Routine 201Tl scintigraphy in the follow-up of patients with differentiated thyroid carcinoma: Diagnostic accuracy and clinical impact

Abstract

The use of 201Tl scintigraphy as a routine imaging modality in the follow-up of patients with differentiated thyroid carcinoma (DTC) is controversial. The purpose of this retrospective study was to evaluate the diagnostic accuracy and clinical impact of routine 201Tl scintigraphy in the follow-up of patients with DTC. Three hundred and twenty-one patients (261 women, 60 men) with DTC (243 papillary thyroid carcinomas, 78 follicular thyroid carcinomas) were enrolled in this study. Two hundred and seventy-six patients underwent total or near total thyroidectomy (group 1) and 45 patients underwent subtotal thyroidectomy or unilateral lobectomy (group 2). A total of 1523 201Tl scintigraphy examinations were performed between 1987 and 2003. The duration of follow-up ranged from 13 to 204 months. 201Tl scintigraphy was performed 10 and 60 min after intravenous administration of 74 MBq 201Tl chloride. In group 1, 55 recurrent lesions were confirmed in 39 patients. In a patient-based analysis, the sensitivity, specificity, positive and negative predictive values, and accuracy of 201Tl scintigraphy for detecting recurrent DTC were 71.8%, 98.3%, 87.5%, 95.5% and 94.6%, respectively. In a lesion-based analysis, the sensitivity, specificity, positive and negative predictive values, and accuracy of 201Tl scintigraphy were 63.6%, 99.7%, 89.7%, 98.5% and 98.3%, respectively. Of the 35 thallium-positive recurrent lesions, 21 (60%) were removed by surgery and seven (20%) were treated with external-beam radiation therapy. All the thallium-negative recurrent lesions were treated with 131I therapy. The difference between the management of thallium-positive and thallium-negative recurrences was statistically significant (P<0.001). In group 2, 10 recurrent lesions were confirmed in seven patients. In a patient-based analysis, the sensitivity, specificity, positive and negative predictive values, and accuracy of 201Tl scintigraphy for detecting recurrent DTC were 85.7%, 94.7%, 75%, 97.3% and 93.3%, respectively. In a lesion-based analysis, the sensitivity, specificity, positive and negative predictive values, and accuracy of 201Tl scintigraphy was 80%, 97.5%, 80%, 97.5% and 95.6%, respectively. All of the seven patients were treated with completion of total thyroidectomy and subsequent 131I ablation therapy. 201Tl scintigraphy was not a highly sensitive imaging modality in routine follow-up of patients with DTC after total thyroidectomy. However, it had a clinical impact on the choice of optimal therapeutic approaches. In the follow-up of patients who underwent partial thyroidectomy, 201Tl scintigraphy was useful in the detection of recurrent DTC.