Research on impedance imaging dates back to the early 1900s. In 1926, the journal Cancer Research published an article, "The electric capacity of tumors of the breast," [Volume 16: pp. 340-376, by H. Fricke and S. Morse of the Cleveland Clinic Foundation, Department of Biophysics]. This article discussed in vitro experimentation with impedance measurements and reported comparison of capacity of human tumors of several types with the capacitance of various normal tissues and found tumorous tissue to have a markedly lower capacitance than normal tissue. The article's concluding remark was: "Future applications of the method {of electric capacity measurement} may include the rapid searching of large masses of tissue for small concealed centers of malignancy and in certain important cases measurements may be made directly on the patient."
Impedance imaging technology has progressed significantly since the research by Fricke and Morse was published in 1926. Engineers at Siemens have worked on the impedance imaging principle for many years. The company TransScan Research and Development Co. Ltd. was founded in 1993 to develop a clinical impedance imaging (T-scan) system. By using the modern high-speed computer processors and advanced electronic and signal processing technologies now available, the impedance imaging principle has been integrated into a practical clinical technology.