Joint Annual Meeting ISMRM-ESMRMB 2014 10-16 May 2014 Milan, Italy

ULTRA-HIGH FIELD (13:30-15:30)
4911-4934 Ultra-High Field for Human Applications

Ultra-High Field for Human Applications

Thursday 15 May 2014
Exhibition Hall  14:30 - 15:30

  Computer #  
4911.   1 Unified Segmentation at 7T
Yosef A Berlow1, Lisa Karstens Vingara1, Manoj K Sammi1, Laura E McMahon1, Ian Tagge1, Brendan Moloney1, John W. Grinstead2, and William D Rooney1
1Advanced Imaging Research Center, Oregon Health & Science University, Portland, Oregon, United States, 2Siemens Healthcare, Portland, OR, United States

Brain segmentation is challenging using data collected from ultra-high magnetic field MRI instruments. Here, we present a robust approach to segment high-spatial resolution T1-w MPRAGE data sets acquired at 7T and demonstrate results from 88 healthy controls.

4912.   2 Comparative magnetic resonance imaging at 3T und 7T for the evaluation of diffuse axonal injuries
Christoph Moenninghoff1,2, Oliver Kraff2, Stefan Maderwald2, Jan Altmeppen1, Lale Umutlu1, Mark E Ladd2,3, Michael Forsting1, and Marc Schlamann1
1Department of Diagnostic and Interventional Radiology and Neuroradiology, University Hospital Essen, Essen, Germany, 2Erwin L. Hahn Institute for MRI, University Duisburg-Essen, Essen, Germany, 3Division of Medical Physics in Radiology, German Cancer Research Center (DKFZ), Germany

Traumatic microbleeds (TMBs) are regarded as a radiological marker for diffuse axonal injury (DAI). This study compares the detection of TMBs on 3T and 7T magnetic resonance images. 8 volunteers with DAI were examined with MR scanners equipped with 32-channel head coils at both field strengths. TMBs were counted on susceptibility weighted images (SWI), with similar and 14-times increased spatial resolution at 7T. 7T SWI depicted 28% and 40% more TMBs compared to 3T with similar and higher spatial resolution, respectively. Hence, 7T SWI may optimize diagnostics of DAI in inconclusive and in medicolegal cases.

4913.   3 PTX-RSI at 7T: Fast in-vivo brain spectroscopic imaging at UHF using an 8-channel parallel transmit system, a shim gradient insert coil and rosette trajectories.
Claudiu Schirda1, Tiejun Zhao2, and Hoby Hetherington1
1Radiology, University of Pittsburgh School of Medicine, Pittsburgh, PA, United States, 2Siemens Medical Solutions, Pittsburgh, PA, United States

We demonstrate in vivo brain, fast spectroscopic imaging at 7T, using non-Cartesian rosette trajectories. Lipid suppression is achieved using an 8-channel PTX system and high field homogeneity is obtained through the use of a gradient insert system with up to 4th order shims.

4914.   4 Initial experience with SPIral Non Selective (SPINS) RF pulses for homogeneous excitation at 7T
Hans Hoogduin1, Ronald Mooiweer2, Giel Mens3, Joseph V Hajnal4, Peter Luijten2, and Shaihan J Malik4
1UMC Utrecht, Utrecht, Utrecht, Netherlands, 2UMC Utrecht, Utrecht, Netherlands, 3Philips Healthcare, Best, Netherlands, 4King's College London, London, United Kingdom

The effectiveness of SPIral Non Selective (SPINS) RF pulses to increase the excitation homogeneity at 7T is investigated for T1W (MP-RAGE) imaging.

