Objective To investigate the differential efficacy of ultrasound gray scale ratio (UGSR) in crumpled thyroid nodules (CTN) and papillary thyroid carcinoma (PTC) and the application value of combined C-TIRADS. Methods Eighty-six subjects with PTC (86 nodules) and 78 subjects with CTN (78 nodules) who were treated in Eastern Theater Command General Hospital Qinhuai Medical Treatment Area of the Chinese People’s Liberation Army from January 2018 to December 2022 were enrolled. Differences in nodule location

maximum diameter

and C-TIRADS positive features were compared; overall gray value

internal gray value

and edge gray value of nodules were measured

and UGSR was calculated and differences were compared. Logistic regression analysis was used to screen independent influencing factors on CTN

and ROC curves were plotted and area under the curve (AUC) calculated. Preoperative diagnosis of nodules based on C-TIRADS was reanalyzed using UGSR and efficacy was evaluated. Results Compared with PTC

CTN had no significant differences in C-TIRADS positive features and overall gray values (P > 0.05)

while it had significant differences in internal gray values

marginal gray values and UGSR (P < 0.05). Logistic regression analysis showed that UGSR was an independent influence factor on CTN (OR = 1.015

95% CI: 0.995-1.026

P=0.007) and had the highest AUC (0.867). UGSR improved the accuracy of the C-TIRADS score compared to the preoperative C-TIRADS score (PTC: χ2 =17.964

P=0.009; CTN: χ2 =10.904

P=0.010). Conclusion UGSR has good efficacy in distinguishing CTN from PTC and effectively improves the accuracy of C-TIRADS diagnosis

which is worthy of further promotion in the clinic.