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Accuracy of attenuation correction with a new gated PET method: Phantom and clinical studies

¹ CHU Amiens, Amiens, France

1662

Objectives: The aim of this study is to evaluate the influence of attenuation correction on images of mobile lesions in PET. Uptake values returned by AW-OSEM algorithm highly depend on the attenuation map, derived from CT images, and so does reliability of SUV. Classical binning methods (following frequency (Freq-based) or amplitude (Amp-based) analysis of respiratory signal) of respiratory gated PET acquisitions don’t solve this issue. We developed an alternative method CT-based which relies on selection of coincidences from respiratory-gated List Mode (LM) acquisitions corresponding to a respiratory state defined by a breath-hold CT (BH-CT).

Methods: The study was performed, on a BiographTM 6 (SIEMENS Medical Solutions), with a dual-density phantom consisted of a balloon filled with an 18F-FDG solution (20 kBq/ml) containing 0.5% of iodized contrast agent. A 0.5 ml sphere filled with 18F-FDG (80 kBq/ml). The sphere was tangential to the balloon in the ‘expiratory state’ and, when moving (20-mm-motion, 15 cycles per minute), pushed on the balloon's mid-section. A reference (REF) acquisition was performed with the phantom in the static expiratory state. Two CT scans were also performed: one in a ‘free breathing’ (CT-std) and BH-CT in ‘expiratory state’. Data were attenuation corrected from CT-std for Ungated (the whole LM acquisition), Freq-based and Amp-based volumes, and from BH-CT for CT-based and REF volumes.

Results: Target-to-background measurements are presented in the table. Application of CT-based method on 10 patients yields a mean increase of 30% of SUVMAX compared to Ungated images.

Conclusions: We showed that CT-based method increases attenuation correction accuracy which is a major stage toward quantification.

Target-to-background values

This Article Services Email this article to a friend Similar articles in this journal Alert me to new issues of the journal Download to citation manager Google Scholar Articles by Daouk, J. Articles by Meyer, M.-E. PubMed Articles by Daouk, J. Articles by Meyer, M.-E.