Kinetics of 201T1 Uptake in Adenomas and Well-Differentiated Carcinomas of the Thyroid a Double Isotope Investigation with 99Tcm and 201T1

Abstract

A visually increased uptake of ²⁰¹TI chloride corresponding to a ‘cold’ (¹³¹I or ⁹⁹Tc^m) thyroid nodule is mostly seen in well-differentiated carcinomas but also often in follicular adenomas. Since a visually increased uptake of ²⁰¹Tl can be due to an increased initial uptake and/or a delayed elimination, an extended dynamic investigation was performed in patients with well-differentiated carcinomas or with follicular adenomas. Data were collected in a dynamic simultaneous double isotope (⁹⁹Tc^m+²⁰¹Tl) study up to 50 min after intravenous administration. Adenomas could be significantly separated from carcinomas by the elimination (p=0.0001), but not by the initial uptake.