J Korean Soc Radiol.  2015 Feb;72(2):108-114. 10.3348/jksr.2015.72.2.108.

The Effects of Proteoglycan and Type II Collagen on T1rho Relaxation Time of Articular Cartilage

• Choi WS
• Yoo HJ
• Hong SH
• Choi JY

• KMID: 2002806
• DOI: http://doi.org/10.3348/jksr.2015.72.2.108

Abstract

PURPOSE
To evaluate the effects of proteoglycan and type II collagen within articular cartilage on T1rho relaxation time of articular cartilage.
MATERIALS AND METHODS
This study was exempted by the institutional and animal review boards, and informed consent was not required. Twelve porcine patellae were assigned to three groups of control, trypsin-treated (proteoglycan-degraded), or collagenase-treated (collagen-degraded). The T1rho images were obtained with a 3 tesla magnetic resonance imaging scanner with a single loop coil. Statistical differences were detected by analysis of variance to evaluate the effects of the enzyme on T1rho relaxation time. Safranin-O was used to stain proteoglycan in the articular cartilage and immunohistochemical staining was performed for type II collagen.
RESULTS
Mean T1rho values of the control, trypsin-treated, and collagenase-treated groups were 37.72 +/- 5.82, 57.53 +/- 8.24, and 45.08 +/- 5.31 msec, respectively (p < 0.001). Histology confirmed a loss of proteoglycan and type II collagen in the trypsin- and collagenase-treated groups.
CONCLUSION
Degradation of proteoglycans and collagen fibers in the articular cartilage increased the articular cartilage T1rho value.

MeSH Terms

Animals
Cartilage
Cartilage, Articular*
Collagen
Collagen Type II*
Informed Consent
Magnetic Resonance Imaging
Osteoarthritis
Patella
Proteoglycans*
Relaxation*
Collagen
Collagen Type II
Proteoglycans

Figure

• 

  Fig. 1 Reconstruction of T1ρ map and measurement of T1ρ value. A. Image shows result of T1ρ map using color scale. B. Image shows positioning of region of interest to calculate the T1ρ value of full-thickness cartilage. Region of interest was placed on the patellar cartilage with a freehand drawing technique.

• 

  Fig. 2 Safranin-O staining for proteoglycans. A. In Safranin-O staining, control cartilage showed a dense and homogeneous distribution of proteoglycans. B. In Safranin-O staining, trypsin degraded articular cartilage showed observable decreases of proteoglycans.

• 

  Fig. 3 Immunohistochemical staining for type II collagen. A. In immunohistochemical staining with antibodies against type II collagen, control cartilage showed a dense and homogeneous distribution of collagen II fibers. B. In immunohistochemical staining with antibodies against type II collagen, collagenase degraded articular cartilage showed observable decreases of collagen II fibers.

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