Usefulness of ultrasound quantitative assessment of microvascularity in the thyroid nodule risk stratification.

Purpose: We primarily assessed the capability of ultrasound quantitative microvascularity imaging (qMI) in identifying high risk thyroid nodules. In addition, the diagnostic performance of computer aided diagnosis (CAD) was evaluated and correlated with qMI and cytology results.

Methods: This single centre prospective study was carried out from 2023 to 2024 and included 165 target thyroid nodules,that were assessed by using CAD for semi-automatic EU-TIRADS classification and qMI, that. Subsequently, all nodules underwent Fine Needle Aspiration Biopsy and Cytology. CAD derived EU-TIRADS and qMI results (Vascularity Index - VI) were correlated with cytology results, that were used as a reference standard, using regression analyses.

Results: Target nodules showed mean size of 15.6 mm ± 9 (range 4-40 mm) and mean vascularity index of 29.03% ± 24.3 (range 0-98.7%)at qMI analysis. Mean vascularity index of 'benign' nodules (TIR2) and low risk nodules (TIR3A) was 35% (range 5-98.7%), that was significantly higher than that of high risk (TIR3B) and malignant nodules (TIR 4/5) (24.2%, p = 0.04.). However, within the malignant group, small nodules (< 10 mm) showed higher vascularity mean VI = 31.45%) than larger nodules (mean VI = 16.91%, p = 0.03). CAD showed very high overall sensitivity and specificity for all EU-TIRADS, allowing for EU-TIRADS 3 and 4 nodules.

Conclusion: Vascularity index showed a weak relationship with nodule size and cytology results. High vascularity may be observed more frequently in small malignant tumours and large benign tumours. Some EU-TIRADS 3 and 4 nodules may benefit of qMI assessment, as CAD shows lower accuracy.