Diagnostic value of ultrasonography and TI-201/Tc-99m dual scintigraphy in differentiating between benign and malignant thyroid nodules

Abstract

Purpose

To evaluate the performance of ultrasonography (US) and TI-201/Tc-99m dual (Tl/Tc) scintigraphy in differentiating between benign and malignant thyroid nodules.

Methods

Eighty-six patients diagnosed to have a thyroid tumor on postoperative histopathologic examination between June 2009 and February 2017 were included in this retrospective study. A radiologist reviewed the US and Tl/Tc scintigraphy reports along with all available clinical and histopathologic information. On Tl/Tc scintigraphy, a nodule in which uptake was higher in the delayed phase than in the surrounding parenchyma was defined as a delayed accumulation pattern and a nodule in which uptake was higher in the delayed phase than in the early phase was defined as a persistent pattern. The Tl/Tc scintigraphy images were evaluated in a blinded manner to assess reproducibility. A statistical analysis was performed to identify features associated with malignancy. Interobserver variability was calculated using the κ statistic.

Results

US had higher sensitivity (81.2%), specificity (88.2%), and positive (96.6%) and negative (53.6%) predictive values than Tl/Tc scintigraphy. An ill-defined margin and microcalcification were independent predictors of a malignant thyroid nodule on multivariate logistic regression (P = 0.003 and P = 0.014, respectively). The persistent pattern had high specificity (85.7%) equivalent to that of US but had lower sensitivity (34.7%). The κ values for the delayed accumulation and persistent patterns were 0.66–0.78 and 0.32–0.50, respectively.

Conclusions

An ill-defined margin and microcalcification on US were independent predictors of a malignant thyroid nodule. A persistent pattern seen on Tl/Tc scintigraphy could contribute to the differential diagnosis.

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