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Proceedings Paper

ECG-gated HYPR reconstruction for undersampled CT myocardial perfusion imaging
Author(s): 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
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Paper Abstract

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.

Paper Details

Date Published: 21 March 2007
PDF: 11 pages
Proc. SPIE 6510, Medical Imaging 2007: Physics of Medical Imaging, 651014 (21 March 2007); doi: 10.1117/12.713740
Show Author Affiliations
Michael A. Speidel, Univ. of Wisconsin, Madison (United States)
Michael S. Van Lysel, Univ. of Wisconsin, Madison (United States)
Scott B. Reeder, Univ. of Wisconsin, Madison (United States)
Mark Supanich, Univ. of Wisconsin, Madison (United States)
Brian E. Nett, Univ. of Wisconsin, Madison (United States)
Joseph Zambelli, Univ. of Wisconsin, Madison (United States)
Su Min Chang, Univ. of Wisconsin, Madison (United States)
Jiang Hsieh, GE Healthcare (United States)
Univ. of Wisconsin, Madison (United States)
Guang-Hong Chen, Univ. of Wisconsin, Madison (United States)
Charles A. Mistretta, Univ. of Wisconsin, Madison (United States)

Published in SPIE Proceedings Vol. 6510:
Medical Imaging 2007: Physics of Medical Imaging
Jiang Hsieh; Michael J. Flynn, Editor(s)

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