Tumor capacitance: electrical measurements of renal neoplasia.
OBJECTIVE
Studies have demonstrated that biological tissues possess unique electrical properties. We evaluate the electrical properties of renal tumors using a specialized probe with the capability of measuring intra-tissue capacitance in an ex vivo model of fresh surgically excised tissue.


METHODS
An electrical monitoring device was used to measure tissue capacitance at a frequency of 1 MHz on 34 ex vivo kidney specimens freshly obtained after surgical excision. Tissue capacitance was promptly measured in the excised tumor as well as surrounding normal parenchyma and fat. Dielectric permittivity in each tissue was calculated using the measured capacitance data. These data were compared and correlated to pathological findings.


RESULTS
The final pathology on the 34 specimens revealed 28 renal cell carcinomas (RCC), 3 oncocytomas and 3 angiomyolipomas. In patients with RCC dielectric permittivity of tumor tissue was 1.43 +/- 0.39 times greater than that of surrounding normal parenchyma (p < 0.001). The average tumor-to-normal tissue dielectric permittivity ratio for RCC was significantly greater than that for angiomyolipoma (1.43 +/- 0.39 vs 0.73 +/- 0.77, p < 0.05) but similar to that for oncocytoma (1.43 +/- 0.39 vs 1.63 +/- 0.77, p = 0.39).


CONCLUSIONS
Tissue capacitance measurements may be used to differentiate renal tumor from surrounding normal tissue. In vivo studies will ultimately determine the clinical use of this technology in localizing renal neoplasms and differentiating between malignant and benign tissues.
Inagaki
Takeshi
T
James Buchanan Brady Urological Institute, The Johns Hopkins Medical Institutions, Baltimore, Maryland 21287-8915, USA.
Bhayani
Sam B
SB
Allaf
Mohamad E
ME
Ong
Albert M
AM
Rha
Koon H
KH
Petresior
Doru
D
Patriciu
Alexandru
A
Varkarakis
Ioannis M
IM
Jarrett
Thomas W
TW
Stoianovici
Dan
D
Kavoussi
Louis R
LR
D018249:Adenoma, Oxyphilic / Q000503:physiopathology; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D018207:Angiomyolipoma / Q000503:physiopathology; D002292:Carcinoma, Renal Cell / Q000503:physiopathology*; D025802:Electric Capacitance; D005260:Female; D006801:Humans; D007680:Kidney Neoplasms / Q000503:physiopathology*; D008297:Male; D008875:Middle Aged