A new method for determination of the rate constant for clearance of radioactive indicators in gamma camera hepatography. Clinical examples with 99mTc-diethyl-IDA and 99mTc-diethyl-iodo-IDA.
Application of Stewart-Hamilton's formula to the activity-time curve recorded over a left ventricular region of interest following an intravenous bolus injection of a radioactive indicator in gamma camera hepatography has resulted in a new method for determination of the clearance rate constant of the indicator (i.e. the ratio of the clearance to the plasma volume). In a group of 19 normal subjects the clearance rate constant was 0.116 +/- 0.036 min-1 (means +/- 1 S.D.) with 99mTc-diethyl-IDA (SOLCO HIDA) and 0.184 +/- 0.037 min-1 (means +/- 1 S.D.) with 99mTc-diethyl-iodo-IDA (SOLCO IODIDA) in 15 normal subjects. The clearance rate constant is assumed to represent mainly hepatic clearance of the radioactive indicator and to a much smaller extent renal clearance. The literature shows diverging results as to the clearance of 99mTc-diethyl-IDA and the reasons for this are discussed. The correlations between the clearance rate constant of 99mTc-diethyl-IDA and a number of laboratory variables with relation to liver function were moderate to non-existent in a group of 16 subjects with abnormal values of at least one of these variables. The rate constant for clearance as described in the paper represents a non-invasive method for rapid evaluation of the uptake capacity of the liver and, in particular, with regard to the polygonal cells of the liver parenchyma when IDA derivatives are employed. The clinical usefulness of the clearance rate constant is probably superior to the group of routine laboratory variables which also describe other functions than liver uptake.
Carlsen
O
O
Department of Clinical Physiology and Nuclear Medicine, Vejle Hospital, Denmark.
Jensen
E K
EK
Axelsson
C K
CK
D000328:Adult; D006801:Humans; D007098:Imino Acids; D008099:Liver / Q000000981:diagnostic imaging*; D015609:Organotechnetium Compounds; D011877:Radionuclide Imaging; D019784:Technetium Tc 99m Diethyl-iminodiacetic Acid
D007098:Imino Acids; D015609:Organotechnetium Compounds; D019784:Technetium Tc 99m Diethyl-iminodiacetic Acid; C051086:technetium Tc 99m 2,6-diethyl-3-iodo-HIDA