Abscess scintigraphy with 99mTc-human immunoglobulin (IgG) using a one-step labeling method

Area of Science:

• Nuclear Medicine
• Radiopharmaceutical Imaging
• Biomedical Research

Background:

• Non-specific human immunoglobulin G (IgG) labeled with Indium-111 (111In-IgG) has been previously established for abscess localization.
• The development of novel radiotracers is crucial for improving diagnostic accuracy in infectious and neoplastic diseases.

Purpose of the Study:

• To evaluate the efficacy of Technetium-99m labeled immunoglobulin G (99mTc-IgG) for localizing abscesses and tumors in animal models.
• To compare the performance of 99mTc-IgG with 111In-IgG in terms of biodistribution and imaging characteristics.

Main Methods:

• A one-step labeling method was employed to prepare 99mTc-IgG.
• The compound was tested in mice, rats, and rabbits with experimentally induced abscesses and tumors.
• Blood clearance studies were conducted in dogs.

Main Results:

• While 111In-IgG showed higher absolute concentrations in abscesses and tumors, 99mTc-IgG exhibited a superior abscess-to-tumor ratio.
• High-quality images were obtained with 99mTc-IgG, enabling abscess detection as early as 30 minutes post-injection.
• Animal models included turpentine and E. coli abscesses, sarcomas, and gliomas.

Conclusions:

• 99mTc-IgG demonstrates significant potential as an effective radiotracer for abscess imaging.
• Advantages of 99mTc-IgG include simpler preparation, lower cost, greater availability, improved physical properties of 99mTc, and the ability to administer higher doses.
• 99mTc-IgG offers a promising alternative to 111In-IgG for abscess localization due to its favorable characteristics and imaging performance.