A novel collagen area fraction index to quantitatively assess bowel fibrosis in patients with Crohn’s disease oleh Xue-hua Li, Zhuang-nian Fang, Tian-ming Guan, Jin-jiang Lin, Can-hui Sun, Si-yun Huang, Ren Mao, Bao-lan Lu, Qing-hua Cao, Shi-ting Feng, Zi-ping Li