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

Scientific Session • Parametric Mapping

Tuesday 2 June 2015

John Bassett Theatre 102

10:00 - 12:00


Mariya Doneva, Ph.D., Diego Hernando, Ph.D.

10:00 0329.   Magnetic Resonance Fingerprinting with Chemical Exchange (MRF-X) for Quantification of Subvoxel T1, T2, Volume Fraction, and Exchange Rate
Jesse I. Hamilton1, Anagha Deshmane1, Stephanie Hougen2, Mark Griswold1,3, and Nicole Seiberlich1,3
1Biomedical Engineering, Case Western Reserve University, Cleveland, OH, United States, 2Physics, Case Western Reserve University, Cleveland, OH, United States, 3Radiology, Case Western Reserve University, Cleveland, OH, United States

A new technique termed MRF-X is introduced that models two-compartment chemical exchange to generate a dictionary for subvoxel mapping of T1, T2, volume fraction, and exchange rate. Simulations indicate that the MRF-X model can map subvoxel parameters in cases where standard mapping sequences would map a single effective T1 or T2 value. MRF-X has the potential to directly measure properties of tissue microstructure.

10:12 0330.   
Magnetic Resonance Fingerprint Compression
Martijn A Cloos1,2, Tiejun Zhao2,3, Florian Knoll1,2, Leeor Alon1,2, Riccardo Lattanzi1,2, and Daniel K Sodickson1,2
1Center for Biomedical Imaging, Department of Radiology, New York University School of Medicine, New York, NY, United States, 2Center for Advanced Imaging Innovation and Research (CAI2R), New York University School of Medicine, New York, NY, United States, 3Siemens Medical Solutions USA Inc., Malvern, PA, United States

Magnetic Resonance Fingerprinting enables rapid multi-parametric mapping. By interweaving multiple transmit-channels into the fingerprinting sequence an elegant parallel transmission framework can be constructed. Forgoing uniform excitations, this generalized MR fingerprinting framework circumvents a pitched battle against the electro-dynamic interactions that cause B1 artifacts in the traditional MR paradigm while maintaining a tractable “plug & play” like workflow. In this work we introduce the concept of “fingerprint compression”, which enables even greater acceleration factors while simultaneously speeding up the reconstruction process. This is of particular importance when using multiple transmit channels.

10:24 0331.   
Fast and Direct Generation of Encoding Gradients for the MRF-Music Acquisition
Dan Ma1 and Mark Griswold2
1Biomedical Engineering, Case Western Reserve University, Cleveland, OH, United States, 2Radiology, Case Western Reserve University, OH, United States

The MRF-Music sequence is a special form of the MRF method that allows one to generate quantitative MR images with a pleasant sounding acquisition. This study introduces a fast converting method that generates the encoding gradients directly from the music for a 2D MRF-Music sequence in less than 1/5000th of the previous calculation time. The resulting gradients generate similar sound effects to the original music and still maintain high efficiency of quantifying T1, T2 and M0 maps simultaneously.

10:36 0332.   
A fast simultaneous water/fat decomposition and T1, T2 quantification method using dual TR bSSFP
Dongyeob Han1, Min-Oh Kim1, Dosik Hwang1, and Dong-Hyun Kim1
1Yonsei University, Seoul, Korea

In body imaging such as knee or liver, fat signal needs to be quantified for applications such as bone marrow diseases or hepatic steatosis. Herein, a fast dual TR bSSFP acquisition method for simultaneous w/f decomposition with T1, T2 quantification is proposed.

10:48 0333.   Simultaneous frequency and T2 mapping, applied to thermometry and to susceptibility-weighted imaging
Cheng-Chieh Cheng1, Chang-Sheng Mei2, Pelin Aksit Ciris3,4, Robert V. Mulkern4,5, Mukund Balasubramanian4,5, Hsiao-Wen Chung1, Tzu-Cheng Chao6, Lawrence P. Panych3,4, and Bruno Madore3,4
1Graduate Institute of Biomedical Electronics and Bioinformatics, National Taiwan University, Taipei, Taiwan, 2Department of Physics, Soochow University, Taipei, Taiwan, 3Department of Radiology, Brigham and Women's Hospital, Boston, MA, United States, 4Harvard Medical School, Boston, MA, United States,5Department of Radiology, Boston Children's Hospital, Boston, MA, United States, 6Department of Computer Science and Information Engineering, National Cheng-Kung University, Tainan, Taiwan

Both T2 mapping and field mapping can provide rich clinically-relevant information. During thermal therapies for example, field maps provide temperature information through the proton resonance frequency effect while T2 can reveal tissue damage and edema. In brain imaging, field maps reveal iron deposits and bleeding through susceptibility effects while T2 enables tumor detection and segmentation. Typically, pulse sequences based on spin echoes are needed for T2 mapping while gradient echoes are needed for field mapping, making it difficult to simultaneously acquire both types of information. A dual-pathway multi-echo pulse sequence is employed here to generate both T2 and field maps from the same acquired data.

