Prospective evaluation of in vivo and phantom repeatability and reproducibility of diffusion-weighted MRI sequences on 1.5 T MRI-linear accelerator (MR-Linac) and MR simulator devices for head and neck cancers

McDonald, Brigid A.; Salzillo, Travis C.; Mulder, Samuel L.; Ahmed, Sara; Dresner, Alex; Preston, Kathryn; He, Renjie; Christodouleas, John P.; Mohamed, A.S.R.; Philippens, M.E.P.; Houdt, Petra J. van; Thorwarth, Daniela; Wang, Jihong; Dave, Amita; Boss, Michael A.; Fuller, Clifton D.

doi:10.1016/j.radonc.2023.109717

Cited by 10 publications

(2 citation statements)

References 45 publications

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“…To the best of our knowledge, our study is the first to report on the in vivo repeatability of ADCs at the MRIdian MR-linac. However, systematic measurements of repeatability for phantoms and in vivo for different body sites have been conducted at the Elekta Unity MR-linac [ 9 , 19 , 39 , 42 , 46 – 48 ]. Lawrence et al investigated in vivo repeatability in different ROIs within the brain [ 19 ].…”

Section: Discussionmentioning

confidence: 99%

Repeatability quantification of brain diffusion-weighted imaging for future clinical implementation at a low-field MR-linac

Rabe,

Dietrich,

Forbrig

et al. 2024

Radiat Oncol

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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.

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Section: Discussionmentioning

confidence: 99%

Repeatability quantification of brain diffusion-weighted imaging for future clinical implementation at a low-field MR-linac

Rabe,

Dietrich,

Forbrig

et al. 2024

Radiat Oncol

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“…Quantitative MRI methods can be paired with radiotherapy treatment to assess response to treatment and progression of disease [90]. As a result, phantoms have been used to measure the reproducibility of ADC on MR-Linac [91,92] and MRI systems used by radiotherapy teams [48]. Given the necessity of phantoms for ensuring proper radiation dose, the MR-Linac community has readily adopted the use of phantoms for MRI measurements.…”

Section: Radiotherapy Treatment Design and Planningmentioning

confidence: 99%

Phantoms for Quantitative Body MRI: a review and discussion of the phantom value

Keenan,

Jordanova,

Ogier

et al. 2024

Magn Reson Mater Phy

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In this paper, we review the value of phantoms for body MRI in the context of their uses for quantitative MRI methods research, clinical trials, and clinical imaging. Certain uses of phantoms are common throughout the body MRI community, including measuring bias, assessing reproducibility, and training. In addition to these uses, phantoms in body MRI methods research are used for novel methods development and the design of motion compensation and mitigation techniques. For clinical trials, phantoms are an essential part of quality management strategies, facilitating the conduct of ethically sound, reliable, and regulatorily compliant clinical research of both novel MRI methods and therapeutic agents. In the clinic, phantoms are used for development of protocols, mitigation of cost, quality control, and radiotherapy. We briefly review phantoms developed for quantitative body MRI, and finally, we review open questions regarding the most effective use of a phantom for body MRI.

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Prostate diffusion-weighted imaging (DWI) in MR-guided radiotherapy: Reproducibility assessment on 1.5 T MR-Linac and 1.5 T MR-simulator

Wong,

Yuan,

Poon

et al. 2024

Magnetic Resonance Imaging

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Prospective evaluation of in vivo and phantom repeatability and reproducibility of diffusion-weighted MRI sequences on 1.5 T MRI-linear accelerator (MR-Linac) and MR simulator devices for head and neck cancers

Cited by 10 publications

References 45 publications

Repeatability quantification of brain diffusion-weighted imaging for future clinical implementation at a low-field MR-linac

Repeatability quantification of brain diffusion-weighted imaging for future clinical implementation at a low-field MR-linac

Phantoms for Quantitative Body MRI: a review and discussion of the phantom value

Prostate diffusion-weighted imaging (DWI) in MR-guided radiotherapy: Reproducibility assessment on 1.5 T MR-Linac and 1.5 T MR-simulator

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