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Multicomponent analysis of T 1 relaxation in bovine articular cartilage at low magnetic fields
Author(s) -
Petrov Oleg V.,
Stapf Siegfried
Publication year - 2019
Publication title -
magnetic resonance in medicine
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.696
H-Index - 225
eISSN - 1522-2594
pISSN - 0740-3194
DOI - 10.1002/mrm.27624
Subject(s) - cartilage , nuclear magnetic resonance , exponential function , relaxation (psychology) , relaxometry , osteoarthritis , logarithm , chemistry , magnetic field , magnetic resonance imaging , physics , mathematics , spin echo , mathematical analysis , anatomy , pathology , medicine , alternative medicine , radiology , quantum mechanics
Purpose The multi‐exponential character of T 1 relaxation in bovine articular cartilage was investigated at low magnetic fields below 0.5 T. The ultimate aim was to identify a parameter based on the T 1 relaxation time distribution as a biomarker to biochemical features of osteoarthritis. Methods Osteoarthritis conditions were simulated by enzymatic digestion of cartilage with trypsin. Fast‐field cycling NMR relaxometry was carried out in the magnetic field range B 0 = 70 μT to 600 mT. The data were analyzed in terms of T 1 distributions on a log‐time scale using inverse Laplace transform, whereas integral properties such as mean T 1 s and distribution widths were obtained without data inversion from logarithmic moment analysis and a stretched‐exponential fit to the data. Attempts were also made to differentiate between water dynamic components through multi‐Lorentzian decomposition of average relaxation‐rate dispersions. Results T 1 distribution in bovine articular cartilage was found to be bimodal, with the dominating, long component shifting toward larger values following trypsin digestion. The effect is more prominent toward lower magnetic field strength. This shift leads to an overall increase of the distribution width and an equivalently more pronounced deviation from exponential behavior. Conclusion The logarithmic width of T 1 distribution functions at fields of 0.5 T and below, and the stretched‐exponential decay fit exponent β , show a significant trend after trypsin digestion of cartilage. These 2 parameters are suggested as possible biomarkers for osteoarthritis in humans and can be acquired entirely in vivo, with increasing significance for lower magnetic field strengths.