4915.   5 Slab registration as a first step towards hippocampus subparts high resolution imaging at 7T
Linda Marrakchi-Kacem1,2, Alexandre Vignaud3, Johanne Germain1,2, Julien Sein4, Thomas R. Henry5, Cyril Poupon3, Lucie Hertz-Pannier3, Stéphane Lehéricy1,6, Olivier Colliot1,2, Pierre-François Van de Moortele4, and Marie Chupin1,2
1UPMC-Paris6, CRICM, CNRS, UMR 7225, Inserm, UMR-S975, ICM, Paris, France, 2Aramis project-team, Inria Paris-Rocquencourt, Paris, France, 3NeuroSpin, CEA, Gif-Sur-Yvette, France, 4CMRR, University of Minnesota, Minneapolis, MN, United States, 5Department of Neurology, University of Minnesota, Minneapolis, MN, United States, 6AP-HP, Hôpital de la Salpêtrière, CENIR, Paris, France

Imaging of the hippocampus subparts with high resolution requires long acquisition time which can generate movement artifacts inside the images. This problem can be solved using multi-slab acquisitions which reduce acquisition time but require an accurate registration method to overcome inter-slab movement. We propose an efficient registration procedure for interleaved slab acquisitions. It consists in registering the slabs containing gaps to a reference image with SPM8 and homogenizing the intensities using synthetic phantoms. This registration method was tested and validated on two datasets acquired for hippocampus subparts imaging in two different centers for a total of 34 subjects. It proved robust for both multi-slab protocols.

4916.   6 An untargeted metabolomics approach to ultra high field MRS in spinocerebellar ataxia
Uzay Emrah Emir1,2, Margarida Julià-Sapé3, Peter Jezzard1, Diane Hutter2, Khalaf O Bushara2, and Gulin Oz2
1FMRIB Centre, University of Oxford, Oxford, United Kingdom, 2University of Minnesota, Minneapolis, Minnesota, United States, 3Centro de Investigación Biomédica en Red en Bioingeniería, Biomateriales y Nanomedicina (CIBER-BBN), Universitat Autònoma de Barcelona, Cerdanyola del Vallès, Spain

A metabolomics approach to analyzing in vivo MRS data might benefit substantially from ultra high field (UHF) due to the improved sensitivity and resolution. In this study, we explored the potential of a metabolomics approach to MRS by comparing patients with spinocerebellar ataxia type 1 (SCA1) to healthy controls both at 3T and 7T. Due to high spectral quality at both fields, distinct clustering with a complete separation between SCA1 and controls was achieved. The improved sensitivity and resolution at 7T enabled identification of three distinct spectral features whereas only 2 distinct features were identified at 3T.

4917.   7 Minimum Intensity Snake Algorithm (MISA) for segmenting brain tissues in MR TBE images
Eleonora Maggioni1,2, Mauro Costagli2,3, Gianluigi Reni4, Anna Maria Bianchi1, and Michela Tosetti3
1Department of Electronics Information and Bioengineering, Politecnico di Milano, Milano, Milano, Italy, 2IMAGO7 Research Center, Pisa, Pisa, Italy, 3IRCCS Stella Maris Scientific Institute, Pisa, Pisa, Italy, 4Bioengineering Lab, Scientific Institute IRCCS E.Medea, Bosisio Parini, Lecco, Italy

The present abstract introduces the Minimum Intensity Snake Algorithm (MISA), an image processing method for the semi-automatic detection of borders into MR images acquired with the recently proposed Tissue Border Enhancement (TBE) Inversion Recovery (IR) technique. In TBE images the interfaces between tissues are enhanced and immediately visible, but difficult to extract with the most common histogram-based segmentation algorithms. Starting from a voxel marked by the user, the proposed method iteratively traces the curve of minimum intensity by exploiting graph theory functions. The MISA results on TBE images are promising and meet the requirements of subsequent quantitative analysis.

4918.   8 Ultra high field MR spectroscopy of the striatum in the human brain: On the relation between striatal metabolites and performance on a search step task
Joost Haarsma1,2, Jannie P Wijnen1, Kathy N Thakkar2, Dennis WJ Klomp1, and Bas Neggers2
1Radiology, University Medical Centre Utrecht, Utrecht, Utrecht, Netherlands, 2Psychiatry, University Medical Centre Utrecht, Utrecht, Utrecht, Netherlands

Response inhibition has been investigated using the oculomotor search-step task. Research into the neural substrates involved in response selection tasks (like the one used in this study) has pointed towards a crucial role for the basal ganglia, which influence action largely via GABAergic neurotransmission. We therefore hypothesized a relation between GABA levels (measured using ultra high field MR-spectroscopy) in the striatum, the input node of the basal ganglia, and performance on the search step-task in healthy participants. At highest MR sensitivity, no significant correlations between GABA levels and performance on the search-step task were found in this study.

