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Authors
Advisor(s)
Abstract(s)
ABSTRACT - Introduction: In all available PET-CT systems, the standard FOV of the CT scanner is 50 cm, which is slightly smaller than the one of the PET scanner. This difference between the two scanners may lead to truncation artifacts, causing some sections of the PET emission data not to have any corresponding attenuation-correction map. This investigation aims to evaluate the influence of TOF-based reconstruction on the truncation artifact when performing cardiac PET-CT exams with Rb-82 and, additionally, to evaluate the influence of this artifact in clinical images. Method: 73 resting studies of myocardial perfusion with Rb-82 – obtained at the Nuclear Medicine Department of the Manchester Royal Infirmary – were selected. CT reconstructions were performed with the standard 50 cm FOV and the 78 cm extended FOV. Truncation on the 50 cm FOV was identified on a purely visual basis and performed by applying a wide image window to the CT, which showed the extent of the reconstructed FOV. TOF and Non-TOF PET images were reconstructed with both the 50cm CT and extended FOV CT. A ratio image was produced by dividing the voxel values of the PET using the 50cm CT by the voxel values of the PET using the extended CT image on a voxel-by-voxel basis. A visual quality assessment was also performed to verify differences between truncated and non-truncated images, with and without TOF. Results: When comparing voxel ratios for non-TOF and TOF reconstructions, a significantly greater variation in the truncated images compared with the non-truncated images was observed. It was also verified that when compared between males and females there were no significant differences in the impact of the truncation artifact. Conclusion: Truncation artifact is more prevalent in patients with large body mass index. Besides, TOF reconstruction may be more robust, and reduce the impact of the CT truncation and therefore is the method of choice for patients with large body mass index.
Description
Mestrado em Radiações Aplicadas às Tecnologias da Saúde. - Área de especialização: Imagem Funcional e Multimodal
Keywords
Nuclear medicine PET-CT Rb-82 Truncation Time-of-flight
Citation
Gaspar RL. Evaluation of the truncation artifact in cardiac PET-CT images acquired with Rb-82 [dissertation]. Lisboa: Escola Superior de Tecnologia da Saúde de Lisboa/Instituto Politécnico de Lisboa; 2020.
Publisher
Instituto Politécnico de Lisboa, Escola Superior de Tecnologia da Saúde de Lisboa