Effect of motion on tracer activity determination in CT attenuation corrected PET images: A lung phantom study Journal Article
| Authors: | Pevsner, A.; Nehmeh, S. A.; Humm, J. L.; Mageras, G. S.; Erdi, Y. E. |
| Article Title: | Effect of motion on tracer activity determination in CT attenuation corrected PET images: A lung phantom study |
| Abstract: | Respiratory motion is known to affect the quantitation of 18FDG uptake in lung lesions. The aim of the study was to investigate the magnitude of errors in tracer activity determination due to motion, and its dependence upon CT attenuation at different phases of the motion cycle. To estimate these errors we have compared maximum activity concentrations determined from PET/CT images of a lung phantom at rest and under simulated respiratory motion. The NEMA 2001 IEC body phantom, containing six hollow spheres with diameters 37, 28, 22, 17, 13, and 10 mm, was used in this study. To mimic lung tissue density, the phantom (excluding spheres) was filled with low density poly-styrene beads and water. The phantom spheres were filled with 18FDG solution setting the target-to-background activity concentration ratio at 8:1. PET/CT data were acquired with the phantom at rest, and while it was undergoing periodic motion along the longitudinal axis of the scanner with a range of displacement being 2 cm, and a period of 5 s. The phantom at rest and in motion was scanned using manufacturer provided standard helical/clinical protocol, a helical CT scan followed by a PET emission scan. The moving phantom was also scanned using a 4D-CT protocol that provides volume image sets at different phases of the motion cycle. To estimate the effect of motion on quantitation of activities in six spheres, we have examined the activity concentration data for (a) the stationary phantom, (b) the phantom undergoing simulated respiratory motion, and (c) a moving phantom acquired with PET/4D-CT protocol in which attenuation correction was performed with CT images acquired at different phases of motion cycle. The data for the phantom at rest and in motion acquired with the standard helical/clinical protocol showed that the activity concentration in the spheres can be underestimated by as much as 75%, depending on the sphere diameter. We have also demonstrated that fluctuations in sphere's activity concentration from one PET/CT scan to another acquired with standard helical/clinical protocol can arise as a consequence of spatial mismatch between the sphere's location in PET emission and the CT data. © 2005 American Association of Physicists in Medicine. |
| Keywords: | comparative study; positron emission tomography; sensitivity and specificity; reproducibility of results; computer assisted tomography; image interpretation, computer-assisted; tomography, x-ray computed; algorithms; image enhancement; subtraction technique; imaging, three-dimensional; fluorodeoxyglucose f 18; positron-emission tomography; lung; tracer; polystyrene; phantom; phantoms, imaging; motion; artifacts; analytical error; longitudinal study; respiratory mechanics; pet/ct; breathing mechanics; movement; respiratory motion; information storage and retrieval; radiation attenuation; lung phantom |
| Journal Title: | Medical Physics |
| Volume: | 32 |
| Issue: | 7 |
| ISSN: | 0094-2405 |
| Publisher: | American Association of Physicists in Medicine |
| Date Published: | 2005-07-01 |
| Start Page: | 2358 |
| End Page: | 2362 |
| Language: | English |
| DOI: | 10.1118/1.1943809 |
| PUBMED: | 16121593 |
| PROVIDER: | scopus |
| DOI/URL: | |
| Notes: | --- - "Cited By (since 1996): 39" - "Export Date: 24 October 2012" - "CODEN: MPHYA" - "Source: Scopus" |
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