Evaluation of the middle and inner lear structures: comparison of hybrid rendering, virtual endoscopy and axial 2D source images

Recent developments in 3D reconstructions can enhance the quality and diagn ostic value of axial 2D image data sets with direct benefits for clinical p ractice. To show the possible advantages of a hybrid rendering method [colo r-coded 3D shaded-surface display (SSD)- and volume rendering method] with the possibility of virtual endoscopy we have specifically highlighted the u se in relation to the middle and inner ear structures. We examined 12 patie nts with both normal findings and postoperative changes, using image data s ets from high-resolution spiral computed tomography (HRSCT). The middle and inner ear was segmented using an interactive threshold interval density vo lume-growing method and visualized with a color-coded SSD rendering method. The temporal bone was visualized using a transparent volume rendering meth od. The 3D- and virtual reconstructions were compared with the axial 2D sou rce images. The evaluated middle and inner ear structures could be seen in their complete form and correct topographical relationship, and the 3D- and virtual reconstructions indicated an improved representation and spatial o rientation of these structures. A hybrid and virtual endoscopic method coul d add information and improve the value of imaging in the diagnosis and man agement of patients with middle or inner ear diseases making the understand ing and interpretation of axial 2D CT image data sets easier. The introduct ion of an improved rendering algorithm aids radiological diagnostics, medic al education, surgical planning, surgical training, and postoperative asses sment.