Design of a logarithmic k-space spiral trajectory. |
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Authors: | H E Cline X Zong N Gai |
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Institution: | General Electric Corporate Research and Development, Schenectady, New York 12309, USA. |
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Abstract: | Spiral acquisitions are used in fast cardiac imaging because they traverse k-space efficiently and minimize flow artifacts. A variable pitch logarithmic spiral trajectory is designed to critically sample the low-frequency region in k-space and gradually undersample the high-frequency region. An approximate analytical expression for the trajectory provides a fast means to calculate the gradient waveforms and the sampled data points. A numerical method is introduced based on the trajectory curvature and the rate of change in the gradient magnitude with time for the composite Archimedean-logarithmic trajectory. The pulse sequence is implemented and images are acquired on phantoms and human hearts. The images show improved image resolution and some improvement in image quality as a result of increased extent in k-space and reduction in aliasing artifacts, respectively. |
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Keywords: | spiral pulse sequence design trajectory logarithmic cardiac |
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