Depth-dependent profiles of glycosaminoglycans in articular cartilage by μMRI and histochemistry

Abstract

Purpose: To quantify the distribution profile of glycosaminoglycans (GAGs) in articular cartilage with the magnetic resonance imaging (MRI) gadolinium (Gd) contrast method (the dGEMRIC procedure in clinical MRT) and correlate with histochemical results. Materials and Methods: Fresh canine cartilage from seven humeral heads was harvested. Sixteen cartilage specimens were imaged at 13 μm pixel resolution using the μMRI T1-Gd method to generate 2D GAG maps in cartilage. Nineteen cartilage specimens from adjacent locations on the same joints were papain-digested to quantify the bulk GAG content in tissue. In addition, six cartilage specimens were microtomed into 40-μm serial sections that were parallel with the articular surface. These sections were biochemically analyzed individually to determine the depth-dependent profiles of GAG concentration. Results: The GAG concentrations between the μMRI measurement and the bulk biochemical method have statistically significant agreement. The depth-dependent GAG profiles from the histochemical method (40 μm depth resolution) have similar line shapes as that determined by μMRI at 13 μm resolution. Conclusion: The GAG concentration as measured by μMRI T1-Gd contrast method provides an accurate account of the macromolecular content in articular cartilage. © 2008 Wiley-Liss, Inc.