Creating a tissue mimicking phantom appropriate for relaxometry, diffusion imaging and ultrasound elastography

Abstract

Introduction To optimize elastography and diffusion weighted imaging (DWI) modalities, it is important to create phantoms that can reliably mimic the properties of human tissue and be used in reference imaging experiments. In this study, we used polyvinyl alcohol cryogel (PVA-C), agar, and agarose gels. Purpose To create a tissue mimicking phantom appropriate for relaxometry, non-Gaussian diffusion imaging and ultrasound elastography and to investigate potential relationships between quantities accessible from different imaging modalities for cancer patients such as prostate cases. Materials and methods Homogenous gel phantoms were created in different concentrations to set MRI and elastography parameters to be consistent with those found in healthy and diseased prostate tissue. Images were acquired on a 3T scanner for relaxometry and DWI studies. In-house software (MATLAB) was used to analyse the images on a pixel-by-pixel basis. Shear Wave Elastography was used to obtain speed and Young’s Modulus of the phantoms. Results As qualitative and quantitative assessments, ultrasound and CT were used and the results were identical for each gel phantoms, confirming homogeneity in addition to slice profiles and field maps obtained from MRI. Relaxation times and diffusion coefficients of the phantoms were found as compatible with the previous studies in the literature. A good correlation was observed in agar gels on their elasticity than other phantoms. Conclusion Our gel phantoms were developed and evaluated for MRI diffusion and elastography imaging modalities and design to mimic tissue parameters for prostate cancer. The phantoms may also model other tissues to various degrees. Disclosure ZGP would like to acknowledge TUBITAK for her financial support with a Project No. 1059B141400677 and Research Fund of Cukurova University , Project No. FDK-2014-2709 during this work. SS acknowledges funding from a Royal Society Leverhulme Trust Senior Fellowship.