Parinaz Massoumzadeh PhD, Presenter: Nothing to Disclose

Dhanashree Rajderkar MD, Abstract Co-Author: Nothing to Disclose

Hongyu An DSc, Abstract Co-Author: Nothing to Disclose

Jon J. Christensen, Abstract Co-Author: Nothing to Disclose

Patricia Aldea BS, Abstract Co-Author: Nothing to Disclose

Joshua S. Shimony MD, PhD, Abstract Co-Author: Nothing to Disclose

Xiaodong Zhang PhD, Abstract Co-Author: Nothing to Disclose

Abraham Z. Snyder PhD, Abstract Co-Author: Nothing to Disclose

Jonathan Edward McConathy MD, PhD, Abstract Co-Author: Research Consultant, Eli Lilly and Company Speakers Bureau, Eli Lilly and Company

Yi Su PhD, Abstract Co-Author: Nothing to Disclose

Andrei Vlassenko MD, PhD, Abstract Co-Author: Nothing to Disclose

Sarah C. Jost MD, Abstract Co-Author: Nothing to Disclose

Daniel Marcus PhD, Abstract Co-Author: Owner, Radiologics, Inc

Keith M. Rich MD, Abstract Co-Author: Nothing to Disclose

Tammie Smith Benzinger MD, PhD, Abstract Co-Author: Research Grant, Eli Lilly and Company

To quantify and compare the cerebral oxygen extraction fraction (OEF) measurement in the normal brain and brain tumors using 15O positron emission tomography (PET) and magnetic resonance(MR)1,2 imaging.  Tumor hypoxia has been associated with sensitivity to radiation therapy, gene expression, and prognosis, but has not been widely studied in brain tumors. 15O-PET and MR1,2 imaging can quantify cerebral oxygen extraction fraction.

 20 participants (10 with brain tumors) were recruited.  MRI included standard clinical sequences plus OEF-MR2; a two-dimensional multi-echo gradient spin echo sequence.  Concurrent with the MR acquisition, subjects with brain tumors underwent PET scanning, which included 2 sets of 3 scans with serial inhalation of  air with 40-75 mCi radiolabeled carbon monoxide (C15O), 40-75 mCi radiolabeled oxygen (15O2), and  injection of 25-50 mCi radiolabeled water (H215O).  MR and PET data were post-processed off line and registered to the anatomic T1 pre-and post-contrast images.  Regions of interest were drawn based upon contrast-enhancing tumor areas, and contra-lateral normal white matter (NWM).  Ratios of OEF (rOEF) were obtained for lesions compared to normal tissue.

In subgroup sample representative analysis of 4 subjects with brain tumors, for NWM a high correlation between OEF-MR and OEF-PET results is obtained (R2 = 0.620) while the correlation for Gd enhanced tumor is low (R2=0.1981).  However, the ratio of the enhanced tumor to NWM (rOEF) show good correlation (R2=0.5445).

Both OEF-MR and OEF-PET have tremendous potential and may offer new insight into the underlying physiology of brain tumors and their response to therapy without requiring radiation or injected contrast.  Although both methods indicate abnormality in the tumor area, preliminary results show some discrepancies between the two methods, which needs future investigation. References: 1He and Yablonskiy (2007), "Quantitative BOLD: mapping of human cerebral deoxygenated blood volume and oxygen extraction fraction: default state." Magn Reson Med 2An and Lin (2000), "Quantitative measurements of cerebral blood oxygen saturation using magnetic resonance imaging." J. Cereb. Blood, Flow Metab.

Both MR and PET show abnormal measurements in tumors and have potential to predict treatment response.  There are some discrepancies between the two methods, which require further investigation.

Massoumzadeh, P, Rajderkar, D, An, H, Christensen, J, Aldea, P, Shimony, J, Zhang, X, Snyder, A, McConathy, J, Su, Y, Vlassenko, A, Jost, S, Marcus, D, Rich, K, Benzinger, T, MR-OEF and PET-OEF Neuroimaging Data for Study of Hypoxia in Human Brain Tumors.  Radiological Society of North America 2012 Scientific Assembly and Annual Meeting, November 25 - November 30, 2012 ,Chicago IL. http://archive.rsna.org/2012/12023539.html