title: Reducing radiation dose in rest-stress cardiac PET/CT by single poststress cine CT for attenuation correction: quantitative validation.
abstract: Cardiac PET/CT is optimized by cine CT with dedicated shift software for manual correction of attenuation-emission misregistration. Separate rest and stress CT scans incur greater radiation dose to patients than does standard helical PET/CT or "pure" PET using rotating rod attenuation sources. To reduce radiation dose, we tested quantitative accuracy of using a single poststress cine CT attenuation scan for reconstructing rest perfusion images to eliminate resting CT attenuation scans.
  
  
  METHODS
  A total of 250 consecutive patients underwent diagnostic rest-dipyridamole myocardial perfusion PET/CT with (82)Rb and a 16-slice PET/CT scanner using averaged cine CT attenuation data during breathing at rest and stress. After correcting for any attenuation-emission misregistration, we quantitatively compared resting perfusion images reconstructed using rest cine CT attenuation data with the same resting emission data reconstructed with poststress cine CT attenuation data. Automated software quantifying average regional quadrant activity, severity, size, and combined size and severity of perfusion defects was used for this comparison.
  
  
  RESULTS
  Resting perfusion images reconstructed using rest cine CT attenuation data were quantitatively comparable to resting images reconstructed with poststress cine CT attenuation data with no clinically significant differences. Twenty-five (10%) of 250 cases required shifting of stress cine CT attenuation data to achieve optimal attenuation-emission coregistration with resting perfusion data. Eliminating rest CT attenuation scans reduced CT radiation dose by 50% below rest-plus-stress cine CT protocols.
  
  
  CONCLUSIONS
  Resting perfusion images reconstructed using poststress cine CT attenuation data are quantitatively comparable to resting images reconstructed with resting cine CT attenuation data. Eliminating the rest CT scan reduces CT radiation dose by 50%.
authors.affiliation: Weatherhead PET Center for Preventing and Reversing Atherosclerosis, University of Texas Medical School at Houston, Houston, Texas 77030, USA. K.Lance.Gould@uth.tmc.edu
authors.forename: K Lance
authors.initials: KL
authors.lastname: Gould
authors.forename: Tinsu
authors.initials: T
authors.lastname: Pan
authors.forename: Catalin
authors.initials: C
authors.lastname: Loghin
authors.forename: Nils P
authors.initials: NP
authors.lastname: Johnson
authors.forename: Stefano
authors.initials: S
authors.lastname: Sdringola
mesh_terms: D003331:Coronary Vessels / Q000000981:diagnostic imaging; D005080:Exercise Test / Q000295:instrumentation*; D006321:Heart / Q000502:physiology*; D006801:Humans; D007091:Image Processing, Computer-Assisted; D049268:Positron-Emission Tomography / Q000379:methods*; D011829:Radiation Dosage; D012146:Rest; D014057:Tomography, X-Ray Computed / Q000379:methods*