99Tcm hydroxyethyl starch: a potential radiopharmaceutical for lymphoscintigraphy

Area of Science:

• Nuclear Medicine
• Radiopharmaceutical Development
• Lymphatic Imaging

Background:

• Accurate visualization of lymphatic channels and lymph nodes is crucial for diagnosing various medical conditions.
• Existing radiopharmaceuticals have limitations in lymphatic imaging efficacy and clearance rates.
• Development of novel radiotracers is needed for improved lymphatic system assessment.

Purpose of the Study:

• To evaluate the utility of 99mTechnetium hydroxyethyl starch (99Tcm HES) for imaging lymphatic channels and lymph nodes.
• To compare the performance of 99Tcm HES against other radiotracers, including 99mTechnetium human serum albumin (99Tcm HSA), 99mTechnetium dextran (99Tcm DXT), and 99mTechnetium sulphur micro colloid (99Tcm SMC).
• To assess the potential of 99Tcm HES as a radiopharmaceutical for clinical lymphoscintigraphy.

Main Methods:

• Preparation of 99Tcm HES with high labeling efficiency (>95%).
• Comparative imaging studies in rabbits using 99Tcm HES, 99Tcm HSA, 99Tcm DXT, and 99Tcm SMC.
• Preliminary lymphoscintigraphy in human subjects, focusing on leg, pelvic, and para-aortic lymph nodes.

Main Results:

• 99Tcm HES demonstrated excellent visualization of lymphatic channels and nodes with the highest clearance rate from the injection site (P < 0.01).
• Significantly higher node uptake of 99Tcm HES compared to 99Tcm DXT (P < 0.001) at 90 minutes post-injection.
• Higher concentration of 99Tcm HES in lymphatic channels than 99Tcm SMC (P < 0.001) at 90 minutes.
• High-quality lymphoscintigrams in humans within 10 minutes, differentiating normal, partially, and completely obstructed lymphatics.

Conclusions:

• 99Tcm HES is a highly effective radiopharmaceutical for visualizing lymphatic channels and lymph nodes.
• Its superior clearance and uptake characteristics make it advantageous over other tested agents.
• 99Tcm HES shows significant potential for clinical application in lymphoscintigraphy, including assessment of lymphatic obstruction.