Temporal analysis of prostate Magnetic Resonance Linac data

Area of Science:

• Radiotherapy and Medical Imaging
• Biomarker Discovery
• Quantitative MRI

Background:

• Daily Magnetic Resonance-Linear Accelerator (MR-Linac) imaging offers potential for intratreatment biomarker extraction.
• Current prediction models rely on pretreatment and follow-up scans, limiting the use of dynamic MRL data.
• Investigating intratreatment MRL signals is crucial for unlocking their full predictive value.

Purpose of the Study:

• To demonstrate the existence of dynamic intratreatment signals in MR-Linac data.
• To explore methods for discovering these temporal signal changes.
• To establish the value of daily MRL imaging for outcome prediction.

Main Methods:

• Analysis of T2-weighted and diffusion MR-Linac data in prostate cancer patients.
• Application of fMRI-inspired exploratory analyses to detect temporal signal changes.
• Correlation of dose deposition with T2w signal changes in pelvic bone tissue.

Main Results:

• Prostate T2w signal decreased, while GTV signal remained constant; GTV diffusion coefficient increased.
• fMRI-inspired analysis revealed localized prostate T2w signal changes and effects in surrounding tissues and bone.
• Pelvic bone T2w signal showed a dose-threshold response, with significant change starting at 1 Gy.

Conclusions:

• fMRI-inspired analyses successfully identified temporal, non-linear trends in MR-Linac data.
• These findings support the potential of dynamic MRL data for future biomarker research.
• Pelvic bone exhibits a dose-threshold response to radiation, commencing at 1 Gy.