Intraobserver and interobserver agreement of US findings in suspected lymph node metastasis in papillary thyroid carcinoma

Abstract

The reproducibility of ultrasound findings of suspected neck lymph node (LN) metastases in patients with papillary thyroid carcinoma (PTC) has not been sufficiently addressed. This prospective cohort study evaluated the intra- and interobserver agreement of ultrasound findings of suspected malignancy in neck LNs in patients with PTC. The US images were evaluated twice in a blinded, randomized, and independent manner by radiologists. Round morphology, absence of fatty hilum, echogenicity looking like thyroid tissue, microcalcifications, and peripheral vascularity were evaluated. Cohen’s kappa and Light’s kappa were used to determine intraobserver and interobserver agreement, respectively. Three radiologists with a mean experience of 6.7 ± 4.7 years in interpreting neck US assessed 114 ultrasound LN images. The ultrasound features with the highest intraobserver agreement were round morphology (κ = 0.63) and peripheral vascularity (κ = 0.67), both of which showed substantial agreement. Interobserver agreement was slight for round morphology (κ = 0.16), absence of fatty hilum (κ = 0.09), and echogenicity looking like thyroid tissue (κ = 0.09). There was moderate agreement for microcalcifications (κ = 0.43) and peripheral vascularity (κ = 0.49). The range of interobserver and intraobserver agreement of ultrasound findings suggestive of PTC metastasis to LNs was wide, even unacceptable, in the same radiologist and between radiologists.