RT Journal Article
SR Electronic
T1 Effect of Patient Arm Motion in Whole-Body PET/CT
JF Journal of Nuclear Medicine
JO J Nucl Med
FD Society of Nuclear Medicine
SP 1891
OP 1897
DO 10.2967/jnumed.111.093583
VO 52
IS 12
A1 Lodge, Martin A.
A1 Mhlanga, Joyce C.
A1 Cho, Steve Y.
A1 Wahl, Richard L.
YR 2011
UL http://jnm.snmjournals.org/content/52/12/1891.abstract
AB 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, scatter-correction 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.