![]() One main advantage of a PET/CT scanner is that it uses the CT image for attenuation correction of the PET data rather than relying on a rotating transmission rod source. In this article, we will describe the basics of PET/CT scanner design, data acquisition, and image artifacts. However, the use of the CT scan for attenuation correction has the drawback of producing artifacts on the resulting PET images. In addition, CT-based attenuation correction in PET/CT imaging is more rapid than the traditional transmission attenuation correction, thus reducing the overall whole-body PET scanning time by 30%–40% and allowing higher patient throughput with less patient discomfort. This capability has been shown to increase the diagnostic accuracy of PET scans from 91% to 98% ( 2), significantly affecting diagnosis and staging of malignant disease, as well as identification and localization of metastases ( 2– 4). One of these advantages is the ability to integrate PET and CT imaging into a single scanning session, thus allowing excellent fusion of the acquired data. This shift to dual-modality imaging is primarily due to the advantages that PET/CT offers over dedicated PET. At this rate, it is not surprising that PET/CT imaging will soon replace dedicated PET imaging. According to a recent market study, sales of PET/CT scanners have surpassed those of dedicated PET scanners by 65% since 2003, and sales of PET/CT scanners are anticipated to grow by more than 95% over the next few years ( 1). In the last 2 years, PET imaging in oncology has been migrating from the use of dedicated PET scanners to the use of PET/CT tomographs. After reading this article, the technologist should be able to describe the principles of PET/CT imaging, identify at least 3 types of image artifacts, and describe the differences between PET/CT artifacts of different causes: metallic implants, respiratory motion, contrast medium, and truncation. Furthermore, the patient’s breathing can introduce mismatches between the CT attenuation map and the PET emission data, and the discrepancy between the CT and PET fields of view can lead to truncation artifacts. For instance, the use of contrast medium and the presence of metallic implants can be associated with focal radiotracer uptake. CT-based attenuation correction can induce artifacts and quantitative errors that can affect the PET emission images. Although PET/CT imaging offers many advantages, this dual-modality imaging also poses some challenges. These combined advantages have rendered PET/CT a preferred imaging modality over dedicated PET. ![]() Moreover, the CT data can also be used for attenuation correction, ultimately leading to high patient throughput. PET/CT is a new imaging modality that integrates functional (PET) and structural (CT) information into a single scanning session, allowing excellent fusion of the PET and CT images and thus improving lesion localization and interpretation accuracy. ![]() The purpose of this paper is to introduce the principles of PET/CT imaging and describe the artifacts associated with it. ![]()
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