ECG-gated HYPR reconstruction for undersampled CT myocardial perfusion imaging

Michael A. Speidel, Michael S. Van Lysel, Scott B. Reeder, Mark Supanich, Brian E. Nett, Joseph Zambelli, Su-Min Chang, Jiang Hsieh, Guang Hong Chen, Charles A. Mistretta

Research output: Chapter in Book/Report/Conference proceedingConference contribution

9 Scopus citations


In this study we develop a novel ECG-gated method of HYPR (HighlY constrained backPRojection) CT reconstruction for low-dose myocardial perfusion imaging and present its first application in a porcine model. HYPR is a method of reconstructing time-resolved images from view-undersampled projection data. Scanning and reconstruction techniques were explored using x-ray projections from a 50 sec contrast-enhanced axial scan of a 47 kg swine on a 64-slice MDCT system. Scans were generated with view undersampling factors from 2 to 10. A HYPR reconstruction algorithm was developed in which a fully-sampled composite image is generated from views collected from multiple cardiac cycles within a diastolic window. A time frame image for a heartbeat was produced by modifying the composite with projections from the cycle of interest. Heart rate variations were handled by automatically selecting cardiac window size and number of cycles per composite within defined limits. Cardiac window size averaged 35% of the R-R interval for 2x undersampling and increased to 64% R-R using 10x undersampling. The selected window size and cycles per composite was sensitive to synchrony between heart rate, gantry rate, and the view undersampling pattern. Temporal dynamics and perfusion metrics measured in conventional short-scan (FBP) images were well-reproduced in the undersampled HYPR time series. Mean transit times determined from HYPR myocardial time-density curves agreed to within 8% with the FBP results. The results indicate potential for an order of magnitude reduction in dose requirement per image in cardiac perfusion CT via undersampled scanning and ECG-gated HYPR reconstruction.

Original languageEnglish (US)
Title of host publicationMedical Imaging 2007
Subtitle of host publicationPhysics of Medical Imaging
EditionPART 1
StatePublished - Oct 15 2007
EventMedical Imaging 2007: Physics of Medical Imaging - San Diego, CA, United States
Duration: Feb 18 2007Feb 22 2007


OtherMedical Imaging 2007: Physics of Medical Imaging
Country/TerritoryUnited States
CitySan Diego, CA


  • Multi-detector CT
  • Myocardial perfusion
  • Undersampled reconstruction

ASJC Scopus subject areas

  • Engineering(all)


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