In a method for localizing at least one focal lesion in a biological
tissue section, the lesion exhibiting an electrical property different
from the tissue section, and the electrical property in the tissue
section being essentially constant, a sequence of electrical excitation
signals having different frequency is supplied to the tissue section,
electrical response signals are measured at a number of measuring
locations on the surface of the tissue section that occur due to the
excitation signals, electrical admittance data are determined from the
response signals dependent on the location on the surface, a maximum of
the admittance data and the appertaining position of the maximum on the
surface are determined, and a depth position of the lesion under the
position of the maximum is determined dependent on the position of the
maximum.