Evaluation of an alternative radiochemical purity testing method for technetium-99m sestamibi

Area of Science:

• Nuclear medicine
• Radiopharmaceutical chemistry
• Analytical chemistry

Background:

• Accurate measurement of radiochemical purity (RCP) is critical for radiopharmaceutical quality control.
• 99mTc-sestamibi is a widely used myocardial perfusion imaging agent.
• Standard RCP testing methods can be time-consuming.

Purpose of the Study:

• To evaluate the accuracy and reliability of two alternative RCP measurement methods for 99mTc-sestamibi.
• To compare the performance of miniaturized and regular-sized Whatman 31 ET paper strips against standard thin-layer chromatography (TLC).

Main Methods:

• Comparison of three RCP measurement methods: standard TLC, miniaturized 31 ET paper strip, and regular 31 ET paper strip.
• 30 experimental runs performed in triplicate (n=90) across an RCP range of 82%-98%.
• Samples were prepared to ensure 50% had RCP values below the 90% limit.

Main Results:

• Both 31 ET methods showed strong correlation with TLC (r=0.92-0.94) but tended to overestimate RCP, especially below 95%.
• False-positive rates were high: 27% for miniature 31 ET and 33% for regular 31 ET.
• Test/retest reliability was 99% for TLC and regular 31 ET, and 91% for TLC and miniature 31 ET.

Conclusions:

• The miniature and regular 31 ET paper strip methods are not suitable for determining the RCP of 99mTc-sestamibi due to high false-positive rates.
• These alternative methods are unacceptable for clinical diagnostic use.
• Standard TLC remains the preferred method for accurate RCP determination.