Loubele Miet, Guerrero Maria Eugenia, Jacobs Reinhide, Suetens Paul, van Steenberghe Daniel
ESAT-PSI, Medical Imaging Center, Katholieke Universiteit Leuven, Belgium.
Int J Oral Maxillofac Implants. 2007 May-Jun;22(3):446-54.
For proper preoperative planning of oral implants, the need has increased for tomographic imaging for precise determination of anatomic dimensions. However, concern for radiation exposure, which is substantial with computerized tomography (CT), has also grown. In the present study, the validity of jawbone width assessment and delineation by means of cone-beam CT (CBCT) and spiral tomography on dry mandibles was compared. Secondly, the subjective image quality of CBCT images with those obtained by multi-slice spiral CT (MSCT) of a fixed ex vivo cadaver with its soft tissues was compared.
The study included 25 dry human mandibles for the dimensional study and 1 formalized maxilla for image quality assessment. Measurements of the mandibles by means of a digital sliding caliper acted as the gold standard. Radiographic examination of the premolar and canine regions was performed with both CBCT and spiral tomography. Observational measurements were carried out by postgraduates in oral imaging. Subjective image quality was assessed on the fixed maxilla, including soft tissues, by comparing CBCT and MSCT. Inter- and intraobserver variability were determined.
Direct mandibular measurements were on average 0.23 mm (SD 0.49) and 0.34 mm (SD 0.90) larger than the CBCT and spiral tomography measurements, respectively. Subjective image quality of the CBCT was significantly better than for the MSCT with regard to visualization and delineation of the lamina dura and periodontal ligament space. Subjective image quality of the MSCT was significantly better for the MSCT than the CBCT for the gingiva and cortical bone.
These results indicate that on dry mandibles, jawbone width measurements by means of CBCT and spiral tomography are reliable, even if on average they slightly underestimate the bone width. For the subjective image quality, the CBCT offered better visualization of details of the small bony structures. Spiral tomography offered better visualization of the cortical bone and the gingiva.
为了进行口腔种植体的术前合理规划，精确确定解剖尺寸的断层成像需求日益增加。然而，对计算机断层扫描（CT）带来的大量辐射暴露的担忧也在增加。在本研究中，比较了锥形束CT（CBCT）和螺旋断层扫描在干燥下颌骨上评估和描绘颌骨宽度的有效性。其次，将CBCT图像与固定离体尸体及其软组织的多层螺旋CT（MSCT）所获得图像的主观图像质量进行了比较。
本研究包括25个用于尺寸研究的干燥人类下颌骨和1个用于图像质量评估的标准化上颌骨。使用数字游标卡尺对下颌骨进行测量作为金标准。用CBCT和螺旋断层扫描对前磨牙区和犬牙区进行影像学检查。由口腔影像学专业研究生进行观察测量。通过比较CBCT和MSCT，对包括软组织在内的固定上颌骨的主观图像质量进行评估。确定观察者间和观察者内的变异性。
下颌骨直接测量值平均分别比CBCT和螺旋断层扫描测量值大0.23 mm（标准差0.49）和0.34 mm（标准差0.90）。在观察硬骨板和牙周膜间隙的可视化和描绘方面，CBCT的主观图像质量明显优于MSCT。在观察牙龈和皮质骨方面，MSCT的主观图像质量明显优于CBCT。
这些结果表明，在干燥下颌骨上，通过CBCT和螺旋断层扫描测量颌骨宽度是可靠的，即使平均而言它们会略微低估骨宽度。对于主观图像质量，CBCT能更好地显示小骨结构的细节。螺旋断层扫描能更好地显示皮质骨和牙龈。
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