title: Dual gated PET/CT imaging of small targets of the heart: method description and testing with a dynamic heart phantom.
abstract: BACKGROUND
  In PET imaging respiratory and cardiac contraction motions interfere the imaging of heart. The aim was to develop and evaluate dual gating method for improving the detection of small targets of the heart.
  
  
  METHODS
  The method utilizes two independent triggers which are sent periodically into list mode data based on respiratory and ECG cycles. An algorithm for generating dual gated segments from list mode data was developed.
  
  
  RESULTS
  The test measurements showed that rotational and axial movements of point source can be separated spatially to different segments with well-defined borders. The effect of dual gating on detection of small moving targets was tested with a moving heart phantom. Dual gated images showed 51% elimination (3.6 mm out of 7.0 mm) of contraction motion of hot spot (diameter 3 mm) and 70% elimination (14 mm out of 20 mm) of respiratory motion. Averaged activity value of hot spot increases by 89% when comparing to non-gated images. Patient study of suspected cardiac sarcoidosis shows sharper spatial myocardial uptake profile and improved detection of small myocardial structures such as papillary muscles.
  
  
  CONCLUSIONS
  The dual gating method improves detection of small moving targets in a phantom and it is feasible in clinical situations.
authors.affiliation: Turku PET Centre, University of Turku, Kiinamyllynkatu 4-8, P.O. Box 52, 20521 Turku, Finland. Tommi.Kokki@tyks.fi
authors.forename: Tommi
authors.initials: T
authors.lastname: Kokki
authors.forename: Hannu T
authors.initials: HT
authors.lastname: Sipilä
authors.forename: Mika
authors.initials: M
authors.lastname: Teräs
authors.forename: Tommi
authors.initials: T
authors.lastname: Noponen
authors.forename: Nicolas
authors.initials: N
authors.lastname: Durand-Schaefer
authors.forename: Riku
authors.initials: R
authors.lastname: Klén
authors.forename: Juhani
authors.initials: J
authors.lastname: Knuuti
mesh_terms: D000465:Algorithms; D055424:Cardiac-Gated Imaging Techniques / Q000379:methods*; D006321:Heart / Q000000981:diagnostic imaging*; D007089:Image Enhancement / Q000379:methods; D007090:Image Interpretation, Computer-Assisted / Q000379:methods; D019047:Phantoms, Imaging; D049268:Positron-Emission Tomography / Q000295:instrumentation / Q000379:methods*; D015203:Reproducibility of Results; D055425:Respiratory-Gated Imaging Techniques / Q000379:methods*; D012680:Sensitivity and Specificity; D013382:Subtraction Technique; D014057:Tomography, X-Ray Computed / Q000295:instrumentation / Q000379:methods*