Microscopy & Perfusion Imaging
Friday 24 April 2009
Room 315 10:30-12:30


Rakesh Sharma and Jeffrey L. Zhang

10:30 822. Sub-Nanoliter Microscopic MR Imaging of the Human Skin in Vivo Using a 12 Mm Superconducting Surface Coil at 1.5 Tesla
    Elmar Laistler1,2, Marie Poirier-Quinot2, Jean-Christophe Ginefri2, Simon Lambert2, Rose-Marie Dubuisson2, Emeline Boriasse2, Ewald Moser1, Luc Darrasse2
MR Centre of Excellence, Medical University of Vienna, Vienna, Austria; 2U2R2M CNRS UMR8081, Université Paris Sud, Orsay, France
    We use a high temperature superconducing surface coil with a diameter of 12 mm to depict the human skin's pertinent structures in vivo at 1.5 T at an isotropic spatial resolution of (80 µm)ł corresponding to a voxel volume of 0.51 nl. Different anatomical structures of the skin can be identified with sufficient SNR at scan times of ~10 min.
10:42 823. Diffusion Weighted Imaging of Human Articular Cartilage Using Fractional Calculus Model: Preliminary Study
    Xu Feng1, Richard L. Magin1, Jun Li2, Carol Muehleman2
Bioengineering, University of Illinois at Chicago, Chicago, IL, USA; 2Biochemistry, Rush Medical College, Chicago , IL, USA
    Restricted diffusion doesn't follow the mono-exponential decay. Some reports have suggested using bi-exponential model. However, bi-exponential fitting is nontrivial and needs some experience to get fast and slow diffusion coefficients. In this paper, we generalize a spatial Laplacian in the Bloch-Torrey equation to incorporate a fractional order Brownian model of diffusivity. A new parameter ¦Â was derived from the new equation of Stejskal-Tanner gradient pulses. We fitted the signal attenuation obtained from the diffusion-weighted images of Sephadex gels and human articular cartilages using fractional order diffusion model. The results show that ¦Â can be used to reflect the structure of the tissue. The ¦Â value obtained from the osteoarthritis (OA) cartilage was larger than from the normal cartilage. Future development of this approach may be useful for detecting the early degeneration of OA.
10:54 824. Hypoxic Environments and the Extracellular Matrix: MRI and Second Harmonic Generation Microscopy Studies
    Samata m. Kakkad1, Meiyappan Solaiyappan1, Kristine Glunde1, Brian O’Rourke2, Arvind Pathak1, Venu Raman1, Marie-France Penet1, Zaver M. Bhujwalla1
JHU ICMIC Program, The Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins University School of Medicine, Baltimore, MD, USA; 2Institute of Molecular Cardiobiology, Johns Hopkins University School of Medicine, Baltimore, MD, USA
    The tumor microenvironment plays an important role in several of the phenotypic traits of cancer. Hypoxia, in particular, leads to drug resistance, radiation resistance, and the selection of a more aggressive phenotype. The relationship between hypoxia, and the transport of macromolecules through the interstitial matrix in vivo is largely unexplored. The purpose of these studies was to determine if hypoxia alters the interstitial fluid transport of macromolecules by altering collagen fiber patterns.
11:06 825. Phenotyping in the Mouse Embryo Using a μMRI Atlas
    Jon Orlando Cleary*1,2, Marc Modat*3, Anthony Nathan Price1, Nicholas D. Greene4, David L. Thomas2,5, Peter J. Scambler6, Roger J. Ordidge2,5, S Ourselin3, Mark Francis Lythgoe1
Centre for Advanced Biomedical Imaging, Department of Medicine and Institute of Child Health, University College London, London, UK; 2Department of Medical Physics and Bioengineering, University College London, London, UK; 3Centre for Medical Image Computing, University College London, London, UK; 4Neural Development Unit, UCL Institute of Child Health, London, UK; 5Wellcome Trust Advanced MRI Laboratory, University College London, London, UK; 6Molecular Medicine Unit, UCL Institute of Child Health, London, *equal contribution
    Voxel and deformation-based morphometry can detect subtle anatomical differences by combining a number of subjects to create an average atlas and comparing two atlases statistically. Studies of adult mouse brain have used these methods but they may be useful for phenotyping the mouse embryo. µMRI is an emerging technique for imaging mouse embryos. However current analysis involves inspection of each embryo. Morphometric methods, where large numbers of embryos may be compared, show promise for high-throughput analysis. We present an initial study to examine the viability of an embryo atlas, focusing on the degree of anatomy preserved after averaging individual embryos.
11:18 826. MRI and OPT Comparison for Mouse Embryonic Development
    Michael David Wong1, Jacob Ellegood1, Jun Dazai1, X Josette Chen1, R. Mark Henkelman1
Mouse Imaging Centre, Hospital for Sick Children, Toronto, Ontario, Canada
    The soft tissue contrast in MRI makes it a candidate for observing the normal development of the mouse embryo along with genetic abnormalities that may affect organogenesis. This study compares MR imaging of mouse embryos with images from another three-dimensional high-resolution imaging modality, Optical Projection Tomography (OPT). OPT and MR images of embryos are compared at equivalent stages of development: in the beginning organogenesis (E9.5), during organ growth (E11.5), and at organ maturity (E15.5).
