Validation of Intravoxel Incoherent Motion MRI Using Perfused Explanted Human Livers

TL;DR

Researchers tested if perfused human livers could validate IVIM MRI by measuring diffusion and perfusion parameters under different flow rates and fibrosis stages.

Contribution

This study introduces perfused explanted human livers as a novel biological model for validating IVIM MRI techniques.

Findings

Diffusion coefficient (D) was not affected by flow rate or applied flow.

Perfusion signal fraction (F_c) increased significantly with applied flow but not with flow rate.

Fibrosis stages significantly reduced perfusion-related IVIM parameters like F_c, V_b, and D*.

Abstract

Evaluate the feasibility of using perfused explanted human livers for validating intravoxel incoherent motion (IVIM).

Eight (n = 8) explanted livers from deceased donors were obtained. The portal vein and hepatic artery of each explanted liver were connected to a perfusion system. IVIM data were acquired at four total volumetric flow rates (0, 0.6, 0.9, and 1.2 L/min). For each IVIM dataset, diffusion coefficient (D), relaxation‐corrected perfusion signal fraction (F

c
), blood velocity SD (V

b
), and/or pseudo‐diffusion coefficient (D*) were estimated. Linear mixed‐effects modeling was performed to determine if the effect of applied flow, flow rate, and fibrosis stage on the estimated IVIM parameters was significant (F‐tests), while correcting for temporal effect(s). Liver fibrosis stages were obtained from clinical histology.

D was independent of applied flow and total volumetric flow rate (p ≥ 0.30). F

c
was approximately zero when no flow was applied and a positive, non‐negligible value that was independent of flow rate with applied flow (p < 0.001 and ≥ 0.58 for applied flow and flow rate effects, respectively). V

b
and D* were dependent on applied flow and flow rate (p ≤ 0.04 with flow rate effect size ≥ 0.69 mm/s per L/min and 25.7 × 10−3 mm2/s per L/min for V

b
and D*, respectively). Significantly lower (p ≤ 0.01) F

c
, V

b
, and D* estimates were observed for livers with moderate‐to‐advanced fibrosis (stages F2‐4) compared to no‐to‐mild fibrosis (stages F0‐1) (effect sizes = −0.74%, −0.60 mm/s, and −19.8 × 10−3 mm2/s, respectively).

Perfused explanted human livers from deceased donors may serve as biologically accurate systems for validation of quantitative IVIM techniques.

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