The role of 99mTc-MIBI in the evaluation of non-functional thyroid gland nodules

Abstract

Aim: The objective of the study is to show the role of 99mTc methoxyisobutylisonitrile (99mTc-MIBI) with planar imaging and single photon emission tomography with “low dose” CT (SPECT-CT) in a work up of non-functioning thyroid nodules on imaging with 99mTc- pertechnetate, which were confirmed by ultrasound examination. Patients and methods: Patients who underwent thyroid imaging with 99mTc-MIBI in the period from 2008 to 2018 were reviewed. The findings were compared with PHD results. The imaging was performed on gamma camera with high resolution collimator as planar scintigraphy and SPECT-CT. The results of fine needle aspiration biopsy were classified by the Bethesda classification, while PHD results were classified, as benign or malignant. Results: In the period from 2008-2018, 271 thyroid imaging with 99mTc- MIBI were performed. In 42 patients all-inclusive criteria were met.Out of those 42 patients, 28 of the PHD findings were concordant with the imaging, i.e. a node was presented as hypermetabolic. The calculated negative predictive value of the procedure is 78.6% (NPV = 11/ (3+11) = 0,786), and positive predictive value 18% (PPV = 5/ (5+23) = 0.179). Conclusion: Given the high negative predictive value, obtained from our results, 99mTc -MIBI imaging may be recommended as a complementary diagnostic method to fine-needle aspiration (FNA) in work up of thyroid nodules.