4919.   9 Ultra-high Resolution In-vivo 7.0T Structural Imaging of the Human Endfolial Pathway
Mansi Parekh1, Ryan Purcell2, Sherveen Parivash1, Brian Rutt1, and Michael Zeineh1
1Radiology, Stanford University, Stanford, CALIFORNIA, United States, 2Neuroscience, University College London, London, United Kingdom

The hippocampal hilus may have unique neuroanatomy in humans compared to monkeys and rodents, with CA3h greatly enlarged and a unique white-matter pathway called the endfolial pathway present. In this stud,y we used newly developed 7.0T whole brain imaging achieving 0.4mm isotropic images to study in vivo the anatomy of the hippocampal hilus. We validate these in vivo finding with 0.1mm isotropic excised specimen images as well as histologically using a myelin stain. The endfolial pathway is a central pathway in the hippocampus, possibly unique to humans, and poorly described. However, our methodology will allow for its study and understanding its function.

4920.   10 Non-Enhanced MR Angiography of the Lower Extremity Arteries at 7T: Correction of Saturation Pulse Artifacts
Sören Johst1,2, Stephan Orzada1,2, Mark E. Ladd1,3, and Stefan Maderwald1
1Erwin L. Hahn Institute for MRI, University Duisburg-Essen, Essen, Germany, 2Diagnostic and Interventional Radiology and Neuroradiology, University Hospital Essen, University Duisburg-Essen, Essen, Germany, 3Medical Physics in Radiology, German Cancer Research Center (dkfz), Heidelberg, Germany

In recently published work, a turbo-FLASH sequence was modified for non-contrast-enhanced imaging of the lower extremity vessels at 7T. To reduce acquisition time, venous saturation RF pulses were applied every second TR. This led to an aliasing artifact caused by periodic signal variation due to alternating TR length. Here, theoretical flip angles for artifact reduction depending on both TRs were calculated and compared to experimental data from phantom measurements. Due to the inhomogeneous transmit field at 7T, the artifact could not be suppressed completely and thus additional methods such as special k-space ordering may need to be implemented.

4921.   11 Improved SNR at 7T for Non-Contrast Enhanced Cardiac Perfusion Imaging Using Arterial Spin Labeling
Xiufeng Li1, Pierre-Francois Van de Moortele1, Kamil Ugurbil1, and Gregory J Metzger1
1Center for Magnetic Resonance Research, University of Minnesota, Minneapolis, MN, United States

Previous applications of ASL in cardiac perfusion imaging indicated low perfusion signal to noise ratio (SNR) and large dominant temporal errors at 3T. Ultra high field 7T has the potential to provide higher SNR for ASL perfusion imaging due to greatly increased blood T1 and imaging SNR. To explore the benefits of 7T for ASL cardiac perfusion imaging, studies were performed on both 3T and 7T with results indicating that 7T could improve cardiac ASL perfusion SNR.

4922.   12 Contrast-enhanced and non-contrast-enhanced renal vessel imaging at 7 Tesla
Oliver Kraff1, Karsten Beiderwellen1,2, Anja Fischer2, Stephan Orzada1,2, Stefan Maderwald1, Mark E Ladd1,3, Thomas C Lauenstein2, and Lale Umutlu2
1Erwin L. Hahn Institute for MRI, University Duisburg-Essen, Essen, Germany, 2Department of Diagnostic and Interventional Radiology and Neuroradiology, University Hospital Essen, Essen, Germany, 3Division of Medical Physics in Radiology, German Cancer Research Center (DKFZ), Heidelberg, Germany

MRA is one of the applications that may benefit dramatically from the increase of the magnetic field strength to 7T. The aim of this study is the evaluation of the diagnostic quality of renal MRA at 7T in non-contrast-enhanced TOF versus contrast-enhanced FLASH imaging under reduction of contrast agent dosage to one-half and one-quarter of the standard dosage. 15 healthy volunteers (9f, 6m) were included in this study. The possibility to perform high-quality native and low-dose vessel imaging may be of high clinical importance for patients with renal insufficiency.

