Human biodistribution of an ultrasound contrast agent (Quantison) by radiolabelling and gamma scintigraphy.

Abstract

The biodistribution and kinetics of an air filled human serum albumin microcapsule formulation (Quantison) intended for use as an intravenous ultrasound contrast agent have been examined. 12 healthy subjects were administered with approximately 50 million microcapsules per kilogram body weight, radiolabelled with 50 MBq 123I. Imaging was performed over a period of 58 h using a large field-of-view gamma camera and the amount of labelled material present in the blood, urine and faeces measured. Imaging demonstrated that the liver was the organ with the highest uptake, with a mean uptake of 41.8% (SD 10.4%) of the administered dose 1 h following administration. The maximum uptake of the agent in the lungs was low, mean 4.0% (SD 3.4%). A small amount of uptake was visible in the bone marrow; however, this was not quantifiable. There was also evidence of minimal myocardial activity within 5 min of administration. No adverse events were observed and there were no changes in any of the individual post-study indices. The present study demonstrates the safety of Quantison. Gamma scintigraphy played a useful role in confirming the biodistribution of the agent with little lung uptake, high liver uptake and evidence of myocardial uptake.

Targeted Microbubbles for Imaging Tumor Angiogenesis: Assessment of Whole-Body Biodistribution with Dynamic Micro-PET in Mice

“…In contrast, in pigs, more than 90% of the albumin microspheres were recovered in the lungs, most likely because of the presence of intravascular macrophages in the porcine lungs (10). In another study, the biodistribution of air-filled iodine 123-labeled human serum albumin microspheres (Quantison) was studied in humans for 58 hours by using scintigraphic imaging (9). One hour after intravenous administration, the greatest amount of radiolabeled microsphere uptake was in the liver (41.8%), followed by the spleen (11%) and the lungs (3.4%) (9).…”

“…In another study, the biodistribution of air-filled iodine 123-labeled human serum albumin microspheres (Quantison) was studied in humans for 58 hours by using scintigraphic imaging (9). One hour after intravenous administration, the greatest amount of radiolabeled microsphere uptake was in the liver (41.8%), followed by the spleen (11%) and the lungs (3.4%) (9). Small amounts of radiotracer were also visible in bone and heart tissue in that study (9).…”

“…One hour after intravenous administration, the greatest amount of radiolabeled microsphere uptake was in the liver (41.8%), followed by the spleen (11%) and the lungs (3.4%) (9). Small amounts of radiotracer were also visible in bone and heart tissue in that study (9). In the work presented here, we provide data in addition to data in these prior biodistribution studies by studying the biodistribution of newer-generation perfluorocarbon-filled lipid-shelled MBs targeted to the angiogenesis marker VEGFR2 with in vivo micro-PET.…”

“…Researchers in two studies (9,10) have evaluated biodistribution of nontargeted MBs in rats, pigs, and humans. To our knowledge, biodistribution of targeted MBs in living animals by using positron emission tomography (PET) has not been studied to date.…”

Molecular Imaging of Tumor Angiogenesis

“…Further, biodistribution studies revealed that microbubbles have low circulation residence times as they are rapidly removed by the reticuloendothelial system (Perkins, Frier et al 1997;Weskott 2008;Willmann, Cheng et al 2008). To increase the circulation time of the microbubbles in serum, additional coatings, such as polyethylene glycol polymer arms are added onto the microbubble shell.…”