Novel Noninvasive Imaging Techniques to Assess Structural, Functional, and Material Properties of Tendon, Ligament, and Cartilage: A Narrative Review of Current Concepts

Background: Novel noninvasive imaging modalities such as quantitative magnetic resonance imaging (qMRI) and shear wave elastography (SWE) allow for assessment of soft tissue microstructure and composition, which ultimately may be associated with functional and material properties. Purpose: To provide a narrative review of the scientific techniques and clinical applications of qMRI and SWE for the evaluation of soft tissue about the knee and shoulder, including the meniscus, the anterior cruciate ligament (ACL), and the rotator cuff. Study Design: Review. Methods: A literature search was performed in October 2022 via PubMed using the following keywords: “quantitative MRI tendon,” quantitative MRI ligament,”“quantitative MRI cartilage,” or “shear wave elastography tendon.” Only articles related to clinical applications were included in this review. Results: Conventional imaging techniques, including standard morphologic magnetic resonance imaging (MRI) and ultrasound imaging, have limited ability to evaluate the material and functional properties of soft tissue; qMRI builds on the limitations of conventional morphologic MRI by allowing for detection of early articular cartilage changes, differentiation of healed versus unhealed meniscal tissue, and quantification of ACL graft maturity. SWE can evaluate the material properties of rotator cuff and Achilles tendons after injury, which may provide insight into both the chronicity and the healing status of the aforementioned injuries. Conclusion: Our review of the literature showed that quantitative imaging techniques, including qMRI and SWE, may both improve early detection of pathology and aid in comprehensive evaluation after treatment.