Repeatability quantification of brain diffusion-weighted imaging for future clinical implementation at a low-field MR-linac
Abstract Background Longitudinal assessments of apparent diffusion coefficients (ADCs) derived from diffusion-weighted imaging (DWI) during intracranial radiotherapy at magnetic resonance imaging-guided linear accelerators (MR-linacs) could enable early response assessment by tracking tumor diffusiv...
| Main Authors: | , , , , , , , |
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| Format: | Article |
| Language: | English |
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BMC
2024-03-01
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| Series: | Radiation Oncology |
| Subjects: | |
| Online Access: | https://doi.org/10.1186/s13014-024-02424-7 |
| _version_ | 1827321323558273024 |
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| author | Moritz Rabe Olaf Dietrich Robert Forbrig Maximilian Niyazi Claus Belka Stefanie Corradini Guillaume Landry Christopher Kurz |
| author_facet | Moritz Rabe Olaf Dietrich Robert Forbrig Maximilian Niyazi Claus Belka Stefanie Corradini Guillaume Landry Christopher Kurz |
| author_sort | Moritz Rabe |
| collection | DOAJ |
| description | Abstract Background Longitudinal assessments of apparent diffusion coefficients (ADCs) derived from diffusion-weighted imaging (DWI) during intracranial radiotherapy at magnetic resonance imaging-guided linear accelerators (MR-linacs) could enable early response assessment by tracking tumor diffusivity changes. However, DWI pulse sequences are currently unavailable in clinical practice at low-field MR-linacs. Quantifying the in vivo repeatability of ADC measurements is a crucial step towards clinical implementation of DWI sequences but has not yet been reported on for low-field MR-linacs. This study assessed ADC measurement repeatability in a phantom and in vivo at a 0.35 T MR-linac. Methods Eleven volunteers and a diffusion phantom were imaged on a 0.35 T MR-linac. Two echo-planar imaging DWI sequence variants, emphasizing high spatial resolution (“highRes”) and signal-to-noise ratio (“highSNR”), were investigated. A test–retest study with an intermediate outside-scanner-break was performed to assess repeatability in the phantom and volunteers’ brains. Mean ADCs within phantom vials, cerebrospinal fluid (CSF), and four brain tissue regions were compared to literature values. Absolute relative differences of mean ADCs in pre- and post-break scans were calculated for the diffusion phantom, and repeatability coefficients (RC) and relative RC (relRC) with 95% confidence intervals were determined for each region-of-interest (ROI) in volunteers. Results Both DWI sequence variants demonstrated high repeatability, with absolute relative deviations below 1% for water, dimethyl sulfoxide, and polyethylene glycol in the diffusion phantom. RelRCs were 7% [5%, 12%] (CSF; highRes), 12% [9%, 22%] (CSF; highSNR), 9% [8%, 12%] (brain tissue ROIs; highRes), and 6% [5%, 7%] (brain tissue ROIs; highSNR), respectively. ADCs measured with the highSNR variant were consistent with literature values for volunteers, while smaller mean values were measured for the diffusion phantom. Conversely, the highRes variant underestimated ADCs compared to literature values, indicating systematic deviations. Conclusions High repeatability of ADC measurements in a diffusion phantom and volunteers’ brains were measured at a low-field MR-linac. The highSNR variant outperformed the highRes variant in accuracy and repeatability, at the expense of an approximately doubled voxel volume. The observed high in vivo repeatability confirms the potential utility of DWI at low-field MR-linacs for early treatment response assessment. |
| first_indexed | 2024-04-25T01:04:18Z |
| format | Article |
| id | doaj.art-d834bdfa1ace44b5b5e6de21bfd69b94 |
| institution | Directory Open Access Journal |
| issn | 1748-717X |
| language | English |
| last_indexed | 2024-04-25T01:04:18Z |
| publishDate | 2024-03-01 |
| publisher | BMC |
| record_format | Article |
| series | Radiation Oncology |
