Hybrid ^99mTc-magnetite tracer for dual modality sentinel lymph node mapping.

Area of Science:

• Biomedical Engineering
• Nanotechnology
• Oncology

Background:

• Sentinel lymph node biopsy is crucial for cancer staging.
• Current radioactive tracers face limitations like radiation scatter and low resolution.
• Complex lymphatic drainage patterns in some cancers hinder accurate node identification.

Purpose of the Study:

• To develop and evaluate a dual radioactive/magnetic tracer for enhanced sentinel lymph node detection.
• To improve accuracy in identifying sentinel nodes, especially in cases of complex lymphatic drainage.
• To combine sensitive lymphoscintigraphy with high-resolution intraoperative detection.

Main Methods:

• Dextran-coated magnetite nanoparticles (33 nm) were labeled with technetium-99m (99mTc).
• The dual tracer's radiolabeling efficiency, biodistribution, and lymph node migration were assessed in rat and swine models.
• Intraoperative detection was performed using gamma probes and magnetometer probes.

Main Results:

• High radiolabeling efficiency (98±2%) was achieved.
• In rats, the tracer migrated through four lymph node tiers within 20 minutes.
• In swine, the dual tracer successfully mapped lymphatic drainage, with magnetometer probes identifying 7 out of 8 primary nodes.

Conclusions:

• The dual radioactive/magnetic tracer demonstrates high purity and early promise for sentinel node identification.
• This novel approach enhances accuracy in complex lymphatic environments.
• Combining preoperative lymphoscintigraphy with intraoperative magnetometer probes offers a significant advancement.