A comparative study of methods for determining Intravoxel incoherent motion parameters in cervix cancer

Xue Wang,Wenxiao Lin,Shengfa Zhou,Zujun Hou,Jiao Song,Zhihan Yan,Yi Lu,Tong San Koh

doi:10.1186/s40644-020-00377-0

Abstract

BackgroundTo compare different fitting methods for determining IVIM (Intravoxel Incoherent Motion) parameters and to determine whether the use of different IVIM fitting methods would affect differentiation of cervix cancer from normal cervix tissue.MethodsDiffusion-weighted echo-planar imaging of 30 subjects was performed on a 3.0 T scanner with b-values of 0, 30, 100, 200, 400, 1000 s/mm2. IVIM parameters were estimated using the segmented (two-step) fitting method and by simultaneous fitting of a bi-exponential function. Segmented fitting was performed using two different cut-off b-values (100 and 200 s/mm2) to study possible variations due to the choice of cut-off. Friedman’s test and Student’s t-test were respectively used to compare IVIM parameters derived from different methods, and between cancer and normal tissues.ResultsNo significant difference was found between IVIM parameters derived from the segmented method with b-value cutoff of 200 s/mm2 and the simultaneous fitting method (P>0.05). Tissue diffusivity (D) and perfusion fraction (f) were significantly lower in cervix cancer than normal tissue (P< 0.05).ConclusionsIVIM parameters derived using fitting methods with small cutoff b-values could be different, however, the segmented method with b-value cutoff of 200 s/mm2 are consistent with the simultaneous fitting method and both can be used to differentiate between cervix cancer and normal tissue.

Highlights

To compare different fitting methods for determining Intravoxel incoherent motion (IVIM) (Intravoxel Incoherent Motion) parameters and to determine whether the use of different IVIM fitting methods would affect differentiation of cervix cancer from normal cervix tissue
Example of a patient with cervical cancer is shown in Fig. 1 together with the IVIM parameter maps generated a f
Bland-Altman plots for pairwise comparison of IVIM parameters derived from the three fitting methods are shown in Fig. 3 for cervix cancer (a) and normal cervix tissue (b)

Summary

Introduction

To compare different fitting methods for determining IVIM (Intravoxel Incoherent Motion) parameters and to determine whether the use of different IVIM fitting methods would affect differentiation of cervix cancer from normal cervix tissue. The IVIM model differentiates water movement in tissues into diffusion in extravascular space and perfusionrelated pseudo-diffusion in blood vessels, represented by the diffusion coefficient (D) and pseudo-diffusion coefficient (D*), respectively [18]. In contrast to a single exponential model which only accounts for diffusion in the tissue interstitial and cells (extravascular space), a major. Wang et al Cancer Imaging (2021) 21:12 advantage of the IVIM model is the ability to account for tumor blood flow (by the pseudo-diffusion coefficient D*). As the malignant tumor relies on its blood supply for growth and progression, additional information on tumor microcirculation derived from IVIM imaging could potentially be used for diagnostic and prognostic purposes in the management of cancer. A biexponential relationship is used to describe diffusionweighted signal Sb acquired at different b-values: Sb S0

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Conclusion