Utility and comparative analysis of 99mTcpertechnetate and 99mTc tetrofosmin a dual radiopharmaceutical approach with FNAC for diagnostic assessment of thyroid nodules

Abstract

Management of thyroid nodules is continued to be a controversial issue for clinicians. The Major challenge in the management of thyroid nodules is to differentiate malignant nodules from benign nodules and to establish whether it requires surgical excision or be treated conservatively. The present study exploited the efficacy of dual use of Tc-99m pertechnetate and Tc-99m tetrofosmin in delineating malignant thyroid nodules from benign ones for selective surgical workup in comparison to FNAC or postsurgical histopathological findings. Method of fractionation of expensive tetrofosmin kit with easy and quick alternate method to the reference method for testing radiochemical purity of Tc-99m tetrofosmin has been proposed. The alternative method is useful to check the RCP of Tc-99m labeled chromatography using Whattman paper 3 as stationary phase while acetone and saline as mobile phase. On quantitative analysis of Tc-99m pertechnetate perfusion scintigraphy, cut-off values of various imaging markers has been established to differentiate between malignant from benign thyroid nodules. In conclusion, two quantitative imaging markers i. e TNB/CAB and TNB/TB in single radiotracer technique increase sensitivity of Tc-99m pertechnetate perfusion thyroid imaging with fair accuracy and moderate specificity of test. The study concludes that the dual radiopharmaceutical approach using Tc-99m pertechnetate and Tc-99m tetrofosmin perfusion thyroid imaging increase the specificity and accuracy to delineate malignant thyroid nodules from benign nodules than compared to single radiotracer tracer technique. However, further clinical studies involving larger number of patients along with quantitative analysis are required to establish the precise role of these radiopharmaceuticals. Though it is not recommended to differentiate between malignant and benign thyroid nodules using dual use of Tc-99m pertechnetate and Tc-99m tetrofosmin.