• 1 January 1980
    • journal article
    • research article
    • Vol. 21  (7) , 641-645
Abstract
The kinetics of the skeletal tracer 99mTc(Sn)methylene diphosphonate (Tc-MDP) were studied in 4 older patients without significant bony disease by compartmental analysis. Solution of the model was obtained by digital computer techniques. Tracer concentrations for target and background areas (to reflect bone and soft-tissue regions) as time functions were generated for 3 different imaging criteria: counting rate, a figure of merit and contrast. The figure of merit reached a maximum early in the 2nd h after dose administration, but contrast attained a plateau at 6 h. Either criterion is in accord with recommendations in the literature for optimal imaging delay time with Tc-MDP. Bone biopsy in 1 patient was in good agreement with the model''s prediction. Compartmental analysis provides an objective method for determining the optimal imaging delay time, depending on the criterion chosen. The method can be used for any radiopharmaceutical if the compartmental model is known and can be solved.