ISMRM 21st Annual Meeting & Exhibition 20-26 April 2013 Salt Lake City, Utah, USA

Translational Scientific Session: Susceptibility Image in the Brain
Monday 22 April 2013
Room 355 BC  16:30 - 18:30 Moderators: E. Mark Haacke, Chunlei Liu

16:30 0161.   
Dependence of Gradient Echo Phase Contrast on the Differential Signal Decay in Subcellular Compartments
Wei Li1, Hui Han1, Arnaud Guidon1, and Chunlei Liu1,2
1Brain Imaging & Analysis Center, Duke University, Durham, North Carolina, United States, 2Radiology, Duke University, Durham, North Carolina, United States

Phase images of gradient-recalled echo (GRE) have provided a new contrast for MRI. It is well known that the magnitude contrast of GRE signal changes as a function of sequence parameters including TR, TE and flip angle. The dependence of phase contrast on these parameters, however, has not been explored. In fact, phase contrast has largely been assumed in the literature to be insensitive to sequence parameters. We show that phase contrast has a profound dependence on sequence parameters that can be described by a multi-compartment model. This dependence may provide further insights of the mechanisms of susceptibility contrast.

16:42 0162.   
Ultra-High-Field 7T in Vivo Normative Atlas of the Hippocampal Subfields Using Susceptibility Weighted Imaging
Maged Goubran1, Brendan Santyr1, Dave A. Rudko1, Joseph S. Gati1, Trevor Szekeres1, Terry M. Peters1, and Ali R. Khan1
1Robarts Research Institute, London, Ontario, Canada

The hippocampus and its substructures are of great importance in the pre-operative evaluation of intractable epilepsy. Quantitative MRI sequences have the added benefit of providing additional information, such as T2* relaxation time and quantitative volume magnetic susceptibility of hippocampal substructures. This work focuses on the construction of a normative atlas of the hippocampal subfields from in vivo susceptibility weighted images of eighteen healthy volunteers on 7T MRI. Using a reliable manual delineation protocol of the subfields, we demonstrated the feasibility of using our atlas in voxel based and morphometry analysis of the hippocampus.

16:54 0163.   A 7-Tesla Longitudinal Study on Proportion of Veins in Plaques of Patients with Multiple Sclerosis
Assunta Dal-Bianco1, Günther Grabner2, Hans Lassmann3, Melanie Schernthaner4, Claudia Kronnerwetter5, Michael Weber4, Clemens Vass6, Karl Kircher6, Andreas Reitner6, Eduard Auff7, and Siegfried Trattnig5
1Department of Neurology, Medical University of Vienna, Vienna, Austria, 2High field MR Center of Excellence, Department of Radiology, Medical University of Vienna, Vienna, Austria, 3Center for Brain Research, Medical University of Vienna/Vienna General Hospital, Vienna, Austria, 4Department of Radiology, Medical University of Vienna/Vienna General Hospital, Vienna, Austria, 5High field MR Center of Excellence, Department of Radiology, Medical University of Vienna/Vienna General Hospital, Vienna, Austria, 6Department of Ophthalmology and Optometrics, Medical University of Vienna/Vienna General Hospital, Vienna, Austria,7Department of Neurology, Medical University of Vienna/Vienna General Hospital, Vienna, Austria

Intralesional veins are known to be a histopathological hallmark of Multiple Sclerosis. Inflammatory tissue of relapsing-remitting and secondary-progressive multiple sclerosis plaques show a significantly higher proportion of deoxygenated veins compared to corresponding non-inflammatory control tissue and corresponding normal appearing white matter tissue. Proportion of visible veins within plaques did not change significantly within 2 years. Ultrahigh spatial resolution provided by the high SNR and the higher phase shift at 7T allows to analyze vein density in MS plaques in comparison to normal appearing white matter which may provide an insight into the pathophysioloy of MS in vivo.

17:06 0164.   
An Improved Susceptibility Weighted Imaging Method Using Multi-Echo Acquisition
Sung Suk Oh1,2, Se-Hong Oh1, HyunWook Park2, and Jongho Lee1
1Department of Radiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, United States, 2Department of Electrical Engineering, KAIST, Daejeon, Korea

We propose a novel method to remove image artifacts in susceptibility weighted imaging. The resulting image show no artifacts in orbitofrontal and temporal lobes.

17:18 0165.   Flow Compensated Quantitative Susceptibility Mapping for Venous Oxygenation Imaging
Bo Xu1,2, Tian Liu2, Pascal Spincemaille2, and Yi Wang1,2
1Biomedical Engineering, Cornell University, Ithaca, New York, United States, 2Weill Cornell Medical College, New York, New York, United States

Flow artifacts in quantitative susceptibility mapping (QSM) are corrected with a fully flow compensated multi-echo gradient echo sequence combined with a hybrid linear-quadratic fitting of the phase data. Phantom experiments and in vivo studies demonstrate improvements in the estimation of the field inhomogeneity and the susceptibility map. This enables more reliable venous oxygenation quantification in the brain with QSM.

