Recommendations towards standards for quantitative MRI (qMRI) and outstanding needs

Keenan, Kathryn E.; Biller, Joshua R.; Delfino, Jana G.; Boss, Michael A.; Does, Mark D.; Evelhoch, Jeffrey L.; Griswold, Mark A.; Gunter, Jeffrey L.; Hinks, R. Scott; Hoffman, Stuart W.; Kim, Geena; Lattanzi, Riccardo; Li, Xiaojuan; Marinelli, Luca; Metzger, Gregory J.; Mukherjee, Pratik; Nordstrom, Robert J.; Peskin, Adele P.; Perez, E.Roda; Russek, Stephen E.; Sahiner, Berkman; Serkova, Natalie J.; Shukla–Dave, Amita; Steckner, Michael; Stupic, Karl F.; Wilmes, Lisa J.; Wu, Holden H.; Zhang, Huiming; Jackson, Edward F.; Sullivan, Daniel C.

doi:10.1002/jmri.26598

Cited by 79 publications

(99 citation statements)

References 79 publications

(137 reference statements)

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“…In radiotherapy-related applications, quantitative MR imaging (qMRI) has been considered to support treatment planning and to implement MRI-only treatment workflows [67,68]. Specifically, qMRI refers to the objective measurement of a biophysical property of the examined tissue that can be expressed in physical units [69,70]. Recent efforts in improving qMRI robustness [69,71] are mainly driven by the clinical need for reliable imaging of biomarkers in oncology [72].…”

Section: Quantitative Imagingmentioning

confidence: 99%

“…Specifically, qMRI refers to the objective measurement of a biophysical property of the examined tissue that can be expressed in physical units [69,70]. Recent efforts in improving qMRI robustness [69,71] are mainly driven by the clinical need for reliable imaging of biomarkers in oncology [72]. This is not necessarily related to MRgRT, whose clinical implementation is still at an early stage, although qMRI principles could further leverage the importance of MR guidance in the field.…”

Section: Quantitative Imagingmentioning

confidence: 99%

“…Technical tolerances related to hardware components should be first identified and then quantified through physical phantoms, by following the available standardized procedures or guidelines and recommendations [71,[98][99][100][101]. These latter are being developed and updated by several bodies [69], although a global procedure is yet to be found [67]. At the same time, the analysis of the MR signal itself should be carried out through robust software.…”

Section: Quantitative Imagingmentioning

confidence: 99%

“…2 Flowchart for validated use of qMRI biomarkers, with representative images at each step. Adapted and reproduced with permission from [69,78,80,89] dosimeters have been published [124,125]. For a 1.5 T field, Matthis et al reported no difference within a 5% criterion, while Wen et al reported directional variations of up to 2.3%.…”

Section: Dose Measurementsmentioning

confidence: 99%

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Medical physics challenges in clinical MR-guided radiotherapy

et al. 2020

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The integration of magnetic resonance imaging (MRI) for guidance in external beam radiotherapy has faced significant research and development efforts in recent years. The current availability of linear accelerators with an embedded MRI unit, providing volumetric imaging at excellent soft tissue contrast, is expected to provide novel possibilities in the implementation of image-guided adaptive radiotherapy (IGART) protocols. This study reviews open medical physics issues in MR-guided radiotherapy (MRgRT) implementation, with a focus on current approaches and on the potential for innovation in IGART. Daily imaging in MRgRT provides the ability to visualize the static anatomy, to capture internal tumor motion and to extract quantitative image features for treatment verification and monitoring. Those capabilities enable the use of treatment adaptation, with potential benefits in terms of personalized medicine. The use of online MRI requires dedicated efforts to perform accurate dose measurements and calculations, due to the presence of magnetic fields. Likewise, MRgRT requires dedicated quality assurance (QA) protocols for safe clinical implementation. Reaction to anatomical changes in MRgRT, as visualized on daily images, demands for treatment adaptation concepts, with stringent requirements in terms of fast and accurate validation before the treatment fraction can be delivered. This entails specific challenges in terms of treatment workflow optimization, QA, and verification of the expected delivered dose while the patient is in treatment position. Those challenges require specialized medical physics developments towards the aim of fully exploiting MRI capabilities. Conversely, the use of MRgRT allows for higher confidence in tumor targeting and organs-at-risk (OAR) sparing. The systematic use of MRgRT brings the possibility of leveraging IGART methods for the optimization of tumor targeting and quantitative treatment verification. Although several challenges exist, the intrinsic benefits of MRgRT will provide a deeper understanding of dose delivery effects on an individual basis, with the potential for further treatment personalization.