4923.   13 Comprehensive coronary artery imaging at 7.0 T: Proof of feasibility
Alexander J.E. Raaijmakers1, Hamza El Aidi1, Maarten Versluis2, Andrew Webb2, Hildo J. Lamb3, Peter R. Luijten1, Cornelis A.T. van den Berg4, and Tim Leiner1
1Radiology, UMC Utrecht, Utrecht, Utrecht, Netherlands, 2J.C. Gorter Institute, LUMC, Leiden, Netherlands, 3Radiology, LUMC, Leiden, Netherlands,4Radiotherapy, UMC Utrecht, Utrecht, Netherlands

Coronary MR imaging at 7.0T has the potential to improve imaging quality. The objective of this work is to demonstrate the feasibility of comprehensive coronary artery MR imaging at 7.0T, including all three major coronary arteries. Imaging is performed using a novel 8-channel transmit receive array with modified dipole antennas. The LCX and LAD have been imaged successfully in respectively 4 and 5 out of 7 cases; the RCA in 5 out of 5. Image quality is good while there is even room for improvement. The results provide a promising showcase that coronary artery imaging is feasible at 7 Tesla.

4924.   14 Quantitative comparison of localized in vivo hepatic 31P MRS at 7T.
Marek Chmelik1, Michal Povazan1, Martin Krššák1,2, Stephan Gruber1, Ladislav Valkovic1, Siegfried Trattnig1, and Wolfgang Bogner1
1High Field MR Centre, Department of Biomedical Imaging and Image-Guided Therapy, Medical University of Vienna, Vienna, Austria, Austria, 2Division of Endocrinology and Metabolism, Department of Internal Medicine III, Medical University of Vienna, Austria

The feasibility of commonly used 31P-MRS localization techniques (1D-ISIS, 3D-ISIS, 2D CSI and 3D CSI; n=9) that are suitable for both localized MRS of focal lesions and semi-localized MRS for use in diffuse pathologies in the human liver was demonstrated at 7T. Liver 31P MRS at 7T provides improved data quality in acceptable measurement time. All methods provided data with high spectral quality regarding signal to noise, small linewidth and low CRLB(<11%). Voxel volume and acquisition time corrected SNR was similar for all the methods.

4925.   15 Dual Tuned Proton/Lithium RF array Development; Feasibility Study at 7T MRI
Junghwan Kim1,2, Kyongtae Ty Bae1,2, Narayan Krishnamurthy1, Tiejun Zhao3, Hoby Hetherington2, and Tamer S. Ibrahim1,2
1Bioengineering, University of Pittsburgh, Pittsburgh, PA, United States, 2Radiology, University of Pittsburgh, Pittsburgh, PA, United States,3Siemens Medical Solutions, Inc, Pittsburgh, PA, United States

We tested the feasibility of Proton/Lithium MR imaging using a dual-tuned RF array. To evaluate the coil performance, SNR at 1) three ROIs, 2) different thicknesses and 3) different concentrations were measured. SNR was ~90-180 at different ROIs and spectrum at different concentration was compared using 2D CSI sequence.

4926.   16 Construction of a 2-Channel Transmit/Receive Neck Array for Carotid Artery Vessel Wall Imaging at 7 Tesla
Konstantinos Papoutsis1,2, Linqing Li1, Jamie Near3, Stephen J Payne2, David Edwards2, and Peter Jezzard1
1FMRIB Centre, Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, United Kingdom, 2Department of Engineering Science, University of Oxford, Oxford, United Kingdom, 3Centre d'Imagerie Cérébrale, McGill University, Montreal, Quebec, Canada

A 2-channel transmit/receive neck coil has been constructed for carotid artery vessel wall imaging at 7 Tesla. The coil comprises 2 elements operating in parallel transmit and receive via a custom T/R switch. The coil has been evaluated for RF safety via estimation of worst case SAR with electromagnetic simulations and temperature measurements in meat phantoms. A black blood FLASH sequence with DANTE preparation pulses has been implemented for evaluation of the benefits of the ultra high field with promising results. The resolution achieved in a male subject was 0.6mm isotropic with 4 min acquisition time.

