Computer Analysis of Thallium-201/Technetium-99m Parathyroid Images

Abstract

Objective: There is a lack of concensus regarding the analysis of ²⁰¹TI/^99mTc dual-isotope subtraction parathyroid images. We retrospectively evaluated two computer subtraction methods for the ability to increase the certainty of localization of parathyroid adenomas when compared to camera images only.

Methods: We evaluated 20 parathyroid studies using three sets of images: digital camera images (TI survey, TI pinhole and Tc pinhole of 100K counts each); a simple subtraction image of the Tc pinhole from the TI pinhole without background subtraction or normalization; and multiple subtractions of 60, 80, 100, 120 and 140% of the background-subtracted Tc pinhole image from the background-subtracted, normalized TI pinhole image.

Results: Simple subtraction decreased the certainty of adenoma localization as often as it increased it. Multiple subtractions increased the certainty in three cases and never decreased it. The sensitivities of the three techniques were calculated to be 84% for both camera images and simple subtraction and 90% for multiple subtraction.

Conclusion: If computer subtraction is desired to increase the certainty of diagnosis, it should be performed with multiple subtractions of the Tc pinhole image from the TI pinhole image, as described in this paper.