title: Bayesian analysis of high-resolution ultrasonography and guided fine needle aspiration cytology in diagnosis of palpable thyroid nodules.
abstract: BACKGROUND
  To evaluate diagnostic accuracy of high-resolution ultrasonography in differentiation of benign and malignant thyroid nodules in comparison to results of guided fine needle aspiration cytology based on the Bayes rule.
  
  
  OBJECTIVE
  To assess the validity of ultrasonography results of thyroid nodules in comparison to guided fine needle aspiration cytology findings.
  
  
  METHODS
  This study was done on randomly chosen 80 patients presented with palpable thyroid nodules, undergone real-time sonographic evaluation of thyroid nodules to characterize features, internal consistency, margins, echotexture, calcification, peripheral lucent halo and vascularity. Ultrasonography guided fine needle aspiration cytology studies of thyroid nodules were done.
  
  
  RESULTS
  Palpable thyroid nodules were highly prevalent in fourth and fifth decades of life with female-male ratio, 4:1. Solid internal consistency was demonstrated by 75% malignant nodules. Hypoechogenicity and intra-nodular micro-calcifications were observed in 92% malignant nodules; 83% malignant nodules had intra-nodular vascularity and absence of peripheral halo. The pre-test prevalence of malignant nodules in the targeted population was 17.5%. As type I error, 2.5% false-positive cases and as type II error, 5.0% false-negative cases were detected. Values of sensitivity and specificity of the ultrasonography test were 71.43 and 96.97%, respectively.
  
  
  CONCLUSIONS
  Malignant thyroid nodules demonstrated ultrasonography characteristics of hypoechoic texture, intra-nodular micro-calcifications, solid consistency, internal vascularity and absence of peripheral halo. The ultrasonography test has 92.5% diagnostic accuracy to differentiate malignant from benign lesions in comparison to the gold standard fine needle aspiration cytology test.
authors.affiliation: Siksha 'O' Anusandhan University, Institute of Medical Sciences and Sum Hospital, Department of Radiodiagnosis, Odisha, India.
authors.forename: Niranjan
authors.initials: N
authors.lastname: Sahu
authors.affiliation: Siksha 'O' Anusandhan University, Institute of Medical Sciences and Sum Hospital, Central Research Laboratory, Odisha, India. Electronic address: rnpadhy54@gmail.com.
authors.forename: Rabindra Nath
authors.initials: RN
authors.lastname: Padhy
keywords: Bayes rule; Bócio coloide; Colloid goiter; High-resolution ultrasonography; Malignant thyroid nodule; Nódulo maligno da tireoide; Regra de Bayes; Sensibilidade e especificidade; Sensitivity and specificity; Ultrassonografia de alta resolução