The 67 Ga-transferrin PLI is a sensitive and specific measure of pulmonary capillary permeability, which is utilized for noninvasive assessment of severity of a broad range of pulmonary conditions [19] [20] [21] . The PLI roughly parallels clinical severity (i.e. the LIS) [19, 20] . Although it involves the use of relatively routine equipment, the diagnostic method has not gained broad application, partly because of its laborious nature [20] . It has the advantage that bedside measurements are possible in mechanically ventilated critically ill patients, who cannot easily be transported. Pulmonary inflammation, of whatever cause, increases the PLI up to four times normal values in the most severe forms of lung injury, including ARDS. In less severe injury, such as impending ARDS and interstitial lung disease, the PLI is also elevated, albeit to a lesser extent, as reported by us and other groups [20, 21] .