Wilting J E, Timmer J
Department of Computed Tomography, Philips Medical Systems Nederland BV, Best, The Netherlands.
Eur Radiol. 1999;9(2):316-22. doi: 10.1007/s003300050673.
This qualitative study is intended to create awareness of artefacts that are associated with spiral-CT imaging. A simple description of spiral-CT reconstruction is used to explain how these artefacts depend on the pitch and subject morphology, and shows when these artefacts are likely to impair the diagnostic value of the acquired images. We scanned a cone and rod phantom with pitch 2, and used the acquired images to demonstrate how spiral data acquisition and interpolation leads to artefacts in the reconstructed images. We then demonstrated the effects of various pitches in scans of a human cadaver, whereas the slice thickness was kept constant. Some patient studies are presented in order to show the possible clinical consequences. Spiral acquisition may cause geometric distortions and apparent inhomogeneity of homogeneous structures. We were able to link these artefacts to the way in the acquisitions were done, and the reconstructions were performed. We have shown how these artefacts can be anticipated in clinical studies. When areas of low contrast, surrounded by hypo- or hyperdense structures, are scanned with a large pitch and viewed with a narrow window, spiral artefacts may influence the diagnostic quality of the images. These effects should be considered when choosing the pitch.
这项定性研究旨在提高对与螺旋CT成像相关伪影的认识。通过对螺旋CT重建进行简单描述，解释这些伪影如何取决于螺距和受检者形态，并说明这些伪影何时可能损害所采集图像的诊断价值。我们以螺距2扫描了一个锥体和棒状体模，并利用所采集的图像展示螺旋数据采集和插值如何导致重建图像中出现伪影。然后，我们展示了在人体尸体扫描中不同螺距的影响，同时保持层厚不变。还呈现了一些患者研究以显示可能的临床后果。螺旋采集可能会导致几何变形以及均匀结构出现明显的不均匀性。我们能够将这些伪影与采集方式和重建方式联系起来。我们已经展示了如何在临床研究中预测这些伪影。当低对比度区域被低密度或高密度结构包围，以大螺距进行扫描并用窄窗宽观察时，螺旋伪影可能会影响图像的诊断质量。在选择螺距时应考虑这些影响。
