title: Quantitative assessment of early liver fibrosis in rats using 13N-NH3·H2O PET/CT.
abstract: OBJECTIVE
  To investigate the value of N-NH3·H2O PET/computed tomography (CT) and the inhibitor, acetazolamide (ACZ), in the quantitative diagnosis of early liver fibrosis and the assessment of liver fibrosis stage.
  
  
  METHODS
  Twenty-four male Wistar rats (293.54±37.99 g) were used in this study and grouped by pathology after biopsy. Using N-NH3·H2O as an imaging agent and ACZ as an aquaporin 1 inhibitor, the rats were subjected to a dynamic PET/CT scan for 45 min. According to data reconstruction and imaging analysis, we calculated the mean standard uptake value (SUVmean) of the liver at the time points of 20, 90 s, 5, 10, 15, 20, and 25 min. From the results of N-NH3·H2O, the liver SUVmean in the control group and the liver fibrosis model group at different time points were compared. In addition, blood perfusion, interstitial diffusion, and N-NH3·H2O metabolism of the two groups were compared. Single-factor analysis of variance was used to analyze the differences between the SUVs in the groups at any time point and the paired-sample t-test was used to compare the SUVs before and after addition of the inhibitor.
  
  
  RESULTS
  We included four rats in the control group (S0) and 20 rats in the liver fibrosis group (which included early-stage S1: 11 rats, progressive-stage S2+S3+S4: nine rats). Three rats in S0, seven rats in S1, and six rats in S2+S3+S4 were paired. The SUVmean at 90 s was statistically different (P<0.05); however, the other groups showed statistical difference at all time points (P>0.05). After the addition of the inhibitor, ACZ, the SUVmean of S0 and S2+S3+S4 at 10, 15, 20, and 25 min was statistically different (P<0.05).
  
  
  CONCLUSIONS
  N-NH3·H2O PET/CT may aid the diagnosis of liver fibrosis. N-NH3·H2O PET/CT combined with ACZ may help distinguish between the early stage and the progressive stage of liver fibrosis.
authors.affiliation: aShengjing Hospital, China Medical University, Shenyang bGeneral Electronic Company Healthcare (China), Beijing, China.
authors.forename: Ting-Ting
authors.initials: TT
authors.lastname: Han
authors.forename: Ming
authors.initials: M
authors.lastname: Du
authors.forename: Xin
authors.initials: X
authors.lastname: Zhang
authors.forename: Li
authors.initials: L
authors.lastname: Cao
authors.forename: Hong
authors.initials: H
authors.lastname: Li
authors.forename: Zhou-She
authors.initials: ZS
authors.lastname: Zhao
authors.forename: Qi-Yong
authors.initials: QY
authors.lastname: Guo
authors.forename: Jun
authors.initials: J
authors.lastname: Xin
mesh_terms: D000641:Ammonia / Q000737:chemistry*; D000818:Animals; D051398:Aquaporin 1 / Q000378:metabolism; D042241:Early Diagnosis; D005786:Gene Expression Regulation; D008099:Liver / Q000000981:diagnostic imaging / Q000378:metabolism; D008103:Liver Cirrhosis / Q000000981:diagnostic imaging*; D008297:Male; D064847:Multimodal Imaging; D009590:Nitrogen Radioisotopes; D049268:Positron-Emission Tomography; D051381:Rats; D017208:Rats, Wistar; D014057:Tomography, X-Ray Computed; D014867:Water / Q000737:chemistry*
chemical_list: D009590:Nitrogen Radioisotopes; D014867:Water; D051398:Aquaporin 1; D000641:Ammonia