99Tcm-citrate: a new bone imaging radiopharmaceutical

Area of Science:

• Nuclear Medicine
• Radiopharmacology
• Skeletal Imaging

Background:

• Conventional bone scintigraphy uses agents like technetium-99m-MDP.
• Technetium-99m-citrate exhibits distinct skeletal incorporation and biodistribution patterns.
• Understanding these differences is crucial for optimizing bone imaging techniques.

Purpose of the Study:

• To confirm the bone-imaging capabilities of technetium-99m-citrate.
• To identify factors affecting its skeletal uptake.
• To compare technetium-99m-citrate uptake with technetium-99m-MDP and assess its role in bone scintigraphy.

Main Methods:

• Animal studies and human studies (n=45) were conducted.
• Lesion-to-bone uptake ratios of technetium-99m-citrate and technetium-99m-MDP were compared in over 150 lesions.
• Lesions were categorized into osteoblastic, healing, and degenerative/healed types.

Main Results:

• Optimal bone uptake of technetium-99m-citrate was observed at pH 6.0-6.5.
• Technetium-99m-citrate and technetium-99m-MDP showed competition for bone uptake, indicating different accumulation sites.
• Uptake ratios were concordant for osteoblastic lesions but significantly lower for degenerative/healed lesions, suggesting differential uptake.

Conclusions:

• Technetium-99m-citrate localizes differently in bone, potentially binding to the organic matrix, unlike phosphonates.
• While skeletal uptake is lower than technetium-99m-MDP, technetium-99m-citrate may offer improved specificity for active bone disease.
• This agent could be valuable in predicting the healing of bone metastases, fractures, and osteomyelitis.