Abstract
BACKGROUND/AIM: Diffraction enhanced imaging (DEI) is a synchrotron radiation X-ray phase-contrast imaging technique that can better reveal the microstructure of biological soft tissues than conventional X-rays. The aim of this study is to investigate the angio-architectural changes of the liver during fibrosis, cirrhosis and its subsequent regression by applying synchrotron radiation based DEI. METHODS: DEI experiments were performed at the 4W1A station of Beijing Synchrotron Radiation Facility. Twenty-four Sprague-Dawley rats were induced with liver fibrosis by carbon tetrachloride (CCl4) for up to 10 weeks, after which spontaneous regression started and continued until week 30. Quantitative analysis of the DEI images yielded the mean vascular density and intercapillary distance, which was then re-confirmed by immunohistochemical analysis of CD34. RESULTS: Based on the DEI results, the mean vascular density was 1.4-fold higher in fibrotic rats (at week 6) and 2-fold higher in cirrhotic rats (at week 10) compared with the control (p<0.05). Accordingly, the intercapillary distance decreased to 563.89 ± 243.35 µm in fibrotic rats and 392.90 ± 92.68 µm in cirrhotic rats compared with 673.85 ± 214.16 µm in the control (p<0.05). During fibrosis regression at week 30, vascular density was 0.7-fold lower and intercapillary distance increased to 548.60 ± 210.94 µm as compared with cirrhotic rats (p<0.05).In parallel to the DEI results, immunohistochemical analysis of CD34 showed similar changes. CONCLUSION: Synchrotron-based DEI can conduct radiological as well as pathological analysis. Our results are consistent with previous reports indicating that angiogenesis is directly proportional to fibrosis progression. Furthermore, by clarifying the vascular characteristics of liver diseases, DEI reveals that cirrhosis cannot fully reverse during fibrosis regression.