Original Article
Copyright ©2012 Baishideng Publishing Group Co., Limited. All rights reserved.
World J Gastroenterol. Dec 28, 2012; 18(48): 7225-7233
Published online Dec 28, 2012. doi: 10.3748/wjg.v18.i48.7225
Magnetic resonance-based total liver volume and magnetic resonance-diffusion weighted imaging for staging liver fibrosis in mini-pigs
Hang Li, Tian-Wu Chen, Xiao-Li Chen, Xiao-Ming Zhang, Zhen-Lin Li, Nan-Lin Zeng, Li Zhou, Li-Ying Wang, Hong-Jie Tang, Chun-Ping Li, Li Li, Xian-Yong Xie
Hang Li, Tian-Wu Chen, Xiao-Li Chen, Xiao-Ming Zhang, Nan-Lin Zeng, Li Zhou, Li-Ying Wang, Hong-Jie Tang, Chun-Ping Li, Sichuan Key Laboratory of Medical Imaging, Department of Radiology, Affiliated Hospital of North Sichuan Medical College, Nanchong 637000, Sichuan Province, China
Zhen-Lin Li, Department of Radiology, West China Hospital of Sichuan University, Chengdu 610041, Sichuan Province, China
Li Li, Xian-Yong Xie, Department of Pathology, Affiliated Hospital of North Sichuan Medical College, Nanchong 637000, Sichuan Province, China
Author contributions: Li H, Chen TW, Li ZL and Zeng NL contributed equally to this work; Li H, Chen TW, Chen XL, Zhang XM, Li ZL and Zeng NL designed the research; Li H, Chen XL, Zhou L, Wang LY and Tang HJ performed the research; Li CP, Li L and Xie XY contributed new reagents/analytic tools; Li H and Chen TW analyzed the data; Li H, Chen TW and Chen XL wrote the paper.
Supported by National Natural Science Foundation of China, No. 81050033; Key Projects in the Sichuan Province Science and Technology Pillar Program, No. 2011SZ0237; the Science Fund for Distinguished Young Scholars of Sichuan Province, China, No. 2010JQ0039
Correspondence to: Tian-Wu Chen, MD, Professor, Sichuan Key Laboratory of Medical Imaging, Department of Radiology, Affiliated Hospital of North Sichuan Medical College, 63# Wenhua Road, Shunqing District, Nanchong 637000, Sichuan Province, China. twchenscu@yahoo.com.cn
Telephone: +86-817-2262236 Fax: +86-817-2262236
Received: August 29, 2012
Revised: November 11, 2012
Accepted: December 5, 2012
Published online: December 28, 2012
Processing time: 154 Days and 20.4 Hours
Abstract

AIM: To determine whether and how magnetic resonance imaging (MRI)-based total liver volume (TLV) and diffusion weighted imaging (DWI) could predict liver fibrosis.

METHODS: Sixteen experimental mature mini-pigs (6 males, 10 females), weighing between 20.0 and 24.0 kg were prospectively used to model liver fibrosis induced by intraperitoneal injection of 40% CCl4 dissolved in fat emulsion twice a week for 16 wk, and by feeding 40% CCl4 mixed with maize flour twice daily for the subsequent 5 wk. All the survival animals underwent percutaneous liver biopsy and DWI using b = 300, 500 and 800 s/mm2 followed by abdominal gadolinium-enhanced MRI at the 0, 5th, 9th, 16th and 21st weekend after beginning of the modeling. TLV was obtained on enhanced MRI, and apparent diffusion coefficient (ADC) was obtained on DWI. Hepatic tissue specimens were stained with hematoxylin and Masson’s trichrome staining for staging liver fibrosis. Pathological specimens were scored using the human METAVIR classification system. Statistical analyses were performed to determine whether and how the TLV and ADC could be used to predict the stage of liver fibrosis.

RESULTS: TLV increased from stage 0 to 2 and decreased from stage 3 (r = 0.211; P < 0.001). There was a difference in TLV between stage 0-1 and 2-4 (P = 0.03) whereas no difference between stage 0-2 and 3-4 (P = 0.71). TLV could predict stage ≥ 2 [area under receiver operating characteristic curve (AUC) = 0.682]. There was a decrease in ADC values with increasing stage of fibrosis for b = 300, 500 and 800 s/mm2 (r = -0.418, -0.535 and -0.622, respectively; all P < 0.001). Differences were found between stage 0-1 and 2-4 in ADC values for b = 300, 500 and 800 s/mm2, and between stage 0-2 and 3-4 for b = 500 or 800 s/mm2 (all P < 0.05). For predicting stage ≥ 2 and ≥ 3, AUC was 0.803 and 0.847 for b = 500 s/mm2, and 0.848 and 0.887 for b = 800 s/mm2, respectively.

CONCLUSION: ADC for b = 500 or 800 s/mm2 could be better than TLV and ADC for b = 300 s/mm2 to predict fibrosis stage ≥ 2 or ≥ 3.

Keywords: Magnetic resonance imaging; Total liver volume; Liver fibrosis; Apparent diffusion coefficient; Stage