11:00 0334.   K-space Based Estimation for R2* mapping
Giang Chau Ngo1,2 and Bradley P. Sutton1,2
1Bioengineering, University of Illinois at Urbana-Champaign, Urbana, IL, United States, 2Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, IL, United States

T2* maps are used in many applications from functional brain imaging to targeted contrast agents. However, in-plane magnetic field inhomogeneity leads to a non-exponential decay of the T2* signal. This work proposes a method to estimate T2* by taking into account intra-voxel magnetic gradients. A k-space estimation approach is developed, combined with a single shot multi-echo spiral out trajectory.

11:12 0335.   High Resolution Water/Fat Imaging in Animal Models
Abraam S Soliman1,2, Lanette J Friesen-Waldner3, Kevin J Sinclair3, Timothy R.H Regnault4,5, and Charles A McKenzie1,3
1Biomedical Engineering, University of Western Ontario, London, Ontario, Canada, 2Imaging Research Laboratories, Robarts Research Institute, London, Ontario, Canada, 3Medical Biophysics, University of Western Ontario, London, Ontario, Canada, 4Obstetrics and Gynaecology, University of Western Ontario, London, Ontario, Canada, 5Physiology and Pharmacology, University of Western Ontario, London, Ontario, Canada

High resolution water and fat imaging is recommended in animal research to depict detailed tissue structures. Current multi-gradient-echo unipolar sequences employ flyback readout gradients, which prolongs the acquisition time. In this work, a recently proposed bipolar acquisition is utilized to achieve double the spatial resolution of the conventional unipolar sequence during the same acquisition time, allowing clear identification of adipose tissue structures without further increase in scan time.

11:24 0336.   
In vivo Assessment of Cold Stimulation Effects on the Fat Fraction of Brown Adipose Tissue using Dixon MRI
Vanessa Stahl1, Florian Maier1, Ralf O. Floca2, Moritz C. Berger1, Mauricio Berriel Diaz3, Martin T. Freitag2, Marc-André Weber4, Antonia Dimitrakopoulou-Strauss5, and Armin M. Nagel1
1Medical Physics in Radiology, German Cancer Research Center, Heidelberg, Germany, 2Department of Radiology, German Cancer Research Center, Heidelberg, Germany, 3Molecular Metabolic Control, German Cancer Research Center, Heidelberg, Germany, 4Diagnostic and Interventional Radiology, University Hospital of Heidelberg, Heidelberg, Germany, 5Clinical Cooperation Unit Nuclear Medicine, German Cancer Research Center, Heidelberg, Germany

Brown adipose tissue (BAT) is subject of ongoing research because of its ability to dissipate energy through non-shivering thermogenesis giving therapeutic potential for the treatment of obesity and metabolic diseases in humans. The purpose of this work was to evaluate in vivo the acute activation of BAT by induced cooling of the skin using Dixon water-fat-separated MRI. The fat fraction (FF) of BAT was determined over time in five volunteers in a temperature-controlled measurement including 90 minutes of cooling time. Focusing on the two interscapular BAT depots, a mean FF decrease of (-4.0 ± 1.7) % / h was detected and therefore FF changes over time in BAT during cooling could be observed.

11:36 0337.   Bias in liver fat quantification using chemical shift-encoded techniques with short echo times
Diego Hernando1, Utaroh Motosugi1,2, and Scott B. Reeder1,3
1Radiology, University of Wisconsin-Madison, Madison, WI, United States, 2Radiology, University of Yamanashi, Yamanashi, Japan, 3Medical Physics, University of Wisconsin-Madison, Madison, WI, United States

Chemical Shift Encoded (CSE) techniques for fat quantification enable rapid and accurate quantification of proton-density fat-fraction (PDFF), a fundamental biomarker of triglyceride concentration in tissue. However, these techniques suffer from relatively low SNR due to the rapid acquisition with parallel imaging acceleration and the use of very low flip angles. In order to improve the SNR, acquisitions with short echo times (eg: initial TE<1ms) and moderate spatial resolution may be performed. In this work, we show that these acquisitions present elevated signal at short TE, leading to positive bias (1.6%-1.9%) in liver PDFF relative to standard CSE or single-voxel spectroscopy.

11:48 0338.   Comparison of T2* correction methods for vertebral bone marrow fat quantification using chemical shift encoding-based water-fat imaging
Dimitrios C Karampinos1, Stefan Ruschke1, Michael Dieckmeyer1, Holger Eggers2, Hendrik Kooijman3, Ernst J Rummeny1, Jan S Bauer4, and Thomas Baum1
1Diagnostic and Interventional Radiology, Technische Universität München, Munich, Germany, 2Philips Research Laboratory, Hamburg, Germany, 3Philips Healthcare, Hamburg, Germany, 4Neuroradiology, Technische Universität München, Munich, Germany

Spine fat fraction mapping is emerging with growing applications in osteoporosis and radiation therapy. Vertebral bone marrow is characterized by short T2* relaxation times. Therefore, vertebral bone marrow fat quantification using chemical shift encoding-based water-fat imaging needs to correct for T2* decay effects. The present study compares different approaches for T2* correction in water-fat imaging of vertebral bone marrow using single-voxel MRS as a reference standard. The advantage of a method correcting for a common T2′ and using a priori known T2 relaxation times for water and fat components is evaluated on the data from 26 young healthy volunteers.