Toward Clinical 7T from Toe to Head
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Thursday May 12th
Room 518-A-C  13:30 - 15:30 Moderators: Dan Sodickson and Jeanette Schulz-Menger

13:30 591.   Introduction
Daniel K. Sodickson


13:42 592.   MRI of the Human Prostate in Vivo at 7T 
Tom W.J. Scheenen1,2, Stephan Orzada2,3, Thiele Kobus1, Miriam W Lagemaat1, Marnix C Maas1, Oliver Kraff2, Stefan Maderwald2, Irina Brote2,3, Mark E Ladd2,3, and Andreas K Bitz2,3
1Radiology, Radboud University Nijmegen Medical Centre, Nijmegen, Gelderland, Netherlands, 2Erwin L. Hahn Institute for Magnetic Resonance Imaging, Essen, Germany,3Diagnostic and Interventional Radiology and Neuroradiology, University Hospital Essen, Essen, Germany

MRI of the prostate with an 8-channel multi TxRx body array coil at 7T was explored in four healthy volunteers. With a multiple spin echo pulse sequence with prolonged 180 degree pulses, images of 7 separate echoes were used to calculate T2 values of peripheral zone and transition zone tissue in the prostate. Small but significant differences in T2 demand long echo times for T2 weighted contrast. Moreover, the large radiofrequency power deposition of multi spin echo pulse sequences point to the need for alternatives for anatomical imaging, which is explored with true balanced gradient echo imaging.

13:54 593.   Dynamically Applied Multiple B1+ Shimming Scheme for Arterial Spin Labeling of the Prostate at 7T 
Xiufeng Li1, Pierre-Francois Van de Moortele1, Kamil Ugurbil1, and Greg Metzger1
1Center for Magnetic Resonance Research, University of Minnesota, Minneapolis, MN, United States

The destructive interference of RF pulses is one well-known challenge for ultrahigh field MR imaging. B1+ shimming for the target anatomy alone is not sufficient for ASL, where each RF pulse in the sequence has varying requirements with respect to B1+ amplitude, homogeneity, location and spatial coverage. To optimally use the RF power available and simultaneously manage the RF deposition in the body, different RF optimization solutions were applied dynamically during an ASL sequence. Preliminary results show that optimization of B1+ for each RF pulse in a sequence and applying those solutions dynamically during imaging acquisition appear to improve ASL perfusion results in the prostate at 7T.

14:06 594.   7 Tesla Abdominal Imaging using TIAMO 
Stephan Orzada1,2, Sören Johst1,2, Andreas K. Bitz1,2, Oliver Kraff1,3, Irina Brote1,2, Susanne C. Ladd1,2, Mark E. Ladd1,2, and Stefan Maderwald1,3
1Erwin L. Hahn Institute for Magnetic Resonance Imaging, Essen, NRW, Germany, 2Department of Diagnostic and Interventional Radiology and Neuroradiology, University Hospital Essen, Essen, NRW, Germany, 3University of Duisburg-Essen, Essen, NRW, Germany

With increasing field strength, the wavelength of the B1 field is shortened, making abdominal imaging at 7 Tesla and above very challenging due to the severe B1 inhomogeneities. Recently, Time Interleaved Acquisition of Modes (TIAMO) has been proposed as an easy and robust scheme for mitigating these inhomogeneity effects. In this work, we present first abdominal images acquired with TIAMO at 7 Tesla. The results appear to render promising contrasts and homogeneous images. Abdominal imaging at 7 Tesla seems feasible with TIAMO, since images without signal dropouts can be acquired within a reasonable acquisition time.

14:18 595.   Initial Results of Abdominal MRI at 7T Using a 16 channel Transmit/Receive Coil 
Fabian Hezel1, Peter Kellman2, Christof Thalhammer1, Celal Özerdem1, Wolfgang Renz3, and Thoralf Niendorf4
1Berlin Ultrahigh Field Facility, Max Delbrueck Center for Molecular Medicine, Berlin, Germany, 2Laboratory of Cardiac Energetics, National Institutes of Health/NHLBI, Bethesda, MD, United States, 3Siemens Medical Systems, Erlangen, Germany, 4Berlin Ultrahigh Field Facility, Max Delbrueck Center for Molecular Medicine, Berlin, Berlin, Germany

This pilot study examines the feasibility of abdominal imaging at 7.0 T using (i) in-phase and out-of-phase imaging, (ii) high spatial resolution T1-weighted imaging, (iii) fat/water imaging and (iv) T2* mapping in conjunction with a 16 channel torso TX/RX coil array. Despite the observed non-uniformities of the RF field distribution, our initial results suggest that high spatial resolution anatomic details accomplished at 7.0 T can be considered to be beneficial in future clinical liver imaging.

