title: Repeatability Investigation of Reduced Field-of-View Diffusion-Weighted Magnetic Resonance Imaging on Thyroid Glands.
abstract: OBJECTIVE
  To investigate the repeatability of the quantitative magnetic resonance imaging (MRI) metric (apparent diffusion coefficient [ADC]) derived from reduced field-of-view diffusion-weighted (rFOV DWI) on thyroid glands in a clinical setting.
  
  
  METHODS
  Ten healthy human volunteers were enrolled in MRI studies performed on a 3-T MRI scanner. Each volunteer was designed to undergo 3 longitudinal examinations (2 weeks apart) with 2 repetitive sessions within each examination, which included rFOV and conventional full field-of-view (fFOV) DWI scans. Diffusion-weighted images were assessed and scored based on image characteristics. Apparent diffusion coefficient values of thyroid glands from all participants were calculated based on regions of interest. Repeatability analysis was performed based on the framework proposed by the Quantitative Imaging Biomarker Alliance, generating 4 repeatability metrics: within-participant variance ((Equation is included in full-text article.)), repeatability coefficients, intraclass correlation coefficient, and within-participant coefficient of variation. Student t test was used to compare the performance difference between rFOV and fFOV DWI.
  
  
  RESULTS
  The overall image quality from rFOV DWI was significantly higher than that from fFOV DWI (P = 0.04). The ADC values calculated from rFOV DWI were significantly lower than corresponding values from fFOV DWI (P < 0.001). There was no significant difference in ADC values across sessions and examinations in either rFOV or fFOV DWI (P > 0.05). Reduced field-of-view DWI had lower values of (Equation is included in full-text article.), repeatability coefficient, and within-participant coefficient of variation and had a higher value of intraclass correlation coefficient compared with fFOV DWI across either sessions or examinations.
  
  
  CONCLUSIONS
  This study demonstrated that rFOV DWI produced more superior-quality DWI images and more repeatable ADC measurements compared with fFOV DWI, thus providing a feasible quantitative imaging tool for investigating thyroid glands in clinical settings.
authors.affiliation: From the Departments of *Medical Physics and †Radiology, Memorial Sloan-Kettering Cancer Center, New York, NY; ‡Global Applied Sciences Laboratory, GE Healthcare, Menlo Park, CA; and Departments of §Epidemiology and Biostatistics, ∥Surgery, and ¶Medicine, Memorial Sloan-Kettering Cancer Center, New York, NY.
authors.forename: Yonggang
authors.initials: Y
authors.lastname: Lu
authors.forename: Vaios
authors.initials: V
authors.lastname: Hatzoglou
authors.forename: Suchandrima
authors.initials: S
authors.lastname: Banerjee
authors.forename: Hilda E
authors.initials: HE
authors.lastname: Stambuk
authors.forename: Mithat
authors.initials: M
authors.lastname: Gonen
authors.forename: Ajit
authors.initials: A
authors.lastname: Shankaranarayanan
authors.forename: Yousef
authors.initials: Y
authors.lastname: Mazaheri
authors.forename: Joseph O
authors.initials: JO
authors.lastname: Deasy
authors.forename: Ashok R
authors.initials: AR
authors.lastname: Shaha
authors.forename: R Michael
authors.initials: RM
authors.lastname: Tuttle
authors.forename: Amita
authors.initials: A
authors.lastname: Shukla-Dave
mesh_terms: D000328:Adult; D000465:Algorithms; D038524:Diffusion Magnetic Resonance Imaging / Q000379:methods*; D006801:Humans; D007089:Image Enhancement / Q000379:methods*; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D008875:Middle Aged; D012016:Reference Values; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013961:Thyroid Gland / Q000033:anatomy & histology*; D055815:Young Adult