Received: 5 June 2001 Accepted: 17 August 2001 Published online: 11 October 2001 © Springer-Verlag 2001 Abstract Cartilage degenerative diseases, such as osteoarthritis, affect million of people. Magnetic reso- nance imaging is presently the most accurate imaging modality in evalu- ating the state of hyaline cartilage; however, clinical MRI does not ac- curately reveal early degenerative al- terations in cartilage, due mainly to low spatial resolution. Magnetic res- onance microscopy (MRM, or μMRI) appears exceptionally well suited to the in vitro or ex vivo study of this heterogeneous tissue, due to its high spatial resolution; however, despite this, further studies are nec- essary to evaluate the potential of MRM in the detection of early carti- lage damage. Herein we briefly re- view the current applications of MRM in the study of hyaline carti- lage. In particular, we review the MR appearance of hyaline cartilage on high-resolution images, the dif- ferent MRM techniques used to im- age normal and enzymatically or chemically degraded cartilage and the potential use of contrast agents. The future directions and the rele- vance of MRM findings for a better understanding of cartilage physiolo- gy in health and disease are also dis- cussed. Keywords Cartilage · MR imaging · MR microscopy · Review Eur Radiol (2002) 12:814–823 DOI 10.1007/s003300101128 MUSCULOSKELETAL Maria Cova Renato Toffanin MR microscopy of hyaline cartilage: current status Introduction The most common cause of hyaline articular cartilage damage is osteoarthritis, either primary or due to trauma. It is estimated that currently within Europe there are 150,000 individuals with traumatic defects of the knee cartilage. In total there are 30 million Europeans that suffer from osteoarthritis. Since this degenerative disease affects mainly people over the age of 40 years, in Europe the number of middle-aged and elderly people suffering cartilage diseases is set to rise dramatically in the com- ing years. For this reason, the use and development of new methodologies for cartilage evaluation are a key is- sue for a better understanding and treatment of the de- generative process of articular cartilage. Morphological and biochemical information can be obtained by MRI, which is presently the most accurate imaging modality in evaluating the state of hyaline cartilage [1, 2]; however, clinical MRI does not accurately reveal early degenera- tive alterations in articular cartilage, due mainly to low spatial resolution [3]. Magnetic resonance microscopy (MRM, or μMRI) appears exceptionally well suited to the in vitro or ex vivo study of this heterogeneous tissue, due to its high spatial resolution [4]; however, despite this, further studies are necessary to evaluate the poten- tial of MRM in the detection of early cartilage damage. In this review we describe the MR appearance of hya- line cartilage on high resolution images, the different MRM techniques used to image normal and enzymati- cally or chemically degraded cartilage and the potential use of contrast agents. The future directions and the rele- vance of MRM findings for a better understanding of cartilage physiology in health and disease are also dis- cussed. M. Cova ( ✉ ) Department of Radiology, University of Trieste, Ospedale di Cattinara, Strada di Fiume 447, 34149 Trieste, Italy e-mail: cova@gnbts.univ.trieste.it Tel.: +39-040-3994372 Fax: +39-040-3994500 R. Toffanin Department of Biochemistry, Biophysics and Macromolecular Chemistry, Via L. Giorgieri 1, 34127 Trieste, Italy R. Toffanin PROTOS Research Institute, P.O. Box 972, 34100 Trieste, Italy