Technical feasibility of Magnetic Resonance Fingerprinting on a 1.5T MRI-Linac

TL;DR

This study demonstrates that gradient spoiled 2D Magnetic Resonance Fingerprinting (MRF) is technically feasible on a 1.5T MRI-Linac system, producing reliable and accurate quantitative MRI data suitable for clinical radiotherapy applications.

Contribution

It provides the first evidence that MRF can be effectively implemented on a 1.5T MRI-Linac system, matching diagnostic system performance for clinical use.

Findings

MRF signals are stable and reliable on the MRI-Linac.

Quantitative values align with literature and reference measurements.

Image quality is sufficient for clinical radiotherapy guidance.

Abstract

Hybrid MRI-linac (MRL) systems enable daily multiparametric quantitative MRI to assess tumor response to radiotherapy. Magnetic Resonance Fingerprinting (MRF) may provide time efficient means of rapid multiparametric quantitative MRI. The accuracy of MRF, however, relies on adequate control over system imperfections, such as eddy currents and B1+, which are different and not as well established on MRL systems compared to diagnostic systems. In this study we investigate the technical feasibility of gradient spoiled 2D MRF on a 1.5T MRL. We show with phantom experiments that the MRL generates reliable MRF signals that are temporally stable during the day and have good agreement with spin-echo reference measurements. Subsequent in-vivo MRF scans in healthy volunteers and a patient with a colorectal liver metastasis showed good image quality, where the quantitative values of selected organs corresponded with the values reported in literature. Therefore we conclude that gradient spoiled 2D MRF is feasible on a 1.5T MRL with similar performance as on a diagnostic system. The precision and accuracy of the parametric maps are sufficient for further investigation of the clinical utility of MRF for online quantitatively MRI-guided radiotherapy.