Modality evaluation of the flat-panel volume CT with regard to the visualization of middle ear structures on human petrous bones

Introduction In the field of petrous bone imaging, it could be shown that flat-panel volume CT (fpVCT) and in particular its secondary reconstructions (fpVCT_SECO) have advantages over multislice CT (MSCT) in terms of displaying the smallest anatomical structures. Therefore, the aim of this study was to evaluate the image quality of different protocols and slice thicknesses of the fpVCT_SECO using middle ear structures, especially with regard to their radiation dose and recording time.

Materials and methods Two anatomical skull specimens were examined using six different fpVCT protocols adjusted for radiation dose and acquisition time (4, 8, and 14 seconds). Subsequently fpVCT_SECO of different layer thicknesses were generated and significant structures in the area of ​​the middle ear were evaluated subjectively using a score and objectively using a gray scale plots. The applied radiation doses were measured using an anthropomorphic phantom model and an ionization chamber.

Results It turned out that the delimitability improved with decreasing layer thickness. It was also shown that higher scores could be achieved with a higher dose and longer exposure time. However, the score/dose quotient yielded better results for shorter radiation doses and the score/time quotient yielded better results for shorter exposure times. Objective investigations using grey-scale plots were able to confirm this.

Conclusion When evaluating middle ear structures, the creation of supplementary reconstructions of the fpVCT is recommended. Image quality/dose and image quality/time relationships are intended to guide the clinician in selecting the protocol for imaging the middle ear with an fpVCT.

Publication History

Article published online:
12 May 2023