Evaluation of thyroid nodules for malignancy using 99Tcm-sestamibi

Area of Science:

• Nuclear Medicine
• Oncology
• Endocrinology

Background:

• Technetium-99m-sestamibi (99Tcm-MIBI) is used for myocardial perfusion imaging and has shown potential in localizing tumors.
• 99Tcm-pertechnetate is the standard radionuclide for thyroid scanning.
• Solitary thyroid nodules present a diagnostic challenge, requiring differentiation between benign and malignant lesions.

Purpose of the Study:

• To evaluate the utility of 99Tcm-MIBI thyroid scans in conjunction with 99Tcm-pertechnetate scans for characterizing solitary thyroid nodules.
• To compare the diagnostic accuracy of 99Tcm-MIBI scans with fine-needle aspiration cytology (FNAC) and surgical findings.

Main Methods:

• 161 patients with solitary thyroid nodules underwent both 99Tcm-MIBI and 99Tcm-pertechnetate thyroid scans.
• Fine-needle aspiration cytology (FNAC) and surgery were performed on consenting patients.
• Nodules were classified as cold, warm, or hot on both imaging modalities.

Main Results:

• Of 58 surgically treated patients, 14 (24%) had thyroid cancer and 44 (76%) had benign lesions.
• Cancerous nodules were typically cold on 99Tcm-pertechnetate scans, while 11 of 14 were warm on 99Tcm-MIBI scans.
• 99Tcm-MIBI scan demonstrated an overall sensitivity of 79% and specificity of 80% for detecting malignancy.
• Warm nodules on 99Tcm-MIBI scans had a positive predictive value of 55% and a negative predictive value of 92%.

Conclusions:

• 99Tcm-MIBI scintigraphy can be a valuable adjunct to conventional thyroid scanning for evaluating solitary thyroid nodules.
• Warm nodules identified on 99Tcm-MIBI scans warrant surgical consideration due to a higher likelihood of malignancy.
• The combination of imaging and cytology improves the diagnostic accuracy for thyroid nodule assessment.