Tissue mimicking materials for a multi-imaging modality prostate phantom

Materials that simultaneously mimic soft tissue in vivo for magnetic resonance imaging (MRI), ultrasound (US), and computed tomography (CT) for use in a prostate phantom have been developed. Prostate and muscle mimicking materials contain water, agarose, lipid particles, protein, Cu + + , EDTA, glass beads, and thimerosal (preservative). Fat was mimicked with safflower oil suffusing a random mesh (network) of polyurethane. Phantom material properties were measured at 22 °C. (22 °C is a typical room temperature at which phantoms are used.) The values of material properties should match, as well as possible, the values for tissues at body temperature, 37 °C. For MRI, the primary properties of interest are T1 and T2 relaxations times, for US they are the attenuation coefficient, propagation speed, and backscatter, and for CT, the x-ray attenuation. Considering the large number of parameters to be mimicked, rather good agreement was found with actual tissue values obtained from the literature. Using published values for prostate parenchyma, T1 and T2 at 37 °C and 40 MHz are estimated to be about 1100 and 98 ms, respectively. The CT number for in vivo prostate is estimated to be 45 HU (Hounsfield units). The prostate mimicking material has a T1 of 937 ms and a T2 of 88 ms at 22 °C and 40 MHz; the propagation speed and attenuation coefficient slope are 1540 m/s and 0.36 dB/cm/MHz, respectively, and the CT number of tissue mimicking prostate is 43 HU.