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

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.