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Arvind P. Pathak¹, Melina Jones¹, Jiangyang Zhang¹

¹The Johns Hopkins University School of Medicine, Baltimore, Maryland, USA

Knowledge of the 3D architecture of blood vessels is crucial because neuropathologies ranging from alzheimers disease to brain tumors involve anomalous blood vessels, and development of transgenic mouse models of disease has created a need to characterize the cerebral vasculature.  While histological techniques such as optical microscopy and corrosion casting are excellent for imaging microvasculature at submicron resolutions, they suffer from limited coverage, and 3D blood vessel geometry once destroyed by sectioning requires complex reconstruction.  Here we describe two novel methods for “whole brain” mapping of murine vasculature using magnetic resonance microscopy to obtain exquisite images with different “physiological stains”.

Henry H. Ong¹, Felix W. Wehrli¹

¹University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania, USA

Knowledge of white matter intra- and extra-cellular volume fraction (ICF and ECF) would provide important insight into injury and pathology. Current diffusion MRI techniques measure ICF by numerically solving a difficult ill-posed Laplace inversion of the signal decay or fitting the decay to a model, which requires assumptions of the system. Recently, an experiment has been proposed to empirically measure ICF based on the different dependences on diffusion gradient length of restricted and Gaussian diffusion of the ICF and ECF, respectively. Here, we apply this technique to quantify ICF of healthy mouse spinal cords and compare the data to histology.

Brian J. Nieman¹, ², Daniel H. Turnbull¹

¹New York University School of Medicine, New York, USA

Self-gated imaging methods permit collection of motion sensitive data for use in artifact correction or gating without the need to interrupt image acquisition for additional radiofrequency or gradient events. These methods are attractive for implementation in studies involving mice, due to their small size, or wherever external measures are cumbersome or unavailable. In this abstract, we explored the possibility that a self-gated method would permit detection of embryonic cardiac events in utero and show calculated physiological traces correlate with the heart cycle, suggesting that cine cardiac MRI of the mouse in utero should be possible.

Tina Pavlin¹, Morten Bruvold¹, Per Jynge¹, John Georg Seland¹

¹Norwegian University of Science and Technology, Trondheim, Norway

The aim of this work was to study compartmentation and water diffusivity in isolated rat hearts by correlating time-dependent diffusion coefficient and T₂ relaxation constant.  Compartmental diffusivity enabled us to obtain structural information about the intra- and extra-cellular compartments in rat myocardium.  Using a short-time diffusion model and assuming a cylindrical geometry of myocardial cells, we estimated the diameter of the cells to be 35 µm, and the inter-cell distance to be 20 µm.

Timo Spehl¹, Dominik Paul¹, Michael Markl¹, Dominik von Elverfeldt¹, Heike Göbel¹, Alex Frydrychowicz¹, Andreas Hetzel¹, Cornelius Weiller¹, Joachim Schöllhorn¹, Jürgen Hennig¹, Andreas Harloff¹

¹Albert-Ludwigs Universität, Freiburg, Germany

The composition of high-grade internal carotid artery (ICA) stenosis is one major determinant for the occurrence and recurrence of ischemic stroke. MRI has been greatly improved over the past decade and proven to be useful in tissue classification and detection of thrombi in patients with high-risk carotid artery plaques. In our study, we evaluated the additional impact provided by T2* gradient echo imaging at ultra-high field MRI (9.4T) for the enhanced discrimination between plaque calcification, acute and old hemorrhage and the detection of intra-luminal thrombi.

Michael Bock¹, Eva Christina Wönne¹, Fabian Kiessling¹, Wolfhard Semmler¹, Reiner Umathum¹

¹Deutsches Krebsforschungszentrum (dkfz), Heidelberg, Germany

The interaction of different cell types with tissue can be studied in a living animal with the help of a skin chamber that is surgically implanted under the skin. In this work two types of inductively coupled coils were integrated into skin chambers to enhance the signal from the interior of the chamber. MR images with isotropic 100 μm resolution have been acquired in mice at 1.5T and 3T in less than 10 min, which clearly show the neovasculature induced by tumor cells in the chamber.

Charles Qingchuan Li¹, Jeremy F. Magland¹, Chamith S. Rajapakse¹, X Edward Guo², Xiaohui Henry Zhang², Felix W. Wehrli¹

¹University of Pennsylvania, Philadelphia, Pennsylvania, USA; ²Columbia University, New York City, New York, USA

Magnetic resonance micro-imaging (μMRI), in conjunction with digital image processing techniques, has been shown to be capable of non-invasively imaging trabecular bone and assessing structural changes caused by osteodegenerative disease. This work evaluated the effects of image noise and resolution on the accuracy of the derived structural parameters, and explored potential methods for correcting such errors. By simulating μMR images with controlled levels of noise and resolution, structural parameter calculations were shown to be skewed in a systematic but correctable manner.

Markus Weiger¹, Michael Fey¹

¹Bruker BioSpin AG, Faellanden, Switzerland

An extensive analysis of the alternative NMR microscopy technique DESIRE is presented. Simulations and experiments are used to investigate the aspects of signal enhancement, true spatial resolution, and contrast in structured objects.

Tuhin Kumar Sinha¹, Zhengyu Yang¹, William Michael Hardesty¹, John C. Gore¹

¹Vanderbilt University, Nashville, USA

We demonstrate a method to investigate the systematic spatial variances found in MR images using MALDI imaging mass spectrometry.  Using this technique we are able to correlate the observed MR relaxation phenomena with the underlying tissue composition.  This research is aimed at determining which factors in tissue govern the contrast in MR imaging.

Joerg Peter¹, Reiner Umathum¹, Katharina Schneider¹, Gregor Schlosser¹, Matthias Korn¹, Michael Bock¹, Wolfhard Semmler¹

¹German Cancer Research Center, Heidelberg, Germany