and Pierre-Francois Van de Moortele1
1Center for Magnetic Resonance Research, University of Minnesota, Minneapolis, MN, United States

Transmit B1 inhomogeneity, a significant challenge at ultra-high fields, has previously been addressed using spokes and kt-pulses applied with prototype parallel transmission (pTX) systems. However, since the phase/gain setting during a single spoke (or kt-point) is kept constant, a pTX system is not required. Instead, a less expensive dynamic B1+ shimming system, capable of switching fast enough the shim sets between the sub-pulses, may also be used. In this work we demonstrate the feasibility of applying 2-spoke pulses to two different targets at 7T using a dynamic B1+ shimming system: slab-selective TOF angiography and slice-selective cardiac MRI.

3142.   75 Measuring the Rate of Phosphocreatine Recovery in Human Skeletal Muscle after Exercise by Localized 1H MRS without Water Suppression at 7T
Jimin Ren1,2, Baolian Yang3, A. Dean Sherry1,4, and Craig R. Malloy1,5
1Advanced Imaging Research Center, University of Texas Southwestern Medical Center, Dallas, Texas, United States, 2Department of Radiology, University of Texas Southwestern Medical Center, Dallas, Texas, United States, 3Philips Healthcare, Cleveland, Ohio, United States, 4Department of Chemistry, University of Texas at Dallas, Richardson, Texas, United States, 5VA North Texas Health Care System, Dallas, Texas, United States

There has been great interest in measuring ATP synthesis in skeletal muscle in vivo. Conventional methods are 31P NMR-based, either by measuring Piright arrow lower case Greek gamma-ATP exchange rate using magnetization transfer, or by measuring the rate of phosphocreatine (PCr) recovery after exercise. This work, based on an early assignment of 1H signal at 3.9 ppm to the methylene of PCr, explores the feasibility of measuring the rate of PCr recovery in exercised muscle using localized 1H MRS without water suppression at 7T. Consistent rate constants were obtained between 1H and 31P MRS by interleaved scans conducted during the same exercise period.

3143.   76 MR imaging of the temporomandibular joint at 7.0 Tesla: a feasibility study using novel high permittivity dielectric pads
Andrei Manoliu1,2, Georg Spinner2, Michael Wyss2, Daniel Nanz1, Dominik Ettlin3, Luigi M Gallo3, and Gustav Andreisek1
1Department of Radiology, University Hospital Zurich, Zurich, Switzerland, 2Institute for Biomedical Engineering, University and ETH Zurich, Zurich, Switzerland, 3Center for Dental and Oral Medicine and Maxillofacial Surgery, University of Zurich, Zurich, Switzerland

The current study evaluates the use of high-permittivity dielectric pads for imaging the temporomandibular joint (TMJ) at 7T. 12 healthy volunteers were examined at 7T using a 32-channel head coil with and without dielectric pads. For quantitative analysis, B1+ field maps and signal-to-noise-ratio (SNR) maps were calculated. For qualitative analysis, proton density weighted images were assessed. The application of dielectric pads increased local B1+ and SNR, which translated into significantly increased visibility of the TMJ. The presented results demonstrate the feasibility of high-resolution MR-imaging of the TMJ at 7T for the first time.

3144.   77 A 32 Channel Bi-lateral Breast Array for High Resolution Accelerated MR Imaging
R. O. Giaquinto1,2, R. G. Pratt1, W. M. Loew1, H. Friel3, L. Bickford3, C. Ireland1, B. Daniels1, B. Williams1, L. Haas1, J. M. Lanier1, K. M. Cecil1,2, M. Mahoney2, E. A. Morris4, and C. L. Dumoulin1,2
1Imaging Research Center, Cincinnati Childrens Hospital Medical Center, Cincinnati, Ohio, United States, 2UC College of Medicine, University of Cincinnati, Cincinnati, Ohio, United States, 3Philips Healthcare, Best, Netherlands, 4Memorial Sloan Kettering Cancer Center, New York, New York, United States

We have designed and fabricated a new 32 channel ultra-high resolution 3T breast imaging coil array which enables spatial resolution approaching that of X-ray. The new coil permits acceleration factors of 16 or more and full bi-lateral coverage of the breasts with an isotropic resolution down to 0.3 mm. In this study, benchmark comparisons were made with a commercially available 7 channel breast array. The 32-channel coil provided increased speed and resolution for DWI, T1-weighted and T2-weighted images in phantoms and human volunteers.

78 Overcoming the SAR limitation of magnetization transfer pulses at 7 Tesla using parallel transmission
Bastien Guerin1, Jonathan R Polimeni1, Thomas Witzel1, and Lawrence L Wald1,2
1Department of Radiology, Massachusetts General Hospital, Charlestown, MA, United States, 2Division of Health Sciences Technology, Harvard-MIT, MA, United States

Magnetization transfer (MT) pulses are useful for background reduction in time-of-flight angiography but are difficult to deploy at high fields because of their high specific absorption rate (SAR). We design MT pulses at 7 Tesla with improved saturation performance by control of SAR using parallel transmission (pTx). A first performance improvement is obtained by constraining local SAR in the pulse design using the virtual observation point concept. Saturation performance at constant SAR is further improved by irradiating multiple frequencies simultaneously. Indeed, as in Simultaneous Multi-Slice, this allows the design algorithm to better control local SAR using “SAR hopping” between frequencies.

