Comparison of contrast-enhanced ultrasound characteristics of inflammatory thyroid nodules and papillary thyroid carcinomas using a quantitative time-intensity curve: a propensity score matching analysis

BACKGROUND: This study aims to compare the contrast-enhanced ultrasound (CEUS) characteristics of inflammatory thyroid nodules with those of papillary thyroid carcinomas using time-intensity curve (TIC) analysis. METHODS: This was a retrospective cohort study. Among the thyroid nodules in 2161 patients who underwent CEUS from July 2014 to April 2018, 44 nodules in 44 patients ultimately diagnosed as inflammatory nodules and 44 nodules in 44 patients confirmed as papillary carcinomas (enrolled from July 2016 to April 2018) were included after propensity score matching analysis (1:1). The average diameters of lesions in the inflammatory and malignant groups (n=44 each) were 0.92±0.34 cm and 0.89±0.42 cm, respectively. CEUS patterns were evaluated and classified into four types, namely concentric hypo-enhancement, heterogeneous hypo-enhancement, hypo-enhancement with a sharp margin, and homogeneous hyper/iso-enhancement. The measured TIC parameters included peak intensity (PI), rise time (RT), time to peak (TTP), maximum slope rate of the ascending curve (AS), and maximum slope rate of the descending curve (DS). The CEUS patterns and TIC parameters were compared between the inflammatory nodules and papillary carcinomas. RESULTS: The heterogeneous hypo-enhancement CEUS pattern was predominantly present in the inflammatory nodules. The concentric hypo-enhancement pattern was identified as a valuable predictive pattern for papillary carcinomas. For the TIC, inflammatory nodules had a lower PI [55.42 (45.41, 76.91) vs. 84.43 (74.93, 90.92)] [median (interquartile range)] and a smaller AS [22.39 (13.37, 29.93) vs. 29.54 (19.37, 44.77)], compared with papillary carcinomas (P<0.05). CONCLUSIONS: CEUS patterns with TIC parameters could provide effective and quantitative information for characterizing microvascular perfusion of inflammatory thyroid nodules and papillary carcinomas.