TRADITIONAL POSTER - ismrm

Poster Sessions
975. In Vivo Characterisation of Orthotopic Prostate Tumor and Healthy Rat Prostate Metabolism Using
1 H
MRS at 4.7 T
Xavier Tizon 1 , Peggy Provent 1 , Sebastien Parfait 2 , Gilles Crehange 3 , Johel Miteran 2 , Philippe Genne 1 ,
François Brunotte 2 , Olivier Duchamp 1 , Paul Michael Walker 2
1 Oncodesign, Dijon, France; 2 Laboratoire Le2i - UMR CNRS 5158, Dijon, France; 3 Centre Georges-Francois Leclerc, Dijon, France
1 H-MRS appears to be a sensitive technique to detect prostate cancer in the clinic. The aim of this study was to establish an experimental setting to monitor
the metabolism of orthotopic prostate cancer in rats, as a candidate biomarker of efficacy for anticancer drugs.
The metabolism of healthy prostates and orthotopic PC3-MM2 tumor models was monitored by 1 H-MRS on Nude rats. Despite the highlighted differences
between human and rat prostate metabolism, we show that the follow-up of prostate tumor metabolism in rats is possible and that the tumor metabolism is
different from its host gland.
976. Investigation of Region Specific Frequency Differences Between Water and N- Acetyl Aspartate
Resonances Within the Human Brain
Grzegorz Lukasz Chadzynski 1 , Adriane Groeger 2 , Uwe Klose 3
1 Department for Diagnostic and Interventional Neuroradiology, University Hospital Tuebingen, Tuebingen, Baden- Wuerttemberg,
Germany; 2 Department of Neurodegeneration, Hertie Institute for Clinical Brain Research, Tuebingen, Baden-Wuertemberg,
Germany; 3 Department for Diagnostic and Interventional Neuroradiology, University Hospital Tuebingen, Tuebingen, Baden-
Wuertemberg, Germany
Recent studies showed that the frequency distance between water and NAA measured with 1HMRS may be used for temperature evaluation. We examined
regional difference of this distance in the human brain at the level of the lateral ventricles. CSI measurement were performed for 11 healthy volunteers.
Spectra were acquired at 3T with PRESS localization without water suppression. We found water to NAA frequency distance to be greater in white than in
gray matter with mean difference value of 0.013 ppm. According to the literature this would be approximately equal to 1 o C. More reliable results can be
obtained after calibration measurements.
977. An Optimized Frequency Offset for Refocusing RF Pulses in Measurement of Lactate Using PRESS
MR Spectroscopy
Yan Zhang 1 , Jun Shen 1
1 National Institute of Mental Health, Bethesda, MD, United States
This work demonstrates the use of an optimized RF frequency offset for the point resolved spectroscopy (PRESS) in measurement of Lactate. The partially
refocused methine proton spins due to limited RF bandwidth give rise to anomalous J-modulation for methyl proton spins, resulting in signal cancellation.
With the offset of 4.1ppm, all selected methine proton spins are on resonance, and therefore no methyl proton spins are anomalously modulated, except there
is a portion of the methyl proton spins are outside the RF bandwidth due to the chemical shift. But this part of methyl proton spins are to be saturated by the
out volume suppression. The phantom experiment shows the net signal (ratio to NAA at 2 ppm) is enhanced by ~50% compared with that using the offset at
1.3ppm.
978. Feedback-Based Interleaved Reference Spectroscopy
Thomas Lange 1 , Martin Buechert 1 , Maxim Zaitsev 1
1 Dept. of Diagnostic Radiology, Medical Physics, University Hospital Freiburg, Freiburg, Germany
Magnetic resonance spectroscopy experiments can be severely affected by frequency drifts, for example when a spectroscopy scan is run right after an
imaging experiment involving a high gradient duty cycle. In this work we propose a feedback-based interleaved reference scan (IRS) method which updates
the carrier frequency of RF pulses and ADCs in real time, using water reference spectra acquired in an interleaved fashion. Compared to a frequency lock
using the residual water peak in the actual spectrum, the proposed method is more robust, particularly in the presence of strong lipid contamination.
Additionally, it allows for retrospective phase correction.
979. Highly Efficient Square Wave Distant Dipolar Field and Its Applications for in Vivo MRI
Zhong Chen 1 , Congbo Cai 1 , Shuhui Cai 1 , Jianhui Zhong 2
1 Departments of Physics and Communication Engineering, Fujian Key Laboratory of Plasma and Magnetic Resonance, Xiamen
University, Xiamen, Fujian, China; 2 Departments of Radiology and Biomedical Engineering, University of Rochester, Rochester, NY,
United States
The iMQC signal intensity can be enhanced by replacing the conventional sinusoidal distant dipolar field (DDF) with square wave DDF. In this abstract,
instead of a series of adiabatic inversion pulses proposed previously, a more efficient composite adiabatic inversion pulse was applied to create square wave
DDF. The square wave DDF was applied to MR imaging for the first time. The experimental results show that using the proposed square wave DDF in the
ZEBRA sequence can enhance the iMQC signal intensity by about 1.5 times in comparison to the conventional CRAZED sequence.