title: Intravoxel incoherent imaging of renal fibrosis induced in a murine model of unilateral ureteral obstruction.
abstract: OBJECTIVE
  To evaluate non-invasive imaging biomarkers for assessing renal fibrosis. DWI is used to assess renal function; intravoxel incoherent motion (IVIM) provides additional measures of perfusion-related diffusion (D*, blood flow; f, perfusion fraction). We aim to determine if reduced ADC seen in renal fibrosis is attributable to perfusion-related diffusion changes or to known reduction in tissue diffusivity (D).
  
  
  METHODS
  Unilateral ureteral obstruction (UUO) was created in six mice to induce renal fibrosis. DWI was performed the day before and 7 days post-UUO. A range of b-values from 0 to 1200 s/mm(2) were used. IVIM parameters were obtained using region of interests drawn over the renal parenchyma. Histopathological analysis of both kidneys was performed in all mice. Results were analyzed using the paired t-test with P<0.05 considered statistically significant.
  
  
  RESULTS
  D and f were significantly lower in the ligated kidneys at Day 7 compared to before ligation and no significant difference was found for D*. Comparing non-ligated and ligated kidneys within the same mouse at Day 7, significantly lower D values were observed in the ligated kidneys, while no significant difference was found for f and D*, although the values of f were generally lower. Histopathological analysis confirmed development of fibrosis and reduction in glomeruli in all the ligated kidneys at Day 7.
  
  
  CONCLUSIONS
  Our study shows that the reduction in ADC seen in renal fibrosis is attributable not only to reduced D as previously encountered but also a decrease in vascularity as assessed by f. Reduction in f is possibly related to a reduction in glomeruli.
authors.affiliation: Department of Oncologic Imaging, National Cancer Centre, Singapore. Electronic address: tiffanyhennedige@gmail.com.
authors.forename: Tiffany
authors.initials: T
authors.lastname: Hennedige
authors.affiliation: Department of Oncologic Imaging, National Cancer Centre, Singapore.
authors.forename: Tong San
authors.initials: TS
authors.lastname: Koh
authors.affiliation: Department of Oncologic Imaging, National Cancer Centre, Singapore.
authors.forename: Septian
authors.initials: S
authors.lastname: Hartono
authors.affiliation: Department of Oncologic Imaging, National Cancer Centre, Singapore.
authors.forename: Yet Yen
authors.initials: YY
authors.lastname: Yan
authors.affiliation: SingHealth Experimental Medicine Centre, Singapore.
authors.forename: In Chin
authors.initials: IC
authors.lastname: Song
authors.affiliation: SingHealth Experimental Medicine Centre, Singapore.
authors.forename: Lin
authors.initials: L
authors.lastname: Zheng
authors.affiliation: SingHealth Experimental Medicine Centre, Singapore.
authors.forename: Wing Sum
authors.initials: WS
authors.lastname: Lee
authors.affiliation: Singapore General Hospital, Singapore.
authors.forename: Helmut
authors.initials: H
authors.lastname: Rumpel
authors.affiliation: Roche-Singapore Hub for Translational Medicine, Singapore.
authors.forename: Laurent
authors.initials: L
authors.lastname: Martarello
authors.affiliation: Department of Oncologic Imaging, National Cancer Centre, Singapore.
authors.forename: James B
authors.initials: JB
authors.lastname: Khoo
authors.affiliation: Royal Marsden Hospital, Surrey, UK.
authors.forename: Dow-Mu
authors.initials: DM
authors.lastname: Koh
authors.affiliation: Singapore Bioimaging Consortium, Singapore.
authors.forename: Kai Hsiang
authors.initials: KH
authors.lastname: Chuang
authors.affiliation: Department of Oncologic Imaging, National Cancer Centre, Singapore.
authors.forename: Choon Hua
authors.initials: CH
authors.lastname: Thng
mesh_terms: D000818:Animals; D038524:Diffusion Magnetic Resonance Imaging / Q000379:methods*; D004195:Disease Models, Animal; D005355:Fibrosis; D007090:Image Interpretation, Computer-Assisted; D007668:Kidney / Q000473:pathology; D007674:Kidney Diseases / Q000150:complications / Q000473:pathology*; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D012680:Sensitivity and Specificity; D014517:Ureteral Obstruction / Q000150:complications / Q000473:pathology*
keywords: Diffusion weighted imaging; Intravoxel incoherent motion; Kidney; Magnetic resonance imaging