99mTc-mebrofenin scintigraphy for evaluating liver disease in a rat model of Wilson's disease.

UNLABELLED The purpose of this study was to establish whether (99m)Tc-mebrofenin could noninvasively assess liver function in Wilson's disease. METHODS Long-Evans Cinnamon (LEC) rats, which reproduce Wilson's disease with copper toxicosis, and their normal counterparts, Long-Evans Agouti (LEA) rats, were studied. Scintigraphic findings were correlated with biliary mebrofenin excretion and residual organ counts and with hepatic copper content, histology, copper excretion capacity, and liver test results. RESULTS Serum alanine aminotransferase (ALT) levels were elevated in some LEC rats, whereas serum bilirubin levels were normal. Liver histology was normal in LEA rats, whereas LEC rats showed multiple abnormalities. Mebrofenin was incorporated rapidly in LEA rats, with a mean time to peak liver activity of 80 +/- 30 s, followed by prompt biliary excretion of the tracer. In LEC rats, the mean time to peak activity, 283 +/- 190 s, was significantly longer (P = 0.001). The time to half of peak activity, indicating tracer clearance, was significantly greater in LEC rats than in LEA rats (1,825 +/- 1,642 s vs. 524 +/- 82 s, P = 0.002). Hepatic mebrofenin handling correlated with hepatic copper content, histologic grade, copper excretion capacity, and serum ALT. CONCLUSION Correlation of (99m)Tc-mebrofenin handling with liver morphology, function, and copper accumulation in LEC rats suggests that mebrofenin scintigraphy can be useful for noninvasively monitoring disease progression and therapeutic response in Wilson's disease. Although the data were obtained in an animal model of Wilson' disease, these biochemical parameters likely reflect liver damage in general, suggesting that there may be a role for mebrofenin scintigraphy in other chronic liver diseases as well.