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Proton MRI (proton + mri)

Distribution by Scientific Domains

Medical Sciences	75%

Selected Abstracts

Visualization of alveolar recruitment in a porcine model of unilateral lung lavage using 3He-MRI

ACTA ANAESTHESIOLOGICA SCANDINAVICA, Issue 10 2009
A. RUDOLPH
Background: In the acute respiratory distress syndrome potentially recruitable lung volume is currently discussed. 3He-magnetic resonance imaging (3He-MRI) offers the possibility to visualize alveolar recruitment directly. Methods: With the approval of the state animal care committee, unilateral lung damage was induced in seven anesthetized pigs by saline lavage of the right lungs. The left lung served as an intraindividual control (healthy lung). Unilateral lung damage was confirmed by conventional proton MRI and spiral-CT scanning. The total aerated lung volume was determined both at a positive end-expiratory pressure (PEEP) of 0 and 10 mbar from three-dimensionally reconstructed 3He images, both for healthy and damaged lungs. The fractional increase of aerated volume in damaged and healthy lungs, followed by a PEEP increase from 0 to 10 mbar, was compared. Results: Aerated gas space was visualized with a high spatial resolution in the three-dimensionally reconstructed 3He-MR images, and aeration defects in the lavaged lung matched the regional distribution of atelectasis in proton MRI. After recruitment and PEEP increase, the aerated volume increased significantly both in healthy lungs from 415 ml [270,445] (median [min,max]) to 481 ml [347,523] and in lavaged lungs from 264 ml [71,424] to 424 ml [129,520]. The fractional increase in lavaged lungs was significantly larger than that in healthy lungs (healthy: 17% [11,38] vs. lavage: 42% [14,90] (P=0.031). Conclusion: The 3He-MRI signal might offer an experimental approach to discriminate atelectatic vs. poor aerated lung areas in a lung damage animal model. Our results confirm the presence of potential recruitable lung volume by either alveolar collapse or alveolar flooding, in accordance with previous reports by computed tomography. [source]

Magnetic resonance imaging of cartilage glycosaminoglycan: Basic principles, imaging technique, and clinical applications,

JOURNAL OF ORTHOPAEDIC RESEARCH, Issue 3 2008
Martha L. Gray
Abstract Many new therapeutic strategies have been and are being developed to prevent, correct, or slow the progression of osteoarthritis. Our ability to evaluate the efficacy of these techniques, or to determine the situations for which they might provide the most benefit, critically depends on diagnostic measures that can serve as proxies for the present or predicted state of the cartilage. We focus here on a body of work surrounding the development of magnetic resonance imaging (MRI) techniques to noninvasively image the glycosaminoglycan (GAG) concentration of articular cartilage. These techniques are based on the concept of fixed charge in cartilage resulting from the glycosaminoglycans. Starting with sodium MRI, and the subsequent development of delayed gadolinium-enhanced MRI of cartilage (dGEMRIC) based on proton MRI, these techniques permit "visualization" of the charged GAG distribution in cartilage in vitro or in vivo. The dGEMRIC technique has been used in preliminary clinical studies to understand treatment strategies and to monitor disease, and as such is allowing studies that a decade ago would have been impossible. This new technical capability offers the promises of speeding development of effective therapies and focusing their use in areas where they can be most successful. © 2007 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 26:281,291, 2008 [source]

Non-contrast-enhanced perfusion and ventilation assessment of the human lung by means of fourier decomposition in proton MRI

MAGNETIC RESONANCE IN MEDICINE, Issue 3 2009
Grzegorz Bauman
Abstract Assessment of regional lung perfusion and ventilation has significant clinical value for the diagnosis and follow-up of pulmonary diseases. In this work a new method of non-contrast-enhanced functional lung MRI (not dependent on intravenous or inhalative contrast agents) is proposed. A two-dimensional (2D) true fast imaging with steady precession (TrueFISP) pulse sequence (TR/TE = 1.9 ms/0.8 ms, acquisition time [TA] = 112 ms/image) was implemented on a 1.5T whole-body MR scanner. The imaging protocol comprised sets of 198 lung images acquired with an imaging rate of 3.33 images/s in coronal and sagittal view. No electrocardiogram (ECG) or respiratory triggering was used. A nonrigid image registration algorithm was applied to compensate for respiratory motion. Rapid data acquisition allowed observing intensity changes in corresponding lung areas with respect to the cardiac and respiratory frequencies. After a Fourier analysis along the time domain, two spectral lines corresponding to both frequencies were used to calculate the perfusion- and ventilation-weighted images. The described method was applied in preliminary studies on volunteers and patients showing clinical relevance to obtain non-contrast-enhanced perfusion and ventilation data. Magn Reson Med, 2009. © 2009 Wiley-Liss, Inc. [source]