Based upon our discovery of a new NMR phenomenon in lung tissue, we propose to develop a new method of distinguishing lung water in aerated lung from lung water in regions without air (i.e., blood vessels, atelectatic lung, lung edema with alveolar flooding). We propose, in addition, a new method for quantitating the diagnosis of lung edema and its distribution. In previous work we established that NMR imaging techniques have the potential to become the first fundamental in-vivo standard for noninvasive measurement of the spatial distribution of absolute lung water content. We have carried out the initial steps in validating (establishing the accuracy and precision of) the NMR methods for measuring lung water content by comparing them with gravimetric measurements in rat lungs. We now propose further studies with rats to develop the NMR techniques to a practical stage for research and clinical purposes by the following steps. (1) Complete the validation of the NMR methods by establishing the accuracy and precision of NMR measurements of the distribution of lung water. (2) Test a new method for quantitating the diagnosis of lung edema and its distribution. Our method consists of displaying fraction lung volume (Vf) versus water density (pH2O) in a manner similar to West and Wagner's quantitation of the distribution of ventilation and perfusion as a function of their ratio. We will determine whether the Vf vs pH2O method can be used to identify specific pulmonary injuries and to discriminate between intravascular and extravascular water. (3) Test another new method for distinguishing lung water in aerated from lung water in nonaerated lung by using NMR measurements made with both symmetrical (with respect to time and intensity) and asymmetrical field gradients. The proposed work is important because it would establish the validity of NMR imaging techniques as a fundamental standard for the noninvasive measurement of the spatial distribution of the absolute water content of the lung, an issue of great importance in pulmonary medicine and physiology. The proposed work should result in new NMR techniques which will permit clinical and physiologic cardiopulmonary studies not achievable with present methods.
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