Quantitative magnetic resonance imaging of enzymatically induced degradation of the nucleus pulposus of intervertebral discs.
METHODS
The structural integrity of the nucleus pulposus (NP) of intervertebral discs was targeted by enzyme-specific degradations to correlate their effects to the magnetic resonance (MR) signal.


OBJECTIVE
To develop quantitative MR imaging as an accurate and noninvasive diagnostic tool to better understand and treat disc degeneration.


BACKGROUND
Quantitative MR analysis has been previously shown to reflect not only the disc matrix composition, but also the structural integrity of the disc matrix. Further work is required to identify the contribution of the structural integrity versus the matrix composition to the MR signal.


METHODS
The bovine coccygeal NPs were injected with either enzyme or buffer, incubated at 37 degrees C as static, unloaded and closed 3-disc segments, and analyzed by a 1.5-Tesla MR scanner to measure MR parameters.


RESULTS
Collagenase degradation of the NP significantly decreased the relaxation times, slightly decreased the magnetization transfer ratio, and slightly increased the apparent diffusion coefficient. Targeting the proteoglycan and/or hyaluronan integrity by trypsin and hyaluronidase did not significantly affect the MR parameters, except for an increase in the apparent diffusion coefficient of the disc after trypsin treatment.


CONCLUSIONS
Our results demonstrate that changes in the structural integrity of matrix proteins can be assessed by quantitative MR.
Antoniou
John
J
Lady Davis Institute and Department of Surgery, McGill University, Montreal, Quebec, Canada. janton@orl.mcgill.ca
Mwale
Fackson
F
Demers
Caroline N
CN
Beaudoin
Gilles
G
Goswami
Tapas
T
Aebi
Max
M
Alini
Mauro
M
D000818:Animals; D002417:Cattle; D003094:Collagen / Q000378:metabolism; D017364:Collagenases / Q000494:pharmacology; D006820:Hyaluronic Acid / Q000378:metabolism; D006821:Hyaluronoglucosaminidase / Q000187:drug effects; D007403:Intervertebral Disc / Q000187:drug effects / Q000378:metabolism / Q000473:pathology*; D007404:Intervertebral Disc Chemolysis; D008279:Magnetic Resonance Imaging; D011489:Protein Denaturation; D011509:Proteoglycans / Q000378:metabolism; D014357:Trypsin / Q000494:pharmacology
D011509:Proteoglycans; D006820:Hyaluronic Acid; D003094:Collagen; D006821:Hyaluronoglucosaminidase; D014357:Trypsin; D017364:Collagenases