3146.   79 The three-dimensional shape of the myopic eye measured with MRI
Jan-Willem M Beenakker1,2, Denis P Shamonin3, Andrew G Webb1, Gregorius PM Luyten2, and Berend C Stoel3
1Department of Radiology, C.J.Gorter Center for High Field MRI, Leiden University Medical Center, Leiden, Zuid-Holland, Netherlands, 2Department of Ophthalmology, Leiden University Medical Center, Leiden, Zuid-Holland, Netherlands, 3Department of Radiology, devision of Image Processing, Leiden University Medical Center, Leiden, Zuid-Holland, Netherlands

To fully understand the visual defects in a patient's vision, a 3D model of the eye is needed, which current ophthalmic techniques cannot give. We present a method, using high-field MRI and subsequent image processing, to automatically construct patient-specific eye-models with high accuracy. We have examined 21 eyes, of which 10 patients with mild to severe myopia. The resulting eye-models show an increased retinal curvature in the myopic group compared to the subjects with healthy eyes.

3147.   80 It goes to 11: A scalable home-built transmit array beyond eight channels
Andre Kuehne1,2, Patrick Waxmann3, Werner Hoffmann3, Harald Pfeiffer3, Reiner Seemann3, Frank Seifert3, Oliver Speck4, and Bernd Ittermann3
1Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Vienna, Austria, 2MR Centre of Excellence, Medical University of Vienna, Vienna, Austria, 3Physikalisch-Technische Bundesanstalt (PTB), Braunschweig und Berlin, Berlin, Germany, 4Otto-von-Guericke-University, Magdeburg, Germany

To be filled

3148.   81 Phosphorus 3D CSI at 9.4 T using a 27-channel Receiver array
Shajan G1, Christian Mirkes2, Rolf Pohmann1, and Klaus Scheffler1,2
1Max Planck Institute for Biological Cybernetics, Tuebingen, Baden Wuerttemberg, Germany, 2University Hospital, Tuebingen, Baden Wuerttemberg, Germany

In this work, a three-layered coil arrangement, originally proposed for 23Na MRI at 9.4 T, was adapted for phosphorus spectroscopy and proton imaging to perform 31P 3D chemical shift imaging (CSI) of the human brain at 9.4 T. Owing to the high field strength and the sensitive 27-channel receiver array 31P 3D CSI data could be acquired within 13 min with an acceptable signal-to-noise ratio.

3149.   82 Multi-Slice gagCEST Sequence for Whole-Joint gagCEST mapping: Application to Articular Cartilage in the Ankle
Feliks Kogan1, Brian Hargreaves1, and Garry Gold1
1Department of Radiology, Stanford University, Stanford, CA, United States

Chemical exchange saturation transfer (CEST) is promising new sensitivity enhancement mechanism that detects GAG content (GagCEST), an important marker for early diagnosis of osteoarthritis (OA) and potential treatment monitoring. One of the key concerns of current gagCEST imaging techniques is long imaging times, which often limits acquisition to a single slice and thus may not fully describe the cartilage variation. In this work, we demonstrated the feasibility of multi-slice gagCEST mapping of articular cartilage. Further work to decrease scan time will help advance the clinical utility of gagCEST imaging of articular cartilage.

3150.   83 Upper extremity neural and vascular imaging with UHF 7T MRI
Shailesh Raval1, Tiejun Zhao2, Narayanan Krishnamurthy3, Tales Santini3, Vijay S. Gorantla3, and Tamer S. Ibrahim3
1UPMC, Pittsburgh, Pennsylvania, United States, 2Siemens Medical Solutions, Pittsburgh, Pennsylvania, United States, 3University of Pittsburgh, Pittsburgh, Pennsylvania, United States

Musculoskeletal MRI is widely used to evaluate soft tissues for space-occupying lesions, infection, atrophy, or fibrotic scarring. 7T MRI can comprehensively explore nerve (diffusion imaging) and vessel (non-contrast enhanced MRA imaging and vessel segmentation) via homogeneous excitation. Our goal is to compare SNR and CNR findings of 3T vs. 7T MRI for upper extremity with specific emphasis on peripheral nerve and vasculature. Taken together, this is a demonstration of the potential utility and relevance of UHF 7T MRI in upper extremity applications such as vascular and nerve imaging.

3151.   84 Stability Test Method for Cartesian Feedback Power Amplifier in pTx Array
Samaneh Shooshtary1, Adam Buck1, and Klaus Solbach1
1Institute of Microwave and RF Technology, Duisburg-Essen University, Duisburg, Germany

A 7 Tesla system with parallel transmission is under construction. The system will employ 32 near-magnet power amplifiers (PA) with output power of 1 kW. Coil current variation due to load variation can be compensated by applying a Cartesian feedback loop in the PA implementation. In order to avoid instability in the pTx system, conditions and limits of stability have to be investigated for every possible mode of operation. This contribution presents the principle architecture of our PA with control loop and proposes the root locus method for concise stability check. We propose to use this approach for stability investigations of the large pTx array.

3152.   85 B0 shimming further improves human cardiac 31P-MRS at 7 tesla
Lance DelaBarre1, Stefan Neubauer2, Matthew D. Robson2, J. Thomas Vaughan1, and Christopher T. Rodgers2
1CMRR, University of Minnesota, Minneapolis, MN, United States, 2OCMR, University of Oxford, Oxon, United Kingdom

Human cardiac 31P-MRS was recently shown to give 2.8x the SNR at 7T compared to 3T when using the scanner’s default B0-shims. In this study, we present the first human cardiac 7T 31P spectra with B0 shimming; we introduce a modification to the Siemens product 3D shimming tool to mitigate the strong variations in image intensity across the heart at 7T; and we quantify the further improvements in spectral quality due to shimming in 6 volunteers. In the septum, we observe 30–39% reductions in linewidth, 37–47% increases in SNR, and a 33% decrease in the PCr/ATP Cramer-Ráo bound.

