Dependence of intravoxel incoherent motion diffusion MR threshold b-value selection for separating perfusion and diffusion compartments and liver fibrosis diagnostic performance
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Intravoxel incoherent motion (IVIM) tissue parameters depend on the threshold b-value.

To explore how threshold b-value impacts PF (f), Dslow (D), and Dfast (D*) values and their performance for liver fibrosis detection.

Material and Methods
Fifteen healthy volunteers and 33 hepatitis B patients were included. With a 1.5-T magnetic resonance (MR) scanner and respiration gating, IVIM data were acquired with ten b-values of 10, 20, 40, 60, 80, 100, 150, 200, 400, and 800 s/mm2. Signal measurement was performed on the right liver. Segmented-unconstrained analysis was used to compute IVIM parameters and six threshold b-values in the range of 40–200 s/mm2 were compared. PF, Dslow, and Dfast values were placed along the x-axis, y-axis, and z-axis, and a plane was defined to separate volunteers from patients.

Higher threshold b-values were associated with higher PF measurement; while lower threshold b-values led to higher Dslow and Dfast measurements. The dependence of PF, Dslow, and Dfast on threshold b-value differed between healthy livers and fibrotic livers; with the healthy livers showing a higher dependence. Threshold b-value = 60 s/mm2 showed the largest mean distance between healthy liver datapoints vs. fibrotic liver datapoints, and a classification and regression tree showed that a combination of PF (PF < 9.5%), Dslow (Dslow < 1.239 × 10–3 mm2/s), and Dfast (Dfast < 20.85 × 10–3 mm2/s) differentiated healthy individuals and all individual fibrotic livers with an area under the curve of logistic regression (AUC) of 1.

For segmented-unconstrained analysis, the selection of threshold b-value = 60 s/mm2 improves IVIM differentiation between healthy livers and fibrotic livers.
All Author(s) ListWang Yi Xiang J, Li Yao T, Chevallier Oliver, Huang Hua, Leung Jason Chi Shun, Chen Weitian, Lu Pu-Xuan
Journal nameActa Radiologica
Volume Number60
Issue Number1
Place of PublicationEngland
Pages3 - 12
LanguagesEnglish-United Kingdom
KeywordsMagnetic resonance imaging (MRI), intravoxel incoherent motion (IVM), diffusion, perfusion, liver, fibrosis

Last updated on 2020-05-07 at 01:02