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Analysis of Magnetic Resonance Image Signal Fluctuations Acquired During MR-Guided Radiotherapy

Magnetic resonance-guided radiotherapy (MRgRT) is a new and evolving treatment modality that allows unprecedented visualization of the tumor and surrounding anatomy. MRgRT includes daily 3D magnetic resonance imaging (MRI) for setup and rapidly repeated near real-time MRI scans during treatment for...

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Autores principales: Breto, Adrian L, Padgett, Kyle R, Ford, John C, Kwon, Deukwoo, Chang, Channing, Fuss, Martin, Stoyanova, Radka, Mellon, Eric A
Formato: Online Artículo Texto
Lenguaje:English
Publicado: Cureus 2018
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5973490/
https://www.ncbi.nlm.nih.gov/pubmed/29850380
http://dx.doi.org/10.7759/cureus.2385
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author Breto, Adrian L
Padgett, Kyle R
Ford, John C
Kwon, Deukwoo
Chang, Channing
Fuss, Martin
Stoyanova, Radka
Mellon, Eric A
author_facet Breto, Adrian L
Padgett, Kyle R
Ford, John C
Kwon, Deukwoo
Chang, Channing
Fuss, Martin
Stoyanova, Radka
Mellon, Eric A
author_sort Breto, Adrian L
collection PubMed
description Magnetic resonance-guided radiotherapy (MRgRT) is a new and evolving treatment modality that allows unprecedented visualization of the tumor and surrounding anatomy. MRgRT includes daily 3D magnetic resonance imaging (MRI) for setup and rapidly repeated near real-time MRI scans during treatment for target tracking. One of the more exciting potential benefits of MRgRT is the ability to analyze serial MRIs to monitor treatment response or predict outcomes. A typical radiation treatment (RT) over the span of 10-15 minutes on the MRIdian system (ViewRay, Cleveland, OH) yields thousands of “cine” images, each acquired in 250 ms. This unique data allows for a glimpse in image intensity changes during RT delivery. In this report, we analyze cine images from a single fraction RT of a glioblastoma patient on the ViewRay platform in order to characterize the dynamic signal changes occurring during RT therapy. The individual frames in the cines were saved into DICOM format and read into an MIM image analysis platform (MIM Software, Cleveland, OH) as a time series. The three possible states of the three Cobalt-60 radiation sources—OFF, READY, and ON—were also recorded. An in-house Java plugin for MIM was created in order to perform principal component analysis (PCA) on each of the datasets. The analysis resulted in first PC, related to monotonous signal increase over the course of the treatment fraction. We found several distortion patterns in the data that we postulate result from the perturbation of the magnetic field due to the moving metal parts in the platform while treatment was being administered. The largest variations were detected when all Cobalt-60 sources were OFF. During this phase of the treatment, the gantry and multi-leaf collimators (MLCs) are moving. Conversely, when all Cobalt-60 sources were in the ON position, the image signal fluctuations were minimal, relating to very little mechanical motion. At this phase, the gantry, the MLCs, and sources are fixed in their positions. These findings were confirmed in a study with the daily quality assurance (QA) phantom. While the identified variations were not related to physiological processes, our findings confirm the sensitivity of the developed approach to identify very small fluctuations. Relating these variations to the physical changes that occur during treatment shows the methodical ability of the technique to uncover their underlying sources.
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spelling pubmed-59734902018-05-30 Analysis of Magnetic Resonance Image Signal Fluctuations Acquired During MR-Guided Radiotherapy Breto, Adrian L Padgett, Kyle R Ford, John C Kwon, Deukwoo Chang, Channing Fuss, Martin Stoyanova, Radka Mellon, Eric A Cureus Medical Physics Magnetic resonance-guided radiotherapy (MRgRT) is a new and evolving treatment modality that allows unprecedented visualization of the tumor and surrounding anatomy. MRgRT includes daily 3D magnetic resonance imaging (MRI) for setup and rapidly repeated near real-time MRI scans during treatment for target tracking. One of the more exciting potential benefits of MRgRT is the ability to analyze serial MRIs to monitor treatment response or predict outcomes. A typical radiation treatment (RT) over the span of 10-15 minutes on the MRIdian system (ViewRay, Cleveland, OH) yields thousands of “cine” images, each acquired in 250 ms. This unique data allows for a glimpse in image intensity changes during RT delivery. In this report, we analyze cine images from a single fraction RT of a glioblastoma patient on the ViewRay platform in order to characterize the dynamic signal changes occurring during RT therapy. The individual frames in the cines were saved into DICOM format and read into an MIM image analysis platform (MIM Software, Cleveland, OH) as a time series. The three possible states of the three Cobalt-60 radiation sources—OFF, READY, and ON—were also recorded. An in-house Java plugin for MIM was created in order to perform principal component analysis (PCA) on each of the datasets. The analysis resulted in first PC, related to monotonous signal increase over the course of the treatment fraction. We found several distortion patterns in the data that we postulate result from the perturbation of the magnetic field due to the moving metal parts in the platform while treatment was being administered. The largest variations were detected when all Cobalt-60 sources were OFF. During this phase of the treatment, the gantry and multi-leaf collimators (MLCs) are moving. Conversely, when all Cobalt-60 sources were in the ON position, the image signal fluctuations were minimal, relating to very little mechanical motion. At this phase, the gantry, the MLCs, and sources are fixed in their positions. These findings were confirmed in a study with the daily quality assurance (QA) phantom. While the identified variations were not related to physiological processes, our findings confirm the sensitivity of the developed approach to identify very small fluctuations. Relating these variations to the physical changes that occur during treatment shows the methodical ability of the technique to uncover their underlying sources. Cureus 2018-03-28 /pmc/articles/PMC5973490/ /pubmed/29850380 http://dx.doi.org/10.7759/cureus.2385 Text en Copyright © 2018, Breto et al. http://creativecommons.org/licenses/by/3.0/ This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
spellingShingle Medical Physics
Breto, Adrian L
Padgett, Kyle R
Ford, John C
Kwon, Deukwoo
Chang, Channing
Fuss, Martin
Stoyanova, Radka
Mellon, Eric A
Analysis of Magnetic Resonance Image Signal Fluctuations Acquired During MR-Guided Radiotherapy
title Analysis of Magnetic Resonance Image Signal Fluctuations Acquired During MR-Guided Radiotherapy
title_full Analysis of Magnetic Resonance Image Signal Fluctuations Acquired During MR-Guided Radiotherapy
title_fullStr Analysis of Magnetic Resonance Image Signal Fluctuations Acquired During MR-Guided Radiotherapy
title_full_unstemmed Analysis of Magnetic Resonance Image Signal Fluctuations Acquired During MR-Guided Radiotherapy
title_short Analysis of Magnetic Resonance Image Signal Fluctuations Acquired During MR-Guided Radiotherapy
title_sort analysis of magnetic resonance image signal fluctuations acquired during mr-guided radiotherapy
topic Medical Physics
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5973490/
https://www.ncbi.nlm.nih.gov/pubmed/29850380
http://dx.doi.org/10.7759/cureus.2385
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