3153.   86 Diffusion-sensitized Ophthalmic MRI Free of Geometric Distortion in Patients with Intraocular Masses
Katharina Paul1, Andreas Graessl1, Jan Rieger1,2, Darius Lysiak1,2, Till Huelnhagen1, Lukas Winter1, Robin Heidemann3, Tobias Lindner4, Stefan Hadlich5, Annette Zimpfer6, Andreas Pohlmann1, Paul-Christian Krueger5, Soenke Langner5, Oliver Stachs4,7, and Thoralf Niendorf1,8
1Max-Delbrueck Centre for Molecular Medicine, Berlin Ultrahigh Field Facility (B.U.F.F.), Berlin, Berlin, Germany, 2MRI.TOOLS GmbH, Berlin, Germany,3Siemens Healthcare Sector, Erlangen, Germany, 4University Medicine Rostock, Pre-clinical Imaging Research Group, Rostock, Germany, 5University of Greifswald, Institute for Diagnotic Radiology and Neuroradiology, Greifswald, Germany, 6University Medicine Rostock, Institute of Pathology, Rostock, Germany, 7University Medicine Rostock, Department of Ophthalmology, Rostock, Germany, 8Experimental and Clinical Research Center, a joint cooperation between the Charité Medical Faculty and the Max-Delbrueck-Center, Berlin, Germany

Diffusion-weighted imaging (DWI) of the eye and orbit is an emerging MRI application to provide guidance during diagnostic assessment and treatment of ophthalmological diseases. This study employs a RARE based diffusion-sensitized technique that provides images of the eye and orbit free of geometric distortion. A small patient cohort (n=6) is investigated including patients with uveal melanoma and/or retinal detachment. In one exemplary case the eye was enucleated as part of the therapy and ex vivo MR microscopy as well as histology were conducted. The obtained results underscore the value of ophthalmic DWI which adds profound clinical value versus conventional anatomic imaging.

3154.   87 GAGCEST imaging of Knee at 7T a Reproducibility Study - permission withheld
Anand Kumar Venkatachari1, Cory Wyatt1, Doug Kelley2, and Sharmila Majumdar1
1Radiology and Biomedical Imaging, University of California San Francisco, San Francisco, California, United States, 2GE Healthcare Technologies, San Francisco, CA, United States

Osteoarthritis (OA) is one of the most common forms of arthritis affecting millions of people around the world. It is believed that the initiation of OA is predominantly due to the loss of proteoglycans from the cartilage. Glycosaminoglycan (GAG) are side chains attached to protein core of Proteoglycans. Multiple studies have reported Chemical Exchange Saturation Transfer (CEST) imaging using Glycosaminoglycan (GAG) as the endogenous agent at 7T in the Knee. In the current work we have looked at GAGCEST imaging of Knee cartilage at 7T in controls and performed a reproducibility study.

3155.   88 Multi-Parametric Renal MRI at 7T
Xiufeng Li1, Edward J. Auerbach1, Pierre-Francois Van de Moortele1, Kamil Ugurbil1, and Gregory J. Metzger1
1Radiology-CMRR, University of Minnesota, Minneapolis, MN, United States

With advances in RF coil engineering, RF shimming strategies and acquisition methods, ultra high field MRI technical development and translational research has been expanded from the human brain to the abdominal and pelvic organs. To facilitate MRI research on renal physiology and clinical studies of kidney diseases, we are developing multi-parametric renal MRI at 7T, combining the ASL based renal perfusion imaging with T1 and T2 imaging to measure tissue MRI properties and T2* imaging to evaluate oxygen level or bioavailability. Our efforts towards this multi-parametric protocol for assessing the kidneys at 7T are presented.

3156.   89 Construction of a 4-channel Transmit/ 4-channel Receive Neck Array for Carotid Artery Vessel Wall Imaging at 7 Tesla
Konstantinos Papoutsis1,2, Linqing Li2, Stephen J Payne1, and Peter Jezzard2
1Department of Engineering science, University of Oxford, Oxford, United Kingdom, 2FMRIB Centre, Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, United Kingdom

A 4 channel transmit array was designed to meet the required B1 field for a black blood sequence at 7 Tesla. The pulse width, flip angle, available power, optimal RF shim as well as the blood velocity and average arterial anatomy were factored in for the design. A 4 element separate receive array was preferred for improved SNR and was constructed and placed around the neck. The completed coil, 4Tx/4Rx, was thoroughly characterised and its safety was assessed with simulations and temperature measurement experiments. Healthy volunteers were scanned with satisfactory blood suppression and resolution.

3157.   90 MRI of the Pulleys of the Flexor Tendons of the Fingers at 11.7T - video not available
Kenyu Iwasaki1, Reni Biswas1, Betty Tran1, Sheronda Statum1, Christine Chung1, Nikolaus M Szeverenyi1, and Graeme Bydder1
1University of California, San Diego, CA, United States

Six cadaveric fingers were examined at 11.7T to determine the appearances of the annular and cruciate pulleys of the flexor tendons. All named pulleys were seen. The pulleys showed different anatomic features including internal structure and magic angle effects depending on their orientation to Bo. These could increase or decrease contrast with the surrounding connective tissue. The study provides a basis for understanding the visualization of pulleys with clinical systems at higher field strengths.

