title: Multi-institutional validation of a novel textural analysis tool for preoperative stratification of suspected thyroid tumors on diffusion-weighted MRI.
abstract: OBJECTIVE
  Ultrasound-guided fine needle aspirate cytology fails to diagnose many malignant thyroid nodules; consequently, patients may undergo diagnostic lobectomy. This study assessed whether textural analysis (TA) could noninvasively stratify thyroid nodules accurately using diffusion-weighted MRI (DW-MRI).
  
  
  METHODS
  This multi-institutional study examined 3T DW-MRI images obtained with spin echo echo planar imaging sequences. The training data set included 26 patients from Cambridge, United Kingdom, and the test data set included 18 thyroid cancer patients from Memorial Sloan Kettering Cancer Center (New York, New York, USA). Apparent diffusion coefficients (ADCs) were compared over regions of interest (ROIs) defined on thyroid nodules. TA, linear discriminant analysis (LDA), and feature reduction were performed using the 21 MaZda-generated texture parameters that best distinguished benign and malignant ROIs.
  
  
  RESULTS
  Training data set mean ADC values were significantly different for benign and malignant nodules (P = 0.02) with a sensitivity and specificity of 70% and 63%, respectively, and a receiver operator characteristic (ROC) area under the curve (AUC) of 0.73. The LDA model of the top 21 textural features correctly classified 89/94 DW-MRI ROIs with 92% sensitivity, 96% specificity, and an AUC of 0.97. This algorithm correctly classified 16/18 (89%) patients in the independently obtained test set of thyroid DW-MRI scans.
  
  
  CONCLUSIONS
  TA classifies thyroid nodules with high sensitivity and specificity on multi-institutional DW-MRI data sets. This method requires further validation in a larger prospective study. Magnetic Resonance in Medicine published by Wiley Periodicals, Inc. on behalf of International Society for Magnetic Resonance.
authors.affiliation: Cancer Research UK Cambridge Institute, University of Cambridge, Li Ka Shing Centre, Robinson Way, Cambridge, United Kingdom.|Duke University School of Medicine, Durham, North Carolina, USA.
authors.forename: Anna M
authors.initials: AM
authors.lastname: Brown
authors.affiliation: Addenbrooke's Hospital Department of Otolaryngology, Cambridge, United Kingdom.
authors.forename: Sidhartha
authors.initials: S
authors.lastname: Nagala
authors.affiliation: Cancer Research UK Cambridge Institute, University of Cambridge, Li Ka Shing Centre, Robinson Way, Cambridge, United Kingdom.
authors.forename: Mary A
authors.initials: MA
authors.lastname: McLean
authors.affiliation: Department of Medical Physics, Memorial Sloan Kettering Cancer Center, New York, New York, USA.
authors.forename: Yonggang
authors.initials: Y
authors.lastname: Lu
authors.affiliation: Addenbrooke's Hospital Department of Radiology, Cambridge, United Kingdom.
authors.forename: Daniel
authors.initials: D
authors.lastname: Scoffings
authors.affiliation: Department of Medical Physics, Memorial Sloan Kettering Cancer Center, New York, New York, USA.
authors.forename: Aditya
authors.initials: A
authors.lastname: Apte
authors.affiliation: Department of Epidemiology and Biostatistics, Memorial Sloan Kettering Cancer Center, New York, New York, USA.
authors.forename: Mithat
authors.initials: M
authors.lastname: Gonen
authors.affiliation: Department of Radiology, Memorial Sloan Kettering Cancer Center, New York, New York, USA.
authors.forename: Hilda E
authors.initials: HE
authors.lastname: Stambuk
authors.affiliation: Department of Surgery, Memorial Sloan Kettering Cancer Center, New York, New York, USA.
authors.forename: Ashok R
authors.initials: AR
authors.lastname: Shaha
authors.affiliation: Department of Medicine, Memorial Sloan Kettering Cancer Center, New York, New York, USA.
authors.forename: R Michael
authors.initials: RM
authors.lastname: Tuttle
authors.affiliation: Department of Medical Physics, Memorial Sloan Kettering Cancer Center, New York, New York, USA.
authors.forename: Joseph O
authors.initials: JO
authors.lastname: Deasy
authors.affiliation: Addenbrooke's Hospital Department of Radiology, Cambridge, United Kingdom.
authors.forename: Andrew N
authors.identifier: http://orcid.org/0000-0002-9771-4290
authors.initials: AN
authors.lastname: Priest
authors.affiliation: Cambridge Teaching Hospitals ENT Department, Cambridge, United Kingdom.
authors.forename: Piyush
authors.initials: P
authors.lastname: Jani
authors.affiliation: Department of Medical Physics, Memorial Sloan Kettering Cancer Center, New York, New York, USA.|Department of Radiology, Memorial Sloan Kettering Cancer Center, New York, New York, USA.
authors.forename: Amita
authors.initials: A
authors.lastname: Shukla-Dave
authors.affiliation: Cancer Research UK Cambridge Institute, University of Cambridge, Li Ka Shing Centre, Robinson Way, Cambridge, United Kingdom.
authors.forename: John
authors.initials: J
authors.lastname: Griffiths
mesh_terms: D000328:Adult; D000368:Aged; D019540:Area Under Curve; D015331:Cohort Studies; D038524:Diffusion Magnetic Resonance Imaging / Q000379:methods*; D005260:Female; D006801:Humans; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D008297:Male; D008875:Middle Aged; D015203:Reproducibility of Results; D013961:Thyroid Gland / Q000000981:diagnostic imaging*; D013964:Thyroid Neoplasms / Q000000981:diagnostic imaging*
keywords: diffusion-weighted MRI; textural analysis; thyroid tumors