Ex-vivo phantom for evaluation of ultrasound speckle tracking in the uterus

Uterine peristaltic movement plays an important role for the success of embryo implantation. This is especially relevant in the context of assisted reproductive technology. Unfortunately, the lack of tools for quantitative analysis limits our understanding of the uterine contractility. Recently, strain analysis by ultrasound speckle tracking has gained attention for the assessment of the uterine contractility. However, the absence of a ground truth hampers the optimization of this technology. This work proposes the first phantom based on a human ex-vivo uterus able to generate controlled tissue motion by sinusoidal (0,05 Hz), linear displacement of a syringe piston, injecting 3-mL water through a balloon catheter inserted into the uterine cavity. This way, controlled, realistic peristaltic movement was generated while maintaining original speckle characteristics. Uterine motion analysis was obtained by US speckle tracking on acquired B-mode imaging data using two block matching techniques, normalized cross-correlation (NCC) and sum of absolute differences (SAD). The proposed phantom based on a human ex-vivo uterus showed its value to assess US speckle tracking techniques providing a realistic ground truth that is fully controlled.