TRADITIONAL POSTER - ismrm

Poster Sessions
3014. A Fast Spin-Echo Multi Gradient-Echo Sequence to Reduce Distortions on T2-Weighted Images at
High Field
Ludovic de Rochefort 1 , Martine Guillermier 1 , Diane Houitte 1 , Marion Chaigneau 1 , Philippe Hantraye 1 ,
Vincent Lebon 1
1 MIRCen, I2BM, DSV, CEA, Fontenay-aux-Roses, France
Susceptibility-induced magnetic field and chemical shift increase image distortion at high field. In a 2D FSE sequence, increasing the bandwidth to limit
these artifacts implies degrading SNR by reducing the ratio of the observation time (TO) per unit time rapidly reaching SAR and gradient duty cycle
limitations. We propose to replace the readout within the 180 pulses by a train of gradient echoes with a larger bandwidth and the same TO. It is shown in
vivo on rat brain that susceptibility induced distortions are suppressed by this approach while preserving SNR and contrast.
Phase Imaging
Monday 14:00-16:00
3015. Removing Air-Tissue Artifacts in Phase Images by Modulating the Air Susceptibility
José P. Marques 1,2 , Rolf Gruetter 1,3
1 Centre d'Imagerie BioMédicale, EPFL, Lausanne, Vaud, Switzerland; 2 Department of Radiology, University of Lausanne, Lausanne,
Vaud, Switzerland; 3 Department of Radiology, Universities of Lausanne and Geneva, Switzerland
In this work, the susceptibility of air was varied by changing its oxygen fraction. Such a variation of the air susceptibility allowed to exclusively map the
contribution from oxygen towards the measured frequency shift maps in phantoms and volunteers. This allowed removal of a significant part of the observed
frequency shift around air-water interfaces, making the frequency shift maps more specific to their rich tissue contrast.
3016. Myelin as a Primary Source of Phase Contrast Demonstrated in Vivo in the Mouse Brain
Nicoleta Baxan 1 , Laura-Adela Harsan 1 , Iulius Dragonu 1 , Annette Merkle 1 , Juergen Hennig 1 , Dominik von
Elverfeldt 1
1 Diagnostic Radiology, Medical Physics, University Hospital Freiburg, Freiburg, Germany
While most of MRI studies are focused on the magnitude data, the phase contrast has only recently proved its ability to improve the contrast to noise in highresolution
images at high-field strength. The origin of phase contrast between white matter (WM) and gray matter (GM) has been widely discussed; several
sources were suggested including paramagnetic blood deoxyhemoglobin, tissue iron concentrations, water-macromolecules exchange or tissue myelin
content. In the present study we examine the contribution of tissue myelin content to the phase contrast by exploiting the frequency shift variation in a
chronic model of cuprizone induced demyelination.
3017. Phase Imaging: A Novel Tool for Myelin Quantification.
Gregory A. Lodygensky 1 , Rajika Maddage 2 , Alexandra Chatagner 3 , Petra S. Hüppi 3 , José Pedro Marques 2 ,
Stephane V. Sizonenko 3 , Rolf Gruetter 2
1 Pediatrics, Pediatric and Neonatal ICU, University of Geneva, Geneva 14, Switzerland; 2 Laboratory for Functional and Metabolic
Imaging, Ecole Polytechnique Fédérale de Lausanne, Lausanne, Switzerland; 3 Pediatrics, Division of Child Growth & Development,
University of Geneva, Geneva, Switzerland
Phase imaging may allow fast and accurate myelin quantification at high resolution. A quantitative MRI-histology study of myelination on the developing rat
brain.
3018. Chemically Selective Asymmetric Spin-Echo EPI Phase Imaging for Internally Referenced MR
Thermometry
Markus Nikola Streicher 1 , Andreas Schäfer 1 , Bibek Dhital 1 , Dirk Müller 1 , Robin Martin Heidemann 1 ,
Andre Pampel 1 , Dimo Ivanov 1 , Robert Turner 1
1 Max Planck Institute for Human Cognitive and Brain Sciences, Leipzig, Germany
We implemented a novel spin-echo EPI sequence that can acquire phase images of different chemically-shifted protons at the same slice positions. Chemical
selection was achieved by applying different slice-select gradient amplitudes for excitation and refocusing RF pulses, and phase sensitivity was obtained
using an asymmetric EPI readout. MR Thermometry was then performed on a mixture of water and dimethyl sulfoxide (DMSO), which has a proton
chemical shift of -2 ppm from water. The two compounds were then imaged alternately, water for temperature sensitivity and DMSO to monitor field
changes. Fat can also be selectively imaged as a reference compound.
3019. A Novel Method of Increasing the Contrast to Noise Ratio of Phase Images Using Balanced SSFP
Jongho Lee 1 , Masaki Fukunaga 1 , Jeff H. Duyn 1
1 Advanced MRI/LFMI/NINDS, National Institutes of Health, Bethesda, MD, United States
A new method of generating phase contrast is proposed. Using balanced SSFP sequence a significant contrast to noise ratio improvement was achieved.
Using this method, the line of Genari in the visual cortex was shown at 3 T in a high resolution.