Non-invasive measurement of regional pulmonary edema and blood flow using magnetic resonance imaging.

摘要

on-cardiogenic pulmonary edema is a result of many dysfunctions that cause microvascular lung injury. A non-invasive method to measure pulmonary edema formation or lung microvascular barrier permeability would be useful in evaluating patient status. Hypothesized was that magnetic resonance imaging (MRI) could be used without contrast agent to measure pulmonary edema formation and, additionally, provide a measure of regional pulmonary blood flow. Methods to measure edema using three-dimensional MRI techniques were developed and compared with conventional methods in a canine model of lung injury. Other MRI scans were used to measure blood flow in pulmonary arteries at three progressively-distal levels. Gradient echo 3D MRI scans, designed for visualizing water signal in the lung, were obtained at baseline encompassing the entire lung. Also at baseline, phase contrast MRI was used to measure pulmonary blood flow. After injury was induced via venous infusion of oleic acid, images were obtained at roughly ten minute intervals for 1.5-2 hours to measure edema formation. Post-injury MRI flow measurements were also taken. For standards of comparison, multiple indicator dilution curves were sampled at baseline and after injury to measure lung water (EVLW), cardiac output and permeability-related parameters. Edema was measured in the MR images as signal-to-noise ratio (SNR) of the image pixels within the lungs. Pulmonary edema was confirmed by increases in the following standards: permeability, as represented by the ratio of permeability