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ACR TI-RADS Risk Score Escalation Observed in Benign Thyroid Nodules following Radiofrequency Ablation
Tess J Battiola1, Richard H Wiggins2, Devaprabu Abraham3
1From the Division of Endocrinology (T.J.B., D.A.), Department of Internal Medicine, University of Utah Health, Salt Lake City, Utah tess.j.lange@gmail.com.
Background And Purpose:
Radiofrequency ablation (RFA) has emerged as an effective nonsurgical treatment for symptomatic benign thyroid nodules and toxic adenomas. While post-RFA ultrasonographic changes are expected, they may inadvertently evoke alarm and prompt unnecessary interventions when risk stratification models such as the American College of Radiology Thyroid Imaging Reporting & Data System (ACR TI-RADS) are applied. This study aims to quantify ultrasound imaging changes of thyroid nodules using TI-RADS scoring before and after RFA and highlights that these changes should not be used as a basis for clinical action.
Materials And Methods:
This retrospective study analyzed patients who underwent RFA for symptomatic thyroid nodules at a quaternary care academic medical center between May 2021 and May 2024. All nodules were assessed using the ACR TI-RADS calculator and underwent fine-needle aspiration (FNA) biopsy before treatment. Following RFA, ultrasonography was conducted at 3-month intervals, and TI-RADS scores were reassessed. The primary end point was the change in TI-RADS classification following RFA.
Results:
A total of 28 nodules from 25 patients were monitored after RFA for a median follow-up duration of 419 days. Most (92.9%) were benign (Bethesda II) on FNA. The mean volume reduction ratio (VRR) was 66.7% (range 33.0% to 91.6%), with therapeutic success (VRR >50%) achieved in 86% of patients. Post-RFA risk stratification increased following RFA, with the mean TI-RADS score increasing from 3.04 to 4.25 (P < .001), predominantly driven by increased hypoechogenicity and new echogenic foci/calcifications.
Conclusions:
Thyroid nodules frequently undergo post-RFA structural changes that result in misleading upstaging on the ACR TI-RADS stratification system. These changes are expected and require cautious interpretation to avoid overdiagnosis, patient anxiety, and mismanagement.
