Improvements in Skull Base Imaging through High Resolution Flat-Panel Detector-Based Volume-CT (fpVCT)

Introduction: It was shown in numerous experimental studies using small-sized specimens that flat-panel based Volume-CT (fpVCT) allows the imaging of high-contrast structures such as the temporal bone in much higher resolution than current multislice-CT (MSCT). Unfortunately, when larger objects such as whole human skull bases are scanned, the image quality can be expected to be lower due to several effects that include, among others, scatter, beam hardening, and dose desaturation.

Material and Methods: To investigate the performance of fpVCT in whole skull bases we scanned two human skull bases in current MSCT (GE Lightspeed Qx/i) and in an experimental gantry-based fpVCT (GE CR & D, Schenectady, NY, USA) installed in the Department of Diagnostic Radiology, Goettingen University Hospital, Germany. (Two flat-panel detectors; scanFOV: 27 cm; through Nyquist's limit given minimal resolution: ∼150₃ μm³; 10% MTF: 200–250 μm). Visual image quality was compared between both scanners. Further, the assessment of high contrast structures was compared.

Results: The image quality of MSCT and VCT was somewhat similar in axial-oriented slices. Here almost all structures were equally visible in both modalities, but in z-direction VCT was clearly superior to MSCT. For example the outline of the lower bony limit of the facial nerve canal could be clearly assessed in VCT, while it was not assessable in MSCT.

Conclusions: Scanning whole skull bases is possible in fpVCT. Image quality is not as good as in an exiled specimen, but the high-contrast resolution, especially in z-direction, is still better than in current MSCT. Potential diagnostic applications and possible applications in highly accurate intraoperative navigation will be demonstrated at the meeting. Further, causeless dose concerns will be discussed.