Respiratory-gated positron emission tomography and breath-hold computed tomography coupling to reduce the influence of respiratory motion: methodology and feasibility

Acta Radiol. 2009 Mar;50(2):144-55. doi: 10.1080/02841850802627437.


Background: Respiratory motion causes uptake in positron emission tomography (PET) images of chest and abdominal structures to be blurred and reduced in intensity.

Purpose: To compare two respiratory-gated PET binning methods (based on frequency and amplitude analyses of the respiratory signal) and to propose a "BH-based" method based on an additional breath-hold computed tomography (CT) acquisition.

Material and methods: Respiratory-gated PET consists in list-mode (LM) acquisition with simultaneous respiratory signal recording. A phantom study featured rectilinear movement of a 0.5-ml sphere filled with (18)F-fluorodeoxyglucose ((18)F-FDG) solution, placed in a radioactive background (sphere-to-background contrast 6:1). Two patients were also examined. Three figures of merit were calculated: the target-to-background ratio profile (TBRP) in the axial direction through the uptake (i.e., the sphere or lesion), full-width-at-half-maximum (FWHM) values, and maximized standard uptake values (SUV(max)).

Results: In the phantom study, the peak TBRP was 0.9 for non-gated volume, 1.83 for BH-based volume, and varied between 1.13 and 1.73 for Freq-based volumes and between 1.34 and 1.66 for Amp-based volumes. A reference volume (REF-static) was also acquired for the phantom (in a static, "expiratory" state), with a peak TBRP at 1.88. TBRPs were computed for patient data, with higher peak values for all gated volumes than for non-gated volumes.

Conclusion: Respiratory-gated PET acquisition reduces the blurring effect and increases image contrast. However, Freq-based and Amp-based volumes are still influenced by inappropriate attenuation correction and misregistration of mobile lesions on CT images. The proposed BH-based method both reduces motion artifacts and improves PET-CT registration.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Artifacts
  • Contrast Media / administration & dosage
  • Equipment Design
  • Feasibility Studies
  • Fluorodeoxyglucose F18 / administration & dosage
  • Humans
  • Liver Neoplasms / diagnostic imaging
  • Lung Neoplasms / diagnostic imaging
  • Phantoms, Imaging
  • Positron-Emission Tomography / methods*
  • Respiratory-Gated Imaging Techniques*
  • Tomography, X-Ray Computed / methods*


  • Contrast Media
  • Fluorodeoxyglucose F18