title: Cystic change in thyroid nodules: a confounding factor for real-time qualitative thyroid ultrasound elastography.
abstract: OBJECTIVE
  To evaluate real-time qualitative ultrasound elastography for focal thyroid masses undergoing fine-needle aspiration in a routine thyroid ultrasound clinic.
  
  
  METHODS
  Ninety-four thyroid nodules scheduled for fine-needle aspiration cytology in a thyroid ultrasound clinic also underwent real-time freehand elastography. Colour-scaled elastograms were graded visually on the stiffness of the solid component of nodules relative to thyroid parenchyma using an elastography score (ES) scale from 1 (soft) to 4 (stiff). The ES for benign and malignant nodules and the influence of cystic change on ES were analysed using Chi-square with trend and Fishers exact tests, with a p<0.05 used to indicate statistical significance.
  
  
  RESULTS
  There were 19 papillary carcinomas, five metastases, 57 hyperplastic nodules, and four follicular adenomas based on definitive cytology (n=54) or histology (n=31). Nine nodules were excluded due to indeterminate cytology and no histology. Of malignancies (all solid), two were ES=1, four were ES=2, eight were ES=3, and 10 were ES=4. Of benign nodules, 17 were ES=1, 17 were ES=2, 16 were ES=3, and 11 were ES=4. An ES>2 was more common in benign nodules with predominant cystic components (17/18) than mildly cystic (3/12) or completely solid (7/31) benign nodules (p=0.0004, p<0.0001). The ES was not significantly different between benign and malignant nodules (p=0.09) unless partially cystic nodules were excluded (p=0.005). For solid nodules, an ES>2 optimally predicted malignancy, achieving 74% sensitivity, 77% specificity, and 76% accuracy.
  
  
  CONCLUSIONS
  Qualitative real-time thyroid elastography predicts malignancy only if predominantly cystic nodules are excluded, which may limit its utility in routine clinical practice.
authors.affiliation: Department of Imaging & Interventional Radiology, The Chinese University of Hong Kong, Prince of Wales Hospital, Shatin N.T, Hong Kong, PR China.
authors.forename: K S S
authors.initials: KS
authors.lastname: Bhatia
authors.forename: D P
authors.initials: DP
authors.lastname: Rasalkar
authors.forename: Y P
authors.initials: YP
authors.lastname: Lee
authors.forename: K T
authors.initials: KT
authors.lastname: Wong
authors.forename: A D
authors.initials: AD
authors.lastname: King
authors.forename: H Y
authors.initials: HY
authors.lastname: Yuen
authors.forename: A T
authors.initials: AT
authors.lastname: Ahuja
mesh_terms: D000236:Adenoma / Q000000981:diagnostic imaging* / Q000473:pathology; D000368:Aged; D044963:Biopsy, Fine-Needle; D002291:Carcinoma, Papillary / Q000000981:diagnostic imaging* / Q000473:pathology; D015331:Cohort Studies; D003560:Cysts / Q000000981:diagnostic imaging*; D054459:Elasticity Imaging Techniques / Q000379:methods*; D005260:Female; D006801:Humans; D007090:Image Interpretation, Computer-Assisted / Q000379:methods; D008297:Male; D008875:Middle Aged; D015203:Reproducibility of Results; D013964:Thyroid Neoplasms / Q000000981:diagnostic imaging* / Q000473:pathology; D016606:Thyroid Nodule / Q000000981:diagnostic imaging* / Q000473:pathology