Medical imaging is an emerging field in the healthcare industry that provides precise images to reduce medical costs and validate disease diagnosis and treatments. Despite much advancement in the last few decades, varieties of imaging parameters that differ with the manufacturer restrict its further development. In order to enhance the level of control in quality and reliability of image, a phantom should be used to calibrate the imaging device. There has been many research on the phantom materials; however, there has been no attempt to study on the material that mimics the structure of lung or fibrous tissue. With the need for development of gel with such structure, we tried to fabricate silica aerogel as synthetic tissues to mimic the porous structure of fibrous tissue. Silica aerogels have unique properties that include low density (0.003g/cm) and mesoporosity (pore size 2-50nm), with a high thermal insulation value (0.005W/mK) and high surface area (500-1200m2/g). In this study, we cross-linked with di-isocyanate, which is a group in polyurethane to covalently bond the polymer to the surface of silica aerogel to enhance the mechanical properties. In order to examine its potential as medical imaging phantom, silica aerogel will be examined with magnetic resonance imaging (MRI) and computed tomography (CT).