Comparison of Thyroid Uptake Values Measured from 131I Scintigraphy and Uptake Probe in Hyperthyroid Patients.

Objective: Thyroid uptake test plays an important role in diagnosis, treatment planning and radioiodine dose determination in patients with hyperthyroidism. The aim of this study was to compare the % uptake values calculated with gamma camera and uptake probe after diagnostic 131I application in hyperthyroid patients.

Materials and methods: In this study, % uptake values were measured using a thyroid uptake probe and gamma camera in 32 patients who underwent thyroid radioiodine uptake measurement in our Nuclear Medicine center. Thyroid uptake measurements were prepared in the neck phantom with 0.74-0.925 MBq activity of 131I radionuclide. After counting the phantom with 131I separately in the uptake probe and gamma camera, 131I sample was orally administered to the patient. % uptake values were calculated by the uptake probe measurements and drawing regions of interest (ROI) from scintigraphic images at 2 and 24 h.

Results: The 2-h mean % uptake values in the probe and gamma camera were calculated as 30.5 ± 20.4 and 27.1 ± 18.6, respectively. The 24-h mean % uptake values in the thyroid probe and gamma camera were calculated as 57.6 ± 21.9 and 55.3 ± 21.5, respectively. Linear regression analyses for the 2- and 24-h % uptake values calculated with the probe and gamma camera were found as R2 = 0.8412 and R2 = 0.7313, respectively.

Conclusion: The 2- and 24-h % uptake values with the probe and gamma camera were found to be consistent with each other, indicating that they can be safely used interchangeably in patients with hyperthyroidism.