Lung transplantation in the rat: II. lung perfusion scintigraphy in normal and left lung-transplanted rats

Lung perfusion scintigraphy with technetium 99m-labeled microspheres was performed in a series of 14 normal rats. The mean value of left lung perfusion was 36.9 +/- 4.9% of total lung perfusion. Duplicate determinations on three possible error levels were evaluated statistically: (1) separation of the lung fields on the computer scintigram, (2) positioning of the animal under the gamma camera, and (3) measurement after a one-week interval. The determinations resulted in standard deviations of (1) 2.8%, (2) 0, and (3) 1.4%, respectively. These results are comparable with those of lung perfusion studies in dogs. Lung perfusion scintigraphy, chest roentgenography, and postmortem examination were used in the functional evaluation of two groups of left lung-transplanted rats: Group A (n = 12) had short-term follow-up and Group B (n = 11) had long-term follow-up. A common finding in Group A was a subnormally perfused and aerated graft, showing normal lung tissue for the most part at postmortem examination. In Group B, grafts were rarely perfused and aerated. At postmortem examination, they were fibrotic or abscessed, possibly due to chronic rejection. A good correlation was found between perfusion scintigraphy, chest roentgenography, and postmortem findings.