ABSTRACT
@#Cone beam computed tomography (CBCT) has been widely used in various fields of dentistry. The diagnosis of root fractures, especially vertical root fractures (VRFs) with CBCT images, has been a research hotspot since then. Research on this area mainly includes the following five aspects: ① the diagnostic efficiency of CBCT images for root fractures; ② the influence of scanning parameters on the diagnostic accuracy of CBCT images in root fractures, such as scanning field of view, spatial resolution, tube current and tube voltage; ③ whether the application of image postprocessing techniques, especially metal artifact reduction (MAR), can improve the diagnostic accuracy of root fractures after root canal treatment and/or there is a post core in the root canal; ④ establishment and validation of clinical diagnosis model for vertical root fracture; and ⑤ application of artificial intelligence technology and contrast agent in root canals for the diagnosis of CBCT image in root fractures. Compared with periapical radiographs, CBCT images can improve the diagnostic accuracy of root fractures in nonendodontic treated teeth; however, for teeth that have undergone endodontic treatment, the diagnosis of VRF must be combined with clinical signs. Vertical bone resorption in the buccolingual (palatal) direction is a characteristic indicator of VRF. The width of the VRF is an important factor affecting the diagnostic accuracy, but the voxel size used in CBCT scanning is not a necessary factor affecting its diagnostic accuracy; the fracture direction does not affect the diagnostic accuracy of the VRF. Image postprocessing techniques, especially MAR, cannot improve the diagnostic accuracy of VRF and may also reduce the diagnostic efficiency, so they are not recommended for clinical application.
ABSTRACT
Abstract@#Introduction: Computed tomography (CT) has been widely used for postoperative spine assessment. However, the effectiveness of CT is limited by the presence of multiple artefacts surrounding metal implants. An artefact causes degradation of image quality and obscures the interpretation of spine CT images by a radiologist. The purpose of this study was to evaluate the optimum angle of gantry tilt and metal rod placement which produced the least metal artefact on CT images. Methods: A customised phantom was developed with different transverse angles of metal placement. The transverse angles of metal placement inside the phantom varied at 20°, 30°, 40° and 45°. The phantom was scanned with CT scanner at 0° axial scan angle. It was followed by acquisitions at different gantry tilt angles ranging from −12° to 20°. Quantitative and qualitative assessment by determining the signal-to-noise ratios (SNRs) of the CT images was performed. Results: The severity of the metal streak artefact increased as the metal insertion angles became wider up to 45° due to the widespread of streaking area. The severity of artefacts was reduced with the increment of the gantry tilt angle, which was observed in images acquired at 20°. Conclusion: For the gantry tilt angulation technique, the optimum gantry angle for metal artefact reduction is at the widest angle, which is +20° angulation. Although the gantry tilt technique did not eliminate the metal artefacts, it enabled a significant reduction of metal artefacts and improved image quality.