Validation of Functional Diffusion Maps (FDMs) as a Biomarker for Human Glioma Cellularity
Benjamin M. Ellingson^1,2, Mark G. Malkin^2,3, Scott D. Rand^1,2, Jennifer M. Connelly^2,3, Carolyn Quincey³, Pete S. LaViolette^2,4, Devyani P. Bedakar^1,2, Kathleen M. Schmainda^1,2
1Dept. of Radiology, Medical College of Wisconsin, Milwaukee, WI, United States; ²Translational Brain Tumor Program, Medical College of Wisconsin, Milwaukee, WI, United States; ³Dept. of Neurology and Neurosurgery, Medical College of Wisconsin, Milwaukee, WI, United States; ⁴Dept. of Biophysics, Medical College of Wisconsin, Milwaukee, WI, United States

The purpose of the current study was to comprehensively validate the assumptions made in human functional diffusion map (fDM) analyses and provide a biological and clinical basis for thresholds used in fDM tissue classification.

Detecting Blood Oxygen Level Dependent (BOLD) Contrast in the Breast
Rebecca Rakow-Penner¹, Bruce Daniel¹, Gary Glover^1
1Department of Radiology, Stanford University School of Medicine, Stanford, CA, United States

Detecting and understanding breast tissue oxygenation may help characterize tumors, predict susceptibility to treatment, and monitor chemotherapeutic response.  We have developed a robust methodology for detecting BOLD contrast in the breast and have tested this technique on healthy volunteers and patients.  We found that BOLD signal positively correlates to a carbogen stimulus in healthy glandular tissue.  In a small patient pilot study, we found that BOLD signal negatively correlates to a carbogen stimulus in breast cancer.

Quantitative 4D Transcatheter Intraarterial Perfusion MRI for Monitoring Chemoembolization of Hepatocellular Carcinoma
Dingxin Wang¹, Brian Jin², Robert Lewandowski², Robert Ryu², Kent Sato², Mary Mulcahy^3,4, Laura Kulik⁵, Frank Miller², Riad Salem^2,3, Debiao Li¹, Reed Omary^1,4, Andrew Larson^1,4
1Departments of Radiology and Biomedical Engineering, Northwestern University, Chicago, IL, United States; ²Department of Radiology, Northwestern University, Chicago, IL, United States; ³Department of Medicine, Northwestern University, Chicago, IL, United States; ⁴Robert H. Lurie Comprehensive Cancer Center, Northwestern University, Chicago, IL, United States; ⁵Department of Hepatology, Northwestern University, Chicago, IL, United States

Quantitative 4D TRIP-MRI can be performed successfully in a combined x-ray DSA-MRI unit to monitor intra-procedural reductions in liver tumor perfusion during TACE procedures in patients with HCC.

Three Dimensional Rapid Diffusion Tensor Microimaging for Anatomical Characterization and Gene Expression Mapping in the Mouse Brain
Manisha Aggarwal¹, Susumu Mori¹, Tomomi Shimogori², Seth Blackshaw³, Jiangyang Zhang^1
1Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins University School of Medicine, Baltimore, MD, United States; ²RIKEN Brain Science Institute, Saitama, Japan; ³The Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD, United States

Diffusion tensor imaging (DTI) can reveal superior contrasts than relaxation-based MRI in premyelinated developing mouse brains. Current challenges for the application of DTI to mouse brain imaging at microscopic levels include the limitation on the achievable spatial resolution. In this study, high resolution rapid DT-microimaging of the embryonic and adult mouse brains (up to 50-60 µm) based on a 3D diffusion-weighted gradient and spin echo (DW-GRASE) scheme with twin-navigator echo phase correction is presented. We also demonstrate successful 3D mappings of gene expression data from in situ hybridization to high resolution DTI images in the early embryonic mouse brain.

B₁ Mapping by Bloch-Siegert Shift
Laura Sacolick¹, Florian Wiesinger¹, W. Thomas Dixon², Ileana Hancu², Mika W. Vogel^1
1GE Global Research, Garching b. Munchen, Germany; ²GE Global Research, Niskayuna, NY, United States

Here we present a novel method for B1+ field mapping based on the Bloch-Siegert shift. The Bloch-Siegert shift refers to the effect where the resonance frequency of a nucleus shifts when an off-resonance RF field is applied. This shift is proportional to the square root of the RF field magnitude B12. An off-resonance RF pulse is added to an imaging sequence following spin excitation. This pulse induces a B1 dependent phase in the acquired image. A B1 map is calculated from the square of the phase difference between two images, with the RF pulse applied at two frequencies symmetrically around the water resonance. In-vivo Bloch-Siegert B1+ maps with 25.6 seconds/ 128x128 slice were found to be quantitatively comparable to 13 minute conventional double-angle maps. The method can be integrated into a wide variety of fast imaging sequences, and is compatible with EPI, alternative readout trajectories, receive array acceleration, etc. Insensitivity to B0, chemical shift, TR, T1, and magnetization transfer is shown as well.

Improved Arterial Spin Labeling After Myocardial Infarction in Mice Using Respiratory and Cardiac Gated Look-Locker Imaging with Fuzzy C-Means Clustering for T1 Estimation
Moriel H. Vandsburger¹, Robert L. Janiczek¹, Yaqin Xu¹, Brent A. French¹, Craig H. Meyer¹, Christopher M. Kramer¹, Frederick H. Epstein^1
1University of Virginia, Charlottesville, VA, United States

Arterial spin labeling is used to quantify myocardial perfusion in mice, but not after myocardial infarction (MI). We developed a cardio-respiratory triggered ASL method which incorporates a fuzzy C-means clustering algorithm during image reconstruction in order to reduce respiratory motion artifact and improve perfusion quantification after MI. Using this technique, we measured myocardial perfusion in distinct reperfused infarct and remote zones of myocardium during the time course of infarct healing in mice. Our data indicate that while perfusion in remote zone myocardium is unchanged, infarct zone perfusion drops significantly 1 day post-MI and recovers by 28 days post-MI.