Elastography-Based Evaluation of Treatment Response Following Radiofrequency Ablation of Thyroid Nodules

Summary

A standardized shear-wave and strain elastography follow-up protocol was applied before and after thyroid nodule radiofrequency ablation to quantify stiffness changes longitudinally. Using mixed-effects modeling and multivariable regression, early post-ablation elastography changes were independently associated with 12-month volume reduction response.

Abstract

Radiofrequency ablation (RFA) is an established minimally invasive treatment for benign thyroid nodules, yet response assessment relies largely on delayed volume reduction, limiting early post-procedural decision-making. In this retrospective cohort, participants with a single index thyroid nodule underwent standardized B-mode ultrasound and elastography at baseline, immediately post-ablation, and at 1, 3, 6, and 12 months. Shear-wave elastography (SWE) stiffness and strain ratio were acquired using prespecified regions of interest and quality-control criteria. Twelve-month response was defined by a volume reduction ratio (VRR) ≥ 50%. Longitudinal changes were evaluated using linear mixed-effects models, and immediate post-RFA elastography changes (immediate minus baseline) were related to 12-month VRR using correlation and multivariable regression adjusted for baseline nodule volume, nodule composition, delivered energy, and age. Among the 187 included participants, 146 were responders, and 41 were non-responders. SWE increased immediately after RFA in responders (31.5 ± 5.1 kPa to 41.7 ± 5.6 kPa) and non-responders (35.1 ± 5.3 kPa to 43.4 ± 5.8 kPa), followed by progressive decline with lower 12-month SWE in responders than non-responders (21.6 ± 4.7 vs 31.2 ± 5.2 kPa). VRR separated early, with 12-month VRR of 73.6 ± 6.9% in responders versus 38.5 ± 8.7% in non-responders. In mixed-effects models, the immediate SWE increase was significant (estimate +10.22 kPa, P < 0.001), and late group divergence was evident (non-responder × 12 months estimate +9.41 kPa, P < 0.001). Early elastography change correlated with 12-month VRR (Δstrain ratio: r = 0.445, P < 0.001; ΔSWE: r = 0.302, P < 0.001) and remained independently associated with VRR in adjusted models (Δstrain ratio β = 14.80% per +1.0, P < 0.001; ΔSWE β = 1.80% per +5 kPa, P = 0.011). Immediate post-RFA elastography changes capture early tissue effects and provide independent prognostic information for 12-month volumetric response.

Introduction

Thyroid nodules have become a defining “disease of detection” in modern endocrine practice, not because their biology has abruptly changed, but because imaging has made the thyroid exquisitely visible^1,2,3. The measured prevalence depends strongly on how nodules are sought: classic epidemiologic syntheses estimate 2%–6% by palpation, approximately 19%–35% by ultrasound, and up to about 8%–65% in autopsy series, illustrating how method sensitivity reshapes the apparent epidemiology¹. In iodine-deficient settings and with hi....

Protocol

Ethics statement
All procedures involving human participants were conducted in accordance with the institutional guidelines of Xingtai Hospital and in compliance with the principles of the Declaration of Helsinki and its later amendments. The study was reviewed and approved by the Human Research Ethics Committee of Xingtai Hospital; because all participants provided standard written clinical informed consent for RFA and ultrasound examinations as part of routine care, the committee approved the study with a waiver of additional written research consent and permitted verbal consent for study participation where required. Participant confidentiality....

Results

Study design and overall schematic
The excluded participants did not meet predefined eligibility criteria, had incomplete baseline imaging data, or lacked standardized longitudinal follow-up. Among the 187 included participants, complete 12-month outcome classification was available for all cases included in the primary analysis, although isolated intermittent missing observations at individual follow-up visits were accommodated within the mixed-effects modeling framework (Figure.......

Discussion

This study evaluated an elastography-based approach for assessing treatment response after RFA of thyroid nodules by using elastography as a quantitative imaging biomarker associated with post-ablation stiffness change. The central proposal is that stiffness, measured by SWE and strain elastography, can serve as an early indicator of ablation effect and a longitudinal marker of post-ablation remodeling, complementing conventional volume-based endpoints. The findings support this concept at two levels. First, both SWE sti.......

