title: Intratumoral heterogeneity of breast cancer xenograft models: texture analysis of diffusion-weighted MR imaging.
abstract: OBJECTIVE
  To investigate whether there is a relationship between texture analysis parameters of apparent diffusion coefficient (ADC) maps and histopathologic features of MCF-7 and MDA-MB-231 xenograft models.
  
  
  METHODS
  MCF-7 estradiol (+), MCF-7 estradiol (-), and MDA-MB-231 xenograft models were made with approval of the animal care committee. Twelve tumors of MCF-7 estradiol (+), 9 tumors of MCF-7 estradiol (-), and 6 tumors in MDA-MB-231 were included. Diffusion-weighted MR images were obtained on a 9.4-T system. An analysis of the first and second order texture analysis of ADC maps was performed. The texture analysis parameters and histopathologic features were compared among these groups by the analysis of variance test. Correlations between texture parameters and histopathologic features were analyzed. We also evaluated the intraobserver agreement in assessing the texture parameters.
  
  
  RESULTS
  MCF-7 estradiol (+) showed a higher standard deviation, maximum, skewness, and kurtosis of ADC values than MCF-7 estradiol (-) and MDA-MB-231 (p < 0.01 for all). The contrast of the MCF-7 groups was higher than that of the MDA-MB-231 (p = 0.004). The correlation (COR) of the texture analysis of MCF-7 groups was lower than that of MDA-MB-231 (p < 0.001). The histopathologic analysis showed that Ki-67mean and Ki-67diff of MCF-7 estradiol (+) were higher than that of MCF-7 estradiol (-) or MDA-MB-231 (p < 0.05). The microvessel density (MVD)mean and MVDdiff of MDA-MB-231 were higher than those of MCF-7 groups (p < 0.001). A diffuse-multifocal necrosis was more frequently found in MDA-MB-231 (p < 0.001). The proportion of necrosis moderately correlated with the contrast (r = -0.438, p = 0.022) and strongly with COR (r = 0.540, p = 0.004). Standard deviation (r = 0.622, r = 0.437), skewness (r = 0.404, r = 0.484), and kurtosis (r = 0.408, r = 0.452) correlated with Ki-67mean and Ki-67diff (p < 0.05 for all). COR moderately correlated with Ki-67diff (r = -0.388, p = 0.045). Skewness (r = -0.643, r = -0.464), kurtosis (r = -0.581, r = -0.389), contrast (r = -0.473, r = -0.549) and COR (r = 0.588, r = 0.580) correlated with MVDmean and MVDdiff (p < 0.05 for all).
  
  
  CONCLUSIONS
  The texture analysis of ADC maps may help to determine the intratumoral spatial heterogeneity of necrosis patterns, amount of cellular proliferation and the vascularity in MCF-7 and MDA-MB-231 xenograft breast cancer models.
authors.affiliation: Department of Radiology, Seoul National University Hospital, Seoul National University College of Medicine, Seoul 110-744, Korea. ; Department of Radiology, Seoul National University Bundang Hospital, Seongnam 463-707, Korea.
authors.forename: Bo La
authors.initials: BL
authors.lastname: Yun
authors.affiliation: Department of Radiology, Seoul National University Hospital, Seoul National University College of Medicine, Seoul 110-744, Korea.
authors.forename: Nariya
authors.initials: N
authors.lastname: Cho
authors.affiliation: Department of Radiology, Seoul National University Hospital, Seoul National University College of Medicine, Seoul 110-744, Korea.
authors.forename: Mulan
authors.initials: M
authors.lastname: Li
authors.affiliation: Department of Pathology, Seoul National University Bundang Hospital, Seongnam 463-707, Korea.
authors.forename: Min Hye
authors.initials: MH
authors.lastname: Jang
authors.affiliation: Department of Pathology, Seoul National University Bundang Hospital, Seongnam 463-707, Korea.
authors.forename: So Yeon
authors.initials: SY
authors.lastname: Park
authors.affiliation: Department of Computer Science and Engineering, Seoul National University, Seoul 151-744, Korea.
authors.forename: Ho Chul
authors.initials: HC
authors.lastname: Kang
authors.affiliation: Department of Radiology, Seoul National University Bundang Hospital, Seongnam 463-707, Korea.
authors.forename: Bohyoung
authors.initials: B
authors.lastname: Kim
authors.affiliation: Department of Radiology, Seoul National University Hospital, Seoul National University College of Medicine, Seoul 110-744, Korea.
authors.forename: In Chan
authors.initials: IC
authors.lastname: Song
authors.affiliation: Department of Radiology, Seoul National University Hospital, Seoul National University College of Medicine, Seoul 110-744, Korea.
authors.forename: Woo Kyung
authors.initials: WK
authors.lastname: Moon
mesh_terms: D000818:Animals; D001943:Breast Neoplasms / Q000000981:diagnostic imaging* / Q000378:metabolism / Q000473:pathology; D045744:Cell Line, Tumor; D038524:Diffusion Magnetic Resonance Imaging; D004958:Estradiol / Q000378:metabolism; D005260:Female; D006801:Humans; D007090:Image Interpretation, Computer-Assisted; D007150:Immunohistochemistry; D019394:Ki-67 Antigen / Q000378:metabolism; D061986:MCF-7 Cells; D051379:Mice; D008819:Mice, Nude; D011859:Radiography; D014183:Transplantation, Heterologous
chemical_list: D019394:Ki-67 Antigen; D004958:Estradiol
keywords: Animal; Breast neoplasms; Computer-assisted; Diffusion magnetic resonance imaging; Image interpretation