14:30 596.   Balanced SSFP cardiac imaging at 7T 
Lance DelaBarre1, J. Thomas Vaughan1, Carl Snyder1, and Pierre-Francois van de Moortele1
1CMRR - Dept. of Radiology, University of Minnesota, Minneapolis, MN, United States

The challenges of balanced steady-state free precession (bSSFP) cardiac cine increase with field strength. The effect static field inhomogeneities and RF efficiency are explored for 7T, and 7T bSSFP cines are presented.

14:42 597.   Fat-water separated imaging at 7T: initial results for cardiac applications 
Peter Kellman1, Fabian Hezel2, Saurabh Shah3, Wolfgang Renz4, Christof Thalhammer2, Jeanette Schulz-Menger2,5, and Thoralf Niendorf2,6
1NIH, Bethesda, MD, United States, 2Berlin Ultrahigh Field Facility, Max-Delbrueck-Center for Molecular Medicine, Berlin, Germany, 3Siemens Medical Solutions, USA, Chicago, IL, United States, 4Siemens Healthcare, Erlangen, Germany, 5Charité Campus Buch, Helios Klinkum, Berlin, Germany, 6Experimental and Clinical Research Center, Charité Campus Buch, Humboldt-University, Berlin, Germany

Fat-water separated imaging has been demonstrated at 7T for cardiac imaging application using a multi-echo Dixon approach. This approach overcomes limitations of conventional chemical shift fat suppression which is difficult at high field strength. Fat-water separated imaging is an important tool for characterizing tissue and providing fat suppression.

14:54 598.   Contrast Enhancement in TOF cerebral angiography at 7 Tesla under SAR constraints: trading between Saturation, VERSE and Magnetization Transfer RF pulses. 
Sebastian Schmitter1, Edward J Auerbach1, Gregor Adriany1, Kamil Ugurbil1, and Pierre-Francois Van de Moortele1
1Center for Magnetic Resonance Research, University of Minnesota, Minneapolis, MN, United States

It has been shown that time-of-flight (TOF) cerebral angiography can be obtained at 7T. However, because of SAR limitations additional techniques like standard Saturation pulses (SAT) to target veins, and Magnetization Transfer (MT) to target background tissues cannot be applied. The goal of this work is to demonstrate 7T-TOF contrast enhancement using MT and/or SAT without exceeding SAR limitations. For this purpose, VERSE was applied on excitation and SAT pulses, MT was only applied during a subset of k-space lines. Our results indicate that VERSE SAT and sparse MT pulses successfully increase TOF contrast at 7T without exceeding SAR limits.

15:06 599.   Further reduction of SAR for T2-weighted hyper-TSE imaging at 7 Tesla 
K A Danishad1, Niravkumar Darji1, and Oliver Speck1
1Department of Biomedical Magnetic Resonance, Otto-von-Guericke University, Magdeburg, Saxony Anhalt, Germany

High RF power deposition caused by multiple 1800 refocusing pulses is a major limitation of TSE sequences in ultra high field MR imaging. In this study, the flip angle variation of the hyper-TSE sequence was optimized to further reduce SAR. T2-contrast and image artifacts of the modified hyper-TSE sequence were compared with standard TSE and hyper-TSE sequences. Our results indicate that the hyper-TSE sequence with further reduced FA can be used in high-field systems without compromising the T2-contrast and SNR and with the benefit of increased coverage or reduced SAR.

15:18 600.   Adiabatic turbo spin echo for human applications at 7T. 
Irene Maria Louise van Kalleveen1, Vincent O. Boer1, Peter Luijten1, Jaco J.M. Zwanenburg1, and Dennis W.J. Klomp1
1Radiology, UMC Utrecht, Utrecht, Netherlands

Limitations and potentials of adiabatic TSE for human application at 7T have been demonstrated. The limitations of the adiabatic regime, when going to lower B1 fields, are discussed and the importance of correct k-space sampling has been shown. Furthermore, compared to a conventional TSE, an adiabatic TSE improves the homogeneity of the image. This is simulated and confirmed in phantom measurements as well as in vivo, on the primary visual cortex and the left carotid artery, using a transmit and receive surface coil.