3158.   91 T1- and TR-Independent B1+ Mapping by Bloch-Siegert Shift for 7T Human Cardiac 31P-MRS
William T Clarke1, Matthew D Robson1, and Christopher T Rodgers1
1OCMR, RDM Cardiovascular Medicine, University of Oxford, Oxford, United Kingdom

Human Cardiac 31P-MRS at 7T suffers from low peak B1, making B1 insensitive adiabatic or composite pulses impossible. Accurate B1 values are required to correct partially saturated metabolite amplitudes and ratios. Long T1s and 3D-CSI acquisition makes magnitude B1 mapping approaches infeasible. Bloch-Siegert shift B1 mapping is insensitive to metabolite T1s and sequence TR. In this work Bloch-Siegert mapping is validated against gold standards in phantoms and against a previously published dual TR method in skeletal muscle. The feasibility of the approach for cardiac 31P-MRS is demonstrated in a single subject.

3159.   92 Ultrahigh field MRI after upper extremity transplantation.
Shailesh B. Raval1, Tiejun Zhao2, Yujuan Zhao1, Vijay S. Gorantla1, and Tamer S. Ibrahim1
1University of Pittsburgh, Pittsburgh, Pennsylvania, United States, 2Siemens Medical Solutions, Pittsburgh, Pennsylvania, United States

As of 2005, 1.6 million civilians suffer from limb loss in the US alone. If only 1% of this population qualifies for transplant surgery, that mandates additional transplant infrastructure in addition to standardized pre and post-surgical evaluation and monitoring methods. We present first 7T results from a bilateral upper extremity transplantation (UET) subject 4 years after surgery as part of post–transplant clinical MR assessment. This study shows a potential of not only using UHF MRI in post-transplant evaluation after UET but also in hand surgery practice in diagnosis and interpretation of various other diseases including vascular abnormalities,connective tissue disorders or micro vascular disease conditions.

3160.   93 MRI of the Cartilaginous and Fibrous Structure of the Meniscus of the Knee: In Vitro Studies at 11.7T
Hongda Shao1, Soorena A. Zanganeh1, Jihye Baek1, Daryl D'Lima1, Jiang Du1, Nikolaus M. Szeverenyi1, and Graeme Bydder1
1University of California, San Diego, CA, United States

Human and bovine menisci specimens were imaged at 11.7T to demonstrate their cartilaginous and fibrous structure using 2D spin echo and 3D gradient echo sequences. Central and superficial cartilaginous regions were readily differentiated from internal and peripheral fibrous regions. Circumferential, radial, vertical, oblique and curved fiber groups were shown and related to the position of blood vessels and to the presence of cartilage. Previously undescribed MRI features of the meniscus were readily seen and may provide a basis for understanding clinical images obtained at higher field strengths.

3161.   94 In-vivo 31P chemical shift imaging sensitivity improvement utilizing high dielectric pads
Rita Schmidt1, Wyger Brink1, and Andrew Webb1
1Leiden University Medical Center, Leiden, Netherlands

31P spectroscopy and imaging benefit greatly from ultrahigh field MRI. However, voxel sizes are typically still quite large and the low phosphorus metabolite concentrations require long acquisition times. In previous work it has been demonstrated that the image signal-to-noise ratio (SNR) can be improved by using high dielectric pads. This work has mainly focused on in vivo 1H imaging at 3 T and 7 T. Here, we show the first in vivo results of 31P CSI with improved SNR with a dielectric pad with an intermediate relative permittivity of ~300 (BaTiO3).

3162.   95 Parallel Imaging of the Prostate at 7T using a B0 Crusher Coil to suppress Aliasing Artifacts
Remco Krijthe1, Vincent Boer1, Arjan Hendriks1, and Dennis Klomp1
1Radiology, University Medical Center Utrecht, Utrecht, Utrecht, Netherlands

A many element body receive array has a high, but inhomogeneous receive sensitivity. When performing parallel imaging of the prostate at 7T, aliasing artifacts occur due to this inhomogeneity. A B0 crusher coil, which is placed around the patients waist, can suppress these artifacts by crushing the signal coming from the outer rim of the patient while the signal coming from the prostate stays unimpaired. Compared to other methods, this technique can be used in combination with each desired sequence.

3163.   96 Functional 31P Magnetic Resonance Spectroscopic Imaging of the Human Calf Muscle at 7 T by means of Echo–Planar Acquisition Techniques
Andreas Korzowski1 and Peter Bachert1
1Medical Physics in Radiology, German Cancer Research Center, Heidelberg, Baden-Württemberg, Germany

Fast spectroscopic imaging techniques such as 31P echo–planar spectroscopic imaging in high B0 can help to detect small changes in cellular energy metabolism on a time scale of a few seconds. The presented data show that 31P echo–planar spectroscopic imaging techniques enable functional spectroscopic studies of human energy metabolism in vivo at 7 T with good spatial and temporal resolution.

Monday 1 June 2015
Exhibition Hall 15:15 - 16:15

  Computer #  
3188.   25 Whole Brain 3D-FLAIR Imaging at 7T
Eberhard Daniel Pracht1, Daniel Brenner1, and Tony Stöcker1,2
1German Center for Neurodegenerative Diseases (DZNE), Bonn, Germany, 2Department of Physics and Astronomy, University of Bonn, Bonn, Germany

FLAIR imaging is the most important technique for lesion detection in the human brain. To our knowledge, there is still no 7T alternative available which delivers images with similar dark-fluid T2 contrast, as the “gold standard” at 3T. In this work we present a fluid suppressed Turbo-Spin-Echo sequence for ultra-high-field application which bridges this gap. Our approach is based on a double inversion recovery preparation. To obtain images comparable with 3T results, prolonged tissue T1, and high field issues such as B0/B1 inhomogeneities had to be addressed. Furthermore, an efficient fat suppression technique had to be implemented to enhance image quality.

