INCREASED LUNG CLEARANCE OF 99MTCDTPA IN ALLOGRAFT LUNG REJECTION

To investigate whether lung Tc-99m-DTPA clearance is altered during allograft lung rejection, a group of four double lung and 24 heart-lung transplant patients was studied using serial measurement of the clearance rate of aerosolized Tc-99m-DTPA (DTPA-Cl), in association with pulmonary function tests, bronchoalveolar lavage, and transbronchial lung biopsies. Using histologic diagnosis as a standard, we compared 56 episodes with normal lung histology to 32 episodes with allograft lung rejection. A control group of 20 healthy nonsmokers was used to define normal DTPA-Cl. In patients with normal lung histology, DTPA-Cl was higher than in control subjects (2.62 +/-0.25 versus 1.20 +/- 0.12 %/min; p < 0.001). In the episodes of allograft lung rejection, DTPA-Cl increased to 3.65 +/- 0.41 %/min (p < 0.02) as compared with episodes of normal lung histology. The change in DTPA-Cl during allograft lung rejection was correlated (r = 0.3, p < 0.01) with the increased percentage of lymphocytes in bronchoalveolar lavage (27.8 +/- 3.5% in rejection versus 19.9 +/- 2.2% in normal histology; p < 0.02). Sensitivity and specificity of DTPA-Cl measurement in detecting lung rejection were 69 and 82%, respectively, versus 45 and 85% for FEV1 measurement. These results suggest that DTPA-Cl monitoring could be used in conjunction with pulmonary function testing as a noninvasive approach for the detection of lung rejection.