11:30 827. True MR Microscopy on a Clinical 7 Tesla Scanner: Application to Plaque Detection in Ex Vivo HCHWA-D Samples
    Andrew Webb1
Radiology, Leiden University Medical Center, Leiden, Netherlands
    A flexible MR microscopy probe has been constructed to obtain high resolution isotropic images on a clinical 7 tesla scanner of plaques in ex vivo brain specimens from individuals who have had hereditary cerebral haemorrhage with amyloidosis-Dutch type, a form of Alzheimers disease. Images acquired at a spatial resolution of 40 x 50 x 100 microns show individual iron-containing plaques, which both confirm previous results obtained at much poorer spatial resolution, but also add detailed information on the biodistribution of these plaques.
11:42 828. MR Microscopy of Human Skin Vasculature in Vivo at 3 Tesla Using a Small Copper Surface Coil
    Elmar Laistler1, Ewald Moser1
MR Centre of Excellence, Medical University of Vienna, Vienna, Austria
    We show that using small surface coils and 3D GE sequences, imaging of the human skin in vivo with an isotropic resolution of (100 µm)ł is feasible at reasonable scan times with normal conducting surface coils at 3 T. Small cutaneous and subcutaneous vessels are well delineated and SNR is sufficient for manual segmentation. At such high spatial resolutions, subject motion is one of the limiting factors for good image quality. Using rather short sequences (~10min) limits motion artifacts. SNR loss due to the short measurement time can be compensated for by averaging over multiple acquisitions after coregistration.
11:54 829. MRI Tissue Window Chamber System for Validation and Optimization of Dynamic Contrast Enhanced Tumor Imaging
    Olivier Maciej Girard1,2, Ahmet Erten2,3, Mark Bydder1, Milan T. Makale2, David A. Cheresh2, David Gilderdale4, Sadik Esener2,3, Robert Frederick Mattrey1,2
Department of Radiology, University of California, San Diego, CA, USA; 2Moores Cancer Center, University of California, San Diego, CA, USA; 3Electrical Engineering , University of California, San Diego, CA, USA; 4PulseTeq, UK
    Magnetic Resonance Imaging (MRI) holds significant promise to achieve quantitative analysis of tumor vasculature. However with deep tumor MRI there is no means by which to validate in vivo methods and results, especially those of a dynamic nature. We report here on the design and fabrication of a MRI and light microscope compatible window chamber, and initial time course data following Gd injection. Such a system is a significant step toward validation of permeability measurement by MRI with the light microscope.
12:06 830. Blood Volume Fraction Measurements Using MRI: A Correlation Between Two-Photon and in Silico MR Estimates
    Thomas Christen1,2, Nicolas Joudiou1,2, Raphael Serduc1,2, Gregoire Malandain3, Nicolas Pannetier1,2, Jean-Claude Vial1,2, Christoph Segebarth1,2, Chantal Rémy1,2, Emmanuel L. Barbier1,2
Inserm, U836, Grenoble, F-38043, France; 2Université Joseph Fourier, Grenoble Institut des Neurosciences, UMR-S836, Grenoble, France; 3Asclepios team, INRIA, Sophia-Antipolis, France
    The aim of this study is to evaluate the accuracy of MR estimates of Blood volume fraction (BVf). Brain cortical microvascular networks were digitized using a two-photon microscope. BVf was then obtained in two ways. First, BVf was quantified from the microscopic data using morphologic tools. Second, a steady-state MR protocol designed for measuring BVf was performed in silico. Comparison of BVf estimates obtained with the two techniques indicates that they are well correlated. However results show a systematic error (20% on average) on absolute quantification, possibly induced by approximations in modelling the microvascular network in MR.
12:18 831. An Oxygen Consuming Phantom for Simulating Oxygen Perfusion in Tissue Using 19F MRI Oximetry
    Steven H. Baete1,2, Yves De Deene1,2
1Laboratory for Quantitative Nuclear Magnetic Resonance in Medicine and Biology, ECNURAD, Ghent University, Ghent, Oost-Vlaanderen, Belgium; 2Medisip-IBBT, Ghent University, Ghent, Oost-Vlaanderen, Belgium
    Tumor hypoxia is well known to reduce cancer treatment efficacy. 19F MRI oximetry can be used to map oxygen concentrations in hypoxic tissue. However, validation of pO2-measurements in vivo is difficult. In this study, an oxygen consuming phantom simulating oxygen perfusion in tissue is presented. The phantom consists of a hemodialysis filter of which the outer compartment is filled with a gel containing viable yeast cells. pO2-images reveal oxygen consumption by the yeast after injection of a bolus of oxygen rich hexafluorobenzene in the fibers of the hemodialysis filter. The phantom can be used for validation of 19F MRI oximetry.