Abstract
Purpose: Four-dimensional magnetic resonance imaging (4DMRI) is an emerging technique in radiotherapy treatment planning for organ motion quantification. In this paper, the authors present a novel 4DMRI retrospective image-based sorting method, providing reduced motion artifacts than using a standard monodimensional external respiratory surrogate. Methods: Serial interleaved 2D multislice MRI data were acquired from 24 liver cases (6 volunteers + 18 patients) to test the proposed 4DMRI sorting. Image similarity based on mutual information was applied to automatically identify a stable reference phase and sort the image sequence retrospectively, without the use of additional image or surrogate data to describe breathing motion. Results: The image-based 4DMRI provided a smoother liver profile than that obtained from standard resorting based on an external surrogate. Reduced motion artifacts were observed in image-based 4DMRI datasets with a fitting error of the liver profile measuring 1.2±0.9 mm (median ± interquartile range) vs 2.1±1.7 mm of the standard method. Conclusions: The authors present a novel methodology to derive a patient-specific 4DMRI model to describe organ motion due to breathing, with improved image quality in 4D reconstruction.
Original language | English |
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Pages (from-to) | 4814-4821 |
Number of pages | 8 |
Journal | Medical Physics |
Volume | 42 |
Issue number | 8 |
DOIs | |
Publication status | Published - Aug 1 2015 |
Keywords
- 4DMRI
- radiotherapy
- retrospective sorting
- time-resolved imaging
- treatment planning
ASJC Scopus subject areas
- Biophysics
- Radiology Nuclear Medicine and imaging