Magnetic Resonance Imaging of the Hip

Hip pain is common in all age groups, and osteoarthritis of this joint is an increasingly recognized problem particularly in aging populations. One of the primary goals in the diagnostic evaluation in patients with hip pain is to identify and correct pathologies that could progress to osteoarthritis. Magnetic resonance imaging (MRI) has become an important noninvasive method for characterizing hip anatomy and pathology in these patients. Improvements in MRI hardware and techniques have allowed high spatial and contrast resolution imaging to detect subtle abnormalities, such as acetabular labral and articular cartilage injuries, which often contribute to patient symptoms. Newer MRI techniques, such as delayed gadolinium-enhanced MRI of cartilage and T2 mapping, can give insight into the biochemical structure of tissues such as the articular cartilage. In turn, these can allow quantitative assessment and enable imagers to more directly compare the findings of patients at earlier stages of disease. It is important to understand the fundamental principles of various MRI techniques and their limitations to know when these techniques can best be applied. In addition, understanding of normal hip anatomy and common anatomic variants is useful for being able to accurately detect and localize areas of pathology and to prevent misinterpreting normal structures as diseased. The aims of this work were to briefly review normal hip anatomy and common anatomic variants seen on routine MRI examination, to discuss principles often used in high-resolution hip MRI and newer techniques for biochemical evaluation, and to examine several intra-articular pathologic conditions of the hip joint that are of current clinical interest.