The potential of magnetic resonance imaging (MRI) for quantifying articular cartilage thickness - A methodological study

The thickness of patellar articular cartilage was assessed in a cadaveric human knee joint by magnetic resonance imaging. Imaging was conducted at 1.0 T, using three-dimensional gradient-echo sequences. From each of the sequences the total cartilage volume, the size of the articular surface, the mean cartilage thickness and the regional distribution of cartilage thickness were determined by image analysis. These values were then compared with those obtained from anatomical sections. The fat-suppressed FLASH sequence was found to allow the most accurate evaluation of the total volume and the regional distribution of the articular cartilage. Slight underestimation of the cartilage thickness by about 5% may be due to the fact that the calcified layer is not made visible by magnetic resonance imaging. There is, however, a very high degree of similarity between the distribution patterns obtained from the MR images and the anatomical sections. The contrast-to-noise ratios and reproducibility were also highest with the fat-suppressed FLASH sequence. This pulse sequence can therefore be recommended for experimental and clinical use. Relevance-Assessment of articular cartilage Thickness provides useful data in theoretical and practical medicine. However, the methods used for this purpose have usually been destructive and have therefore not been applicable to the living subject. This study shows that the total volume and the thickness distribution of articular cartilage can be accurately determined with magnetic resonance imaging, if the proper pulse-sequence is chosen. The rapid technical developments make it a promising method for the high resolution in vivo determination of articular cartilage thickness.