Real-time 3-T MRI of peroneal tendon motion during active ankle movement: feasibility and image quality

OBJECTIVE: To evaluate the feasibility and image quality of dynamic 3-T magnetic resonance imaging (MRI) for visualizing and quantifying peroneal tendon motion during active dorsiflexion and plantarflexion. MATERIALS AND METHODS: This prospective pilot study was approved by the Swedish Ethical Review Authority (Dnr 2020-00029). Asymptomatic adults without prior ankle trauma underwent dynamic ankle MRI at 3 T using a balanced fast field-echo sequence (axial at the lateral malleolus) during active dorsiflexion/plantarflexion. Three musculoskeletal radiologists rated five image-quality criteria (five-point Likert); agreement was quantified with Gwet's AC2 and Fleiss' κ. The highest-rated sequence was analyzed. One musculoskeletal radiologist manually segmented the peroneus longus and peroneus brevis tendons; Euclidean centroid distance was computed per frame. For intra-rater analysis, an independent person randomly selected three volunteers; segmentation was repeated after 1 month, and reliability was assessed with the intraclass correlation coefficient (ICC) (2,1). RESULTS: Ten volunteers aged 36.6 ± 7.8 years (mean ± stasndard deviation) were included. Tendon motion was visualized in all volunteers with good image quality (median 4; mean 4.04-4.10). Agreement was strongest for retinaculum visibility and ability to follow tendon motion (AC2 = 0.621 and 0.557, respectively). Centroid distance increased in dorsiflexion and decreased in plantarflexion (excursion 2.95-4.83 mm). Intra-rater reliability was good (ICC = 0.85; 95% confidence interval 0.723-0.922; p < 0.001). CONCLUSION: Dynamic MRI enabled reproducible, high-quality visualization and quantification of peroneal tendon motion during active ankle movement and warrants evaluation in suspected peroneal tendon instability. RELEVANCE STATEMENT: Dynamic real-time 3-T MRI enables visualization and quantitative tracking of peroneal tendon motion during active ankle movement, and may complement static imaging in future studies of suspected peroneal tendon instability. KEY POINTS: Real-time 3-T MRI showed peroneal tendon motion in all volunteers. Image quality was consistently good for tracking tendons during ankle movement. Centroid-to-centroid distance between tendons was highly repeatable over time.