Double-tracer scintigraphy with 67Ga-citrate and 99mTc-sulfur colloid in the diagnosis of hepatic tumors.

A method of liver scanning based on a subtraction technique with simultaneous use of two tracers, 67Ga-citrate and 99mTc-sulfur colloid, is described. The subtraction technique isolates radiogallium uptake by the space-occupying hepatic lesions by subtracting interference due to tracer uptake by healthy hepatic tissue. In 82 patients, the method yielded a correct result in 94.7% of the positive scans and in 97.7% of the negatives. Two false positives and one false negative occurred. Very poor results were obtained in the same patients using conventional technetium and gallium scans: only 20.7% of these interpretations were correct. The method proved very helpful in differentiating malignant from benign lesions.