Purpose The objective of this study was to compare the false negative rate, sensitivity and false positive rate of ultrasound (US)‐guided fine needle aspiration (FNA) with those of US‐guided core needle biopsy (CNB) for large thyroid nodules ≥2.0 cm, which reportedly have an increased risk of thyroid malignancy. Methods We retrospectively studied surgically confirmed thyroid nodules that had preoperative US‐guided FNA or CNB between March 2005 and December 2013. We reviewed nodule size, sonographic features, cytohistologic results, and final surgical pathology. We assessed false negative rates, sensitivity, and false positive rates by biopsy method and nodule size for diagnosis of thyroid malignancy. We assessed complications for procedures. Results US‐guided CNB showed better diagnostic performance, in terms of lower false negative rates and greater sensitivity, than US‐guided FNA in large thyroid nodules. There was no significant difference in false positive rate according to biopsy methods in large thyroid nodules. The false negative rates of large thyroid nodules (≥2.0 cm) were higher than those of small nodules (<2.0 cm). There were no major complications, and no significant differences in complication according to biopsy methods. Conclusion US‐guided CNB improved the false negative rate and sensitivity for large nodules. Therefore, US‐guided CNB can be considered a useful diagnostic method for large thyroid nodules that might reduce the risk of unnecessary diagnostic surgery.

Introduction This study sought to assess preoperative concurrent chemoradiotherapy (CRT) magnetic resonance imaging (MRI)‐based findings according to a structured MRI report template for primary staging of rectal cancer, and to evaluate the prognostic relevance of the pre‐CRT MRI‐based findings in patients with rectal cancer after CRT. Methods We retrospectively evaluated pre‐ and post‐CRT MRI data of patients with pathologically proven rectal adenocarcinoma, between January 2008 and October 2019. Image interpretation was performed independently by two radiologists and each reviewer assessed the cancer characteristics on MRI, based on the structured MRI report for primary staging. MRI‐based findings associated with pathologic complete tumour regression grade (TRG) after CRT were analysed by univariate and multivariate analysis. Significant factors from pre‐CRT MRI were weighted to score mrTRG in post‐CRT MRI. Results On univariate analysis, MR T‐stage, tumour infiltration, mesorectal fascia involvement, extramural vascular invasion and serum carcinoembryonic antigen level correlated significantly with pathologic complete response (pCR). Multivariate analysis identified that only MR T‐stage was independently associated with pCR (odds ratio, 3.89, 95% confidence interval, 1.18–12.84; P = 0.0278). Adding MRI‐based T2‐stage as an ancillary finding to mrTRG statistically significantly improved the sensitivity as compared to using only mrTRG for considering a CR. T2_mrTRG was significantly different in terms of the time to tumour progression between the CR and non‐CR group. Conclusions The MR T2‐stage was independently associated with pCR after CRT in patients with rectal cancer and was helpful as ancillary predictive factor, adding to mrTRG for prediction of pCR.

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