4927.   17 Transmit/receive array for prostate imaging with fully flexible dipole antennas
Alexander J.E. Raaijmakers1, Tim van Daalen1, Ingmar Voogt1, Michel Italiaander2, Peter R. Luijten1, Cornelis A.T. van den Berg3, and Dennis W.J. Klomp1
1Radiology, UMC Utrecht, Utrecht, Utrecht, Netherlands, 2MR Coils B.V., Drunen, Netherlands, 3Radiotherapy, UMC Utrecht, Utrecht, Utrecht, Netherlands

Surface transmit arrays provide great advantages for ultra-high field imaging in terms of efficiency. More recently, dipole antennas have improved their performance considerably. However, their rigid structure does not always allow them to adapt to the body curvature. This work presents a dipole antenna prostate array that consists of foam and flexible PCB. The structure always adapts well to the shape of the subject. Matching was shown to be acceptable for three different subjects while coupling between elements is minimal. Imaging performance was characterized by a T2w TSE prostate image.

4928.   18 Rotating RF Coil (RRFC) for flip angle and specific absorption rate management applications at 7T MRI
Adnan Trakic1, Jin Jin1, Mingyan Li1, Darryl McClymont1, Ewald Weber1, Hector Sanchez Lopez1, Miguel Fuentes1, Feng Liu1, and Stuart Crozier1
1The School of Information Technology and Electrical Engineering, The University of Queensland, Brisbane, QLD, Australia

This new study explores the feasibility of using a single-channel mechanically Rotating RF Coil (RRFC) for flip angle (FA) and specific absorption rate (SAR) management applications at 7T MRI. Compared to the 8-channel Parallel Coil Array, RRFC yielded a much more uniform FA distribution and a lower SAR. This initial study suggests that RRFC may be very useful in alleviating the FA and SAR issues associated with contemporary high field MRI.

4929.   19 Multi-channel Array Safety Simulations Validated with Field and Temperature Measurements
Cem Murat Deniz1,2, Ryan Brown1, Leeor Alon1,2, Martijn Cloos1,2, Gene Y Cho1,2, Graham Wiggins1, Christopher M Collins1,2, and Daniel K. Sodickson1,2
1The Bernard and Irene Schwartz Center for Biomedical Imaging, Department of Radiology, New York University School of Medicine, New York, NY, United States, 2The Sackler Institute of Graduate Biomedical Sciences, New York University School of Medicine, New York, NY, United States

At high field strength, safety assessment of local multi-channel arrays currently relies on electromagnetic field simulations. Additional verifications of the accuracy of the simulated RF array can be performed using E-field or temperature measurements with additional probes, or with B1+ measurements. In this work, we investigated the use of MR thermometry as a validation tool of the representation of the RF array in simulations. Our results suggest that MR thermometry is a valuable tool readily available in any MR scanner for transmit array safety assessment

4930.   20 Effects of the load size on the maximum local SAR at 7T
Gianluigi Tiberi1, Nunzia Fontana2, Riccardo Stara3, Mark Roger Symms4, Agostino Monorchio2, Mauro Costagli1, Laura Biagi5, Mirco Cosottini6, and Michela Tosetti5
1Imago7, Pisa, PI, Italy, 2Dipartimento di Ingegneria dell’Informazione, Pisa, Italy, 3Dipartimento di Fisica, Pisa, Italy, 4General Electric ASL Scientist (EMEA), Pisa, Italy, 5IRCCS Stella Maris, Pisa, Italy, 6Dipartimento di Neuroscienze, Pisa, Italy

In this study we investigated the effects of the load size on the maximum local SAR at 7T. Specifically, we resorted to: i) 3D full wave numerical electromagnetic simulations for analyzing a surface loop loaded with anatomic human calves models; ii) 2D analytical approach for analyzing a volume resonator loaded with homogeneous cylindrical phantoms having average tissue dielectric properties. In both cases we noticed that the maximum local SAR decreases with decreasing load size: this holds true if the RF magnetic fields (B1+) for the different load sizes are scaled so to achieve the same slice average value of 1ìT.

