Study objectives: In regard to nuclear medicine
literature reporting lung uptake of colloidal radiopharmaceuticals in
patients with liver diseases, it has been hypothesized that liver
abnormalities could trigger induction of pulmonary intravascular
macrophages (PIMs) in humans normally lacking them. Recently,
experimental induction of PIMs in rats in which they are not normally
prevalent has been demonstrated to be at the origin of pulmonary
hemodynamic alterations with an increased susceptibility to ARDS. If
such induction may occur in humans, the risk of pulmonary hemodynamic
alterations has to be considered and detected. This study demonstrates
in a rodent model of biliary cirrhosis that scintigraphy of phagocytic
function as commonly used for liver exploration is a suitable strategy
for staging PIM development.
Design: Sixty rats were
randomized as follows: bile duct section (n = 40), sham operation
(n = 10), and no operation (n = 10). The rats were submitted to
scintigraphy of phagocytic function every 5 days over 35 days for the
assessment of radiocolloid uptake within lung and liver. At day 35,
radioactivity of blood was counted and immunohistochemistry was
performed on lung specimens.
Results: As disease
progressed, radiopharmaceutical uptake decreased within the liver,
while increasing considerably in the lung. At day 35, lung uptake
averaged about 66% as compared to 3% before surgery. Lung histologic
findings revealed numerous intravascular mononuclear cells closely
related to the monocyte-macrophage lineage.
Conclusion: Scintigraphy of phagocytic function commonly
used for liver scanning could be a suitable strategy for the diagnosis
of the induction of PIMs under pathologic situations.