An Error Analysis of Pulmonary Vascular Permeability Measurements Made with Positron Emission Tomography

Abstract

Positron emission tomography (PET) is a powerful, quantitative, nuclear medicine imaging technique, useful for studying many problems in lung physiology and biochemistry (1). With PET, compounds are labeled with positron-emitting isotopes. After being administered either. intravascularly or inhalationally, the tissue activity concentration of the isotope is determined with an imaging device similar in appearance to an X-ray computed tomography scanner. Multiple two-dimensional images are then reconstructed from the activity data and interpreted to represent a physiologic process of interest. PET derives its power from several factors: (1) the labeled compounds are themselves biologically important; (2) the isotope half-life is often sufficiently short that studies may be repeated if desirable; (3) the isotope tissue concentration can be determined quantitatively, accurately, and in many instances, noninvasively; and (4) the activity distribution can be located with great accuracy. Because of this latter feature in particular, the activity data can be presented regionally, in an image format, so that measurements may be correlated with other regionally specific measurements over time.