Radiologic examinations in human temporal bone specimens using digital volume tomography and high-resolution computed tomography after implantation of middle ear prosthesis and cochlear implant electrode array.

INTRODUCTION

Adequate imaging of the middle ear and its surrounding structures is an essential preoperative part in ear surgery. In the past, the main disadvantage of computed tomography (CT) scanners was the decreased diagnostic quality due to metallic artifacts. Furthermore, these scanners showed mostly an inferior image quality compared to digital volume tomography (DVT) in the temporal bone. It was the aim of this experimental study to compare the image quality of a state-of-the-art dual-source 2 × 128-slice CT scanner to DVT in temporal bone specimen.

MATERIALS AND METHODS

Metallic prosthesis (PORP, TORP, stapes piston, cochlear implant electrode array) and an autologous incus were implanted in temporal bone specimen to analyze the diagnostic quality concerning the characterization of anatomic structures. Three further temporal bones were scanned without any preparation. Independently, 2 otologists and 2 radiologists scored the image quality of defined anatomic structures, using a range from 4 (excellent) to 0 (no diagnostic value).

RESULTS

The general score for DVT was 2.67, whereas CT reached a score of 2.76. The diagnostic value for hard contrast objects was 3.0 for DVT and 2.9 for CT, whereas the score for soft tissue was 1.1 for DVT and 2.3 for CT. Almost no quality reduction of the display of anatomic structures caused by metallic artifacts could be detected in both diagnostic modalities.

DISCUSSION

Both DVT and high-resolution CT allow good overall image quality in temporal bones, with discrete advantages for digital volume tomographic scans in terms of the image quality of hard contrast objects like bony structures or metallic implants.