A practical approach to the hepatobiliary kinetics of 99mTc-HIDA. Clinical validation of the method and a preliminary report on its use for parametric imaging.

99mTc-diethyl-HIDA cholescintigraphy was performed on 24 patients with histologically proven liver disease and on 10 normal adult subjects. Liver mass transport of HIDA was interpreted with the aid of a probabilistic model, assuming that the tracer particles undergo mixed random walks with drifts. The radiohepatograms were thus fitted with a gamma-variate function and the fitting parameters were evaluated as estimates of the severity of the disease. These parameters, together with the transit times, were also used to generate parametric images of liver function. The advantages of this approach are discussed and the following conclusions are drawn: (1) The gamma-fit is highly satisfactory with any type of experimental curve (0.98 less than r less than 1). (2) The parameters derived from the gamma-fit make it possible to objectively assess the extent of liver functional impairment. (3) Parametric imaging of the liver mass transport of HIDA is easily implemented, but still more experience is needed to assess its impact on patient care.