Tendon Microvascular Structure Imaging Using Contrast-Free Super-Resolution Ultrasound in Humans

Tendon overuse injuries, marked by neovessel ingrowth, pose a clinical challenge. The limited observation time of conventional ultrasound imaging methods, such as color Doppler and power Doppler imaging, makes it difficult to visualize slow-flow events. These methods can only detect blood flow when the tendon is significantly diseased. A fast contrast-free super-resolution ultrasound technique (SURE) has been hypothesized to reliably reveal microvasculature in injured human patellar tendons at a resolution below λ/2. Unlike conventional Doppler, SURE identified more detailed microvasculature, achieving vessels as small as 44 μm. Consistent detection of microvascular structures was demonstrated in six 4.8-second segments, with a maximum standard deviation in vessel width of 7.0 μm.