ISMRM 21st Annual Meeting & Exhibition ○ 20-26 April 2013 ○ Salt Lake City, Utah, USA
SCIENTIFIC SESSION
Sequences & Applications Tuesday 23 April 2013
Room 355 EF | 10:00 - 12:00 | Moderators: | Oliver Bieri, Vibhas Deshpande
10:00 | 0244. | T1-Weighted Imaging of Lumbar Spine Using Multiband Slice Accelerated Spin Echo Dingxin Wang1,2, Peter D. Kollasch3, Edward J. Auerbach2, Steen Moeller2, Bhat Himanshu4, Kamil Ugurbil2, and Vibhas Deshpande5 1Siemens Medical Solution USA, Inc., Minneapolis, MN, United States, 2Center for Magnetic Resonance Research, University of Minnesota, Minneapolis, MN, United States, 3Siemens Medical Solutions USA, Inc., Minneapolis, MN, United States, 4Siemens Medical Solutions USA, Inc., Charlestown, MA, United States, 5Siemens Medical Solutions USA, Inc., Austin, TX, United States Our study demonstrates the clinical application of multiband slice accelerated SE for T1-weighted lumbar spine imaging. Better T1 contrast can be achieved was this newly developed sequence than clinical standard TSE.
10:12 | 0245. | Fast T2 Weighted Imaging with PSIF in the Abdomen at 3T Chao Zou1, Wensha Guo1, Xin Liu1, and Yiu-Cho Chung1 1Paul C. Lauterbur Research Center for Biomedical Imaging, Shenzhen Key Laboratory for MRI, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen, Guangdong, China At 3T, conventional free breathing T2 weighted imaging in the abdomen by HASTE is limited by SAR constraint and B1 inhomogeneity. This work shows that PSIF offers good T2 contrast in abdomen under 3T with a flip angle of around 20o ¨C 30o, drastically reducing SAR and is more robust than HASTE. For 2D PSIF in healthy volunteers, the SNR of liver is around 17 and spleen-liver CNR is around 18 and is sufficient for diagnostic purpose. The short TR in PSIF shortens the scan time to within 1s/slice, and eliminates the need for breathholding or respiratory triggering.
10:24 | 0246. | A Variable Bandwidth Radial Gradient and Spin-Echo (VB-RadGRASE) Method for Improved T2 and Fat-Water Parameter Estimation Mahesh Bharath Keerthivasan1, Jean-Philippe Galons2, Puneet Sharma2, Diego R. Martin2, Ali Bilgin1,3, and Maria I. Altbach2 1Electrical and Computer Engineering, University of Arizona, Tucson, AZ, United States, 2Medical Imaging, University of Arizona, Tucson, AZ, United States,3Biomedical Engineering, University of Arizona, Tucson, AZ, United States Acquisition schemes based on gradient and spin-echo (GRASE) methods have been developed for the fast fat-water and T2 estimation. In this work we present a variable bandwidth radial GRASE (VB-radGRASE) sequence with the goal of optimizing the SNR of T2 and fat-water parameter estimation. The new method is evaluated in phantoms and in vivo data.
10:36 | 0247. | Multi-Echo Acquisition of 3D TOF and SWI of Radiation-Induced Cerebral Microbleeds at 7T Wei Bian1,2, Suchandrima Banerjee3, Douglas A.C. Kelly4, Susan M. Chang5, Sarah J. Nelson1,2, and Janine M. Lupo2 1Graduate Program in Bioengineering, University of California San Francisco & Berkeley, San Francisco, CA, United States, 2Radiology and Biomedical Imaging, University of California San Francisco, San Francisco, CA, United States, 3Global Applied Science Laboratory, GE Healthcare, Menlo Park, CA, United States, 4Global Applied Science Laboratory, GE Healthcare, San Francisco, CA, United States, 5Neurological Surgery, University of California San Francisco, San Francisco, CA, United States We designed a multi-echo sequence for the simultaneous acquisition of 3D TOF and SWI images at 7T for depicting radiation-induced cerebral microbleeds, intracranial arteries, and veins in one acquisition. The first echo was used to create TOF images of arteries, while those from the remaining three were combined to reconstruct SWI images for visualization of microbleeds and veins. Experimental results from a volunteer and two patients showed that the images acquired from the multi-echo sequence achieved a level of quality comparable to that of each obtained with a single-echo sequence.
10:48 | 0248. | Optimization of Cube-FLAIR 3D FSE Imaging at 7T Manojkumar Saranathan1, Thomas Tourdias1, Michael Zeineh1, Adam Kerr2, Jeffrey D. Bernstein3, Geoff A. Kerchner3, and Brian K. Rutt1 1Dept. of Radiology, Stanford University, Stanford, CA, United States, 2Electrical Engineering, Stanford University, Stanford, CA, United States, 3Dept. of Neurology and Neurological Sciences, Stanford University, Stanford, CA, United States Refocusing flip angle modulation schemes like SPACE and Cube [1-2] enable use of longer echo-train-lengths in 3D T2-weighted imaging. For improved lesion conspicuity, an inversion prep is used to null CSF but adds undesirable T1 weighting at 7T due to incomplete T1 recovery at the CSF null point, reducing SNR and contrast. The use of a magnetization preparation (MP) scheme [3] can help mitigate this effect but further increases the already high SAR at 7T. We added an MP-FLAIR module to a Cube sequence and optimized the MP-FLAIR-Cube sequence, taking into account image contrast, SAR, and SNR as well as T1/T2 values of WM/GM at 7T. Whole brain MP-FLAIR-Cube scans were performed on 20 patients at 7T using these modifications.
