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Aim: Liver vessel density can be evaluated by DDVD (diffusion derived vessel density): DDVD(b0b1) = Sb0/ROIarea0-Sb1/ROIarea1, where Sb0 and Sb1 refer to the liver signal when b is 0 or 1 (s/mm 2); ROIarea0 and ROIarea1 refer to the region-of-interest on b= 0 or 1 images. Sb1 and ROIarea1 may be replaced by Sb25 and ROIarea25 or Sb50 and ROIarea50 (i.e., by images of b=25 or 50 s/mm 2). With rat biliary duct ligation (BDL) model, this study assessed the usefulness of liver DDVD computed from a simplified IVIM imaging protocol. Materials and Methods: Male Sprague-Dawley rats were used, and 1, 2, 3, 4 weeks post BDL had rat number of 5, 5, 5,3 respectively. Partial recanalization (n=12) was performed with rats had BDL for 7 days and MRI was done mean 14 days after recanalization. Liver diffusion MR images were acquired using with a 3.0T magnet with a b-value distribution of 0, 30, 50, 75, 100, 150, 300, 700, 1000 s/mm 2. DDVDmean (control rats n=6) was the mean of DDVD(b0b25) and DDVD(b0b50). IVIM fitting started from b = 0 with segmented fitting and a threshold b of 50 s/mm 2 (n=5 for control rats). Three 3-D space was constructed using PF, D slow , and D fast ; PF, D slow , and DDVD mean ; or PF, D fast , and DDVD mean. Results: BDL week 1, 2, 3, 4 rats and partial recanalization rats had mean liver fibrosis METAVIR score of 1.5, 2.4, 3.25, 3.7 and 2.42 respectively. The control rats and BDL rats (n=18) had a liver DDVD mean of 84.0±26.2 and 44.7±14.4 au/pixel (p

Liver vessel density can be evaluated by an imaging biomarker diffusion-derived vessel density (DDVD): DDVD/area(b0b2) = Sb0/ROIarea0 - Sb2/ROIarea2, where Sb0 and Sb2 refer to the liver signal when b is 0 or 2 (s/mm2); ROIarea0 and ROIarea2 refer to the region of interest (ROI) on b = 0 or 2 images; and Sb2 may be replaced by Sb15 (b = 15). This concept was validated in this study. Liver diffusion images were acquired at 1.5 T. For a scan-rescan repeatability study of six subjects, b values of 0 and 2 were used. The validation study was composed of 26 healthy volunteers and 19 consecutive suspected chronic viral hepatitis B patients, and diffusion images with b values of 0, 2, 15, 20, 30, 45, 50, 60, 80, 100, 200, 300, 600, and 800 were acquired. Four patients did not have liver fibrosis, and the rest were four stage 1, three stage 2, four stage 3, and one stage 4 patients, respectively. The intraclass correlation coefficient for repeatability was 0.994 for DDVD/area(Sb0Sb2) and 0.978 for DDVD/area(Sb0Sb15). In the validation study, DDVD/area(Sb0Sb2) and area(Sb0Sb15) were 14.80 ± 3.06 and 26.58 ± 3.97 for healthy volunteers, 10.51 ± 1.51 and 20.15 ± 2.21 for stage 1-2 fibrosis patients, and 9.42 ± 0.87 and 19.42 ± 1.89 for stage 3-4 fibrosis patients. For 16 patients where IVIM analysis was performed, a combination of DDVD/area, PF, and Dfast achieved the best differentiation for nonfibrotic livers and fibrotic livers. DDVD/area were weakly correlated with PF or Dfast. Both DDVD/area(Sb0Sb2) and area(Sb0Sb15) are useful imaging biomarkers to separate fibrotic and nonfibrotic livers, with fibrotic livers having lower measurements.

AimLiver vessel density can be evaluated by an imaging biomarker DDVD (diffusion derived vessel density): DDVD/area(b0b2) = Sb0/ROIarea0 – Sb2/ROIarea2, where Sb0 and Sb2 refer to the liver signal whenbis 0 or 2 (s/mm2); ROIarea0 and ROIarea2 refer to the region-of-interest onb= 0 or 2 images; and Sb2 may be replaced by Sb15 (b=15). This concept was validated in this study.Materials and MethodsLiver diffusion images were acquired at 1.5T. For a scan-rescan repeatability study of 6 subjects,b-values of 0 and 2 were used. The validation study composed of 26 healthy volunteers and 19 consecutive suspected chronic viral hepatitis-b patients, and diffusion images with 16b-values of 0, 2, 4, 7, 10, 15, 20, 30, 46, 60, 72, 100, 150, 200, 400, 600 were acquired. Four patients did not have liver fibrosis, and the rest were four stage-1, three stage-2, four stage 3, and one stage-4 patients respectively.ResultsIntraclass correlation coefficient for repeatability was 0.994 for DDVD/area(Sb0Sb2), and 0.978 for DDVD/area(Sb0Sb15). In the validation study, DDVD/area(Sb0Sb2) and area(Sb0Sb15) were 14.80±3.06 and 26.58±3.97 for healthy volunteers, 10.51±1.51 and 20.15±2.21 for stage 1-2 fibrosis patients, and 9.42±0.87 and 19.42±1.89 for stage 3-4 fibrosis patients. For 16 patients where IVIM analysis was performed, a combination of DDVD/area, PF, and Dfast achieved the best differentiation for non-fibrotic livers and fibrotic livers. DDVD/area were weakly correlated with PF or Dfast.ConclusionBoth DDVD/area(Sb0Sb2) and area(Sb0Sb15) are useful imaging biomarker to separate fibrotic and non-fibrotic livers, with fibrotic livers had lower measurements.

Background: Recently a small cohort study demonstrated that intravoxel incoherent motion (IVIM) diffusion MRI can detect early stage liver fibrosis. Using modified IVIM data acquisition parameters, the current study aims to confirm this finding. Methods: Twenty-six healthy volunteers, three patients of chronic viral hepatitis-b but without fibrosis and one mild liver steatosis subject, and 12 viral hepatitis-b patients with fibrosis (stage 1–2=7, stage 3–4=5) were included in this study. With a 1.5-T MR scanner and respiration-gating, IVIM diffusion imaging was acquired using a single-shot echo-planar sequence with a b -value series of 2, 0, 1, 15, 20, 30, 45, 50, 60, 80, 100, 200, 300, 600, 800 s/mm 2 . Signal measurement was performed on right liver parenchyma. The first three very low b -values were excluded to improve the curve fitting stability, and bi-exponential segmented fitting was performed using the 12 b -values of 15~800 s/mm 2 . Both threshold b -values of 60 s/mm 2 and 200 s/mm 2 were tested. With a 3-dimensional tool, Dslow ( D ), PF ( f ) and Dfast ( D* ) values were placed along the x-axis, y-axis, and z-axis, and a plane was defined to separate healthy volunteers from liver fibrosis patients. Results: Threshold b -value of 60 s/mm 2 was preferred over 200 s/mm 2 for separating healthy volunteers and liver fibrosis patients. The IVIM measures of the four patients without fibrosis resembled those of healthy volunteers. When threshold b -value =60 s/mm 2 was applied, PF (PF