title: Correlation of ADC value with pathologic indexes in colorectal tumor homografts in Balb/c mouse.
abstract: OBJECTIVE
  Noninvasive diffusion-weighted magnetic resonance imaging (DWI) is a well-studied MR imaging technique for quantifying water diffusion especially in tumor area. The correlation between apparent diffusion coefficient (ADC) value and apoptosis or proliferation is not clear by now. This study aimed to investigate whether DWI-ADC value could be used as an imaging marker related with pathologic indexes of tumors.
  
  
  METHODS
  A total of 30 Balb/c mice with HT29 colorectal carcinoma were subjected to DWI and histologic analysis. The percentage of ADC changes and the apoptotic and proliferating indexes were calculated at predefined time points. Kolmogorov-Smirnov distances were considered to determine whether the percentage of ADC changes, and the apoptotic and proliferating indexes were normally distributed. An independent-samples t-test was used to analyze the difference between apoptotic and proliferating indexes in the two groups.
  
  
  RESULTS
  THERE WAS A STATISTICALLY SIGNIFICANT DIFFERENCE IN PROLIFERATING INDEX BETWEEN THE RADIOTHERAPY AND CONTROL GROUPS (MEAN PROLIFERATING INDEX: 49.27% vs. 83.09%), and there was a statistically significant difference in apoptotic index between the two groups (mean apoptotic index: 37.7% vs. 2.71%). A significant positive correlation was found between the percentage of ADC changes of the viable tissue and apoptotic index. Pearson's correlation coefficient was 0.655 (P=0.015). A significant negative correlation was found between the percentage of ADC changes of the viable tissue and ki-67 proliferation index. Pearson's correlation coefficient was 0.734 (P<0.001).
  
  
  CONCLUSIONS
  Our results suggest that ADC value may be used in measurement of cell apoptotic and proliferating indexes in colorectal carcinoma.
authors.affiliation: 1 Department of Radiology, 2 Department of Breast Surgery, the 2nd Hospital of Shanxi Medical University, Taiyuan 030001, China.
authors.forename: Xiaojun
authors.initials: X
authors.lastname: Li
authors.affiliation: 1 Department of Radiology, 2 Department of Breast Surgery, the 2nd Hospital of Shanxi Medical University, Taiyuan 030001, China.
authors.forename: Hongnan
authors.initials: H
authors.lastname: Jiang
authors.affiliation: 1 Department of Radiology, 2 Department of Breast Surgery, the 2nd Hospital of Shanxi Medical University, Taiyuan 030001, China.
authors.forename: Jinliang
authors.initials: J
authors.lastname: Niu
authors.affiliation: 1 Department of Radiology, 2 Department of Breast Surgery, the 2nd Hospital of Shanxi Medical University, Taiyuan 030001, China.
authors.forename: Ying
authors.initials: Y
authors.lastname: Zheng
keywords: Diffusion-weighted magnetic resonance imaging (DWI); HT29; apoptosis; apparent diffusion coefficient (ADC); proliferation