ACOUSTIC PROPERTIES OF DIALYZED KIDNEY BY SCANNING ACOUSTIC MICROSCOPY

Background, A correlation between acquired renal cysts in the dialysed kidney and renal cancer has long been debated, but no changes in the physical properties of kidneys at the microscopic level have been repo rted. The purpose of the present study was to classify the physical pr operties of the kidneys of patients undergoing haemodialysis at severa l stages of pathology by use of the scanning acoustic microscope. Meth ods, Sixteen surgically excised kidneys of dialysis patients were inve stigated. Tissues were fixed in 10% formalin, frozen in acetone, and c ut 10 mu m thick on a cryostat. We used a scanning acoustic microscope operated in the frequency range of 100-200 MHz. Attenuation constant and sound speed were measured on a two-dimensional distribution. Resul ts, The attenuation constant for inflammatory granulation tissue was s ignificantly higher than that for hyaline degeneration tissue (P<0.001 ). Sound speed was high for granulation tissue, but tended to diminish gradually for hyaline degeneration. Sound speed increased again with progression to cystic degeneration (P<0.001), but the attenuation cons tant remained low. When a cystic kidney contained a malignant lesion, the previously low attenuation constant rose at that site (P<0.001), a nd the previously high sound speed was diminished (P<0.001). Conclusio n, Our data suggest that the physical properties of dialysed kidneys a t different stages of pathology can be classified by their acoustic pr operties. Simultaneous evaluation of attenuation constant and sound sp eed is considered applicable to determining whether tissues contain ma lignant elements.