Healthy and tumoral tissue resistivity in wild-type and sparc-/- animal models.

Despite the technological improvement of radiologic, endoscopic and nuclear imaging, the accuracy of diagnostic procedures for tumors can be limited whenever a mass-forming lesion is identified. This is true also because bioptical sampling cannot be properly guided into the lesions so as to puncture neoplastic tissue and to avoid necrotic areas. Under these circumstances, invasive and expensive procedures are still required to obtain diagnosis which is mandatory to plan the most appropriate therapeutic strategy. In order to test if electrical impedance spectroscopy may be helpful in providing further evidence for cancer detection, resistivity measurements were taken on 22 mice, 11 wild-type and 11 sparc-/- (knock out for the protein SPARC: secreted protein acidic and rich in cysteine), bearing mammary carcinomas, by placing a needle-probe into tumor, peritumoral and contralateral healthy fat areas. Tumor resistivity was significantly lower than both peritumoral fat and contralateral fat tissues. Resistivity in sparc-/- mice was lower than wild-type animals. A significant frequency dependence of resistivity was present in tissues analyzed. We conclude that accurate measurements of resistivity may allow to discriminate between tissues with different pathological and/or structural characteristics. Therefore, resistivity measurements could be considered for in vivo detection and differential diagnosis of tumor masses.