We evaluated pulmonary vascular permeability in 15 patients after lung transplantation (21 allografts) by measuring the pulmonary transcapillary escape rate (PTCER) for Ga-68-labeled transferrin, using positron emission tomography. Seven recipients (four unilateral, three bilateral lung transplants) were studied within 3 days of transplantation, and each developed hypoxemia and allograft infiltrates consistent with the "reimplantation response." PTCER was higher in subjects studied within 1 day than in those studied at a later time, and fell in seven allografts studied serially. The initial PTCER also correlated (r = 0.77) with length of ischemic (preservation) time, even in the three subjects with bilateral allografts. Eight other recipients (five unilateral, three bilateral transplants) were evaluated for possible organ rejection at least 1 wk after transplantation. PTCER was normal in patients without clinical or histologic evidence of rejection, and it was elevated in recipients with rejection. PTCER fell each time after treatment for rejection with increased immunosuppression in the three patients studied serially. These data suggest that positron emission tomography measurements of PTCER might be a useful way to evaluate both the reimplantation response and organ rejection after lung transplantation.

We evaluated pulmonary vascular permeability with positron emission tomography (PET) in 16 patients with interstitial lung disease (ILD) by measuring the pulmonary transcapillary escape rate (PTCER) for transferrin labeled with gallium-68. In patients with active ILD, defined by lung biopsy or clinical criteria, mean PTCER was significantly greater than in normal subjects (118 +/- 46 versus 21 +/- 11 x 10(-4) min-1, respectively, p less than 0.05). Mean PTCER in patients with inactive ILD, in contrast, was not different from that in normal subjects (32 +/- 10 x 10(-4) min-1, p = NS). Thus, these data suggest that PET measurements of PTCER might serve as an index of disease activity in patients with ILD.

We measured extravascular density (EVD) and the pulmonary transcapillary escape rate (PTCER) for 68Ga-transferrin using positron emission tomography in 14 normal volunteers and 29 patients with radiographic infiltrates, including six patients with congestive heart failure (CHF), eight patients with the adult respiratory distress syndrome (ARDS), and 15 patients with focal pneumonia. Contralateral, radiographically normal regions were also evaluated in the patients with focal pneumonia. Mean EVD was elevated in the patients with CHF, ARDS, and pneumonia in regions of radiographic infiltrate compared with values from normal subjects (p less than 0.05), but it was not significantly different among the three patient groups. PTCER in normal subjects and in patients with CHF was not significantly different (21 +/- 11 versus 44 +/- 16 x 10(-4) min-1, respectively, p = NS). PTCER was elevated in regions of infiltrate because of either pneumonia (173 +/- 99) or ARDS (170 +/- 79). PTCER was also elevated in regions contralateral to those with focal infiltrate during pneumonia, even though these regions were radiographically normal and had normal EVD values. These results suggest that PTCER is a sensitive but nonspecific index of abnormal pulmonary vascular permeability, which may be useful for classifying patients in clinical studies of pulmonary edema.

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Positron emission tomography (PET) can be used to evaluate pulmonary vascular endothelial permeability by measuring the pulmonary transcapillary escape rate (PTCER) for radiolabeled transferrin. Because epithelial permeability, as evaluated by other techniques, is significantly affected by cigarette smoking, we used PET to compare the effects of smoking on extravascular lung density (EVD) and PTCER in seven normal chronic cigarette smokers within 30 min of smoking a cigarette and seven normal nonsmokers. We found no difference in PTCER and EVD between the two groups. We conclude that the interpretation of acute or chronic lung injury studies with PET should not be affected by cigarette smoking in the subject population.