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Toward magnetic resonance fingerprinting for low-field MR-guided radiation therapy. Med Phys 2021 Nov;48(11):6930-6940

Date

09/07/2021

Pubmed ID

34487357

Pubmed Central ID

PMC8733901

DOI

10.1002/mp.15202

Scopus ID

2-s2.0-85114987814   3 Citations

Abstract

PURPOSE: The acquisition of multiparametric quantitative magnetic resonance imaging (qMRI) is becoming increasingly important for functional characterization of cancer prior to- and throughout the course of radiation therapy. The feasibility of a qMRI method known as magnetic resonance fingerprinting (MRF) for rapid T1 and T2 mapping was assessed on a low-field MR-linac system.

METHODS: A three-dimensional MRF sequence was implemented on a 0.35T MR-guided radiotherapy system. MRF-derived measurements of T1 and T2 were compared to those obtained with gold standard single spin echo methods, and the impacts of the radiofrequency field homogeneity and scan times ranging between 6 and 48 min were analyzed by acquiring between 1 and 8 spokes per time point in a standard quantitative system phantom. The short-term repeatability of MRF was assessed over three measurements taken over a 10-h period. To evaluate transferability, MRF measurements were acquired on two additional MR-guided radiotherapy systems. Preliminary human volunteer studies were performed.

RESULTS: The phantom benchmarking studies showed that MRF is capable of mapping T1 and T2 values within 8% and 10% of gold standard measures, respectively, at 0.35T. The coefficient of variation of T1 and T2 estimates over three repeated scans was < 5% over a broad range of relaxation times. The T1 and T2 times derived using a single-spoke MRF acquisition across three scanners were near unity and mean percent errors in T1 and T2 estimates using the same phantom were < 3%. The mean percent differences in T1 and T2 as a result of truncating the scan time to 6 min over the large range of relaxation times in the system phantom were 0.65% and 4.05%, respectively.

CONCLUSIONS: The technical feasibility and accuracy of MRF on a low-field MR-guided radiation therapy device has been demonstrated. MRF can be used to measure accurate T1 and T2 maps in three dimensions from a brief 6-min scan, offering strong potential for efficient and reproducible qMRI for future clinical trials in functional plan adaptation and tumor/normal tissue response assessment.

Author List

Mickevicius NJ, Kim JP, Zhao J, Morris ZS, Hurst NJ Jr, Glide-Hurst CK

Author

Nikolai J. Mickevicius PhD Assistant Professor in the Radiology department at Medical College of Wisconsin




MESH terms used to index this publication - Major topics in bold

Benchmarking
Brain
Humans
Image Processing, Computer-Assisted
Magnetic Resonance Imaging
Magnetic Resonance Spectroscopy
Phantoms, Imaging