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


Tuesday 13 May 2014
Space 3  13:30 - 15:30 Moderators: Curtis A. Corum, Ph.D., Alex L. MacKay, D.Phil.

13:30 0335.   
Fast B1-insensitive T2 relaxometry of the human brain at high to ultra-high fields
Rahel Heule1, Peter Bär2, Christian Mirkes3,4, Klaus Scheffler3,4, Siegfried Trattnig2, and Oliver Bieri1
1Division of Radiological Physics, Department of Radiology, University of Basel Hospital, Basel, Switzerland, 2MR Centre of Excellence, Department of Biomedical Imaging and Image-guided Therapy, Medical University of Vienna, Vienna, Austria, 3MRC Department, Max Planck Institute for Biological Cybernetics, Tübingen, Germany, 4Department of Biomedical Magnetic Resonance, University of Tübingen, Tübingen, Germany

Quantitative imaging at high to ultra-high fields suffers from prominent B1 field inhomogeneities that affect quantification accuracy. Recently, a 3D triple echo steady-state (TESS) approach has been presented that offers fast B1-insensitive T2 quantification. In this work, the sensitivity to subject motion of 3D-TESS is reduced by investigating a rapid 2D technique suited for brain applications. The feasibility and reliability of 2D TESS-T2 relaxometry is demonstrated in human brain scans at high (3 T) and ultra-high (7 T and 9.4 T) fields. The results accentuate the potential of TESS-T2 to act as valuable measure for the detection of brain tissue alterations.

13:42 0336.   Quantitative MR imaging method
Bruno Madore1, Cheng-Chieh Cheng2, and Chang-Sheng Mei1
1Department of Radiology, Harvard Medical School, Brigham and Womens' Hospital, Boston, MA, United States, 2Department of Electrical Engineering, National Taiwan University, Taipei, Taiwan

From 3D data acquired over no more than a few minutes, the present method aims to evaluate all of the main physical MR parameters: T1, T2, T2*, M0, B0 and B1. A single pulse sequence is employed, and the various MR parameters can be evaluated one at a time and/or through linear equations, as opposed to numerically solving larger and non-linear systems of equations involving many or all parameters at once. As few as only two MR scans may be acquired, using different nominal user-input flips angles and/or different repetition times. Simulated and phantom results are presented.

13:54 0337.   
An Improved Gradient Echo Myelin Water Imaging using a Frequency Offset Model and Early Echoes
Yoonho Nam1, Jongho Lee2, Dosik Hwang1, and Dong-Hyun Kim1
1Department of Electrical and Electronic Engineering, Yonsei University, Seoul, Korea, 2Department of Radiology, University of Pennsylvania, Philadelphia, Pennsylvania, United States

Myelin water imaging has been proposed as a potential biomarker for demyelinating diseases. In this study, we demonstrated that the multi-component model with frequency offsets offers substantially reliable MWF results that are less affected by the number of echoes used in the analysis. Additionally, we revealed that the MWF map generated from early echoes is less sensitive to B0 field inhomogeneity and, hence, provides wider brain coverage. Lastly, we performed a test-retest scan and demonstrated that the frequency offset model with early echoes provides more reproducible results.

14:06 0338.   
The Phase and Magnetization Transfer Characteristics of a Novel Myelin Water Imaging Method (ViSTa)
Hyo Min Lee1,2, Daeun Kim1, Sung Suk Oh1, Joon Yul Choi1, Se-Hong Oh1, and Jongho Lee1
1Radiology, University of Pennsylvania, Philadelphia, PA, United States, 2Bioengineering, University of Pennsylvania, Philadelphia, PA, United States

The signal characteristics of a novel myelin water imaging method, direct visualization of short transverse relaxation time component (ViSTa), have been explored. The results show that the phase evolution and magnetization transfer effects of ViSTa match well with those of myelin water and are substantially different from those of GRE. These results, in addition to short T2* characteristics of ViSTa, further support the origin of ViSTa signal to myelin water.

14:18 0339.   An algorithm for fast and accurate T2* mapping based on Auto-Regression on Linear Operations (ARLO) of data
Mengchao Pei1,2, Thanh D. Nguyen3, Nanda D. Thimmappa3, Carlo Salustri3, Fang Dong2, Mitchell A. Cooper4, Jianqi Li5, Martin Prince3, and Yi Wang3
1East China Normal University, Shanghai, Shanghai, China, 2Yifu Inc, Jiaxing, Zhejiang, China, 3Radiology, Weill Cornell Medical College, New York, NY, United States, 4Cornell University, Ithaca, NY, United States, 5East China Normal University, Shanghai, China

We propose a novel fast and accurate method for calculating transverse relaxation times called Auto Regression on Linear Operations (ARLO). T2*mapping using simulated and in vivo data showed ARLO delivered comparable accuracy compared to the non-linear least squares based Levenberg-Marquardt (LM) algorithm and better accuracy for lower SNR and shorter T2* compared to the Log-Linear (LL) algorithm. ARLO is approximately 100 and 10 times faster than LM and LL, respectively, enabling rapid whole-organ T2* mapping.

