Effect of patient arm motion in whole-body PET/CT

Martin A. Lodge, Joyce C. Mhlanga, Steve Y. Cho, Richard L. Wahl

Research output: Contribution to journalArticle

8 Scopus citations

Abstract

Arm motion during whole-body PET/CT acquisition is not uncommon and can give rise to striking cold artifacts on PET images. We investigated the mechanisms that underlie these artifacts and proposed a potential solution. Methods: A phantom experiment based on 5 clinical cases of suspected arm motion was designed. The experiment involved a central 20-cm-diameter 68Ge/ 68Ga cylinder simulating the neck and 2 peripheral 10-cm-diameter 18F cylinders simulating arms. After motion-free CT and PET on a whole-body PET/CT system, the position of the arms was altered so as to introduce different amounts of misalignment. Twenty sequential PET scans were acquired in this position, alternating between 2-dimensional (2D) and 3-dimensional (3D) acquisition, as the 18F decayed. Decay of 18F in the arms, while the activity in the 68Ge/ 68Ga cylinder remained approximately constant, allowed the relative impact of scatter and attenuation-correction errors to be determined. Results: Image artifacts were largely confined to the local region of motion in 2D but extended throughout the affected slices in 3D, where they manifested as a striking underestimation of radiotracer concentration that became more significant with increasing misalignment. For 3D, scattercorrection error depended on activity in the arms, but for typical activity concentrations scatter-correction error was more significant than attenuation-correction error. 3D image reconstruction without scatter correction substantially eliminated these artifacts in both phantom and patient images. Conclusion: Reconstruction artifacts due to patient arm motion can be substantial and should be recognized because they can affect both qualitative and quantitative assessment of PET.

Original languageEnglish (US)
Pages (from-to)1891-1897
Number of pages7
JournalJournal of Nuclear Medicine
Volume52
Issue number12
DOIs
StatePublished - Dec 1 2011

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Keywords

  • Arm
  • Artifact
  • Motion
  • PET/CT
  • Scatter correction

ASJC Scopus subject areas

  • Radiology Nuclear Medicine and imaging

Cite this

Lodge, M. A., Mhlanga, J. C., Cho, S. Y., & Wahl, R. L. (2011). Effect of patient arm motion in whole-body PET/CT. Journal of Nuclear Medicine, 52(12), 1891-1897. https://doi.org/10.2967/jnumed.111.093583