Linearity, Bias, Intrascanner Repeatability, and Interscanner Reproducibility of Quantitative Multidynamic Multiecho Sequence for Rapid Simultaneous Relaxometry at 3 T: A Validation Study With a Standardized Phantom and Healthy Controls

Objectives The aim of this study was to evaluate the linearity, bias, intrascanner repeatability, and interscanner reproducibility of quantitative values derived from a multidynamic multiecho (MDME) sequence for rapid simultaneous relaxometry. Materials and Methods The NIST/ISMRM (National Institute of Standards and Technology/International Society for Magnetic Resonance in Medicine) phantom, containing spheres with standardized T1 and T2 relaxation times and proton density (PD), and 10 healthy volunteers, were scanned 10 times on different days and 2 times during the same session, using the MDME sequence, on three 3 T scanners from different vendors. For healthy volunteers, brain volumetry and myelin estimation were performed based on the measured T1, T2, and PD. The measured phantom values were compared with reference values; volunteer values were compared with their averages across 3 scanners. Results The linearity of both phantom and volunteer measurements in T1, T2, and PD values was very strong (R2 = 0.973–1.000, 0.979–1.000, and 0.982–0.999, respectively) The highest intrascanner coefficients of variation (CVs) for T1, T2, and PD were 2.07%, 7.60%, and 12.86% for phantom data, and 1.33%, 0.89%, and 0.77% for volunteer data, respectively. The highest interscanner CVs of T1, T2, and PD were 10.86%, 15.27%, and 9.95% for phantom data, and 3.15%, 5.76%, and 3.21% for volunteer data, respectively. Variation of T1 and T2 tended to be larger at higher values outside the range of those typically observed in brain tissue. The highest intrascanner and interscanner CVs for brain tissue volumetry were 2.50% and 5.74%, respectively, for cerebrospinal fluid. Conclusions Quantitative values derived from the MDME sequence are overall robust for brain relaxometry and volumetry on 3 T scanners from different vendors. Caution is warranted when applying MDME sequence on anatomies with relaxometry values outside the range of those typically observed in brain tissue. This is an open-access article distributed under the terms of the Creative Commons Attribution-Non Commercial-No Derivatives License 4.0 (CCBY-NC-ND), where it is permissible to download and share the work provided it is properly cited. The work cannot be changed in any way or used commercially without permission from the journal. Received for publication May 24, 2018; and accepted for publication, after revision, July 27, 2018. Conflicts of interest and sources of funding: This work was supported by AMED under grant number JP18lk1010025; ImPACT Program of Council for Science, Technology, and Innovation (Cabinet Office, Government of Japan); JSPS KAKENHI grant number 16K19852; JSPS KAKENHI grant number JP16H06280, Grant-in-Aid for Scientific Research on Innovative Areas–Resource and Technical Support Platforms for Promoting Research "Advanced Bioimaging Support"; and the Japanese Society for Magnetic Resonance in Medicine. The authors declare no conflict of interest. Supplemental digital contents are available for this article. Direct URL citations appear in the printed text and are provided in the HTML and PDF versions of this article on the journal's Web site (https://ift.tt/2kq7jVD). Correspondence to: Akifumi Hagiwara, MD, Department of Radiology, Juntendo University School of Medicine, 1-2-1, Hongo, Bunkyo-ku, Tokyo, Japan, 113-8421. E-mail: a-hagiwara@juntendo.ac.jp. Copyright © 2018 Wolters Kluwer Health, Inc. All rights reserved.

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