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 labyrin thine bone metabolism due to active otosclerosis, resolution and detec tion limits were examined in a normal human temporal bone model. After incubation in technetium-99m-labeled diphosphonate solution, scintigr aphic 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 mm(2) 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-ra y photographs or by superimposition with masks of the prepared tempora l bones drawn from the X-rays. The correlation of scintigraphic findin gs with X-ray photographs was found to provide a powerful method for i mproving the accuracy of localizing temporal bone metabolic changes as it is applicable clinically for studying the occurrence of small acti ve otosclerotic foci.