title: The influence of precompression on elasticity of thyroid nodules estimated by ultrasound shear wave elastography.
abstract: OBJECTIVE
  To investigate the influence of variations in resting pressure (precompression) on thyroid ultrasound supersonic shear wave elastography (SWE).
  
  
  METHODS
  Thirty-five normal thyroid glands (Norm), 55 benign hyperplastic nodules (BHN), and 17 papillary thyroid cancers (PTC) in 96 subjects underwent thyroid SWE. Four precompression levels were applied manually by the operator, ranging from A (baseline, 0 % strain) to D (high, 22-30 % strain). SWE results at each precompression level were compared using ANOVA tests with P < 0.05 indicating significance.
  
  
  RESULTS
  SWE indices were highest in PTC, followed by BHN and Norm at each precompression level (P < 0.05). All tissue types showed successive increases in SWE results as precompression increased, although the rate was higher for PTC than BHN and Norm (Ps < 0.05). SWE values (kPa) of Norm, BHN, and PTC at baseline precompression (A) were 10.3 ± 3.3, 17.7 ± 7.6, and 22.2 ± 11.9 compared with 21.1 ± 4.2, 42.3 ± 16.0, and 97.6 ± 46.8 at high precompression (D). SWE index differences between precompression levels A and D were 10.8 kPa for Norm, 24.6 kPa for BHN, and 75.4 kPa for PTC.
  
  
  CONCLUSIONS
  PTCs show greater SWE stiffening than BHN as precompression rises. Precompression effects on thyroid nodules are not negligible and may account for wide discrepancies in published SWE discriminatory performance results for thyroid malignancy.
  
  
  CONCLUSIONS
  • Increases in resting pressure (precompression) applied by the operator increases thyroid stiffness. • Papillary cancers show greater increases in stiffness (strain hardening) than benign nodules. • Precompression may affect the diagnostic performance of shearwave elastography for thyroid malignancy.
authors.affiliation: Department of Imaging and Interventional Radiology, The Chinese University of Hong Kong, Prince of Wales Hospital, Shatin, Hong Kong.
authors.forename: A C L
authors.initials: AC
authors.lastname: Lam
authors.affiliation: Department of Imaging and Interventional Radiology, The Chinese University of Hong Kong, Prince of Wales Hospital, Shatin, Hong Kong.
authors.forename: S W A
authors.initials: SW
authors.lastname: Pang
authors.affiliation: Department of Imaging and Interventional Radiology, The Chinese University of Hong Kong, Prince of Wales Hospital, Shatin, Hong Kong.
authors.forename: A T
authors.initials: AT
authors.lastname: Ahuja
authors.affiliation: Department of Imaging and Interventional Radiology, The Chinese University of Hong Kong, Prince of Wales Hospital, Shatin, Hong Kong. drkbhatia@cuhk.edu.hk.
authors.forename: K S S
authors.initials: KS
authors.lastname: Bhatia
mesh_terms: D000328:Adult; D002277:Carcinoma / Q000175:diagnosis; D002291:Carcinoma, Papillary; D004548:Elasticity; D054459:Elasticity Imaging Techniques / Q000379:methods*; D005260:Female; D006801:Humans; D008297:Male; D000077273:Thyroid Cancer, Papillary; D013964:Thyroid Neoplasms / Q000175:diagnosis; D016606:Thyroid Nodule / Q000175:diagnosis*; D014463:Ultrasonography / Q000379:methods*
keywords: Elastography; Precompression; Shear wave imaging; Thyroid nodules; Ultrasound