3189.   26 Proton Observed Phosphorus Editing (POPE) for in vivo detection of phospholipid metabolites
Jannie P. Wijnen1,2, Dennis J.W. Klomp1, Christine I.H.C Nabuurs3, Robin A. de Graaf4, Irene M.L. van Kalleveen1, Wybe J.M. van der Kemp1, Peter R. Luijten1, Mark C. Kruit2, Andrew Webb2, Hermien E. Kan2, and Vincent O. Boer1
1Radiology, University Medical Centre Utrecht, Utrecht, Utrecht, Netherlands, 2Radiology, Leiden University Medical Centre, Leiden, Zuid Holland, Netherlands, 3Radiology, Maastricht University, Maastricht, Limburg, Netherlands, 4Radiology, Yale University, New Haven, CT, United States

We demonstrate the enhanced sensitivity of Proton Observed Phosphorus Editing (POPE) over direct 31P MRS with Ernst angle excitation for 1H-31P coupled metabolites at 7 Tesla. POPE sequences were developed for detecting phosphocholine (PC), phophoethanolamine (PE), glycerophosphocholine (GPC), and glycerophosphoethanolamine (GPE) on the 1H channel, thereby using the enhanced sensitivity of the 1H nuclei over 31P detection. POPE editing showed an enhanced sensitivity of 2.8 in an ideal phantom experiment as compared to direct 31P MRS with Ernst angle excitation. In vivo, despite increased relaxation losses, significant gains in SNR of 30-40% were shown for these metabolites in the human brain.

3190.   27 Zero Echo Time (ZTE) Imaging of Human Brain Tumor at 7T
Douglas A C Kelley1, Angela Jakary2, Qiuting Wen2, Yan Li2, and Sarah Nelson2
1Neuro Apps and Workflow, GE Healthcare, San Francisco, CA, United States, 2Radiology and Biomedical Imaging, UCSF, San Francisco, CA, United States

T1-prepared Zero Echo Time (ZTE) imaging has been shown to deliver high spatial resolution with controllable uniform contrast in normal brain and MS at 7T. We demonstrate the effectiveness of this technique in brain tumor, highlighting the robustness to susceptibility distortions around the surgical cavity.

3191.   28 Comparing different contrasts for myelin-related cortical mapping at 7T
Roy Haast1, Dimo Ivanov1, and Kâmil Uludağ1
1Cognitieve Neuroscience, Maastricht University, Maastricht, Limburg, Netherlands

The current data show a comparison between different MRI contrasts at 7T that were used previously to map cortical myelin content. Previous papers showed that differences in intensity levels between the cortical areas may reflect the overall cortical myelin content. However, it is not clear whether different contrasts (i.e. weighted vs. quantitative) show comparable ‘myelination’ patterns. Minor differences were found between the tested contrasts (T1w, T2*w, R1, qT2*, T1w/T2w, R1/qT2*). These variances could be partially induced by qT2* effects. Nevertheless, other factors like curvature and cortical thickness should be taken into consideration for future analyses.

3192.   29 Reduced specific absorption rate (SAR) and scan time using variable density Magnetization Transfer (vdMT) for 7T
Se-Hong Oh1, Wanyong Shin1, Jongho Lee2, and Mark J Lowe1
1Imaging Institute, Cleveland Clinic Foundation, Cleveland, OH, United States, 2Department of Electrical and Computer Engineering, Seoul National University, Seoul, Korea

Due to much higher SAR of tissue and much longer acquisition time, in vivo studies using MT at UHF MRI has not been feasible in an acceptable scan time. In this work, we described a novel MT acquisition scheme within a clinically reasonable time (<6 min). Our proposed new approach uses a combination of higher density of MT pulses applied to the center k-space lines and sparsely applied MT pulses in the outer k-space lines. With new proposed MT acquisition scheme, the scan time is reduced considerably while maintaining similar MTR contrast comparable to conventional MT.

3193.   30 RF pulse designs for MPRAGE at 9.4T
Desmond Ho Yan Tse1,2, Daniel Brenner3, Johannes G Ramaekers1, Joachim E Wildberger2, and Benedikt A Poser1
1Faculty of Psychology and Neuroscience, Maastricht University, Maastricht, Netherlands, 2Department of Radiology, Maastricht University Medical Centre, Maastricht, Netherlands, 3German Centre for Neurodegenerative Diseases (DZNE), Bonn, Germany

T1-weighted imaging with MPRAGE at 9.4T was improved by using TR-FOCI for inversion and kt-points pulses for excitation. Due to the higher inversion effectiveness of TR-FOCI over hyperbolic secant at low B1+, uniform inversion across the whole brain was achieved. Meanwhile, the excitation inhomogeneity was reduced across the whole brain by replacing the rectangular excitation pulse in CP mode with a MLS optimised full pTx kt-points composite pulse. The improvements from these two modifications have led to reductions in intensity variation due to transmit and contrast loss due to in sufficient B1+ for inversion in the resulting T1-weighted image.

3194.   31 Robust Tissue Segmentation of Human Brain Images Acquired with a Surface Coil at Ultrahigh Field - permission withheld
Byeong-Yeul Lee1, Wei Chen1, and Xiao-Hong Zhu1
1Center for Magnetic Resonance Research, Department of Radiology, University of Minnesota, Minneapolis, MN, United States

Surface coil has been commonly employed in human brain MRI and in vivo MRS research since it offers the best attainable signal-to-noise ratio (SNR) in the brain region of interest. However, quantitative tissue segmentation becomes a challenging task due to the inhomogeneous B1 field of the surface coil, which leads to large variation in the MR signal and image contrast. In this study, we implemented and tested an automatic brain tissue segmentation method including bias field correction and partial volume estimation (PVE) to reliably quantify tissue contents and distributions in the brain region covered by a surface coil at 7T. The results indicate that this segmentation method is robust for differentiating various brain tissues; and the CSF volume can be more accurately estimated by PVE with model parameters as compared to one without optimization. Therefore, this advanced segmentation method will provide a robust and valuable tool for many quantitative brain MRI/MRS studied, and it is particularly critical for ultrahigh-field applications using either a surface coil or transmit-receive array coil or even head volume coil. In all these cases, an inhomogeneous B1 distribution is present in the human head owing to the complication of the RF wave behavior at high/ultrahigh fields.

