Practical considerations of gadoxetate disodium contrast in MRI-guided liver SBRT for primary and secondary liver tumors: optimizing image quality and patient throughput
In brief
In six patients, delayed liver contrast cut median untreated tumor volume by 82%
Among 23 patients receiving MRI-guided liver radiation, images taken 20 to 30 minutes after contrast showed better tumor visibility and border definition than pre-contrast or earlier images. In the six patients assessed for contouring, median tumor volume left untreated fell from 3.68 to 0.68 cm3. The small contouring sample limits certainty, but the findings suggest timing contrast could reduce geographic miss.
- Journal
- Practical radiation oncology (Q1)
- Published
- 26 October 2026
- Study design
- Unclassified
- Evidence level
- Level 5, Expert Opinion (CEBM 5)
- Authors
- Ari A Kassardjian, Borna Maraghechi, Chengyu Shi, Huisi Ai, Eli Grant, William Tyler Watkins, et al.
- PMID
- 42933730
- DOI
- 10.1016/j.prro.2026.10.008
Why clinicians should know about it
- Picked for Medical Physics (paper of the day, 28 October 2026): MR-guided liver RT image quality and contouring variability
Abstract
PURPOSE/OBJECTIVES: Optimal implementation of gadoxetate disodium injection (GDI) in liver-directed MR-guided online adaptive radiotherapy (MRgART) remains poorly characterized. Herein, we evaluated the impact of GDI on physician-reported imaging metrics and quantitative contouring variability during liver MRgART planning. MATERIALS/METHODS: Patients were scanned using a 0.35T MRI onboard the MR-guided LINAC. Pre- and post-contrast TRUFI images were captured at multiple timepoints up to 30 minutes (5-10-minute intervals) following GDI. Four radiation oncologists independently scored each tumor on a 5-point scale (1: poor; 5: excellent) evaluating imaging metrics, such as tumor visualization, border delineation, and image degradation from artifacts. Responses were stratified into pre-contrast, "early" post-contrast (1-15 minutes), and "late" post-contrast (20-30 minutes). Physicians then contoured gross tumor volume (GTV) for 6 patients with either optimal or non-optimal image characteristics. Inter- and intra-observer variability was assessed using Sørensen-Dice coefficient (DICE), Hausdorff distance (HD), volume of tumor not treated (VTNT), and volume of healthy liver erroneously treated (VHL). Comparisons were performed using Mann-Whitney U-test or Wilcoxon Signed-Rank test, as applicable. RESULTS: Twenty-three patients with 37 total liver tumors were treated using MRgART (median 50 Gy; 3-5 fractions). Late post-contrast imaging significantly improved tumor visualization (4.45) compared to early post-contrast (3.73; p<0.001) and pre-contrast (3.25; p<0.001). Late post-contrast also significantly improved border delineation (4.38) versus early post-contrast (3.58; p<0.001) and pre-contrast (3.06; p<0.001). In 6 patients selected for contouring analysis, DICE increased from 0.75 to 0.92 (p<0.01) and HD90 decreased from 4.18 mm to 2.00 mm (p<0.01) when GDI was helpful (n=3). Across all 6 patients, median VTNT significantly decreased from 3.68 cm3 to 0.68 cm3 (p<0.001). CONCLUSIONS: GDI administration 20-30 minutes prior to MRgART planning significantly enhances both physician-reported image quality and quantitative contouring accuracy. Its use should be considered in MRgART workflows to minimize potential geographic miss and optimize treatment delivery.
Abstract as published, via PubMed.
For healthcare professionals. The summary is generated by AI from the published abstract, and the evidence level is assigned automatically from the study design on the Oxford CEBM hierarchy. Neither is medical advice. Read the full paper before changing practice.