gms | German Medical Science

Introduction: Scanning Acoustic Microscopy (SAM) is a powerful technique for structure analysis of ear ossicles. The picture-contrast in SAM originates from local differences of the acoustic impedance Z,. A relevant advantage of SAM lies in the two-dimensional illustration of morphological structures. Resolution can be adjusted almost continuously. SAM has considerable advantages compared to nanoindentation. The measurements are non-destructive and repeatable. Two dimensional surface area can be investigated, instead of discrete point. Topographical influences in high frequency measurements are compensated by the use of multi-layer-technique.

Methods: In the present study, the coustic impedance in slices of human ear ossicles affected by cholesteatoma and chronic otitis media mesotympanalis were measured. Measurements were done with the scanning acoustic microscopes KSI SAM 100 and KSI SAM 2000 (Kraemer Scientific Instruments GmbH, Herborn, Germany) at 50 MHz and 200 MHz. The distribution of acoustic impedance of 13 affected mallei and 15 affected inci were measured. The impedance-picture showed the destruction of the normal bone-structure in cholesteatoma with low acoustic impedance (incus: 7,45 ± 0,47 Mrayl,; malleus: 7,39 ± 0,57 Mrayl; normal: 8 Mrayl).

Conclusion: SAM provides unique information with regard to in vitro elastic tissue properties of human ear ossicles affectedby chronic otitis media. The results may contribute to a better understanding of changes of normal structure and conducting hearing loss caused by chronic otitis media.From this standpoint don’t take any affected ossicel for tympanoplasty!.