Experimental topographic study of high-resolution tympanocochlear scintigraphy using the human temporal bone model.

To determine the diagnostic value of tympanocochlear scintigraphy (TCS), which is still used for the visualization of alterations of labyrinthine bone metabolism due to active otosclerosis, resolution and detection limits were examined in a normal human temporal bone model. After incubation in technetium-99m-labeled diphosphonate solution, scintigraphic imaging showed the zygomatic process and the clivus as landmarks for fine structures of the petrous bone. For further differentiation, labyrinthine fine structures were marked with radioactive tracers of 0.5-1 mm2 each. High-resolution scintigraphic imaging gave two-point discrimination for structures as small as 2.5 mm apart. Localization of the activity patterns was improved by correlating imaging with X-ray photographs or by superimposition with masks of the prepared temporal bones drawn from the X-rays. The correlation of scintigraphic findings with X-ray photographs was found to provide a powerful method for improving the accuracy of localizing temporal bone metabolic changes as it is applicable clinically for studying the occurrence of small active otosclerotic foci.