Correlated noise in brain magnetic resonance elastography
Magnetic Resonance in Medicine
Purpose: Magnetic resonance elastography (MRE) uses phase-contrast MRI to generate mechanical property maps of the in vivo brain through imaging of tissue deformation from induced mechanical vibration. The mechanical property estimation process in MRE can be susceptible to noise from physiological and mechanical sources encoded in the phase, which is expected to be highly correlated. This correlated noise has yet to be characterized in brain MRE, and its effects on mechanical property estimates computed using inversion algorithms are undetermined. Methods: To characterize the effects of signal noise in MRE, we conducted 3 experiments quantifying (1) physiomechanical sources of signal noise, (2) physiological noise because of cardiac-induced movement, and (3) impact of correlated noise on mechanical property estimates. We use a correlation length metric to estimate the extent that correlated signal persists in MRE images and demonstrate the effect of correlated noise on property estimates through simulations. Results: We found that both physiological noise and vibration noise were greater than image noise and were spatially correlated across all subjects. Added physiological and vibration noise to simulated data resulted in property maps with higher error than equivalent levels of Gaussian noise. Conclusion: Our work provides the foundation to understand contributors to brain MRE data quality and provides recommendations for future work to correct for signal noise in MRE.
This is the peer reviewed version of the following article: Hannum, AJ, McIlvain, G, Sowinski, D, McGarry, MDJ, Johnson, CL. Correlated noise in brain magnetic resonance elastography. Magn Reson Med. 2022; 87: 1313– 1328. doi:10.1002/mrm.29050, which has been published in final form at https://doi.org/10.1002/mrm.29050. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Use of Self-Archived Versions. This article may not be enhanced, enriched or otherwise transformed into a derivative work, without express permission from Wiley or by statutory rights under applicable legislation. Copyright notices must not be removed, obscured or modified. The article must be linked to Wiley’s version of record on Wiley Online Library and any embedding, framing or otherwise making available the article or pages thereof by third parties from platforms, services and websites other than Wiley Online Library must be prohibited.
brain, magnetic resonance elastography, physiological noise, pulsation, viscoelasticity
Hannum, AJ, McIlvain, G, Sowinski, D, McGarry, MDJ, Johnson, CL. Correlated noise in brain magnetic resonance elastography. Magn Reson Med. 2022; 87: 1313– 1328. doi:10.1002/mrm.29050