Evaluation of quantitative magnetic resonance imaging, biochemical and mechanical properties of trypsin-treated intervertebral discs under physiological compression loading.
OBJECTIVE
To investigate the influence of targeted trypsin digestion and 16 hours compression loading on MR parameters and the mechanical and biochemical properties of bovine disc segments.


METHODS
Twenty-two 3-disc bovine coccygeal segments underwent compression loading for 16 hours after the nucleus pulposus (NP) of each disc was injected with a solution of trypsin or buffer. The properties of the NP and annulus fibrosus (AF) tissues of each disc were analyzed by quantitative MRI, biochemical tests, and confined compression tests.


RESULTS
Loading had a significant effect on the MR properties (T(1), T(2), T(1rho), MTR, ADC) of both the NP and AF tissues. Loading had a greater effect on the MR parameters and biochemical composition of the NP than trypsin. In contrast, trypsin had a larger effect on the mechanical properties. Our data also indicated that localized trypsin injection predominantly affected the NP. T(1rho) was sensitive to loading and correlated with the water content of the NP and AF but not with their proteoglycan content.


CONCLUSIONS
Our studies indicate that physiological loading is an important parameter to consider and that T(1rho) contributes new information in efforts to develop quantitative MRI as a noninvasive diagnostic tool to detect changes in early disc degeneration.
Mwale
Fackson
F
Lady Davis Institute for Medical Research, SMBD-Jewish General Hospital, McGill University, Montréal, Quebec, Canada.
Demers
Caroline N
CN
Michalek
Arthur J
AJ
Beaudoin
Gilles
G
Goswami
Tapas
T
Beckman
Lorne
L
Iatridis
James C
JC
Antoniou
John
J
D000818:Animals; D001696:Biomechanical Phenomena; D002417:Cattle; D003094:Collagen / Q000032:analysis; D066298:In Vitro Techniques; D007403:Intervertebral Disc / Q000737:chemistry / Q000187:drug effects* / Q000502:physiology*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D011489:Protein Denaturation; D011509:Proteoglycans / Q000032:analysis; D014357:Trypsin / Q000494:pharmacology*; D014867:Water / Q000032:analysis
D011509:Proteoglycans; D014867:Water; D003094:Collagen; D014357:Trypsin