Respiratory motion during PET acquisition degrades image quality. It is mainly the area around the thorax and abdomen which is affected. External devices do provide respiratory gating solutions but are time-consuming to set up on patients and may not always be available. A data-driven gating (DDG) method based on principal component analysis (PCA) was found to provide a reliable respiratory gating signal, discriminating the need for external gating systems with FDG, but it remains to be investigated how well it performs with other PET tracers. The HER2-targeting radiotracer 68Ga-ABY-025 is currently in phase 3 development and is aimed to develop methods to select breast cancer patients that benefit from HER2-targeted treatment. Hence, absolute quantification is important. Respiratory motion correction will be important for improved quantitative accuracy since many patients have metastases in the lower part of the lungs or the liver. DDG was applied to PET/CT list mode data retrospectively using quiescent period gating. Gated images were then compared to reconstructions without gating with a matched number of coincidences. Two iterative reconstructions were evaluated, TOF OSEM (3 iterations, 16 subsets, and a 5 mm gaussian postprocessing filter) and TOF BSREM β 400. Images were evaluated for standardized uptake value (SUV) changes for well-defined lesions in thorax and abdomen where respiratory motion is prevalent. Respiratory motion was detected in a mean 2.1 bed positions per examination. DDG application resulted in a mean increase of 12.7% in SUVmax for TOF OSEM reconstruction (p=0.0156).
| Identifer | oai:union.ndltd.org:UPSALLA1/oai:DiVA.org:umu-172663 |
| Date | January 2020 |
| Creators | Ncuti Nobera, Alain-Klaus |
| Publisher | Umeå universitet, Institutionen för fysik |
| Source Sets | DiVA Archive at Upsalla University |
| Language | English |
| Detected Language | English |
| Type | Student thesis, info:eu-repo/semantics/bachelorThesis, text |
| Format | application/pdf |
| Rights | info:eu-repo/semantics/openAccess |
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