Electric impedance spectroscopy of human atherosclerotic lesions

Abstract

Objective: The aim of this in vitro study was to investigate the feasibility of a new highly flexible microelectrode on human tissue and its potential of differentiating atherosclerotic lesions by electric impedance spectroscopy (EIS). Methods: Electric impedance measurements (EIM) were performed on 148 spots of 7 aortic and 6 femoral human arteries at 1 kHz, 10 kHz and 100 kHz. Results: According to the AHA classification 33 (25%) grade I lesions (PI), 34 (26%) grade II (PII), 21 (16%) grade III (PIII), 21 (16%) grade IV (PIV), 13 (10%) grade Va (PVa) and 10 (8%) grade Vb (PVb) could be identified by histology. At 1 kHz, 10 kHz and 100 kHz the mean electric impedance (MEI) of PI, PII, PIII and PIV was statistically not different. At 100 kHz the MEI of PVa showed significantly higher values compared to the MEI of PI (455 +/- 66 Omega vs. 375 +/- 47 Omega, p = 0.05), PII (455 +/- 66 Omega vs. 358 +/- 63 Omega, p = 0.007), PIII (455 +/- 66 Omega vs. 342 +/- 52 Omega, p = 0.003), PIV (455 +/- 66 Omega vs. 356 +/- 41 Omega p = 0.013) and the MEI of PVb was significantly increased compared to the MEI of PI (698 +/- 239 Omega vs. 375 +/- 47 Omega, p < 0.001), PII (698 +/- 239 Omega vs. 358 +/- 63 Omega p < 0.001), PIII (698 +/- 239 Omega vs. 342 +/- 52 Omega p < 0.001), PIV (698 +/- 239 Omega vs. 356 +/- 41 Omega p < 0.001), PVa (698 +/- 239 Omega vs. 455 +/- 66 Omega, p < 0.001). Performing ROC analyses for the detection of grouped PVa/PVb lesions, the largest AUC was found at 100 kHz with a cut-off value of 441 Omega presenting a sensitivity of 74% and a specificity of 94%. Conclusions: EIM could be performed on human aortic and femoral tissue. The results show that EIS has the potential to distinguish between different plaque types.