title: Gastrointestinal stromal tumours: correlation of modified NIH risk stratification with diffusion-weighted MR imaging as an imaging biomarker.
abstract: OBJECTIVE
  To evaluate the correlation of risk grade of gastrointestinal stromal tumours (GISTs) based on modified National Institutes of Health (NIH) criteria with conventional magnetic resonance (MR) imaging and diffusion-weighted (DW) imaging.
  
  
  METHODS
  We included 22 patients with histopathologically proven GISTs in the stomach or small bowel who underwent pre-operative gadoxetic acid-enhanced MR imaging and DW imaging. We retrospectively assessed correlations between morphologic findings, qualitative (signal intensity, consensus from two observers) and quantitative (degree of dynamic enhancement using signal intensity of tumour/muscle ratio and apparent diffusion coefficient [ADC]) values, and the modified NIH criteria for risk stratification. Spearman partial correlation analysis was used to control for tumour size as a confounding factor. The optimal cut-off level of ADC values for intermediate or high risk GISTs was analyzed using a receiver operating characteristic analysis.
  
  
  RESULTS
  Except tumour size and necrosis, conventional MR imaging findings, including the degree of dynamic enhancement, were not significantly different according to the modified NIH criteria (p>0.05). Tumour ADC values were negatively correlated with the modified NIH criteria, before and after adjustment of tumour size (ρ=-0.754; p<0.001 and ρ=-0.513; p=0.017, respectively). The optimal cut-off value for the determination of intermediate or high-risk GISTs was 1.279 × 10(-3)mm(2)/s (100% sensitivity, 69.2% specificity, 81.8% accuracy).
  
  
  CONCLUSIONS
  Except tumour size and necrosis, conventional MR imaging findings did not correlate with the risk grade. However, the ADC value can be used as an imaging biomarker to assess the risk grade of GISTs, regardless of tumour size.
authors.affiliation: Department of Radiology and Center for Imaging Science, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul 135-710, Republic of Korea.
authors.forename: Tae Wook
authors.initials: TW
authors.lastname: Kang
authors.affiliation: Department of Radiology and Center for Imaging Science, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul 135-710, Republic of Korea. Electronic address: kshyun@skku.edu.
authors.forename: Seong Hyun
authors.initials: SH
authors.lastname: Kim
authors.affiliation: Department of Radiology and Center for Imaging Science, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul 135-710, Republic of Korea.
authors.forename: Kyung Mi
authors.initials: KM
authors.lastname: Jang
authors.affiliation: Department of Radiology and Center for Imaging Science, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul 135-710, Republic of Korea.
authors.forename: Dongil
authors.initials: D
authors.lastname: Choi
authors.affiliation: Department of Pathology, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul 135-710, Republic of Korea.
authors.forename: Sang Yun
authors.initials: SY
authors.lastname: Ha
authors.affiliation: Department of Pathology, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul 135-710, Republic of Korea.
authors.forename: Kyoung-Mee
authors.initials: KM
authors.lastname: Kim
authors.affiliation: Division of Oncology, Department of Medicine, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul 135-710, Republic of Korea.
authors.forename: Won Ki
authors.initials: WK
authors.lastname: Kang
authors.affiliation: Biostatics Unit, Samsung Biomedical Research Institute, Samsung Medical Center, Seoul 135-710, Republic of Korea.
authors.forename: Min Ji
authors.initials: MJ
authors.lastname: Kim
mesh_terms: D000328:Adult; D000368:Aged; D038524:Diffusion Magnetic Resonance Imaging / Q000379:methods; D005260:Female; D019786:Gadolinium DTPA; D005770:Gastrointestinal Neoplasms / Q000000981:diagnostic imaging* / Q000473:pathology; D046152:Gastrointestinal Stromal Tumors / Q000000981:diagnostic imaging* / Q000473:pathology; D006801:Humans; D008297:Male; D008875:Middle Aged; D060787:Neoplasm Grading; D012372:ROC Curve; D011877:Radionuclide Imaging; D015203:Reproducibility of Results; D012189:Retrospective Studies; D012306:Risk; D012680:Sensitivity and Specificity
chemical_list: C073590:gadolinium ethoxybenzyl DTPA; D019786:Gadolinium DTPA
keywords: Apparent diffusion coefficient; Diffusion-weighted imaging; Gastrointestinal stromal tumour; Magnetic resonance imaging; Risk grade