High-resolution Petrous Bone Imaging Using Multi-slice Computerized Tomography

Abstract

Multi-slice computerized tomography (MSCT) is considered to provide superior image quality. We defined a data acquisition protocol for high-resolution (HR) temporal bone imaging using MSCT and assessed its impact on data acquisition and post-processing (PP). The data acquisition protocol was defined in cadaveric phantom studies performed by MSCT and subsequently applied to 38 patients referred for temporal bone assessment. The parameters image quality and diagnostic value of MSCT data were assessed for the cross-sectional source images as well as for 2-dimensional (2D) reformations and 3-dimensional (3D) reconstructions by 3 radiologists by comparison with incremental HR scans of 17 patients with suspected middle ear disorders. The data acquisition protocol yielded HR images with an excellent detail resolution and a comparable image quality of cross-sectional scans and related orthogonal reformations. MSCT achieved higher scores for image quality and diagnostic value (p < 0.001, t-test) than incremental HR CT with regard to both 2D and 3D reconstructions. MSCT improves the image quality of HR cross-sectional scans as well as that of 2D and 3D PP techniques in petrous bone imaging. The radiation exposure of the eye lenses is increased by MSCT as gantry angulation is not yet possible in the helical scan mode.

Image quality and radiation exposure in 320-row temporal bone computed tomography

“…1 With the introduction of multidetector-row CT (MDCT) into clinical imaging in 1999 2 additional scan or post-processing steps such as scanning in different planes became superfluous and three dimensional (3D) visualization techniques were enhanced. 3 While the first generation of MDCT scanners provided unprecedented isotropic high-resolution imaging, the 16-, 32-and 64-slice CT scanner types showed differences with respect to radiation exposure issues rather than image quality; 4 however, all previous MDCT scanners did not exceed a projected detector width coverage in the isocentre of the gantry rotation of 32 to 40 mm.…”

Radiation Dose to the Lens Using Different Temporal Bone CT Scanning Protocols

“…11,12 Additional studies on low-dose pediatric temporal bone CT recommended further reductions in the scanning technique to 120 kV, 50 -75 mAs, and 0.75 pitch. [13][14][15] Other authors have reported using a heavy metal (eg, bismuth) shield to enable up to 50% reduction in radiation to the lens during routine cranial CT; however, patients felt discomfort, and image artifacts in near the eye were serious. 16 High-resolution thin-section direct axial and coronal CT is the standard technique for temporal bone imaging.…”

Experimental Study and Optimization of Scan Parameters That Influence Radiation Dose in Temporal Bone High-Resolution Multidetector Row CT

“…Tube current should be selected to reduce radiation dose as low as reasonably achievable while still meeting the diagnostic requirements for temporal bone imaging. [13][14][15][16] Without such adjustment, particularly for small size or pediatric subjects, patients may receive more radiation dose than is necessary. It is the principal responsibility of CT operators to take patient size into consideration when selecting radiation dose-related parameters, the most commonly adjusted of which is tube current.…”