Non-Proton MRI
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Wednesday May 11th
Room 513A-D  16:00 - 18:00 Moderators: Beavlieu, Christian and N.J. Shah

16:00 468.   Potential of Relaxation-Weighted 23Na-MRI for Brain Tumor Characterization 
Armin Michael Nagel1, Michael Bock1, Christian Hartmann2, Lars Gerigk1, Jan-Oliver Neumann2, Marc-André Weber2, Martin Bendszus2, Alexander Radbruch2, Wolfgang Wick2, Heinz-Peter Schlemmer1, Wolfhard Semmler1, and Armin Biller2
1German Cancer Research Center, Heidelberg, Germany, 2University Hospital Heidelberg, Germany

In this work 16 patients suffering from different brain tumors (14 WHO grade I – IV and 2 metastases) were examined, to evaluate if relaxation-weighted 23Na-MRI can provide information for tumor grading. All glioblastomas (WHO grade IV) showed higher signal intensities in relaxation-weighted imaging than the WHO grad I - III tumors. Regression analysis yielded a positive correlation between the relaxation-weighted 23Na-MRI signal and the MIB-1 proliferation rate, a histological tumor marker. No correlation was found for the total 23Na-signal.

16:12 469.   Brain Lithium and Sodium Concentration in Lithium-treated Euthymic Bipolar Disorder Subjects 
Fernando Emilio Boada1, Mary Phillips2, Yongxian Qian3, and David Kupfer2
1Radiology and Bioengineering, University of Pittsburgh, Pittsburgh, PA, United States, 2Psychiatry, University of Pittsburgh, Pittsburgh, PA, United States, 3Radiology, University of Pittsburgh, Pittsburgh, PA, United States

We demonstrate an imaging protocol for concurrent, in vivo, mapping of brain lithium and sodium concentration and present evidence that brain sodium concentration is normal on lithium-treated, euthymic, bipolar disorder subjects.

16:24 470.   Temporal water mobility and sodium intensity measurements in penumbra and core tissue during acute stroke 
Friedrich Wetterling1,2, Lindsay Gallagher3, William Holmes3, I. Mhairi MacRae3, and Andrew J. Fagan1,4
1School of Physics, University of Dublin, Dublin, Ireland, 2Computer Assisted Clinical Medicine, Heidelberg University, Mannheim, Germany, 3Glasgow Experimental MRI Centre, University of Glasgow, Glasgow, United Kingdom, 4Centre for Advanced Medical Imaging, St. James's Hospital, Dublin, Ireland

The validity of the perfusion-diffusion mismatch in acute stroke diagnosis has been challenged recently, and an alternative approach to identifying penumbral tissue is desirable. A custom-built dual-tuned surface coil was used to obtain high-quality 1H-DWI and 23Na images in the acute phase of a rat stroke (n=6). The mismatch between the perfusion deficit and ischaemic damage determined from histology was used to define core and penumbral tissue regions at ~5hrs after stroke. The 23Na signal evolved differently in both regions, supporting the hypothesis that under-perfused regions which have not yet exhibited an increase in 23Na signal above normal levels indicate penumbral tissue.

16:36 471.   A dual resonator system for whole-body sodium-MRI at 3T  -permission withheld
Friedrich Wetterling1, Andre Rennings2, Raffi Kalayciyan1, Dominique M. Corteville1, Simon Konstandin1, and Lothar R. Schad1
1Computer Assisted Clinical Medicine, Heidelberg University, Mannheim, Germany, 2General and Theoretical Electrical Engineering, University of Duisburg-Essen, Duisburg, Germany

An asymmetric birdcage resonator was integrated into the 3T MRI system and tested in conjunction with a receive-only surface coil for human Na MRI. An up to date unseen B1 homogeneity was demonstrated by the possibility to acquire the world-wide first whole body 23Na image of a male human being. Furthermore, a two-fold SNR benefit of the dual resonator system over a state-of-the-art double-tuned 1H/23Na quadrature birdcage resonator was measured on the example of a human brain scan.

16:48 472.   A 30-Channel Phased Array for Oxygen-17 (17O) Brain MRI at 7 Tesla 
Florian Martin Meise1, Jens Groebner1, Armin M. Nagel1, Reiner Umathum1, Helmut Stark2, Stefan H. Hoffmann1, Wolfhard Semmler1, and Michael Bock1
1Medical Physics in Radiology, German Cancer Research Center (DKFZ), Heidelberg, Germany, 2Stark Contrast GmbH - MR Coils Research, Erlangen, Germany

In this study we designed a 17O phased array coil (17O-PA) with 30 17O receive elements and a 17O transmit coil for 17O brain imaging at 7Tesla. The improvement in imaging quality achieved by a 17O phased array coil system can then be used in future patient studies to improve the image resolution or to shorten scan times during inhalation of the 17O-gas.