| spelling | doaj.art-d834bdfa1ace44b5b5e6de21bfd69b942024-03-10T12:18:42ZengBMCRadiation Oncology1748-717X2024-03-0119111210.1186/s13014-024-02424-7Repeatability quantification of brain diffusion-weighted imaging for future clinical implementation at a low-field MR-linacMoritz Rabe0Olaf Dietrich1Robert Forbrig2Maximilian Niyazi3Claus Belka4Stefanie Corradini5Guillaume Landry6Christopher Kurz7Department of Radiation Oncology, LMU University Hospital, LMU MunichDepartment of Radiology, LMU University Hospital, LMU MunichInstitute of Neuroradiology, LMU University Hospital, LMU MunichDepartment of Radiation Oncology, LMU University Hospital, LMU MunichDepartment of Radiation Oncology, LMU University Hospital, LMU MunichDepartment of Radiation Oncology, LMU University Hospital, LMU MunichDepartment of Radiation Oncology, LMU University Hospital, LMU MunichDepartment of Radiation Oncology, LMU University Hospital, LMU MunichAbstract Background Longitudinal assessments of apparent diffusion coefficients (ADCs) derived from diffusion-weighted imaging (DWI) during intracranial radiotherapy at magnetic resonance imaging-guided linear accelerators (MR-linacs) could enable early response assessment by tracking tumor diffusivity changes. However, DWI pulse sequences are currently unavailable in clinical practice at low-field MR-linacs. Quantifying the in vivo repeatability of ADC measurements is a crucial step towards clinical implementation of DWI sequences but has not yet been reported on for low-field MR-linacs. This study assessed ADC measurement repeatability in a phantom and in vivo at a 0.35 T MR-linac. Methods Eleven volunteers and a diffusion phantom were imaged on a 0.35 T MR-linac. Two echo-planar imaging DWI sequence variants, emphasizing high spatial resolution (“highRes”) and signal-to-noise ratio (“highSNR”), were investigated. A test–retest study with an intermediate outside-scanner-break was performed to assess repeatability in the phantom and volunteers’ brains. Mean ADCs within phantom vials, cerebrospinal fluid (CSF), and four brain tissue regions were compared to literature values. Absolute relative differences of mean ADCs in pre- and post-break scans were calculated for the diffusion phantom, and repeatability coefficients (RC) and relative RC (relRC) with 95% confidence intervals were determined for each region-of-interest (ROI) in volunteers. Results Both DWI sequence variants demonstrated high repeatability, with absolute relative deviations below 1% for water, dimethyl sulfoxide, and polyethylene glycol in the diffusion phantom. RelRCs were 7% [5%, 12%] (CSF; highRes), 12% [9%, 22%] (CSF; highSNR), 9% [8%, 12%] (brain tissue ROIs; highRes), and 6% [5%, 7%] (brain tissue ROIs; highSNR), respectively. ADCs measured with the highSNR variant were consistent with literature values for volunteers, while smaller mean values were measured for the diffusion phantom. Conversely, the highRes variant underestimated ADCs compared to literature values, indicating systematic deviations. Conclusions High repeatability of ADC measurements in a diffusion phantom and volunteers’ brains were measured at a low-field MR-linac. The highSNR variant outperformed the highRes variant in accuracy and repeatability, at the expense of an approximately doubled voxel volume. The observed high in vivo repeatability confirms the potential utility of DWI at low-field MR-linacs for early treatment response assessment.https://doi.org/10.1186/s13014-024-02424-7Diffusion-weighted imagingApparent diffusion coefficientMR-linacLow-field MRIMR-guided radiotherapyFunctional imaging |
| spellingShingle | Moritz Rabe Olaf Dietrich Robert Forbrig Maximilian Niyazi Claus Belka Stefanie Corradini Guillaume Landry Christopher Kurz Repeatability quantification of brain diffusion-weighted imaging for future clinical implementation at a low-field MR-linac Radiation Oncology Diffusion-weighted imaging Apparent diffusion coefficient MR-linac Low-field MRI MR-guided radiotherapy Functional imaging |
| title | Repeatability quantification of brain diffusion-weighted imaging for future clinical implementation at a low-field MR-linac |
| title_full | Repeatability quantification of brain diffusion-weighted imaging for future clinical implementation at a low-field MR-linac |
| title_fullStr | Repeatability quantification of brain diffusion-weighted imaging for future clinical implementation at a low-field MR-linac |
| title_full_unstemmed | Repeatability quantification of brain diffusion-weighted imaging for future clinical implementation at a low-field MR-linac |
| title_short | Repeatability quantification of brain diffusion-weighted imaging for future clinical implementation at a low-field MR-linac |
| title_sort | repeatability quantification of brain diffusion weighted imaging for future clinical implementation at a low field mr linac |
| topic | Diffusion-weighted imaging Apparent diffusion coefficient MR-linac Low-field MRI MR-guided radiotherapy Functional imaging |
| url | https://doi.org/10.1186/s13014-024-02424-7 |
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