Microwave dielectric spectroscopy of renal calculi: A large scale study on dielectric properties from 500 MHz to 18 GHz

Inherent dielectric property discrepancy between biological anomalies and healthy tissue enables the microwave diagnostic and therapeutic technologies. To reveal this discrepancy, microwave dielectric properties of many different biological tissues are tabulated. Although the dielectric properties of biological tissues are well documented in the literature, the knowledge on microwave dielectric property behavior of the renal calculi is limited. This work presents ultra wideband dielectric properties of three renal calculi types between 500 MHz to 18 GHz to pave the way for possible application of microwave technologies for diagnosis, treatment, and prevention of urolithiasis. Microwave dielectric spectroscopy is performed on a total of 66 natural stone samples with open-ended coaxial probe technique. The samples belong to three commonly diagnosed renal calculi categories namely calcium oxalate, cystine, struvite. Analysis of variance (ANOVA) test is performed on fitted Cole-Cole parameters and it was concluded that there is a statistically significant difference between the dielectric properties of the renal calculi types. A patient-to-patient statistical test is also performed and it was concluded that there is no statistical difference between the samples belonging to the same renal calculi category. To this end, based on the relative permittivity discrepancy between the renal calculi types, the category of renal calculi can be identified by measuring the dielectric properties of renal calculi with open-ended coaxial probe technique.