A new thyroid imaging reporting and data system for nodules: Based on grayscale and color Doppler ultrasonography

•It is reported that radiating blood flow is an independent risk factor for thyroid cancer.•BUS TI-RADS based on radiating blood flow and other widely accepted grayscale US features was constructed.•BUS TI-RADS has higher diagnostic value, lower unnecessary FNA rate and false negative rate than ACR TI-RADS and C-TIRADS. To construct and validate a new thyroid imaging reporting and data system (TI-RADS) based on radiating blood flow and grayscale US features. This study enrolled patients from 4 hospitals from January 2018 to November 2023 retrospectively and prospectively. All US features associated with malignant thyroid nodules were assessed by multivariable logistic regression to construct baseline US TI-RADS (BUS TI-RADS), which was tested with internal validation set, external validation set and prospective validation set. Additionally, its potential of reducing biopsy was assessed. There were 2932 patients (2153 female, age: 42.83 ± 11.71; 779 male, age: 42.36 ± 11.78) with 3940 nodules (2831 malignant nodules and 1109 benign nodules). Independent predictive factors included composition, echogenicity, shape, margin, suspicious extrathyroidal extension, punctate echogenic foci, and radiating blood flow. Compared with American College of Radiology (ACR) TI-RADS and Chinese TI-RADS (C-TIRADS), the BUS TI-RADS had higher AUCs of 0.96 (95 % CI: [0.95, 0.97]; P