11:00 | 0249. | SAR and Scan-Time Optimized 3D Whole-Brain Double Inversion Recovery (DIR) Imaging Eberhard Daniel Pracht1, Thorsten Feiweier2, Philipp Ehses3, Daniel Brenner1, Bernd Weber4, and Tony Stöcker1 1German Center for Neurodegenerative Diseases (DZNE), Bonn, Germany, 2Siemens AG, Siemens AG, Erlangen, Germany, 3Max Planck Institute for Biological Cybernetics, Tübingen, Germany, 4Department of Epileptology, University Hospital Bonn, Bonn, Germany The DIR sequence is commonly used for simultaneous white matter and cerebrospinal fluid (CSF) suppression. Gray matter (GM) imaging is important for cortical lesion detection in neurological diseases, such as epilepsy and Alzheimer's. The aim of this project was to optimize the DIR Turbo-Spin-Echo (TSE) sequence, enabling whole brain acquisition at a resolution of 1 x 1 x 1 mm3 or below, in less than 10 minutes scan time. Both, the DIR preparation module, as well as the TSE imaging module were specifically designed for high field applications to overcome SAR limitations and to optimize image quality.
11:12 | 0250. | Rapid Tracking of Soft Palate Motion During Speech Using Pencil Beam and Turbo Navigators Andrew David Scott1, Redha Boubertakh2, Malcolm Birch1, Marie Pinkstone3, and Marc Eric Miquel1,2 1Clinical Physics, Barts Health NHS Trust, London, United Kingdom, 2NHLI Cardiovascular BRU, Barts Health NHS Trust, London, United Kingdom, 3Cleft Lip and Palate Team, Great Ormond Street Hospital for Children, London, United Kingdom Diagnosis of small timing errors in articulation during speech requires high temporal resolution techniques. Currently, 2D real-time MRI is too slow. We use a pencil beam and a novel turbo-spin-echo navigator to track velar motion during speech at 37 and 62 lines/s. The navigators were positioned through the velum and data was acquired with audio recording during speech. The 1D+t images created were compared to a navigator simulated from 2D real-time images and the pattern of palatal motion was similar. The additional temporal resolution of the turbo navigator will permit more precise measurement of the timing of velopharyngeal closure.
11:24 | 0251. | Real-Time MRI Can Differentiate Sleep-Related Breathing Disorders in Children Yoon-Chul Kim1, Shirleen Loloyan2, Ziyue Wu1, Winston Tran1, Roberta Kato2, Sally L.D. Ward2, Michael C.K. Khoo1, and Krishna S. Nayak1 1University of Southern California, Los Angeles, CA, United States, 2Children's Hospital Los Angeles, Los Angeles, CA, United States We propose a novel MRI approach that involves real-time imaging and synchronized collection of several physiological signals (i.e., airway pressure, respiratory effort, heart rate, oxygen saturation) to assess dynamics of the pharyngeal airway in children with sleep-related breathing disorders (SRBD). Our proposed imaging sequence can run continuously for several hours and is compatible with natural sleep. We demonstrate that changes in airway cross-sectional area differ with SRBD phenotype.
11:36 | 0252. | Fat Saturation for 2D Small-Tip Fast Recovery Imaging Using Tailored 3D Spectral-Spatial Pulses Feng Zhao1, Jon-Fredrik Nielsen1, and Douglas C. Noll1 1Biomedical Engineering Department, The University of Michigan, Ann Arbor, MI, United States Small-Tip Fast Recovery imaging (STFR) is a steady state sequence that produces bSSFP-like contrast without banding artifacts. Using tip-down and tip-up pulses, this sequence is compatible with fat sat preparation. Combining with fat sat, a new RF spoiling scheme is required to maintain the steady state of the signal. A 2 ms long 3D tailored spectral-spatial fat sat pulse is designed for the 2D STFR sequence to produce fat free steady state images on a 3T scanner in the presence of B0 inhomogeneities.
11:48 | 0253. | Reduction of Acoustic Noise to Improve Patient Comfort Through Optimized Sequence Design Eric Yann Pierre1, David Manuel Grodzki2, Bjoern Heismann2, Vikas Gulani1,3, Jeffrey Sunshine4, Kecheng Liu5, and Mark A. Griswold1,4 1Biomedical Engineering, Case Western Reserve University, Cleveland, Ohio, United States, 2Siemens AG, Erlangen, Germany, 3Radiology, University Hospitals Case Medical Center, Cleveland, Ohio, United States, 4Radiology, Case Western Reserve University, Cleveland, Ohio, United States, 5Siemens Medical Solutions, USA Inc., Malvern, Pennsylvania, United States Loud acoustic noise is a major cause of patient discomfort. It is mainly introduced during gradient switching, and many efforts have been made to address this issue. Some MR manufacturers encloses the whole gradient coil in a vacuum environment to reduce the noise significantly, increasing manufacturing costs. We present another approach without hardware modification, which relies solely on the optimization of pulse sequences to realize noise reduction for various standard clinical protocols. No significant degradation of imaging time or image quality was observed. With such an approach, for certain specific sequences, acoustic noise can be reduced almost to ambient level.