17:00 473.   In vivo Relaxation Parameters of Oxygen-17 (17O) 
Stefan H Hoffmann1, Armin M Nagel1, Florian M Meise1, Reiner Umathum1, and Michael Bock1
1Medical Physics in Radiology, German Cancer Research Center (DKFZ), Heidelberg, Germany

Cellular energy production is closely connected to the metabolization of oxygen (O2) to water. Direct 17O-MRI can assess the in vivo H217O concentration metabolized from inhaled 17O gas. However, the MR-sensitivity of the 17O nucleus (I = 5/2) is poor. Information on the relaxation parameters is therefore crucial for optimizing the imaging process. In this study we measured the in vivo 17O relaxation times in the human brain (B0 = 7T) to optimize imaging protocols for CMRO2 measurements. Non-localized detection (T1, T2) was carried out in 10 healthy volunteers and 3D T2* determination and anatomical mapping to 1H images was performed in one subject.

17:12 474.   Exploring the New Utility of the 17O-MRS Imaging Technique for Studying CMRO2 and Perfusion in Stroke Mice  -permission withheld
Xiao-Hong Zhu1, James Chen2, Tsang-Wei Tu2, Wei Chen1, and Sheng-Kwei Song2
1Center for Magnetic Resonance Research, Department of Radiology, University of Minnesota, Minneapolis, MN, 55455, United States, 2Department of Radiology, Washington University School of Medicine, St Louis, MO 63110, USA, United States

Deficits or abnormalities in cerebral oxidative metabolism and perfusion have been linked to many brain disorders and diseases. Direct measurements of the cerebral metabolic rate of oxygen (CMRO2) and perfusion (CBF) can provide valuable information for diagnosis and treatment of the disease. An in vivo 17O MRS imaging (MRSI) approach at high/ultrahigh fields has been developed recently for non-invasive mapping of CMRO2 and CBF in small animals such as rats and cats. However, mice provide a more popular preclinical model for studying numerous brain diseases. Imaging CMRO2 in the mouse brain presents new challenges and opportunities for the 17O-MR based CMRO2 imaging technique. In this study, we explored the feasibility and new utility of the 17O-MR imaging approach for studying abnormal CMRO2 and CBF in the mouse brain with a middle cerebral artery (MCA) occlusion.

17:24 475.   Echo-based Single Point Imaging: A Novel Pulsed EPR Imaging Modality for High Spatial and Spectral Resolution for in vivo Quantitative Oximetry 
Sankaran Subramanian1, Nallathamby Devasahayam1, Shingo Matsumoto1, and Murali C Krishna1
1National Cancer Institute, National Institute of Health, Bethesda, MD, United States

Two main approaches are currently in vogue for time-domain spectroscopic EPR imaging. The first one is Single Point Imaging involving global phase encoding which gives high resolution images, where the oximetry, however, is a T2* based approach relying on apparent line widths. The second approach for EPR oximetric imaging utilizes the conventional 90°-lower case Greek tau-180° Spin-Echo pulse and filtered back-projection. The image is T2-weighted but the resolution is subject to susceptibility broadening. A novel time-domain spectroscopic EPR imaging approach, that is a unique combination of the above-mentioned techniques, is presented here. It provides quantitative T2 –based oximetry combined with line-width-independent high resolution.

17:36 476.   Rapid in vivo quantification of oxygen concentration in blood flow with a fluorine nanoparticle reporter and a novel blood enhanced saturation recovery (BESR) sequence 
Lingzhi Hu1, Junjie Chen1, Shelton D Caruthers1, Gregory M Lanza1, and Samuel A Wickline1
1Washington University, St. Louis, MO, United States

We demonstrate the application of PFC nanoemulsion as a blood oxygen pressure probe with use of a novel blood enhanced saturation recovery like (BESR) pulse sequence. Compared to the traditional Look-Locker sequence, the BESR sequence is insensitive to B1 and B0 field inhomogeneity and pulsatile in-flow effects. Compared to the traditional invasive measurement using cardiac catheter, the BESR sequence may provide a simple and rapid method for non-invasive assessment blood oxygenation in vivo.

17:48 477.   In-vivo 19F Imaging of 5-Fluorouracil and its Metabolites in Rat by Two-Element Phased-Array Coil 
Yosuke Otake1, Koji Hirata1, Yoshihisa Soutome1, and Yoshitaka Bito1
1Hitachi, Ltd., Central Resaerch Laboratory, Kokubunji, Tokyo, Japan

A 19F two-element phased-array coil with a transmit 19F/1H dual-tuned linear-birdcage coil for rats was developed. In-vivo 19F imaging of the anticancer drug 5-Fluorouracil and its metabolites in tumor-bearing rats was demonstrated by using the developed coils. Time courses of 5-FU and its active-metabolite (Fnuc) distribution images were obtained in the region of the tumor by using fast spin echo with frequency-selective pulses. This study indicates that the developed 19F two-element phased-array coil will make small-animal studies possible in drug research.