Normal variants, imaging artifacts, and other diagnostic pitfalls in articular cartilage imaging of the extremities

Abstract

Introduction: Imaging of the articular cartilage of the extremities is a complex topic that is continually refined through advancements in imaging, surgery, and conservative management of chondral pathology. However, there are many commonly encountered pitfalls in articular cartilage imaging, which are critical for both radiologists and surgeons to be aware of. Objectives: This review will overview the basic concepts of imaging of the cartilage, with a focus on magnetic resonance imaging, including a discussion of magic angle, chemical shift, and susceptibility artifacts that can be mistaken for abnormal cartilage. Methods: A review of described variant cartilage anatomy and imaging artifacts from the imaging and arthroscopic literature is undertaken with illustrative examples retrieved from the University of Utah picture archiving and communication system (PACS). Results: Tools for distinguishing pathologic cartilage from the expected appearance of normal variant accessory ossicles, coalitions, partitions, and the normal labrum are introduced. Joint-specific considerations of commonly encountered cartilage-related entities in the shoulder, elbow, wrist, hip, knee, ankle, and foot are also reviewed. Conclusions: Correlation of imaging, arthroscopic, and clinical findings is key to reducing diagnostic dilemmas, preventing inadvertent overestimation of disease, and ensuring appropriate intervention.

Keywords

• Cartilage imaging
• Diagnostic pitfalls
• MRI artifact
• Normal cartilage
• Normal variants