Dependence of intravoxel incoherent motion diffusion MR threshold b-value selection for separating perfusion and diffusion compartments and liver fibrosis diagnostic performance. (January 2019)

• Record Type: Journal Article
• Authors: Wáng, Yì Xiáng J; Li, Yáo T; Chevallier, Olivier; Huang, Hua; Leung, Jason Chi Shun; Chen, Weitian; Lu, Pu-Xuan
• Is Part Of: Acta radiologica. Volume 60:Number 1(2019)
• Page Start: 3
• Page End: 12
• Publication Date: 2019-01
• Subjects: Magnetic resonance imaging (MRI) -- intravoxel incoherent motion (IVIM) -- diffusion -- perfusion -- liver -- fibrosis; Radiology, Medical -- Periodicals; Radiography, Medical -- Periodicals; Radiotherapy -- Periodicals; 616.0757
• DOI: 10.1177/0284185118774913
• Languages: English
• ISSNs: 0284-1851

Abstract

Background: Intravoxel incoherent motion (IVIM) tissue parameters depend on the threshold b -value. Purpose: 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/mm 2 . 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/mm 2 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. Results: 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/mm 2 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 mm 2 /s), and Dfast (Dfast < 20.85 × 10 –3 mm 2 /s) differentiated healthy individuals and all individual fibrotic livers with an area under the curve of logistic regression (AUC) of 1. Conclusion: For segmented-unconstrained analysis, the selection of threshold b -value = 60 s/mm 2 improves IVIM differentiation between healthy livers and fibrotic livers.