Artifacts in MSCT

Abstract

Artifacts in CT are usually based on the misinterpretation of raw data due to various physical phenomena. As CT images are generally derived by means of a filtered back-projection [1], artifacts, i.e., image disturbances, do not occur only at the originating location, as known from conventional radiography, but may also affect the entire image. For example, a thin metallic wire causes streak artifacts emanating from its origin, but deteriorates the environmental region up to a greater distance as well. Artifacts can also occur if the source is located outside the reconstructed field of view or even out of the field of measurement (the maximum field of view, which is completely covered by the acquired raw data). The challenge is to decide whether details in the CT image represent the reality or are produced artificially. Therefore, considerable experience as well as a profound knowledge of the technology behind a CT system are essential to be able to interpret images correctly. Although artifacts are commonly caused by a combination of different physical effects the diagnostic quality of CT images can be optimized by choosing appropriate scan parameters. The most common sources for artifacts and their appearance are described in the following. General hints are given to minimize artifacts. Therefore, this article aims to help optimize the MSCT protocols by describing both the appearance of artifacts and their origins. © Springer-Verlag Berlin Heidelberg 2006.