Filtered technetium-99m-sulfur colloid evaluated for lymphoscintigraphy

Area of Science:

• Nuclear Medicine
• Radiopharmacology
• Medical Imaging

Background:

• Lymphoscintigraphy is crucial for diagnosing lymphatic system disorders.
• Existing technetium-99m (99mTc)-labeled agents face limited clinical use in the US.
• Smaller particle size 99mTc-sulfur colloid (99mTc-SC) has been investigated for improved lymphoscintigraphy.

Purpose of the Study:

• To evaluate the efficacy and safety of filtered 99mTc-SC with sub-micron particle sizes for lymphoscintigraphy.
• To compare the performance of filtered 99mTc-SC with a conventional agent, 99mTc antimony sulfide colloid (99mTc-ATC).

Main Methods:

• 99mTc-SC was prepared using a kit and filtered through a 0.1-micron sterile filter.
• Radiochemical purity (RCP) and particle size (electron microscopy, laser light scattering) were analyzed.
• Nineteen patients with suspected lymphedema received intradermal injections of filtered 99mTc-SC, with imaging at various intervals.

Main Results:

• Filtered 99mTc-SC exhibited high radiochemical purity (average 93.4%) and a significant proportion of particles < 50 nm (89.9%), with a mean size of 38.0 nm.
• Lymphoscintigrams using filtered 99mTc-SC were comparable to those from 99mTc-ATC.
• Filtered 99mTc-SC demonstrated faster inguinal lymph node transport and lower radiation dosimetry to the liver, spleen, and whole body compared to 99mTc-ATC.

Conclusions:

• Filtered 99mTc-SC is easily prepared and suitable for routine clinical lymphoscintigraphy.
• The improved characteristics of filtered 99mTc-SC offer advantages over existing agents.
• This agent represents a readily available option for diagnosing lymphatic abnormalities.