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This study presents data on the dynamic distribution and dosimetry of 111In- and 99Tcm-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 111In-IgG and seven patients were injected with 740 MBq 99Tcm-hydrazinonicotinamide derivative (HYNIC)-lgG. 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-IgG, the mean biological half-times in the blood were 0.90 and 46 h for the a- and b-phase, respectively- For 99Tcm-HYNIC-IgG, these half-times were 0.46 and 45 h. For 111In-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 2of the injected dose. For 99Tcm-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 111In-IgG were 0.8, 0.7, 1.2, 0.3 and 0.4 mGy MBq-1respectively. The mean absorbed doses for 99Tcm-HYNIC-IgG to these organs were 16, 24, 15, 10 and 22 μGy MBq-1respectively. The mean effective dose was 0.25 mSv MBq 1and 8.4 μSvMBq-1for 111In-IgG and 99Tcm-HYNIC-IgG respectively. In conclusion, the radiation absorbed doses for both 111In-IgG and 99Tcm-HYNIC-IgG are low and, therefore, these radiopharmaceuticals can be administered safely from a radiation risk perspective. (© 1998 Lippincott Williams & Wilkins)

Indium-111-labeled human nonspecific immunoglobulin G (111In-IgG) is a newly developed radiopharmaceutical for imaging infectious and inflammatory foci. This article presents an overview of the literature concerning In-IgG scintigraphy. The current theory about the mechanism of accumulation suggests that 111In-IgG accumulates in lesions as a result of enhanced vascular permeability and subsequent entrapment of the radiolabeled protein. Human studies show excellent results in imaging bone and joint, abdominal, and intravascular infection. Of special interest is the ability to depict infectious foci in granulocytopenic patients. The value of 111In-IgG scintigraphy for detection of infection is compared with that of gallium-67, labeled-leukocyte, and technetium-99m (99mTc) nanocolloid scintigraphy. The significance of differences between 111In-IgG scintigraphy and two other new scintigraphic techniques, 99mTc-labeled IgG and 99mTc-labeled murine monoclonal anti-granulocyte antibody BW 250/183, are discussed.

Fast and accurate delineation of acute infectious foci is very important for adequate management of patients. All currently available scintigraphic techniques require a relatively long timespan between referral to the nuclear medicine department and final diagnosis. Small peptides that bind to receptors on cells in the infectious focus might improve the diagnostic possibilities. Since activated leukocytes express somatostatin receptors, 111In-octreotide, a somastostatin analogue, was tested for its usefulness in detecting acute infection in rats with a calf muscle infection caused by Staphylococcus aureus.111In-octreotide was compared with the much larger protein 111In-labelled human nonspecific immunoglobulin G (111In-IgG). As early as 0.5 h after injection, the 111In-octreotide uptake in the abscess was significantly lower than that of 111In-IgG. Moreover, no 111In-octreotide retention in the abscess over time was noted. In conclusion, somatostatin receptor imaging does not allow scintigraphic detection of an acute infectious lesion. The uptake in an abscess is relatively poor compared to 111In-IgG.

Objectives: To investigate the biodistribution and specific targeting for tumour necrosis factor (TNF) of a fully human, radiolabelled anti-TNF monoclonal antibody (anti-TNF mAb) in patients with active rheumatoid arthritis (RA). [...]