Assessment of quantitative magnetic resonance imaging metrics in the brain through the use of a novel phantom

ABSTRACT

Objective: Multisite and longitudinal neuroimaging studies are important in uncovering trajectories of recovery and neurodegeneration following traumatic brain injury (TBI) and concussion through the use of diffusion tensor imaging (DTI) and other imaging modalities. This study assessed differences in anisotropic diffusion measurement across four scanners using a human and a novel phantom developed in conjunction with the Chronic Effects of Neurotrauma Consortium.

Method: Human scans provided measurement within biological tissue, and the novel physical phantom provided measures of anisotropic intra-tubular diffusion to serve as a model for intra-axonal water diffusion. Intra- and inter-scanner measurement variances were compared, and the impact on effect size was calculated.

Results: Intra-scanner test–retest reliability estimates for fractional anisotropy (FA) demonstrated relative stability over testing intervals. The human tissue and phantom showed similar FA ranges, high linearity and large within-device effect sizes. However, inter-scanner measures of FA indicated substantial differences, some of which exceeded typical DTI effect sizes in mild TBI.

Conclusion: The diffusion phantom may be used to better elucidate inter-scanner variability in DTI-based measurement and provides an opportunity to better calibrate results obtained from scanners used in multisite and longitudinal studies. Novel solutions are being evaluated to understand and potentially overcome these differences.

KEYWORDS:

• Phantom
• diffusion tensor imaging
• traumatic brain injury
• diffuse axonal injury
• quantitative MRI
• metrology

Acknowledgements

We wish to acknowledge the assistance of Emily Clarke and Rhonda O’Donovan in manuscript preparation and organization of the study. Additionally, we wish to acknowledge additional members of the CENC Neuroimaging Core including: Erin D. Bigler, PhD, Carmen Velez, Jennifer Nathan, M.D., Typhani Morales, Rajan Agarwal, M.D., Michael Lennon, M.D., Aaron M. Betts, M.D., Marice Brown, Joel L. Steinberg, M.D. and Robert Cadrain.

Declaration of interest

This work was supported by grant funding from: Department of Defense, Chronic Effects of Neurotrauma Consortium (CENC) Award W81XWH-13-2-0095 and Department of Veterans Affairs CENC Award I01 CX001135. Funding also comes from the Naval Health Research Center (W911QY-15-C-0043). The views, opinions and/or findings contained in this article are those of the authors and should not be construed as an official Veterans Affairs or Department of Defense position, policy or decision, unless so designated by other official documentation. Drs Wilde, Provenzale, Taylor, Boss, Hachey, Pathak, Tate and Mr Abildskov have nothing to disclose. Mr Zuccolotto and Dr Schneider are associated with the Phantom Metrics Division of Psychology Software Tools Inc., the company that manufactures and distributes the phantom described in this study.