Technetium (99mTc) Mercaptoacetylglycylglycylglycine

The radiation exposure resulting from medical imaging is a topic of some concern. Nuclear medicine provides potentially life-saving information regarding physiological processes, and is of particular value in children where the rapid and unequivocal diagnosis of pathological concerns is essential for the health of these patients. The overall objective of this investigation is to optimize pediatric patient absorbed dose by keeping it as low as possible while maintaining excellent diagnostic quality of nuclear medicine images. This is particularly important since children are at increased risk due to the enhanced radiosensitivity of their tissues and the longer time-period over which radiation effects may manifest. Current dosimetric estimations in children are based on either animal biokinetic or pharmacokinetic data from adults due to paucity of data that exists for children. This situation will be improved through the following specific aims:
* Collect image-based pharmacokinetic (PK) data from patient volunteers in different age groups scheduled for routine nuclear medicine studies for Tc-99m mercaptoacetyltriglycine (MAG3), a radiopharmaceutical commonly used in pediatric nuclear medicine
* Pool and analyze the data for different age groups for each radiopharmaceuticals and
* Generate biokinetic models to be used in subsequent dosimetric models for the optimization of pediatric nuclear medicine procedures.
Since inadequate pharmacokinetic data currently exist in these patients, the investigators will use the data acquired in this study to establish PK models applicable to different age categories. Data on the pharmacokinetics of agents used in pediatric nuclear medicine are almost completely lacking. Internationally adopted dose coefficients (mSv/MBq) for pediatric nuclear medicine make age-dependent adjustments only for patient size and anatomical differences, while time-dependent kinetics from adult PK models are assumed due to the lack of kinetic data for children. The data obtained from this study will make it possible for the first time to determine how the PK in pediatric patients differs from adults. This will be done for Tc-99m MAG3, a radiopharmaceutical commonly used for pediatric nuclear medicine imaging. The overall hope is that results will allow the molecular imaging community to implement pediatric dose-reduction approaches that substantially improve upon current guidelines pointing to future technological advances that could yield even greater dose-reduction while simultaneously improving diagnostic image quality.