A novel amplitude binning strategy to handle irregular breathing during 4DMRI acquisition: improved imaging for radiotherapy purposes.
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Authors
van Kesteren, Z
van der Horst, A
Gurney-Champion, OJ
Bones, I
Tekelenburg, D
Alderliesten, T
van Tienhoven, G
Klaassen, R
van Laarhoven, HWM
Bel, A
van der Horst, A
Gurney-Champion, OJ
Bones, I
Tekelenburg, D
Alderliesten, T
van Tienhoven, G
Klaassen, R
van Laarhoven, HWM
Bel, A
Document Type
Journal Article
Date
2019-05-14
Date Accepted
2019-04-22
Abstract
BACKGROUND: For radiotherapy of abdominal cancer, four-dimensional magnetic resonance imaging (4DMRI) is desirable for tumor definition and the assessment of tumor and organ motion. However, irregular breathing gives rise to image artifacts. We developed a outlier rejection strategy resulting in a 4DMRI with reduced image artifacts in the presence of irregular breathing. METHODS: We obtained 2D T2-weighted single-shot turbo spin echo images, with an interleaved 1D navigator acquisition to obtain the respiratory signal during free breathing imaging in 2 patients and 12 healthy volunteers. Prior to binning, upper and lower inclusion thresholds were chosen such that 95% of the acquired images were included, while minimizing the distance between the thresholds (inclusion range (IR)). We compared our strategy (Min95) with three commonly applied strategies: phase binning with all images included (Phase), amplitude binning with all images included (MaxIE), and amplitude binning with the thresholds set as the mean end-inhale and mean end-exhale diaphragm positions (MeanIE). We compared 4DMRI quality based on: Data included (DI); percentage of images remaining after outlier rejection. Reconstruction completeness (RC); percentage of bin-slice combinations containing at least one image after binning. Intra-bin variation (IBV); interquartile range of the diaphragm position within the bin-slice combination, averaged over three central slices and ten respiratory bins. IR. Image smoothness (S); quantified by fitting a parabola to the diaphragm profile in a sagittal plane of the reconstructed 4DMRI. A two-sided Wilcoxon's signed-rank test was used to test for significance in differences between the Min95 strategy and the Phase, MaxIE, and MeanIE strategies. RESULTS: Based on the fourteen subjects, the Min95 binning strategy outperformed the other strategies with a mean RC of 95.5%, mean IBV of 1.6 mm, mean IR of 15.1 mm and a mean S of 0.90. The Phase strategy showed a poor mean IBV of 6.2 mm and the MaxIE strategy showed a poor mean RC of 85.6%, resulting in image artifacts (mean S of 0.76). The MeanIE strategy demonstrated a mean DI of 85.6%. CONCLUSIONS: Our Min95 reconstruction strategy resulted in a 4DMRI with less artifacts and more precise diaphragm position reconstruction compared to the other strategies. TRIAL REGISTRATION: Volunteers: protocol W15_373#16.007; patients: protocol NL47713.018.14.
Citation
Radiation oncology (London, England), 2019, 14 (1), pp. 80 - ?
Source Title
Publisher
BMC
ISSN
1748-717X
eISSN
1748-717X
Collections
Research Team
Radiotherapy Physics Modelling