title: Apparent diffusion coefficient measurements in diffusion-weighted magnetic resonance imaging of the anterior mediastinum: inter-observer reproducibility of five different methods of region-of-interest positioning.
abstract: OBJECTIVE
  To investigate inter-reader reproducibility of five different region-of-interest (ROI) protocols for apparent diffusion coefficient (ADC) measurements in the anterior mediastinum.
  
  
  METHODS
  In eighty-one subjects, on ADC mapping, two readers measured the ADC using five methods of ROI positioning that encompassed the entire tissue (whole tissue volume [WTV], three slices observer-defined [TSOD], single-slice [SS]) or the more restricted areas (one small round ROI [OSR]), multiple small round ROI [MSR]). Inter-observer variability was assessed with interclass correlation coefficient (ICC), coefficient of variation (CoV), and Bland-Altman analysis. Nonparametric tests were performed to compare the ADC between ROI methods. The measurement time was recorded and compared between ROI methods.
  
  
  RESULTS
  All methods showed excellent inter-reader agreement with best and worst reproducibility in WTV and OSR, respectively (ICC, 0.937/0.874; CoV, 7.3 %/16.8 %; limits of agreement, ±0.44/±0.77 × 10-3mm2/s). ADC values of OSR and MSR were significantly lower compared to the other methods in both readers (p < 0.001). The SS and OSR methods required less measurement time (14 ± 2 s) compared to the others (p < 0.0001), while the WTV method required the longest measurement time (90 ± 56 and 77 ± 49 s for each reader) (p < 0.0001).
  
  
  CONCLUSIONS
  All methods demonstrate excellent inter-observer reproducibility with the best agreement in WTV, although it requires the longest measurement time.
  
  
  CONCLUSIONS
  • All ROI protocols show excellent inter-observer reproducibility. • WTV measurements provide the most reproducible ADC values. • ROI size and positioning influence ADC measurements in the anterior mediastinum. • ADC values of OSR and MSR are significantly lower than other methods. • OSR and WTV methods require the shortest and longest measurement time, respectively.
authors: Department of Diagnostic Imaging, San Luigi Gonzaga University Hospital, Regione Gonzole 10, 10043, Orbassano, Torino, Italy. adriano.priola@inwind.it.
authors: Adriano Massimiliano
authors: AM
authors: Priola
authors: Department of Diagnostic Imaging, San Luigi Gonzaga University Hospital, Regione Gonzole 10, 10043, Orbassano, Torino, Italy.
authors: Sandro Massimo
authors: SM
authors: Priola
authors: Department of Diagnostic Imaging, San Luigi Gonzaga University Hospital, Regione Gonzole 10, 10043, Orbassano, Torino, Italy.
authors: Daniela
authors: D
authors: Parlatano
authors: Department of Diagnostic Imaging, San Luigi Gonzaga University Hospital, Regione Gonzole 10, 10043, Orbassano, Torino, Italy.
authors: Dario
authors: D
authors: Gned
authors: Department of Mathematics "Giuseppe Peano", University of Torino, Via Carlo Alberto 10, 10123, Torino, Italy.
authors: Maria Teresa
authors: MT
authors: Giraudo
authors: Department of Thoracic Surgery, San Luigi Gonzaga University Hospital, Regione Gonzole 10, 10043, Orbassano, Torino, Italy.
authors: Roberto
authors: R
authors: Giardino
authors: Department of Neurology, San Luigi Gonzaga University Hospital, Regione Gonzole 10, 10043, Orbassano, Torino, Italy.
authors: Bruno
authors: B
authors: Ferrero
authors: Department of Thoracic Surgery, San Luigi Gonzaga University Hospital, Regione Gonzole 10, 10043, Orbassano, Torino, Italy.
authors: Francesco
authors: F
authors: Ardissone
authors: Department of Diagnostic Imaging, San Luigi Gonzaga University Hospital, Regione Gonzole 10, 10043, Orbassano, Torino, Italy.
authors: Andrea
authors: A
authors: Veltri
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002648:Child; D038524:Diffusion Magnetic Resonance Imaging / Q000379:methods*; D005260:Female; D006801:Humans; D008297:Male; D008479:Mediastinal Neoplasms / Q000000981:diagnostic imaging*; D008482:Mediastinum / Q000000981:diagnostic imaging*; D008875:Middle Aged; D015588:Observer Variation; D056888:Patient Positioning / Q000379:methods*; D015203:Reproducibility of Results; D012189:Retrospective Studies; D055815:Young Adult
keywords: Anterior mediastinum; Apparent diffusion coefficient; Diffusion-weighted magnetic resonance imaging; Inter-observer variability; Region of interest