3195.   32 An 8-Channel Parallel Transmit System For 7T MRI Based On Custom-Built I/Q Modulators
Sören Johst1, Marcel Gratz1,2, Samaneh Shoostary3, Klaus Solbach3, Mark E. Ladd1,4, and Stephan Orzada1
1Erwin L. Hahn Institute for Magnetic Resonance Imaging, University Duisburg-Essen, Essen, Germany, 2High-field and Hybrid MR Imaging, University Hospital Essen, University Duisburg-Essen, Essen, Germany, 3High Frequency Technology, University Duisburg-Essen, Duisburg, Germany, 4Medical Physics in Radiology, German Cancer Research Center (dkfz), Heidelberg, Germany

In this work we present an add-on parallel transmit (pTx) system based on a Siemens 1-channel 7T MRI system using custom-built I/Q modulators and the 8 standard power amplifiers of the MR system. The single exciter channel is split into subchannels, whereby the modulators control the phase and amplitude of the individual pTx RF pulses. The modulators and pre-calculated pTx gradients are synchronized via trigger signals generated in the imaging sequence. An artifact originating from the modulators’ amplitude offsets could be corrected by applying a variable dynamic range pTx pulse. With this modification, the gradients and modulators could be synchronized successfully.

3196.   33 A Parkinson's disease 31P-MRSI study at 7T
Silvina G Horovitz1, Peter Lauro2, Pascal Sati3, Nora Vanegas-Arroyave2, Codrin I Lungu2, and Mark Hallett1
1MNB, HMCS, NINDS, NIH, Bethesda, MD, United States, 2OCD, NINDS, NIH, Bethesda, MD, United States, 3NIB, TNU, NINDS, NIH, Bethesda, MD, United States

One of the pathological changes in Parkinson’s Disease (PD) is the loss of dopaminergic neurons in the substantia nigra (SN), believed to be related to impaired mitochondrial function. We scanned healthy volunteers, Parkinson’s disease patients and patients with early parkinsonism presentation at 7T. We studied energy and phospholipid metabolism by exploring the stability of the data, and the effects of group, when accounting for age and sex on these measures. Taking into account sex and age, we find significant group differences. 31P-MRSI might become a useful tool for the differential diagnosis of Parkinson’s disease.

3197.   34 7T MRSI using Semi-Adiabatic Spectral-spatial Spectroscopic Imaging (SASSI) for improved B1-insensitivity in refocusing and reduced chemical shift artifact
Rebecca Emily Feldman1 and Priti Balchandani1
1Radiology, Icahn School of Medicine at Mount Sinai, New York, New York, United States

High magnetic fields permit us to leverage increased signal-to-noise ratio and spectral separation between metabolite peaks for more sensitive metabolite detection and quantification as well as higher resolution spectral grids. With high field strengths come challenges such as increased RF power deposition, B1-inhomogeneity, and increased chemical shift artifacts. We used the adiabatic Shinnar Le-Roux algorithm to create a Semi-Adiabatic Spectral-spatial Spectroscopic Imaging (SASSI) sequence to capture the main metabolites at 7T. The sequence was designed to generate spectroscopic grids with improved B1-immunity and reduced chemical shift artifact while having lower SAR than existing adiabatic implementations.

3198.   35 Correction of Artifacts in Ultrahigh Field T2* Imaging Using a Training Model for Field Probe Based B0 Measurements
Anders Garpebring1,2, Joep Wezel1, Vincent O. Boer3, Tijl A. van der Velden3, Andrew G. Webb1, Dennis W.J. Klomp3, and Matthias J. P. van Osch1
1C.J. Gorter center for high field MRI, Radiology, Leiden University Medical Center, Leiden, Netherlands, 2Radiation Sciences, Umeå University, Umeå, Sweden, 3Radiology, University Medical Center Utrecht, Utrecht, Netherlands

In ultrahigh field MRI B0 fluctuations caused by breathing can seriously degrade T2*-weighted images. The purpose of this work was to investigate if field probes in combination with training data can be used for correction of artifacts resulting from heavy breathing. Results based on data from a 7 T scanner show that it is possible to correct B0 induced artifacts and that the new method provided improvements compared to the method normally used today.

3199.   36 Simultaneous T1 and T2 quantitation of the Human Brain at 7 Tesla by MR Fingerprinting
Yun Jiang1, Huihui Ye2,3, Berkin Bilgic2, Dan Ma1, Thomas Witzel2, Stephen F. Cauley2, Elfar Adalsteinsson2,4, Kawin Setsompop2, Mark A. Griswold1,5, and Lawrence L. Wald2,4
1Department of Biomedical Engineering, Case Western Reserve University, Cleveland, Ohio, United States, 2Department of Radiology, Massachusetts General Hospital, Athinoula A. Martinos Center for Biomedical Imaging, Charlestown, Massachusetts, United States, 3Department of Biomedical Engineering, Zhejiang University, Hangzhou, Zhejiang, United States, 4Department of Electrical Engineering and Computer Science; Harvard-MIT Division of Health Sciences, MIT, Cambridge, Massachusetts, United States, 5Department of Radiology, Case Western Reserve University, Ohio, United States

The MRF method has been shown to be extremely efficient in the quantitation of relaxation parameters. In this study we used an MRF method based on the Fast-Imaging with Steady-state free Precession (FISP) type sequence to quantify T1, T2 and proton density at 7 T. A voxel specific dictionary was calculated based on B1+ inhomogeneity estimated via an AFI scan. A template-matching algorithm was used to extract T1 and T2 values by matching a dictionary entry to the acquired signal evolution. With additional B1 measurement time, MRF method is able to quantify T1 and T2 values within one minute per slice.

