Influence of physical activity on T1 and T2 relaxation times of healthy achilles tendons at 3T

Purpose To evaluate longitudinal (T1) and transverse (T2*) relaxation times at different Achilles tendon locations (insertion, mid‐portion, and musculotendinous area) in a cohort of subjects with variable tendon straining activity, but without any signs of tendinopathy. Materials and Methods T1 and T2* relaxation times of the Achilles tendon were measured using an ultrashort echo time (UTE) imaging sequence with flip angle and echo time variation on a 3T whole‐body clinical magnetic resonance (MR) scanner. Twenty‐four tendons of 12 healthy volunteers and 18 tendons of nine healthy recreational long‐distance runners (average weekly running distance of 47.4 ± 5.3 km) were enrolled. Results Mean T1 values of the whole tendon showed no marked group differences, whereas T2* relaxation times of runners were significantly longer (mean percentage increase 15.7 ± 4.9%; P = 0.0181) compared to controls. Regarding group differences for the investigated insertional, mid‐portion, and musculotendinous area of the Achilles tendon, only the mid‐portion of the Achilles tendon in the running group presented significantly longer T2* values (mean percentage increase 29.1 ± 23.0%; P = 0.0420) in comparison to the control group. Conclusion Prolonged T2* values especially in the mid‐portion of the Achilles tendon of runners are likely to reflect an adaptation of the tendon microstructure to repetitive tendon straining activity. J. Magn. Reson. Imaging 2015;41:193–201. © 2013 Wiley Periodicals, Inc.