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International Journal of Biomedical Imaging
Volume 2007 (2007), Article ID 23624, 7 pages
http://dx.doi.org/10.1155/2007/23624
Research Article

Quantitative and O2 Enhanced MRI of the Pathologic Lung: Findings in Emphysema, Fibrosis, and Cystic Fibrosis

1Department of Radiology, Medical University of Vienna, Waehringer Guertel 18-20, Vienna 1090, Austria
2Department of Internal Medicine IV, Medical University of Vienna, Waehringer Guertel 18-20, Vienna 1090, Austria
3Institute of Physics, Experimental Physics 5, University of Wuerzburg, Wuerzburg 97074, Germany
4Department of Radiology, Otto Wagner Hospital, Vienna 1140, Austria

Received 23 November 2006; Accepted 25 February 2007

Academic Editor: Haim Azhari

Copyright © 2007 Alfred Stadler et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Purpose: beyond the pure morphological visual representation, MR imaging offers the possibility to quantify parameters in the healthy, as well as, in pathologic lung parenchyma. Gas exchange is the primary function of the lung and the transport of oxygen plays a key role in pulmonary physiology and pathophysiology. The purpose of this review is to present a short overview of the relaxation mechanisms of the lung and the current technical concepts of T1 mapping and methods of oxygen enhanced MR imaging. Material and Methods: molecular oxygen has weak paramagnetic properties so that an increase in oxygen concentration results in shortening of the T1 relaxation time and thus to an increase of the signal intensity in T1 weighted images. A possible way to gain deeper insights into the relaxation mechanisms of the lung is the calculation of parameter Maps. T1 Maps based on a snapshot FLASH sequence obtained during the inhalation of various oxygen concentrations provide data for the creation of the so-called oxygen transfer function (OTF), assigning a measurement for local oxygen transfer. T1 weighted single shot TSE sequences also permit expression of the signal changing effects associated with the inhalation of pure oxygen. Results: the average of the mean T1 values over the entire lung in inspiration amounts to 1199 +/ 117 milliseconds, the average of the mean T1 values in expiration was 1333 +/ 167 milliseconds. T1 Maps of patients with emphysema and lung fibrosis show fundamentally different behavior patterns. Oxygen enhanced MRT is able to demonstrate reduced diffusion capacity and diminished oxygen transport in patients with emphysema and cystic fibrosis. Discussion: results published in literature indicate that T1 mapping and oxygen enhanced MR imaging are promising new methods in functional imaging of the lung and when evaluated in conjunction with the pure morphological images can provide additional valuable information.