Animal-based model to investigate the minimum tumor size detectable with an electrical impedance scanning technique.
OBJECTIVE
The purpose of this study was to determine the minimum tumor size detectable with electrical impedance scanning (EIS) in laboratory animals.


METHODS
VX2 tumor cells (1 mm3) were implanted bilaterally into the upper leg musculature of five white New Zealand rabbits. EIS and ultrasound (US) were performed before, during, and immediately after implantation and on every 2nd day thereafter until tumors could be visualized with both modalities. This was followed by an extended follow-up regimen until a tumor size of 1 cm3 was reached. Rabbits were anesthetized subcutaneously.


RESULTS
Tumors could not be implanted in one rabbit. Neither EIS nor US were performed in one rabbit due to severe skin alterations at the implantation site. No focal increase in conductance was visible before or immediately after tumor injection. The smallest tumor identified with EIS was determined with US to be approximately 8 mm3. The mean tumor size at initial detection was 52 mm3 (determined with EIS). In two cases, the tumor was first seen with US (EIS detection was delayed with a delay of 1 and 2 days, respectively). In all remaining cases, tumors were detected simultaneously with both EIS and US. All tumors were visible with EIS.


CONCLUSIONS
The animal-based model is feasible. VX2 tumors are detectable with EIS. Tumors characterized by a focal spot at EIS could be detected starting at a tumor size of 7.5 mm3.
Malich
Ansgar
A
Institute of Diagnostic and Interventional Radiology, Friedrich-Schiller University Jena, Bachstrasse 18, 07740 Jena, Germany.
Böhm
Thomas
T
Fritsch
Tobias
T
Facius
Mirjam
M
Freesmeyer
Martin G
MG
Anderson
Roselle
R
Fleck
Marlies
M
Kaiser
Werner A
WA
D000818:Animals; D003937:Diagnosis, Differential; D004195:Disease Models, Animal; D004568:Electrodiagnosis / Q000295:instrumentation* / Q000379:methods*; D005260:Female; D009368:Neoplasm Transplantation; D009374:Neoplasms, Experimental / Q000175:diagnosis*; D011817:Rabbits; D012680:Sensitivity and Specificity; D014407:Tumor Cells, Cultured