Quantitative studies of bone using (99m)Tc-methylene diphosphonate skeletal plasma clearance

Area of Science:

• Nuclear medicine
• Bone metabolism research
• Medical imaging quantification

Background:

• Quantitative bone scan imaging is valuable for studying metabolic bone diseases and treatment efficacy.
• Nuclear medicine offers whole-skeleton or regional analysis of bone remodeling rates.
• Standard bone scans lack detailed kinetic information on bone turnover.

Purpose of the Study:

• To review methods for quantifying technetium-99m methylene diphosphonate ((99m)Tc-MDP) kinetics via plasma clearance.
• To compare plasma clearance with conventional bone scan measurements for assessing bone turnover.
• To evaluate the utility of (99m)Tc-MDP kinetics in metabolic bone disease research.

Main Methods:

• Three methods for measuring whole-skeleton (99m)Tc-MDP plasma clearance (K(bone)) are described: Area Under the Curve (AUC), modified Brenner, and Patlak methods.
• The AUC method involves serial blood sampling and ultrafiltration to measure free (99m)Tc-MDP, requiring simultaneous glomerular filtration rate measurement.
• The modified Brenner method uses soft-tissue region of interest (ROI) counts, while the Patlak method combines gamma camera whole-body retention with plasma data, allowing for regional K(bone) measurements.

Main Results:

• Initial studies show good agreement between the three (99m)Tc-MDP plasma clearance measurement methods.
• Significant correlations were found between changes in K(bone) during treatment and biochemical markers of bone turnover.
• Plasma clearance studies offer a more physiological approach to bone turnover assessment compared to whole-body retention or bone uptake.

Conclusions:

• Quantitative (99m)Tc-MDP plasma clearance measurements provide a robust and physiological assessment of bone turnover.
• These kinetic methods are valuable research tools for evaluating metabolic bone diseases and treatment responses.
• The Patlak method's ability to measure regional K(bone) enhances its utility for localized bone disease assessment.