Stable tissue-mimicking materials and an anatomically realistic, adjustable head phantom for electrical impedance tomography

Objective. To develop dielectrically accurate, easy to mould solid tissue-mimicking materials (TMMs) for use with electrical impedance tomography (EIT) and combine them into a head phantom with realistic anatomy and adjustable pathological lesions. Methods. The conductivity profiles of fat and blood, which span those of most biological tissues, along with aggregate models of the tissues of the head external to the brain, the tissues of the brain, and the cerebellum are identified across the 1 kHz–1 MHz band. TMM mixtures made from polyurethane, graphite, carbon black and either acetone or isopropanol are fabricated to emulate the conductivity profiles of the reference tissues. 3D-printed anatomically realistic moulds of the head and brain are used to cast a two-layer head and brain phantom with cylindrical holes left to allow addition of phantom pathological lesions such as haemorrhages. Results. The TMM spans a wide biological range of fat to blood and is adjustable to match any target tissue. Uniquely, the material is mechanically stable and easy to mould. The fabricated head phantom has excellent anatomic realism, and can represent a healthy brain or one with pathological lesions. The added lesions are easy to adjust in terms of size, shape, and material properties. Conclusion. The presented TMMs can be used to fabricate realistic phantoms for use in EIT studies of most tissue sets. Significance. These TMMs are an important development in phantom technology for EIT; the sample head phantom demonstrates the value and flexibility of the TMMs.