Tl-201 scintigraphy in assessing efficacy of percutaneous ethanol injection (PEI) in non-functioning thyroid nodule

Objectives PEI is a possible alternative to surgery in selected patients with thyroid nodules. The purpose of study was to investigate whether Tl-201(Tl) scan is useful in assessing efficacy of PEI in benign non-functioning thyroid nodule.

Methods Twenty-seven patients with cytologically proven benign and non-functioning thyroid nodules were enrolled. Baseline Tl scan was obtained before treatment. All nodules was positive. PEI was performed as a fractionated session. After local anesthesia, absolute ethanol was selectively injected within the nodule under the guidance of ultrasound. When vascular signal in the nodule on Doppler mode was disappeared, follow up Tl scan was obtained. Based upon Tl scan findings and subsequent management, patients were divided into 3 subgroups; A) complete disappearance of Tl uptake (n=15), B) persistent Tl uptake with additional ethanol injection (n=7), and C) persistent uptake without additional ethanol injection (n=5). Patients were followed up at least 18 mos.

Results There were no statistical differences in the average of volume reduction rate at 6mos. after PEI among 3 groups (group A vs. B vs. C; 82% vs. 75% vs.79%).None of group A showed re-growth of the treated nodule during follow up period. One in group B (14%) showed nodular re-growth. In contrast, 4 out of 5 (80%) in group C showed nodular re-growth until 2 years after PEI

Conclusions Disappearance of Tl uptake is highly predictive of long-lasting efficacy of PEI in volume reduction while persistent Tl uptake indicates need of additional injection. With use of Tl scan, clinical value of PEI may be greatly enhanced.