title: Diffusion Weighted MRI for Hepatic Fibrosis: Impact of b-Value.
abstract: BACKGROUND
  Hepatic fibrosis is a typical complication of chronic liver diseases resulting in cirrhosis that remains a major public health problem worldwide. Liver biopsy is currently the gold standard for diagnosing and staging hepatic fibrosis. Percutaneous liver biopsy; however, is an invasive procedure with risks of complications. Therefore, there is need for alternative non-invasive techniques to assess liver fibrosis and chronic liver diseases. In recent years, MRI techniques, including diffusion weighted imaging (DWI), have been developed for in vivo quantification of liver fibrosis.
  
  
  OBJECTIVE
  The purpose of this study is to evaluate the utility of diffusion weighted MRI in the diagnosis and quantification of the degree of hepatic fibrosis and to investigate the influence of b-value.
  
  
  METHODS
  Twenty-four patients (13 males, 11 females), with a mean age of 46 years (36-73 years) diagnosed as chronic hepatitis and histopathologically proven liver fibrosis and 22 other patients (8 males, 14 females) with no clinical or biochemical findings of liver disease, with a mean age of 51.2 years (32-75 years) were included in the study. All patients with chronic hepatitis underwent percutaneous liver biopsy by an experienced hepatologist without sonographic guidance. The Knodell histology activity index (HAI) for grading of necroinflammatory changes and Metavir scoring system for staging of the liver fibrosis were used to record the severity of the disease. All patients were examined with a 1.5 Tesla MRI system and the patients underwent diffusion weighted imaging (DWI) with a routine hepatic MRI protocol. Different b-values including 250, 500, 750, and 1000 sec/mm (2) were used to calculate apparent diffusion coefficients.
  
  
  RESULTS
  We detected decreased apparent diffusion coefficient values in patients with hepatic fibrosis compared to patients without chronic hepatitis and there was a trend toward decrease in hepatic apparent diffusion coefficient values with an increasing degree of fibrosis.
  
  
  CONCLUSIONS
  Our findings suggest that hepatic apparent diffusion coefficient measurement with a b-value of 750 sec/mm (2) or greater is useful in accurate quantification of liver fibrosis and necroinflammation.
authors.affiliation: Department of Radiology, Sisli Etfal Education and Research Hospital, Istanbul, Turkey.
authors.forename: Huseyin
authors.initials: H
authors.lastname: Ozkurt
authors.affiliation: Department of Radiology, Sisli Etfal Education and Research Hospital, Istanbul, Turkey.
authors.forename: Firat
authors.initials: F
authors.lastname: Keskiner
authors.affiliation: Department of Radiology, Canakkale Onsekiz Mart University, Faculty of Medicine, Canakkale, Turkey.
authors.forename: Ozan
authors.initials: O
authors.lastname: Karatag
authors.affiliation: Department of Gastroenterology, Sisli Etfal Education and Research Hospital, Istanbul, Turkey.
authors.forename: Canan
authors.initials: C
authors.lastname: Alkim
authors.affiliation: Department of Radiology, Sisli Etfal Education and Research Hospital, Istanbul, Turkey.
authors.forename: Sukru Mehmet
authors.initials: SM
authors.lastname: Erturk
authors.affiliation: Department of Radiology, Sisli Etfal Education and Research Hospital, Istanbul, Turkey.
authors.forename: Muzaffer
authors.initials: M
authors.lastname: Basak
keywords: Diffusion Magnetic Resonance Imaging; Liver Cirrhosis; Magnetic Resonance Imaging