Hepatic plasma clearance of 99m Tc-HEPIDA as a diagnostic tool: experimentally derived equations for a simplified determination

Abstract

Determination of the plasma (Cl_Pl) and specific hepatic clearance (Cl_Hp) of ^99mTc-HEPIDA is gaining acceptance as one of the best tests for the assessment of liver parenchyma functional capacity. A standard method utilises numerous blood samples, collected after injection of the radiopharmaceutical, plus collection of the urine if specific hepatic clearance is required.
It is not always necessary to obtain values of the clearances by means of the laborious multi-sample procedure. In the paper there are presented formulas, based on experimental data, that form the basis of a simplified method for determination of Cl_Pl and Cl_Hp using single administration of ^99mTc-HEPIDA. To arrive at the value of Cl_Pl it is sufficient to withdraw 1 blood sample in the time range of 60 to 83 min post administration of the radio-pharmaceutical. If Cl_Hp is required, additional collection of urine over the time from 0 to 88–100 min post injection is necessary.
The values of Cl_Pl and Cl_Hp obtained by the simplified procedure are in full accordance with those obtained by the reference method utilising a series of blood samples, collected from 5 to 90 min post injection. The simplified method is sufficient as a procedure for screening of patients for liver parenchymal damage.