title: Sandwich sign of Borrmann type 4 gastric cancer on diffusion-weighted magnetic resonance imaging.
abstract: OBJECTIVE
  To assess the appearance of Borrmann type 4 (BT-4) gastric cancer on diffusion-weighted magnetic resonance imaging (DWI) and to investigate the potential of qualitative and quantitative DW images analysis to differentiate BT-4 gastric cancer from poorly distended normal stomach wall.
  
  
  METHODS
  DWI was performed on 23 patients with BT-4 gastric cancer and 23 healthy volunteers. The signal characteristics and correlated histopathological basis of the cancers on DWI were investigated. The contrast-to-noise ratios (CNR) of cancer were compared between DWI and T1WI/T2WI(.) The thickness and apparent diffusion coefficient (ADC) of cancer and normal stomach wall were compared.
  
  
  RESULTS
  All of the gastric cancers displayed hyperintensity compared to the nearby normal gastric wall on DWI. A three-layer sandwich sign that demonstrated high signal intensity in the inner and outer layer, and low signal intensity in the intermediate layer was observed in 69.6% of cancers on DWI. The low signal intensity represents the muscularis propria through the comparison with pathology, and it is postulated that scattering distribution of the cancer cells in this layer causes less damage and subsequently less restriction of water movement, which causes the low signal intensity on DWI. The CNR obtained with DWI was higher than that with T1WI and T2WI (P<0.001). The mean ADC value of BT-4 gastric cancer was significantly lower than the poorly distended normal stomach wall (1.12 ± 0.23 × 10(-3)mm(2)/s vs. 1.9 3 ± 0.22 × 10(-3)mm(2)/s, P<0.01).
  
  
  CONCLUSIONS
  DWI can highlight the signals of BT-4 gastric cancer which may present a characteristic three-layer sandwich sign, and ADC values are helpful in the discrimination of gastric cancer from poorly distended stomach wall.
authors.affiliation: Key Laboratory of Carcinogenesis and Translational Research (Ministry of Education), Department of Radiology, Peking University School of Oncology, Beijing Cancer Hospital & Institute, No. 52 Fu Cheng Road, Hai Dian District, Beijing 100142, China. zxp@bjcancer.org
authors.forename: Xiao-Peng
authors.initials: XP
authors.lastname: Zhang
authors.forename: Lei
authors.initials: L
authors.lastname: Tang
authors.forename: Ying-Shi
authors.initials: YS
authors.lastname: Sun
authors.forename: Zi-Yu
authors.initials: ZY
authors.lastname: Li
authors.forename: Jia-Fu
authors.initials: JF
authors.lastname: Ji
authors.forename: Xiao-Ting
authors.initials: XT
authors.lastname: Li
authors.forename: Yi-Qiang
authors.initials: YQ
authors.lastname: Liu
authors.forename: Qi
authors.initials: Q
authors.lastname: Wu
mesh_terms: D000328:Adult; D000368:Aged; D038524:Diffusion Magnetic Resonance Imaging / Q000379:methods*; D005260:Female; D057918:Fiducial Markers; D006801:Humans; D008297:Male; D008875:Middle Aged; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013274:Stomach Neoplasms / Q000473:pathology*