1-Norm waveform analysis for MR elastography-based quantification of inhomogeneity: Effects of the freeze-thaw cycle and Alzheimer's disease

Harish Palnitkar; Rolf Reiter; Shreyan Majumdar; Joseph Crutison; Shujun Lin; Thomas J Royston; Dieter Klatt

doi:10.1016/j.jmbbm.2024.106636

1-Norm waveform analysis for MR elastography-based quantification of inhomogeneity: Effects of the freeze-thaw cycle and Alzheimer's disease

J Mech Behav Biomed Mater. 2024 Jun 18:157:106636. doi: 10.1016/j.jmbbm.2024.106636. Online ahead of print.

Authors

Harish Palnitkar¹, Rolf Reiter², Shreyan Majumdar³, Joseph Crutison⁴, Shujun Lin⁵, Thomas J Royston⁶, Dieter Klatt⁷

Affiliations

¹ Department of Mechanical and Industrial Engineering, University of Illinois Chicago, Chicago, IL, 60607, United States; Department of Radiology, Mayo Clinic, 200 First St SW, Rochester, MN, 55905, United States. Electronic address: palnitkar.harishravindra@mayo.edu.
² Department of Radiology, Charité - Universitätsmedizin Berlin, Corporate member of Freie Universität Berlin and Humboldt-Universität zu Berlin, Hindenburgdamm 30, 12203, Berlin, Germany; Berlin Institute of Health at Charité - Universitätsmedizin Berlin, BIH Biomedical Innovation Academy, BIH Charité Digital Clinician Scientist Program, Charitéplatz 1, 10117, Berlin, Germany; Richard and Loan Hill Department of Biomedical Engineering, University of Illinois Chicago, 830 South Wood Street, Chicago, IL, 60612, United States. Electronic address: rolf.reiter@charite.de.
³ Richard and Loan Hill Department of Biomedical Engineering, University of Illinois Chicago, 830 South Wood Street, Chicago, IL, 60612, United States. Electronic address: majumdar.shreyan@gmail.com.
⁴ Richard and Loan Hill Department of Biomedical Engineering, University of Illinois Chicago, 830 South Wood Street, Chicago, IL, 60612, United States. Electronic address: jcruti2@uic.edu.
⁵ Richard and Loan Hill Department of Biomedical Engineering, University of Illinois Chicago, 830 South Wood Street, Chicago, IL, 60612, United States. Electronic address: slin78@uic.edu.
⁶ Richard and Loan Hill Department of Biomedical Engineering, University of Illinois Chicago, 830 South Wood Street, Chicago, IL, 60612, United States. Electronic address: troyston@uic.edu.
⁷ Richard and Loan Hill Department of Biomedical Engineering, University of Illinois Chicago, 830 South Wood Street, Chicago, IL, 60612, United States. Electronic address: dklatt@uic.edu.

PMID: 38908327
DOI: 10.1016/j.jmbbm.2024.106636

Abstract

Background: Despite its success in the mechanical characterization of biological tissues, magnetic resonance elastography (MRE) uses ill-posed wave inversions to estimate tissue stiffness. 1-Norm has been recently introduced as a mathematical measure for the scattering of mechanical waves due to inhomogeneities based on an analysis of the delineated contours of wave displacement.

Purpose: To investigate 1-Norm as an MRE-based quantitative biomarker of mechanical inhomogeneities arising from microscopic structural tissue alterations caused by the freeze-thaw cycle (FTC) or Alzheimer's disease (AD).

Methods: In this proof-of-concept study, we prospectively investigated excised porcine kidney (n = 6), liver (n = 6), and muscle (n = 6) before vs. after the FTC at 500-2000 Hz and excised murine brain of healthy controls (n = 3) vs. 5xFAD species with AD (n = 3) at 1200-1800 Hz using 0.5 T tabletop MRE. 1-Norm analysis was compared with conventional wave inversion.

Results: While the FTC reduced both stiffness and inhomogeneity in kidney, liver, and muscle tissue, AD led to lower brain stiffness but more pronounced mechanical inhomogeneity.

Conclusion: Our preliminary results show that 1-Norm is sensitive to tissue mechanical inhomogeneity due to FTC and AD without relying on ill-posed wave inversion techniques. 1-Norm has the potential to be used as an MRE-based diagnostic biomarker independent of stiffness to characterize abnormal conditions that involve changes in tissue mechanical inhomogeneity.

Keywords: 1-Norm; Alzheimer's disease; Freezing and thawing; Inhomogeneity; Magnetic resonance elastography.