title: Use of conventional MR imaging and diffusion-weighted imaging for evaluating the risk grade of gastrointestinal stromal tumors.
abstract: OBJECTIVE
  To study the risk grade of gastrointestinal stromal tumors (GISTs) with conventional MR imaging and diffusion-weighted imaging (DWI).
  
  
  METHODS
  The abdominal MR images with DWI of 23 patients with pathologically proven GISTs during January 2010 to May 2011 were retrospectively reviewed. The conventional MR imaging findings and apparent diffusion coefficient (ADC) values of the tumors related to the risk grade were analyzed.
  
  
  RESULTS
  In the 23 patients, there were 13 patients with high-risk, 5 with medium-risk, 5 with low-risk, and 0 with very low-risk GISTs. Most of the conventional MR findings of the tumors did not correlate with the risk grade. The only exception to this was the correlation between risk grade and the enhancement degree of the tumor after Gd-DTPA. The ADC values were, respectively, (1.04 ± 0.13) × 10(-3) mm(2) ·s(-1) , (1.59 ± 0.06) × 10(-3) mm(2) ·s(-1) and (1.94 ± 0.08) × 10(-3) mm(2) ·s(-1) (P < 0.05) in the high-, medium-, and low-risk grade groups. The ADC values of GISTs decreased with the increase of the risk grade of the tumors (r = -0.957; P < 0.05).
  
  
  CONCLUSIONS
  DWI can be used to assess the risk grade of GISTs, but conventional MR imaging is of limited use.
authors.affiliation: Sichuan Key Laboratory of Medical Imaging, Department of Radiology, Affiliated Hospital of North Sichuan Medical College, Sichuan, China.
authors.forename: Hai Ying
authors.initials: HY
authors.lastname: Zhou
authors.forename: Xiao Ming
authors.initials: XM
authors.lastname: Zhang
authors.forename: Nan Lin
authors.initials: NL
authors.lastname: Zeng
authors.forename: Shun Hai
authors.initials: SH
authors.lastname: Jian
authors.forename: Wei
authors.initials: W
authors.lastname: Tang
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D038524:Diffusion Magnetic Resonance Imaging / Q000379:methods*; D005260:Female; D005770:Gastrointestinal Neoplasms / Q000473:pathology*; D046152:Gastrointestinal Stromal Tumors / Q000473:pathology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D060787:Neoplasm Grading; D015203:Reproducibility of Results; D012307:Risk Factors; D012680:Sensitivity and Specificity