Although clinical examination represents the gold standard in the diagnosis of patellar tendinopathy, it is commonplace to perform diagnostic imaging of the patellar tendon to confirm the diagnosis and rule out alternative diagnoses. Furthermore, imaging can be used to estimate response to treatment. This diagnostic imaging work-up usually consists of magnetic resonance imaging (MRI), ultrasound or, occasionally, a combination of both. On "regular" MRI, increased tendon size and visually increased signal intensity within the proximal patellar tendon can be observed in patellar tendinopathy , but altered tendon microstructure is invisible. A novel innovative method to detect tendon abnormalities is the ultrashort echo time (UTE) MRI technique. UTE enables accurate detection of changes in a reactive tendon both visually and in a quantitative manner by measuring T2* relaxation time UTE MRI has also been shown to quantitatively depict changes in tendon microstructure and, therefore, this innovative imaging modality allows in-vivo evaluation of tendon regeneration. It is currently unknown whether quantitative UTE MRI parameters change after exercise treatment, are related to clinical symptoms of patellar tendinopathy, and have prognostic value for exercise treatment response.