17:30 0166.   Magnetic Resonance Venography of the Fetal Brain Using Susceptibility Weighted Imaging (SWI)
Jaladhar Neelavali1, Haacke Mark Ewart1, Swati Mody1, Lami Yeo2,3, Sheena Saleem4, Yashwanth Katkuri1, Pavan Jella5, Ray O. Bahado-Singh3, Sonia Hassan2,3, Robert Romero2, and Moriah Thomason4,6
1Department of Radiology, Wayne State University, Detroit, MI, United States, 2Perinatology Research Branch,NICHD, NIH, DHHS, Detroit, MI, United States,3Department of Obstetrics and Gynecology, Wayne State University, Detroit, MI, United States, 4Department of Pediatrics, Wayne State University, Detroit, MI, United States, 5Biomedical Engineering, Wayne State University, Detroit, MI, United States, 6Perinatology Research Branch, Wayne State University, Detroit, MI, United States

Demonstrating the feasibility of performing fetal cerebral venography using SWI at different gestation ages.

17:42 0167.   Susceptibility Weighted Imaging at 3 Tesla Is Superior to Time-Of-Flight-Angiography for the Detection of Peripheral Thrombi in Patients with Acute Stroke -permission withheld
Alexander Radbruch1,2, Johanna Mucke1, Matthias Roethke2, Heinz-Peter Schlemmer2, Sabine Heiland1, Martin Bendszus1, and Stefan Rohde1
1Department of Neuroradiology, Heidelberg University Medical Center, Heidelberg, Germany, 2Department of Radiology, German Cancer Research Center (DKFZ), Heidelberg, Germany

While time of flight (TOF) angiography detects occlusion of arteries in patients with acute ischemic stroke due to the absence of blood flow in the occluded vessel, Susceptibility Weighted Imaging (SWI) enables visualization of the occluding thrombus. In our study we investigated the sensitivity of both methods for the detection of peripheral and central vessel occlusion and found SWI to be superior to TOF-angiography for the detection of peripheral thrombi.

17:54 0168.   
Regularized QSM in Seconds
Berkin Bilgic1, Itthi Chatnuntawech1, Audrey Peiwen Fan1, and Elfar Adalsteinsson2,3
1EECS, Massachusetts Institute of Technology, Cambridge, MA, United States, 2EECS, MIT, Cambridge, MA, United States, 3Harvard-MIT Division of Health Sciences and Technology, Cambridge, MA, United States

Regularized Quantitative Susceptibility Mapping reconstruction with computation time on the order of seconds is demonstrated by expressing the solution of the associated optimization problem in closed-form. In place of iterative algorithms, this simple and fast reconstruction technique can enable online computation of susceptibility maps on the scan site.

18:06 0169.   
Susceptibility Mapping Using Regularization Enabled Harmonic Artifact Removal
Hongfu Sun1 and Alan H. Wilman1
1Biomedical Engineering, University of Alberta, Edmonton, Alberta, Canada

A new phase/field artifact removal method is introduced that is based on the SHARP (“Sophisticated Harmonic Artifact Reduction for Phase data”) method exploiting the harmonic mean value property. This new method employs Tikhonov regularization at the deconvolution stage of the mean value implementation, and is referred to as Regularization Enabled SHARP (RESHARP). RESHARP was compared to SHARP in a field-forward susceptibility simulation and in human brain experiments, demonstrating that it removes background field artifact more effectively compared to SHARP, leading to susceptibility maps with fewer artifacts and more accurate susceptibility measurement in deep grey matter structures.

18:18 0170.   Efficient and Automatic Harmonic Field Pre-Filtering for Brain Quantitative Susceptibility Mapping
Ludovic De Rochefort1, Hongchen Wang2, Paulo Loureiro de Sousa3, and Jean-Paul Armspach3
1Univ Paris-Sud, Orsay, France, 2Univ. Paris Sud - CNRS, UMR 8081, IR4M, Orsay, France, 3Université de Strasbourg, CNRS, ICube (UMR 7357), FMTS, Strasbourg, France

a full processing of multi-echo gradient-echo data brain is described to efficiently extract the field inhomogeneities inside the brain while removing background effects. First, phase maps including background effect are unwrapped in time using a fast Fourier transform, and then fitted to an affine model to estimate the field. A T1-weigthed scan is then used to segment the brain. Internal field within the brain is finally efficiently extracted using harmonic filtering, i.e. by solving Laplace equation with adequate boundary conditions. Field wrapping in space is removed in the process using the modulo function. Internal field and QSM obtained in vivo at 3T are presented, and compared to R1 (=1/T1) and R2* = (1/T2*) maps.