Friday, 7 may 2010

Non-Proton MRI, Microscopy & ESR

Room A5 10:30-12:30 Moderators: Luisa Ciobanu and Richard A. Komoroski

10:30 724. In Vivo Oxygen-17 (17O) MRI at 7 Tesla

Stefan Hoffmann¹, Paul Begovatz¹, Armin Nagel¹, Reiner Umathum¹, Michael Bock<sup>1

1</sup>Medical Physics in Radiology, German Cancer Research Center, Heidelberg, Germany

The detection of oxygen-17 (17O) provides a method to assess metabolic tissue information at ultra high fields. In this work direct 17O-MR imaging was carried out in vivo on a 7 Tesla MR system with a custom built head coil. Natural abundance imaging of the human head was performed and global relaxation parameters were measured. An inhalation experiment with enriched 17O gas was carried out using an inhalation-triggered oxygen delivery system. Imaging was performed prior to, during and after the inhalation showing an increase of signal intensity during ventilation with enriched oxygen-17 gas.

10:42 725. 3D Regional Measurements of Alveolar Surface Area Using 90° Single Breath XTC

Samuel Patz¹, Iga Muradyan¹, Mikayel Dabaghyan¹, Isabel Maria Dregely², Mirko I. Hrovat³, Hiroto Hatabu¹, F William Hersman⁴, Iulian C. Ruset⁴, James P. Butler<sup>5

1</sup>Department of Radiology, Brigham and Women's Hospital, Boston, MA, United States; ²Department of Physics, University of New Hampshire, Durham, NH, United States; ³Mirtech, Inc, Brockton, MA, United States; ⁴Xemed, LLC, Durham, NH, United States; ⁵Department of Environmental Health, Harvard School of Public Health, Boston, MA, United States

Alveolar surface area is a key determinant of the severity of emphysema. Hence it is important to obtain regional maps of this parameter in order to evaluate disease heterogeneity. To accomplish this goal, we obtained 3D regional measurements of alveolar surface area per unit volume by measuring the septal uptake of hyperpolarized ¹²⁹Xe. Single Breath XTC was used but 90° RF pulses were used for the selective “tissue phase” pulses rather than the traditional 180° pulses.

10:54 726. Indirect ¹⁷O MRI Using T1ρ at 11.7 T

Hsiao-Ying Wey^1,2, Fang Du¹, Ai-Ling Lin¹, Yen-Yu I. Shih¹, Saaussan Madi³, Peter T. Fox^1,2, Pradeep M. Gupte⁴, Timothy Q. Duong<sup>1,2

1</sup>Research Imaging Institute, UT Health Science Center at San Antonio, San Antonio, TX, United States; ²Radiology, UT Health Science Center at San Antonio, San Antonio, TX, United States; ³Bruker Biospin MRI, Inc., Billerica, MA, United States; ⁴Rockland Technimed Ltd., Airmont, NY, United States

Cerebral metabolic rate of oxygen (CMRO₂) is an important physiological parameter associated with normal brain and disease state. The unique characteristic of ¹⁷oxygen makes ¹⁷O MRI a valuable tool for CMRO₂ quantification. Direct ¹⁷O measurement suffers from low spatiotemporal resolution and clinical practicability compared to indirect method, although the quantification is more straightforward. This study demonstrates the feasibility of indirect T1ρ-weighted ¹⁷O detection with ¹⁷O/PFC blood substitute injection in normal and physiologically modulated (hypothermia and ischemic stroke) rats at ultra-high field.

11:06 727. Separation of Sodium Compartments for Characterization of Tumor Tissue by ²³Na-MRI

Armin Michael Nagel¹, Michael Bock¹, Christian Matthies¹, Marc-André Weber², Stephanie Combs³, Wolfhard Semmler¹, Armin Biller, <sup>2

1</sup>Medical Physics in Radiology, German Cancer Research Center, Heidelberg, Germany; ²Department of Diagnostic and Interventional Radiology, University Hospital Heidelberg, Germany; ³Department of Radiation Oncology, University Hospital Heidelberg, Germany

In this work brain-tumor patients were investigated with different ²³Na-image contrasts (spin-density, ²³Na-FLAIR) to gain information from which compartment the ²³Na-signal originates. Using a ²³Na-FLAIR sequence different ²³Na-compartments in many brain tumors can be suppressed, whereas other parts still exhibit a high ²³Na-FLAIR-signal. Our findings indicate that a combination of both ²³Na-sequences allows for separating different ²³Na compartments. Distinguishing these compartments might be important for the determination of potential tumor malignancy.

11:18 728. In Utero MRI of Cerebral Vascular Development in Mice