1. Standardization of T1-mapping in cardiovascular magnetic resonance using clustered structuring for benchmarking normal ranges.
- Author
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Popescu IA, Werys K, Zhang Q, Puchta H, Hann E, Lukaschuk E, Ferreira VM, and Piechnik SK
- Subjects
- Humans, Magnetic Resonance Spectroscopy, Predictive Value of Tests, Reference Standards, Reference Values, Reproducibility of Results, Benchmarking, Magnetic Resonance Imaging
- Abstract
Background: Cardiovascular magnetic resonance T1-mapping is increasingly used for tissue characterization, commonly based on Modified Look-Locker Inversion recovery (MOLLI). However, there are numerous MOLLI variants with differing normal ranges. This lack of standardization presents confusion and difficulty in inter-center comparisons, hindering widespread adoption of T1-mapping., Methods: To address this, we performed a structured literature search for native left ventricular myocardial T1-mapping in healthy humans measured using MOLLI variants at 1.5 and 3 Tesla, across scanner vendors. We then used k-means clustering to structure normal MOLLI-T1 values according to magnetic field strength, and investigated correlations between common imaging parameters: repetition time (TR), echo time (TE), flip angle (FA)., Results: We analyzed data from 2207 healthy controls in 76 independent reports. Normal MOLLI-T1 standard deviations varied by 11-fold, and dependencies on TE, TR, and FA differed between 1.5 T and 3 T, thwarting meaningful T1 standardization even within a single field strength, including the use of Z-score. However, divergent MOLLI-T1 norms may be structured using data clustering. For 1.5 T, two clusters emerged: Cluster1
1.5T : T1 = 958 ± 16 ms (n = 1280); Cluster21.5T : T1 = 1027 ± 19 ms (n = 386). For 3 T, three clusters emerged: Cluster13T : T1 = 1160 ± 21 ms (n = 330); Cluster23T : T1 = 1067 ± 18 ms (n = 178); Cluster33T : T1 = 1227 ± 19 ms (n = 41). We then propose the concept of an online calculator for assigning local norms to a known MOLLI-T1 cluster, allowing benchmarking against published norms., Conclusion: Clustered structuring allows T1 standardization of widely-divergent MOLLI variants, benchmarking local norms (usually based on smaller samples) against published norms (larger samples). This may increase confidence and quality control in method implementation, facilitating wider clinical adoption of T1-mapping., Competing Interests: Declaration of Competing Interest SKP has patent authorship rights for U.S. patent US20120078084A1. Systems and methods for shortened Look Locker inversion recovery (Sh-MOLLI) cardiac gated mapping of T1. Granted March 15, 2016. IP is managed by Oxford University Innovations; the license exclusively transferred to Siemens Healthcare. All other authors have no industry relationships relevant to the contents of this paper to disclose., (Copyright © 2020 The Authors. Published by Elsevier B.V. All rights reserved.)- Published
- 2021
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