Dynamic distribution and dosimetric evaluation of human non-specific immunoglobulin G labelled with 111In or 99Tcm

This study presents data on the dynamic distribution and dosimetry of In-111- and Tc-99(m)-labelled human non-specific immunoglobulin G (IgG), two recently developed radiopharmaceuticals for the detection of infection and inflammation. Five healthy volunteers were injected with 20-75 MBq In-111-IgG and seven patients were injected with 740 MBq Tc-99(m)-hydrazinonicotinamide derivative (HYNIC)-IgG. Blood samples, urine and feces were collected. Whole-body gamma camera imaging studies were performed. The activity in source organs was quantified using the conjugate view counting method and a partial background subtraction technique. Dosimetric calculations were performed using the MIRD technique. For In-111-IgG, the mean biological half-times in the blood were 0.90 and 46 h for the a- and b-phase, respectively. For Tc-99(m)-HYNIC-IgG, these half-times were 0.46 and 45 h. For In-111-IgG, the mean cumulative urinary excretion in the first 48 h was 18% of the injected dose, while excretion in the feces was less than 2% of the injected dose. For Tc-99(m)-HYNIC-IgG, the whole-body retention was always 100% up to 24 h. The mean absorbed doses in the liver, spleen, kidneys, red marrow and testes from In-111-IgG were 0.8, 0.7, 1.2, 0.3 and 0.4 mGy MBq(-1) respectively. The mean absorbed doses for Tc-99(m)-HYNIC-IgG to these organs were 16, 24, 15, 10 and 22 mu Gy MBq(-1) respectively. The mean effective dose was 0.25 mSv MBq(-1) and 8.4 mu Sv MBq(-1) for In-111-lgG and Tc-99(m)-HYNIC-IgG respectively. In conclusion, the radiation absorbed doses for both In-111-IgG and Tc-99(m)-HYNIC-IgG are low and, therefore, these radiopharmaceuticals can be administered safely from a radiation risk perspective. ((C) 1998 Lippincott Williams & Wilkins).