Apparent Diffusion Coefficient as a Predictor of Microwave Ablation Response in Thyroid Nodules: A Prospective Study

Area of Science:

• Radiology
• Oncology
• Medical Imaging

Background:

• Microwave ablation (MWA) is a minimally invasive treatment for benign thyroid nodules, but outcomes vary.
• Predictive imaging biomarkers are needed to optimize patient selection for MWA.
• Diffusion-weighted MRI (DW-MRI) measures tissue microstructure via apparent diffusion coefficient (ADC), potentially correlating with MWA efficacy.

Purpose of the Study:

• To investigate if baseline ADC values from DW-MRI can predict volumetric outcomes after MWA for benign thyroid nodules.
• To identify imaging biomarkers for optimizing patient selection and improving MWA treatment outcomes.

Main Methods:

• Prospective study of 48 patients with 50 benign thyroid nodules undergoing MWA.
• Pre-ablation DW-MRI to measure baseline ADC values.
• Ultrasound assessment of nodule volume at baseline and 1, 3, and 6 months post-MWA.
• Calculation of volume reduction ratio (VRR) and correlation analysis with baseline ADC.
• ROC curve analysis to evaluate ADC's predictive performance for significant volume reduction (VRR ≥ 50%).

Main Results:

• Lower baseline ADC values strongly correlated with greater VRR at 3 and 6 months post-MWA (r = -0.525 and -0.564, respectively; p < 0.001).
• Baseline ADC was the sole independent predictor of 6-month VRR (β = -19.52, p = 0.0004).
• ROC analysis showed excellent discrimination (AUC = 0.915), with an ADC cutoff of 2.20 × 10⁻³ mm²/s predicting favorable volumetric response with 90.9% sensitivity and 83.3% specificity.

Conclusions:

• Baseline ADC values from DW-MRI are strong predictors of volumetric response after MWA for benign thyroid nodules.
• Incorporating ADC assessment in pre-ablation evaluations may enhance patient selection.
• Utilizing ADC measurements can potentially improve therapeutic outcomes for MWA treatments.