title: Interobserver variability of selective region-of-interest measurement protocols for quantitative diffusion weighted imaging in soft tissue masses: Comparison with whole tumor volume measurements.
abstract: BACKGROUND
  To assess the interobserver reliability of three selective region-of-interest (ROI) measurement protocols for apparent diffusion coefficient (ADC) quantifications in soft tissue masses (STMs) compared with whole tumor volume (WTV) ADC measurements.
  
  
  METHODS
  Institutional review board approval was obtained and informed consent was waived. Three observers independently measured minimum and mean ADCs of 73 benign and malignant musculoskeletal STMs using three selective methods (single-slice [SS], predefined three slices [PD], observer-based [OB]) and WTV measurements at 3.0 Tesla. Minimum and mean ADC values derived from each method were compared with WTV measurements, and inter-reader variation was assessed using the intraclass correlation coefficient (ICC). The time required for each method of ADC measurement was recorded.
  
  
  RESULTS
  For the SS, PD, OB, and WTV methods, minimum ADC values ((×10(-3) mm2 /s)) were 0.97, 0.78, 0.73, and 0.67, respectively, and mean ADC values ((×10(-3) mm2 /s)) were 1.49, 1.49, 1.51, and 1.49, respectively. Interobserver agreement was good to excellent for the minimum and mean ADC values for the three readers using the SS, PD, OB, and WTV (ICC range 0.78-0.90). The SS, PD and OB methods required the least amount of measurement time (14 ± 5, 40 ± 17, and 38 ± 15 s, respectively) while the reference WTV method required the longest measurement time (111 ± 54 s) (P < 0.01).
  
  
  CONCLUSIONS
  While all selective and WTV measurements offer good to excellent interobserver agreement, the selective OB method of ADC measurement results in the closest values to WTV measurements and requires significantly less measurement time than that required for the WTV method.
authors.affiliation: The Johns Hopkins Medical Institutions, The Russell H. Morgan Department of Radiology & Radiological Science, Baltimore, Maryland, USA.
authors.forename: Shivani
authors.initials: S
authors.lastname: Ahlawat
authors.affiliation: The Johns Hopkins Medical Institutions, The Russell H. Morgan Department of Radiology & Radiological Science, Baltimore, Maryland, USA.
authors.forename: Paras
authors.initials: P
authors.lastname: Khandheria
authors.affiliation: The Johns Hopkins Medical Institutions, The Russell H. Morgan Department of Radiology & Radiological Science, Baltimore, Maryland, USA.|Department of Radiology, Regional Hospital, Lugano, Switzerland.
authors.forename: Filippo
authors.initials: F
authors.lastname: Del Grande
authors.affiliation: Tulsa Radiology Associates, Tulsa, Oklahoma, USA.
authors.forename: John
authors.initials: J
authors.lastname: Morelli
authors.affiliation: Department of Radiology (R-109), University of Miami, Miami, Florida, USA.
authors.forename: Ty K
authors.initials: TK
authors.lastname: Subhawong
authors.affiliation: The Johns Hopkins Medical Institutions, The Russell H. Morgan Department of Radiology & Radiological Science, Baltimore, Maryland, USA.
authors.forename: Shadpour
authors.initials: S
authors.lastname: Demehri
authors.affiliation: The Johns Hopkins Medical Institutions, The Russell H. Morgan Department of Radiology & Radiological Science, Baltimore, Maryland, USA.
authors.forename: Laura M
authors.initials: LM
authors.lastname: Fayad
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002648:Child; D002675:Child, Preschool; D038524:Diffusion Magnetic Resonance Imaging / Q000379:methods*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D015588:Observer Variation; D015203:Reproducibility of Results; D012189:Retrospective Studies; D012680:Sensitivity and Specificity; D012983:Soft Tissue Neoplasms / Q000473:pathology*; D047368:Tumor Burden; D055815:Young Adult
keywords: ADC measurement; DWI; interobserver reliability; soft tissue masses