|ECR 2019 / C-1761|
|Which number of b-value is better for accurate calculation of virtual MR elastography?|
Aims and objectives
Shear stiffness is an important physical property of tissues and has been found to gradually increase with increasing hepatic fibrosis in chronic liver disease [1, 2]. In magnetic resonance imaging (MRI), it can be measured as image contrast by using magnetic resonance elastography (MRE), a technique that has been widely used to quantitatively assess shear stiffness for a diagnostic staging of hepatic fibrosis [1, 3, 4]. MRE is a completely non-invasive imaging technique, and the results can be easily interpreted in the clinic for molecular diagnosis of liver disease, without the need for liver biopsy.
Recently, virtual MRE has been reported by Le Behan et al . Virtual MRE calculates the shear stiffness of the chronic liver disease from a physical consideration that amount of non-Gaussian diffusion empirically calculated from intravoxel incoherent motion (IVIM) signal attenuation relates the shear stiffness of tissue. There are several IVIM models to empirically detect the non-Gaussian diffusion [6-9]. For example, the amount of non-Gaussian diffusion in biological tissue can be detected by apparent diffusion coefficients (ADCs), which are slopes of signal attenuation for each of the slow and fast diffusion components . In addition, D* derived from the bi-exponential model also reflects the non-Gaussian diffusion . Thus, there is the estimated parameter map which can represent the non-Gaussian diffusion in the IVIM model . Moreover, the estimated parameter map derived from a curve fitted by IVIM model is varied depending on set b-value. Then, b-value would affect accurately calculating the shear stiffness from the IVIM model. Therefore, both an IVIM model and imaging parameters that can reliably detect the amount of non-Gaussian diffusion is required to reflect its dependence on the measured changes in shear stiffness.
The purpose of this study was to investigate the effect of the IVIM model and the number of b-value on accurate calculation of the virtual MRE.
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