4931.   21 On the E-field construction/deconstruction and B1+ Efficiency/Homogeneity with Transmit Array Eigen Modes
Yujuan Zhao1, Tiejun Zhao2, Narayanan Krishnamurthy1, and Tamer S. Ibrahim1
1University of Pittsburgh, Pittsburgh, PA, United States, 2Siemens Medical Solutions, Pittsburgh, PA, United States

The inhomogeneous distribution of the excitation field (B1+) and the potential rise in local RF absorption (SAR) are two of the major obstacles hampering potential clinical applications of the ultrahigh field human MRI (7T and higher.) Ideally, the “quadrature” excitation construction will give the most efficient B1+ field and the destruction of the central E fields will generate less SAR (less power absorptions. While there could be many different optimization solutions (we include many of which into several of our in-vivo studies) for the RF excitation that achieve a very similar fidelity to the targeted excitation pattern (homogenous B1+ field), minimizing the local SAR and maximizing the B1+ efficiency are two of the most important constraints of the optimization procedure.

4932.   22 Segmented TOF MRA with Reduced Venous Saturation Pulses to Decrease SAR at 3T and 7T
Zihao Zhang1,2, Dehe Weng3, Jing An3, Bo Wang1, Yan Zhuo1, Xiaohong Joe Zhou4, and Rong Xue1
1State Key Lab of Brain and Cognitive Science, Beijing MR Center for Brain Research, Institute of Biophysics, Chinese Academy of Sciences, Beijing, Beijing, China, 2Graduate School, University of Chinese Academy of Sciences, Beijing, Beijing, China, 3Siemens Shenzhen Magnetic Resonance Ltd., Shenzhen, Guangdong, China, 4Dept. of Radiology, Center for MR Research, University of Illinois, Chicago, Illinois, United States

Time-Of-Flight (TOF) MR angiography has exhibited considerable advantages at very-high and ultra-high magnetic fields. However, the tracking saturation pulse to suppress venous signals in TOF is commonly omitted at 7T to stay within the SAR limit, leading to venous contamination in MIP angiograms. This study reduces the duty cycle of saturation pulse by introducing segmented TOF. Comparing with the conventional TOF sequence, the new sequence reduces the total number of saturation pulses and the SAR values considerably. As a result, the advantages of 3T and 7T MR angiography are better realized to improve the angiogram quality.

4933.   23 Optimization of a Zero Echo Time (ZTE) Sequence at 7T with Phased Array Coils
Douglas A. C. Kelley1, Graeme C McKinnon2, Laura Sacolick3, Daniel B Vigneron4, and Sarah J Nelson4
1Neuro Apps and Workflow, GE Healthcare, Corte Madera, CA, United States, 2MR Physics, GE Healthcare, Waukesha, WI, United States, 3MR, GE Healthcare, Muenchen, Germany, 4Radiology & Biomedical Imaging, UCSF, San Francisco, CA, United States

A Zero Echo Time (ZTE) sequence compatible with conventional phased array coils was implemented and optimized at 7T for brain imaging with more uniform T1 contrast and high sensitivity while retaining sensitivity to fast relaxing spins. Details of the implementation and optimization are provided along with images from phantoms and normal volunteers. Comparison is provided to a conventional 3D inversion prepared gradient echo imaging sequence of equal scan time. An additional feature of the sequence is that it generates very low levels of acoustic noise.

4934.   24 Optimization of Magnetization Prepared Rapid Gradient Echo (MP-RAGE) at 7T
Manojkumar Saranathan1, Thomas Tourdias1, May Han2, and Brian K Rutt1
1Department of Radiology, Stanford University, Stanford, CA, United States, 2Department of Neurology and Neurological Sciences, Stanford University, Stanford, CA, United States

The purpose of this work was to optimize MP-RAGE imaging at 7T. Two regimes- a conventional cerebral spinal fluid nulled (CSFn) and a white-matter nulled (WMn) MP-RAGE for imaging cortical lesions and thalamus-were optimized for scan time, SNR and contrast efficiency. The effect of α and TR on image blurring was modeled and validated. A novel 2D-centric radial fanbeam (RFB) k-space segmentation scheme was used for reducing scan times. Finally, healthy human subjects and patients with multiple sclerosis (MS) were scanned at 7T to demonstrate novel lesion detectability.