3200.   37 Wide screen visual stimulation: fMRI combined with fast GABA detection
Arjan D. Hendriks1, Catalina S. Arteaga de Castro1, Vincent O. Boer1, Dennis W.J. Klomp1, and Natalia Petridou1
1Department of Radiology, University Medical Center Utrecht, Utrecht, Netherlands

Functional MRI combined with functional MRS of visual cortex can relate BOLD signals to neuronal metabolism. However, functional MRS, particularly for GABA, is limited by SNR. By increasing the limited visual field of view, a larger spatial extend of activation will be obtained. Therefore, by increasing the voxel that encompasses tissue that is uniformly active, GABA signals can be obtained at high temporal resolution . Here, we examine the effectiveness of using a half volume transmit coil with a large screen for visual stimulation, in terms of extent of activation in primary visual cortex and in terms of achievable voxel size for GABA measurements in the same region.

3201.   38 Towards routine application of dynamic parallel transmission for whole-brain imaging at 9.4 Tesla
Jens Hoffmann1,2, G. Shajan1, Christian Mirkes1,3, Tingting Shao1, Anke Henning1,4, Rolf Pohmann1, and Klaus Scheffler1,3
1High-Field Magnetic Resonance Center, Max Planck Institute for Biological Cybernetics, Tuebingen, Germany, 2Graduate School of Neural & Behavioural Sciences, Tuebingen, Germany, 3Department for Biomedical Magnetic Resonance, University of Tuebingen, Germany, 4Institute for Biomedical Engineering, University and ETH Zurich, Switzerland

The requirements for implementing a multi-purpose, pTx-enabled RF setup for whole-brain imaging at 9.4 Tesla are high. They include transmit arrays with sensitivities distributed in all dimensions, receive hardware for high-SNR parallel signal reception, numerical simulations for compliance with SAR limits as well as rapid, volumetric calibration scans. In this work, we report our progress in achieving these objectives. A 16-channel dual-row Tx / 31-channel Rx-array combination was interfaced to an 8-channel pTx system. SAR was evaluated numerically, rapid calibration scans were acquired using a 3D DREAM sequence and superior excitation quality using Spokes pulses is demonstrated in vivo.

3202.   39 The traveling heads: Initial comparisons of multicenter data on 7 Tesla MRI systems
Maximilian N Voelker1,2, Oliver Kraff1, Daniel Brenner3, Astrid Wollrab4, Tony Stoecker3, David Norris5, Mark E Ladd1,6, and Oliver Speck4,7
1Erwin L. Hahn Institute for Magnetic Resonance Imaging, University of Duisburg-Essen, Essen, Germany, 2Diagnostic and Interventional Radiology and Neuroradiology, University Hospital Essen, Essen, Germany, 3German Center for Neurodegenerative Diseases (DZNE), Bonn, Germany, 4Otto-von-Guericke-University, Magdeburg, Germany, 5Erwin L. Hahn Institute for Magnetic Resonance Imaging, University of Duisburg-Essen, Essen, North Rhine-Westphalia, Germany, 6Medical Physics in Radiology, German Cancer Research Center (dkfz), Heidelberg, Germany, 7Leibniz Institute for Neurobiology, Magdeburg, Germany

In this work we present multicenter data from ultra-high-field 7T imaging systems. These data were used to compare image contrast and image quality between the sites. The data showed high agreement between the sites and can be used as a starting point for validating future multicenter trials to be conducted on 7 Tesla MRI systems.

3203.   40 Reliable GABA Spectral Editing BASING-PRESS MRS at 7T
Yan Li1, Bian Wei2, Peder Larson2, Jason C Crane2, Srikantan Nagarajan2, and Sarah J Nelson2,3
1University of California, San Francisco, California, United States, 2Department of Radiology and Biomedical Imaging, University of California, San Francisco, California, United States, 3Department of Bioengineering and Therapeutic Sciences, University of California, San Francisco, California, United States

The purpose of this study was to evaluate acquisition parameters that are important for obtaining reliable GABA signals from volunteers in the regions that are frequently used for clinical studies (auditory cortex, superior temporal gyrus and caudate) at 7T using a single-voxel BASING-PRESS editing sequence.

3204.   41 High resolution MR Spectroscopic imaging of the visual cortex at 9.4T with minimal chemical shift displacement artefact
Desmond H.Y. Tse1, Vincent O. Boer2, Valentin G. Kemper3, Dennis W.J. Klomp2, and Jacobus F.A. Jansen1
1Radiology, Maastricht UMC, Maastricht, Netherlands, 2Radiology, UMC Utrecht, Utrecht, Netherlands, 3Cognitive Neuroscience FPN, Maastricht University, Maastricht, Netherlands

It is demonstrated that by combining an 8 channel half volume coil for relatively high B1 combined with high bandwidth GOIA pulses, one can obtain the full potential of quantified MRSI (2D semi-LASER) at 9.4T in the human visual cortex.

3205.   42 Multi-channel B0 crusher coil for lipid suppression in MRI and MRSI
Vincent Boer1, Mariska Damen2, and Dennis Klomp2
1Radiology, University Medical Center Utrecht, Utrecht, Utrecht, Netherlands, 2University Medical Center Utrecht, Utrecht, Netherlands

Lipid artifacts can contaminate brain imaging and spectroscopy. In this work we present a multi-channel B0 crusher coil that dephases the unwanted lipid signals, without further modifications to the sequence.

