ORIGINAL RESEARCH article

Front. Oncol.

Sec. Radiation Oncology

Volume 15 - 2025 | doi: 10.3389/fonc.2025.1575001

Validating a T1-weighted cine MRI for a 1.5T MR-Linac with temporal resolution appropriate for respiratory motion

Provisionally accepted
Nathan  ShafferNathan Shaffer1Alex  DresnerAlex Dresner2Qi  YingQi Ying3Eveline  AlbertsEveline Alberts4Marijn  KruiskampMarijn Kruiskamp4Joseph  CasterJoseph Caster3Daniel  HyerDaniel Hyer3Jeffrey  SnyderJeffrey Snyder5Joel  St-AubinJoel St-Aubin3*
  • 1The University of Iowa, Iowa City, United States
  • 2Philips Healthcare MR Oncology, Cleveland, United States
  • 3Department of Radiation Oncology, University of Iowa Hospitals and Clinics, Iowa City, Iowa, United States
  • 4Philips Healthcare, Best, Netherlands
  • 5Department of Therapeutic Radiology, School of Medicine, Yale University, New Haven, Connecticut, United States

The final, formatted version of the article will be published soon.

Purpose: High temporal resolution cine magnetic resonance imaging (MRI) for the 1.5T Elekta Unity MR-Linac system currently relies on a balanced contrast sequence for motion monitoring (MM) and tumor tracking. Despite its high signal-to-noise ratio (SNR), a balanced contrast sequence does not always provide the ideal contrast for tumor imaging in all situations. Thus, the investigation of other contrast high temporal resolution cine MRI sequences is needed.Methods: Experiments were conducted to validate the T1-weighting and SNR on a cine MRI sequence with a frame rate of 4 frames-per-second (fps) and sufficient image quality. A ModusQA Quasar MRI4D motion phantom and Alzheimer's Disease Neuroimaging Initiative (ADNI) phantom were used to confirm adequate motion tracking, contrast-to-noise ratio (CNR), SNR, and T1 weighting of the new cine MRI sequence. Target tracking success using Elekta's Comprehensive Motion Management (CMM) algorithm was assessed on in vivo patient images, and the CNR was measured for the patients with liver tumors which are one of the most challenging sites for visualization using the balanced cine MRI sequence.The T1-weighted cine MRI sequence exhibited consistent CNR, SNR and T1-weighting over the duration of the scan while maintaining the ability to capture target motion within 1 mm at 4 fps. In-vivo analysis showed that the T1-weighted sequence had an average tracking success rate of 99.3% ± 1.12% versus the 83.3% ± 23.4% success rate of the bTFE sequence using Elekta's CMM algorithm for all anatomical sites investigated and better CNR compared to the bTFE sequence for all liver tumors investigated.The proposed T1-weighted cine MRI sequence can produce quality T1-weighted images capable of tracking tumor motion over time. This demonstrates the sequence's potential in motion monitoring tasks as an alternative to the bTFE sequence when necessary.

Keywords: MR-linac, T1-weighted cine MRI, motion monitoring, tumor tracking, T1-weighted imaging

Received: 11 Feb 2025; Accepted: 30 Apr 2025.

Copyright: © 2025 Shaffer, Dresner, Ying, Alberts, Kruiskamp, Caster, Hyer, Snyder and St-Aubin. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

* Correspondence: Joel St-Aubin, Department of Radiation Oncology, University of Iowa Hospitals and Clinics, Iowa City, 52242, Iowa, United States

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