Quadriceps tendinopathy is just inflammation of the quadriceps tendon. It can vary from minor acute tears to more chronic tendinitis which was the case with Kawhi. Moreover, you don't necessarily need imaging to detect mild cases of quadriceps tendinitis. For instance I was diagnosed with it at 21 simply from a doctor listening to my symptoms and noticing some swelling in the area. It's a common injury that can occur from overuse or running on hard surfaces. The reason I brought up Springer is because of the fatigue issue that keeps being brought up, it sounds similar to what Kawhi had, but of course it could also be a hundred other things too.