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Section: Quantitative Imagingmentioning

confidence: 99%

Section: Quantitative Imagingmentioning

confidence: 99%

Section: Quantitative Imagingmentioning

confidence: 99%

Section: Dose Measurementsmentioning

confidence: 99%

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Medical physics challenges in clinical MR-guided radiotherapy

et al. 2020

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“…T1 and T2 weighted) techniques, qMRI methods can offer more effective detection and monitoring of different neurological pathologies (1), including stroke (2), neurodegenerative diseases (3-5) and brain tumors (6,7). However, conventional qMRI is limited by very long acquisition times, rendering them unsuitable for routine clinical practice (1,8). Moreover, they suffer from high sensitivity to scanners imperfections (e.g B1 or B0 inhomogeneities).…”

Section: ) Introductionmentioning

confidence: 99%

Magnetic Resonance Fingerprinting with Combined Gradient- and Spin-echo Echo-planar Imaging: Simultaneous Estimation of T1, T2 and T2* with integrated-B1 Correction

Khajehim

Christen

Chen

2019

Preprint

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Purpose: To introduce a novel magnetic-resonance fingerprinting (MRF) framework with single-shot echo-planar imaging (EPI) readout to simultaneously estimate tissue T2, T1 and T2*, and integrate B1 correction.Methods: Spin-echo EPI is combined with gradient-echo EPI to achieve T2 estimation as well as T1 and T2* quantification. In the dictionary matching step, the GE-EPI data segment provides estimates of tissue T1 and T2* with additional B1 information, which are then incorporated into the T2-matching step that uses the SE-EPI data segment. In this way, biases in T2 and T2* estimates do not affect each other.Results: An excellent correspondence was found between our T1, T2, and T2* estimates and results obtained from standard approaches in both phantom and human scans. In the phantom scan, a linear relationship with R 2 >0.96 was found for all parameter estimates. The maximum error in the T2 estimate was found to be below 6%. In the in-vivo scan, similar contrast was noted between MRF and standard approaches, and values found in a small region of interest (ROI) located in the grey matter (GM) were in line with previous measurements (T2 MRF =88±7ms vs T2 Ref =89±11ms, T1 MRF =1153±154ms vs T1 Ref =1122±52ms, T2* MRF =56±4ms vs T2* Ref =53±3ms).Conclusion: Adding a spin echo data segment to EPI based MRF allows accurate and robust measurements of T2, T1 and T2* relaxation times. This MRF framework is easier to implement than spiral-based MRF. It doesn't suffer from undersampling artifacts and seems to require a smaller dictionary size that can fasten the reconstruction process.

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Determining the longitudinal accuracy and reproducibility of T₁ and T₂ in a 3T MRI scanner

Carr

Keenan

Rai

et al. 2021

J Applied Clin Med Phys

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To determine baseline accuracy and reproducibility of T 1 and T 2 relaxation times over 12 months on a dedicated radiotherapy MRI scanner. Methods: An International Society of Magnetic Resonance in Medicine/National Institute of Standards and Technology (ISMRM/NIST) System Phantom was scanned monthly on a 3T MRI scanner for 1 year. T 1 was measured using inversion recovery (T 1 -IR) and variable flip angle (T 1 -VFA) sequences and T 2 was measured using a multi-echo spin echo (T 2 -SE) sequence. For each vial in the phantom, accuracy errors (%bias) were determined by the relative differences in measured T 1 and T 2 times compared to reference values. Reproducibility was measured by the coefficient of variation (CV) of T 1 and T 2 measurements across monthly scans. Accuracy and reproducibility were mainly assessed on vials with relaxation times expected to be in physiological ranges at 3T. Results: A strong linear correlation between measured and reference relaxation times was found for all sequences tested (R 2 > 0.997). Baseline bias (and CV[%]) for T 1 -IR, T 1 -VFA and T 2 -SE sequences were +2.0% (2.1), +6.5% (4.2), and +8.5% (1.9), respectively. Conclusions: The accuracy and reproducibility of T 1 and T 2 on the scanner were considered sufficient for the sequences tested. No longitudinal trends of variation were deduced, suggesting less frequent measurements are required following the establishment of baselines.

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Recommendations towards standards for quantitative MRI (qMRI) and outstanding needs

Abstract: Level of Evidence: 5 Technical Efficacy: Stage 5 J. Magn. Reson. Imaging 2019.

Cited by 79 publications

References 79 publications

Medical physics challenges in clinical MR-guided radiotherapy

Medical physics challenges in clinical MR-guided radiotherapy

Magnetic Resonance Fingerprinting with Combined Gradient- and Spin-echo Echo-planar Imaging: Simultaneous Estimation of T1, T2 and T2* with integrated-B1 Correction

Determining the longitudinal accuracy and reproducibility of T₁ and T₂ in a 3T MRI scanner

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Recommendations towards standards for quantitative MRI (qMRI) and outstanding needs

Abstract: Level of Evidence: 5 Technical Efficacy: Stage 5 J. Magn. Reson. Imaging 2019.

Cited by 79 publications

References 79 publications

Medical physics challenges in clinical MR-guided radiotherapy

Medical physics challenges in clinical MR-guided radiotherapy

Magnetic Resonance Fingerprinting with Combined Gradient- and Spin-echo Echo-planar Imaging: Simultaneous Estimation of T1, T2 and T2* with integrated-B1 Correction

Determining the longitudinal accuracy and reproducibility of T1 and T2 in a 3T MRI scanner

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Determining the longitudinal accuracy and reproducibility of T₁ and T₂ in a 3T MRI scanner