Enhancement of long-term external–internal correlation by phase-shift detection and correction based on concurrent external bellows and internal navigator signals Journal Article
| Authors: | Milewski, A. R.; Olek, D.; Deasy, J. O.; Rimner, A.; Li, G. |
| Article Title: | Enhancement of long-term external–internal correlation by phase-shift detection and correction based on concurrent external bellows and internal navigator signals |
| Abstract: | Purpose: The purpose of this study was to enhance the correlation between external and internal respiratory motions by dynamically determining and correcting the patient-specific phase shift between external and internal respiratory waveforms acquired concurrently during respiratory-correlated 4-dimensional magnetic resonance imaging scans. Methods and Materials: Internal-navigator and external-bellows waveforms were acquired simultaneously during 6- to 15-minute respiratory-correlated 4-dimensional magnetic resonance imaging scans in 10 healthy participants under an institutional review board–approved protocol. The navigator was placed at the right lung–diaphragm interface, and the bellows were placed ∼5 cm inferior to the sternum. Three segments of each respiratory waveform, at the beginning, middle, and end of a scan, were analyzed. Three phase-domain methods were employed to estimate the phase shift, including analytical signal analysis, phase-space oval fitting, and principal component analysis. A robust strategy for estimating the phase shift was realized by combining these methods in a weighted average and by eliminating outliers (>2 σ) caused by breathing irregularities. Whether phase-shift correction affects the external-internal correlation was evaluated. The cross-correlation between the 2 waveforms in the time domain provided an independent check of the correlation enhancement. Results: Phase-shift correction significantly enhanced the external-internal correlation in all participants across the entire 6- to 15-minute scans. On average, the correlation increased from 0.45 ± 0.28 to 0.85 ± 0.15 for the combined method. The combined method exhibited a 99.5% success rate and revealed that the phase of the external waveform leads that of the internal waveform in all 10 participants by 57 o ± 17 o (1.6 ± 0.5 bins) on average. Seven participants exhibited highly reproducible phase shifts over time, evidenced by standard deviations (σ) < 4 o , whereas 8 o < σ < 12 o in the remaining 3 participants. Regardless, phase-shift correction significantly improved the correlation in all participants. Conclusions: Correcting the phase shift estimated by the phase-domain methods provides a new approach for enhancing the correlation between external and internal respiratory motions. This strategy holds promise for improving the accuracy of respiratory-gated radiation therapy. © 2019 The Authors |
| Keywords: | adult; clinical article; controlled study; nuclear magnetic resonance imaging; motion; diaphragm; sternum; institutional review; principal component analysis; waveform; respiratory system; human; male; female; article; respiratory gated radiotherapy; right lung |
| Journal Title: | Advances in Radiation Oncology |
| Volume: | 4 |
| Issue: | 2 |
| ISSN: | 2452-1094 |
| Publisher: | Elsevier Inc. |
| Date Published: | 2019-04-01 |
| Start Page: | 377 |
| End Page: | 389 |
| Language: | English |
| DOI: | 10.1016/j.adro.2019.02.001 |
| PROVIDER: | scopus |
| PMCID: | PMC6460238 |
| PUBMED: | 31011684 |
| DOI/URL: | |
| Notes: | Article -- Export Date: 1 May 2019 -- Source: Scopus |
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