Materials

List of materials used in this article

Name	Company	Catalog Number	Comments
3M Tegaderm Film Dressing	Tegaderm	https://www.3m.com/3M/en_US/p/c/medical/bandages-dressings/film/i/health-care/medical/	Adhesive dressing; Post-procedure site coverage.
Disposable syringe	Becton Dickinson	BD 309628	Hydrodissection and local anesthetic administration
Grounding pads for RFA	3M Healthcare	Model 9547	Single-use return electrodes compatible with RF.
High-frequency linear-array transducer (5–14 MHz)	SuperSonic Imagine	SL15-4 linear probe	Thyroid ultrasound and elastography acquisition
High-frequency linear-array ultrasound transducer (7–15 MHz)	Mindray	L11-3U	Linear probe optimized for thyroid imaging and elastography.
IntelliVue	Philips Healthcare	MX450	Patient monitoring system; ECG, SpO2, noninvasive BP monitor during RFA.
IntelliVue	Philips Healthcare	MP50	Vital signs monitor; Continuous peri-procedural monitoring
Lidocaine hydrochloride injection	Hospira Inc.	NDC 0409-4276-17	Local anesthesia before ablation
lme4 package	CRAN	RRID:SCR_015654	Linear mixed-effects modeling in R.
lmerTest package	CRAN	RRID:SCR_015656	Mixed model testing and p-values in R.
Microflex Powder-Free Gloves	Ansell Healthcare		Aseptic barrier for procedural team.
Non-sterile ultrasound gel	EcoGel		Coupling medium for baseline and follow-up imaging.
Picture Archiving and Communication System (PACS)	GE Healthcare	Centricity PACS	Enterprise-grade image storage and retrieval system.
Povidone-Iodine 10%	Betadine		Pre-procedural antiseptic.
Precision Workstation	Dell	T5820	For image review and data analysis.
PrecisionGlide 22G–27G	BD (Becton Dickinson)	https://www.bd.com/en-us/products-and-solutions/products	Needle set for local anesthesia/hydrodissection.
Premixed Saline Bag 500 mL (0.9% NaCl)	Baxter Healthcare		Fluid for hydrodissection and flushing.
R statistical computing software	R Foundation	RRID:SCR_001905	Statistical analysis environment.
RFA percutaneous cooled electrode	STARmed Co., Ltd.	Star RF Electrode 18-10s10F	Active RFA electrode for thyroid ablation (TaeWoong Medical USA)
RStudio integrated development environment	Posit (formerly RStudio)	RRID:SCR_000432	IDE for R statistical analyses.
Shear-wave elastography software module	Mindray	SWE Module (RESONA Series)	Quantitative stiffness mapping in kPa within the US system.
Sterile drape kit	Medline Industries	DYNJP2500	Sterile preparation for thyroid RFA procedure
Sterile gauze and swabs	Covidien	Sterile Sponge Kit	Used for skin prep and hemostasis.
Sterile normal saline	Baxter Healthcare	2B1324X	Hydrodissection during thyroid RFA
Sterile procedure drapes (Blue Drape Pack)	Medline Industries		Standard drape for sterile percutaneous RFA setup.
Sterile ultrasound gel	Aquasonic 100	Conductive Gel 100 mL	Sterile coupling medium for US guidance.
Sterile ultrasound probe cover	Parker Laboratories	Model 1001	Sterile cover for intra-procedural imaging.
Strain elastography software module	Mindray	SE Module (RESONA Series)	Strain ratio calculation with integrated quality indicator.
Syringes (5/10/20 mL)	BD (Becton Dickinson)	Monoject Syringes	For anesthetic and hydrodissection delivery.
Three-way stopcock	BD (Becton Dickinson)	Model 305129	Stopcock and tubing for controlled fluid management.
Thyroid RF Electrode	STARmed Co., Ltd.	https://en.starmed4u.com/	Internally cooled RF electrode; Radiofrequency ablation of thyroid nodules
Ultrasound coupling gel	Parker Laboratories	Aquasonic 100	Ultrasound and elastography acquisition
Ultrasound imaging system with elastography capability	SuperSonic Imagine	Aixplorer	Used for B-mode ultrasound, Doppler imaging, SWE, and strain elastography
VIVA Combo RF Generator	STARmed Co., Ltd.		RF generator for percutaneous thyroid ablation (TaeWoong Medical USA)
VIVA RF Generator	STARmed Co., Ltd.		Ultrasound-guided thyroid radiofrequency ablation
Xylocaine 1% 10 mL	AstraZeneca		Local anesthetic (lidocaine) for procedural analgesia.