Treatment of glioblastoma using MRIdian® A3i BrainTx™: Imaging and treatment workflow demonstration

Rosa, Alonso La; Mittauer, K.E.; Rzepczynski, Amy E.; Chuong, Michael D.; Kütük, Tuğçe; Bassiri, Nema; McAllister, Nicole C.; Hall, Matthew D; McCulloch, James; Alvarez, Diane; Herrera, Roberto; Gutiérrez, Alonso N.; Tolakanahalli, Ranjini; Odia, Yazmín; Ahluwalia, Manmeet; Mehta, Minesh P.; Kotecha, Rupesh

doi:10.1016/j.meddos.2023.02.001

Cited by 6 publications

(2 citation statements)

References 17 publications

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“…Identifying these progressing patients during the first stages of treatment is key for applying aggressive second-line therapy or even dose escalation with multiparametric MRI (mpMRI) and image analysis. Early studies with MRgRT in this setting have been conducted with conventional fractionation [94][95][96], but ongoing phase II studies include moderate hypofractionation delivered in three weeks with reduced margins (Table 2).…”

Section: Central Nervous System Tumorsmentioning

confidence: 99%

MR-LINAC, a New Partner in Radiation Oncology: Current Landscape

Ocanto,

Torres,

Montijano

et al. 2024

Cancers

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Technological advances in radiation oncology are oriented towards improving treatment precision and tumor control. Among these advances, magnetic-resonance-image-guided radiation therapy (MRgRT) stands out, with technological advances to deliver targeted treatments adapted to a tumor’s anatomy on the day while minimizing incidental exposure to organs at risk, offering an unprecedented therapeutic advantage compared to X-ray-based IGRT delivery systems. This new technology changes the traditional workflow in radiation oncology and requires an evolution in team coordination to administer more precise treatments. Once implemented, it paves the way for newer indication for radiation therapy to safely deliver higher doses than ever before, with better preservation of healthy tissues to optimize patient outcomes. In this narrative review, we assess the technical aspects of the novel linear accelerators that can deliver MRgRT and summarize the available published experience to date, focusing on oncological results and future challenges.

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Section: Central Nervous System Tumorsmentioning

confidence: 99%

MR-LINAC, a New Partner in Radiation Oncology: Current Landscape

Ocanto,

Torres,

Montijano

et al. 2024

Cancers

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“…While MR-linacs are predominantly employed for irradiating mobile tumors in the abdominal, thoraic, or pelvic region [ 3 , 4 ], the high soft tissue contrast of MRI and the potential for online treatment plan adaptation also allows intracranial treatments with increased precision. Intracranial treatments at MR-linacs can be performed with smaller target volumes and reduced neurotoxicity compared to treatments at conventional linacs [ 2 , 5 – 7 ]. Another key feature of MR-linacs, not yet fully exploited in clinical practice, is the technical feasibility of functional MRI.…”

Section: Introductionmentioning

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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