Association Between T₂^* Relaxation Times Derived From Ultrashort Echo Time MRI and Symptoms During Exercise Therapy for Patellar Tendinopathy: A Large Prospective Study

Abstract

Background Exercise therapy is considered preferential treatment for patellar tendinopathy (PT). However, there is conflicting evidence for structural patellar tendon adaptation in response to exercise therapy and its association with symptoms is weak. Purpose To assess the association between 1) T2* relaxation times and symptom severity; 2) baseline T2* and clinical outcome; and 3) longitudinal T2* changes and clinical outcome in athletes with PT performing exercise therapy. Study Type Randomized controlled clinical trial. Subjects Seventy‐six athletes (18–35 years) with clinically diagnosed and ultrasound‐confirmed PT. Field strength/Sequence 3D gradient echo sequence (3.0 T). Assessment Patients were enrolled in a randomized trial of progressive tendon‐loading exercises (PTLE) versus eccentric exercise therapy (EET). Symptoms were assessed using the Victorian Institute of Sports Assessment (VISA‐P) questionnaire. 3D‐Ultrashort echo time (UTE)‐MRI was acquired at baseline, 12 and 24 weeks. Voxel‐wise T2* relaxation times were quantified using mono‐exponential and bi‐exponential models. T2* analysis was performed in three patellar tendon tissue compartments representing: aligned collagen, degenerative tissue, and interface. Statistical Tests Adjusted general linear, mixed‐linear models, and generalized estimating equations. Results We included 76 patients with PT (58 men, mean age 24 ± 4 years); 38 in the PTLE‐group and 38 in the EET‐group, of which 57 subjects remained eligible for analysis. T2* relaxation times were significantly associated with VISA‐P in degenerative and interface tissues of the patellar tendon. No association was found between baseline T2* and VISA‐P after 24 weeks (P > 0.29). The estimated mean T2* in degenerative tissue decreased from 14 msec (95%CI: 12–16) at baseline to 13 msec (95%CI: 11–15) at 12 weeks and to 13 msec (95%CI: 10–15) at 24 weeks. The significant decrease in T2* from baseline to 24 weeks was associated with improved clinical outcome. Data Conclusion Tissue‐specific T2* relaxation times, identified with 3D‐UTE‐MRI, decreased significantly in athletes with patellar tendinopathy performing exercise therapy and this decrease was associated with improved clinical outcome. Evidence Level 1 Technical Efficacy Stage 4

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“…For example, in patellar tendinopathy, the GAG content increases fivefold, accompanied by a fluid increase of more than 16% 34. Yet, the amount of free fluid also appears to increase in tendinopathy 138. Within our conceptual model, tendon swelling also occupies a central position, as it is necessary to obtain swelling stress and consequently an increase in IRP.…”

Advanced MRI Approaches for Evaluating Common Lower Extremity Injuries in Basketball Players: Current and Emerging Techniques

“…81 in studies examining the effectiveness of various treatments for patellar tendinopathy using imaging techniques. [41][42][43][44] UTE-MRI IN THE PATELLAR TENDON. 3D-UTE-MRI has recently been used to assess the severity of and treatments for patellar tendinopathy.…”

Ultrashort Echo Time Magnetic Resonance Imaging Techniques: Met and Unmet Needs in Musculoskeletal Imaging

“…UTE bi-component analysis has been developed to quantify T2* values and the short-and long-T2* fractions of water components in a variety of MSK tissues. [59][60][61][62][63][64][65][66][67] Short T2* values and/or fractions have shown significant correlations with tissue properties, such as cartilage degeneration or bone biomechanics. 63,64 More recently, UTE tri-component analysis has been proposed to evaluate both short-and long-T2* components as well as fat in cortical bone, 68 but the inclusion of additional components requires more echo images, a longer scan time, and more complicated modeling.…”

“…Biological tissues frequently contain different water compartments which each have distinct T2 or T2* values. UTE bi‐component analysis has been developed to quantify T2* values and the short‐ and long‐T2* fractions of water components in a variety of MSK tissues 59–67 . Short T2* values and/or fractions have shown significant correlations with tissue properties, such as cartilage degeneration or bone biomechanics 63,64 .…”