14:30 0340.   
Automatic Brain Segmentation using Fractional Signal Modelling of a Multiple Flip-Angle Spoiled Gradient-Recalled Echo Acquisition
André Ahlgren1, Ronnie Wirestam1, Freddy Ståhlberg1,2, and Linda Knutsson1
1Department of Medical Radiation Physics, Lund University, Lund, Sweden, 2Department of Diagnostic Radiology, Lund University, Lund, Sweden

Brain segmentation based on multi-component modelling of quantitative MRI data has yielded great interest recently. Those methods are attractive due to their simplicity in modelling and processing. In this work, we present a novel method to segment gray matter, white matter, and cerebrospinal fluid, based on a spoiled gradient-recalled echo (SPGR) sequence acquired with varying flip angles (VFA). The method, dubbed ‘SPGR-SEG’, yielded robust and realistic segmentation maps in good agreement with a reference method based on inversion recovery data.

14:42 0341.   Maximizing Tissue Contrast in MRI Using RAFFn Preparation with SWIFT and Spin Echo Readouts
Timo Liimatainen1, Djaudat Idiyatullin2, Jinjin Zhang2, Hanne Hakkarainen1, Silvia Mangia2, Michael Garwood2, and Shalom Michaeli2
1A.I.Virtanen Institute, University of Eastern Finland, Kuopio, FI, Finland, 2Center for Magnetic Resonance Research, University of Minnesota, Minneapolis, MN, United States

The general procedure of generating tissue contrast which is characterized predominantly by slow motion by altering steady state in SWIFT with RAFFn preparation pulses is described. It is shown that high rotating frame relaxation contrasts obtained with RAFFn provide enhanced sensitivity to slow motion in tissue and is associated with myelin in the brain.

14:54 0342.   Robust adiabatic T2 preparation for fast whole brain spiral myelin water imaging at 3 Tesla
Thanh D. Nguyen1, Kofi Deh1, Ashish Raj1, Martin Prince1, Yi Wang1, and Susan A. Gauthier2
1Radiology, Weill Cornell Medical College, New York, NY, United States, 2Neurology and Neuroscience, Weill Cornell Medical College, New York, NY, United States

An adiabatic T2prep design based on the modified BIR-4 pulse is proposed for multicomponent T2 relaxometry of the brain at 3T. When compared to the conventional composite refocusing T2prep, our results show that the proposed BIR-4 design provides more accurate T2 weighting against increased field inhomogeneities at 3T, enabling fast and reliable whole brain myelin water mapping in 10 minutes.

15:06 0343.   
Multi-site, multi-vendor reproducibility of R2* relaxometry on an SPIO phantom at 1.5T and 3T
Diego Hernando1, Ihab Kamel2, Li Pan3, Ivan Pedrosa4,5, Shreyas Vasanawala6, Takeshi Yokoo4,5, Qing Yuan4, and Scott B. Reeder1,7
1Radiology, University of Wisconsin-Madison, Madison, WI, United States, 2Radiology, Johns Hopkins University, MD, United States, 3Corporate Technology, Siemens Corporation, Baltimore, MD, United States, 4Radiology, UT Southwestern Medical Center, Dallas, TX, United States, 5Advanced Imaging Research Center, UT Southwestern Medical Center, Dallas, TX, United States, 6Radiology, Stanford University, CA, United States, 7Medicine, University of Wisconsin-Madison, Madison, WI, United States

Recently developed R2* relaxometry techniques may enable rapid, accurate and robust liver iron quantification. However, the reproducibility of these techniques across multiple sites and MRI platforms has not been established, precluding their widespread dissemination. In this work, we studied the reproducibility of R2* mapping on a phantom with different iron concentrations, at four sites and on eight different scanning platforms including 1.5T and 3T. Results demonstrate excellent reproducibility across sites and platforms at each field strength over a wide range of R2* values.

15:18 0344.   T1 Measurement of the Myelin Water Fraction
Peter van Gelderen1, Xu Jiang1, Jacco A de Zwart1, and Jeff H Duyn1
1AMRI, LFMI, NINDS, National Institutes of Health, Bethesda, MD, United States

To investigate the possibility of using T1 contrast to selectively image myelin water, inversion-recovery prepared multi-gradient-echo imaging was performed on human subjects at 7T. Multi-component fitting of the T2* decay curve allowed distinguishing between water inside and outside the myelin sheath and quantifying individual T1-decay time constants. When properly accounting for imperfect inversion efficiency, no substantial difference between apparent T1 of the different compartments was found, suggesting a relatively rapid exchange of water within and outside the myelin sheath.