3206.   43 3D Eigenmodes Optimizations for 3D Imaging at 7T
Yujuan Zhao1, Narayanan Krishnamurthy1, Sossena Wood1, Tiejun Zhao2, Shailesh B. Raval1, and Tamer S. Ibrahim1
1University of Pittsburgh, Pittsburgh, Pennsylvania, United States, 2Siemens Medical Solutions USA, Pittsburgh, Pennsylvania, United States

In this work, calculated eigenmodes of a 20-channel array coil (Tic-Tac-Toe based) were used to optimize B1+ field. An exhaustive search was used to go through all possible eigenmodes combinations. Field uniformity, field efficiency and SAR are used to evaluate the optimized cases. Multi-level/row coil with eigenmode optimization methods could facilitate field’s uniformity in the entire brain including the cerebellum region. High quality 3D MPRAGE could be acquired.

3207.   44 Laminar variation of population receptive field center-surround properties in human primary visual cortex revealed by 7T fMRI
Alessio Fracasso1, Serge O Dumoulin1, and Natalia Petridou2
1Experimental Psychology, Helmholtz institute, Utrecht University, Utrecht, Netherlands, 2Radiology, Imaging Division, University Medical Center, Utrecht, Netherlands

Receptive field (RF) properties change across visual hierarchy. A similar hierarchy exists across cortical lamina in primary visual cortex (V1) but little is known about its organization. We acquired functional T2*-w 3-dimensional EPI (3D-EPI) at 7T. We performed lamina segmentation on 3D-EPI space. A forward modeling approach (population receptive field, pRF) was adopted to estimate pRF properties across lamina, in humans. pRF center and surround varies according to a U-shaped function across cortical thickness with a constant balance. These results extend the variation of pRF properties across visual field maps hierarchy to a laminar hierarchy within a single map.

3208.   45 High-resolution 3D EPI at 9.4 Tesla with parallel transmit B1+ field homogenisation
Benedikt A Poser1, Daniel Brenner2, and Desmond H Y Tse1,3
1Faculty of Psychology and Neuroscience, Maastricht University, Maastricht, Netherlands, 2German Centre for Neurodegenerative Diseases (DZNE), Bonn, Germany, 3Department of Radiology, Maastricht University, Maastricht, Netherlands

We show high-resolution 3D EPI acquisitions at 9.4T, using kT-points excitation for B1+ homogenisation. Remarkable image quality at 0.75mm isotropic resolution is achieved across the whole-brain, whereas images acquired in CP mode suffer considerably loss of signal and contrast especially in central regions. The images shown hold promise for application to high-resolution BOLD fMRI, as well as fast structural imaging including applications such as rapid quantitative susceptibility mapping (QSM).

3209.   46 7T Multi-slab Whole-Head Homogenous and Low SAR T2 Acquisitions with Limited RF Power Amplifiers Capabilities
Narayanan Krishnamurthy1, Yujuan Zhao2, Shailesh Raval2, Junghwan Kim2, Sossena Wood2, Tales Santini2, Tiejun Zhao3, and Tamer Ibrahim2
1University of Pittsburgh, Pittsburgh, PA, United States, 2University of Pittsburgh, PA, United States, 3Siemens Medical Solutions, PA, United States

The main challenges of UHF imaging are RF absorption and B1+ inhomogeneity, and increased patient coil interactions. These issues can impact the feasibility as we as the quality of power hungry T2 weighted sequences. In addition, the limitation of 8KW RF power amplifiers on most UHF human MRI scanner presents serious challenges for achieving high quality T2 weighted imaging. Here we present a non-patient specific multi-slab imaging approach optimized for SAR as well as input power that achieves homogenous whole head 7T TSE and FLAIR

3210.   47 Systematic investigation of influence factor on parallel transmit pulse performance at 9.4 Tesla
Tingting Shao1, Nikolai Avdievich1, Paul Chang1, Jens Hoffmann1, Klaus Scheffler1, and Anke Henning1,2
1Max Planck Institute for Biological Cybernetics, Tübingen, Baden-Württemberg, Germany, 2Institute for Biomedical Engineering, UZH and ETH Zurich, Zurich, Switzerland

This work systematically investigates the factors that could pose negative influence on the transmit pulse performance at 9.4 tesla. These factors are B1 mapping inaccuracy, B0 inhomogeneity, actual RF and gradient pulse deviations, among which B1 mapping inaccuracy and actual RF pulse deviations are deemed as the major influence factor. Comparative measurements with and without consideration of these factors during the pulse design process, including one in vivo experiment, are performed.

3211.   48 Expected Homogeneity Gain and Hardware Requirements for Slice-Wise 3rd Order Dynamic Shim Updating for fMRI
Ariane Fillmer1 and Anke Henning2
1Institute for Biomedical Engineering, UZH and ETH Zurich, Zurich, Switzerland, 2Max Planck Institute for Biological Cybernetics, Tuebingen, Germany

EPI allows for very fast acquisition, and is the “work horse” of conventional fMRI. To exploit the full advantage of applying ultra-high fields to fMRI, sophisticated B0 shim strategies are required. An auspicious approach for improving B0 homogeneity is DSU. As eddy-currents arise from fast switching of shim currents a careful pre-emphasis calibration is necessary. The application of pre-emphasis requires the limitation of the shim fields, which limits the homogeneity gain expected from DSU. This work compares the expected homogeneity gain from a global and a slice-wise DSU shim approach and investigates the hardware requirements for optimal slice-wise dynamic shimming.