A multiobserver comparison of 99mTcO4 and 123I thyroid imaging

Area of Science:

• Nuclear Medicine
• Radiopharmacology
• Diagnostic Imaging

Background:

• Thyroid imaging is crucial for diagnosing various thyroid conditions.
• Technetium-99m (99mTc) pertechnetate and Iodine-123 (123I) iodide are commonly used radiotracers.
• Comparative analysis is needed to determine optimal radioisotope selection for thyroid scintigraphy.

Purpose of the Study:

• To compare the diagnostic performance of 123I iodide and 99mTc pertechnetate for thyroid imaging.
• To evaluate observer confidence and interobserver agreement between the two radiotracers.
• To determine the most suitable radioisotope for modern thyroid scintigraphy.

Main Methods:

• Forty patients underwent thyroid imaging using both 99mTc pertechnetate and 123I iodide.
• Eight observers evaluated morphological criteria and assigned diagnostic categories with confidence grading.
• Image quality and diagnostic concordance were assessed using specific indices and compared to a six-month follow-up diagnosis.

Main Results:

• 123I iodide imaging demonstrated significantly lower mean observer index scores (5.6-6.8) compared to 99mTc pertechnetate (9.2), indicating higher confidence and agreement.
• Diagnostic concordance with final diagnosis was higher for 123I iodide (75-77%) than for 99mTc pertechnetate (63%).
• 123I iodide offers superior image quality and diagnostic accuracy in thyroid imaging.

Conclusions:

• 123I iodide is diagnostically superior to 99mTc pertechnetate for thyroid imaging.
• 123I iodide provides better observer confidence and interobserver agreement.
• 123I iodide is recommended for thyroid imaging due to its favorable characteristics and diagnostic performance.