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Automatic phase determination for retrospectively gated cardiac CT
Author(s) -
Manzke R.,
Köhler Th.,
Nielsen T.,
Hawkes D.,
Grass M.
Publication year - 2004
Publication title -
medical physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.473
H-Index - 180
eISSN - 2473-4209
pISSN - 0094-2405
DOI - 10.1118/1.1791351
Subject(s) - cardiac cycle , computer vision , artificial intelligence , artifact (error) , iterative reconstruction , projection (relational algebra) , computer science , image quality , visualization , cardiac imaging , image resolution , phase (matter) , algorithm , image (mathematics) , physics , radiology , medicine , quantum mechanics
The recent improvements in CT detector and gantry technology in combination with new heart rate adaptive cone beam reconstruction algorithms enable the visualization of the heart in three dimensions at high spatial resolution. However, the finite temporal resolution still impedes the artifact‐free reconstruction of the heart at any arbitrary phase of the cardiac cycle. Cardiac phases must be found during which the heart is quasistationary to obtain outmost image quality. It is challenging to find these phases due to intercycle and patient‐to‐patient variability. Electrocardiogram (ECG) information does not always represent the heart motion with an adequate accuracy. In this publication, a simple and efficient image‐based technique is introduced which is able to deliver stable cardiac phases in an automatic and patient‐specific way. From low‐resolution four‐dimensional data sets, the most stable phases are derived by calculating the object similarity between subsequent phases in the cardiac cycle. Patient‐specific information about the object motion can be determined and resolved spatially. This information is used to perform optimized high‐resolution reconstructions at phases of little motion. Results based on a simulation study and three real patient data sets are presented. The projection data were generated using a 16‐slice cone beam CT system in low‐pitch helical mode with parallel ECG recording.