Early-stage Dielectric Characterisation of Renal Cell Carcinoma for Positive Surgical Margin Detection

Partial nephrectomy is preferred to total nephrectomy for clinically localised renal cell carcinoma. In order to minimise the risk of local tumour recurrence after partial nephrectomy, ideally, the surgical margins of the excised sample should be negative for the disease. Currently, the risk of positive margins during partial nephrectomy is minimised with the use of intraoperative ultrasound. In this study, dielectric spectroscopy is proposed for the detection of positive margins during partial nephrectomy. Specifically, the feasibility of using an open-ended coaxial probe operating at microwave frequencies is evaluated for in vivo differentiation between positive and negative surgical margins. Due to the lack of dielectric properties of renal cancerous tissue in the literature, early stage ex vivo dielectric measurements were conducted on five human renal samples immediately after excision. A wide range of dielectric measurement results were obtained due to the heterogeneity of renal samples and the different longitudinal location of the cancerous tissue across the samples. This outcome suggests the need to refine the protocol for dielectric characterisation of renal cell carcinoma and highlights the limitations of a coaxial probe at detecting renal tumour margins.