Low-cost gynecologic ultrasound phantom with tissue-mimicking properties for hysterosalpingo contrast sonography

Infertility is a major global health concern, with fallopian tube blockages contributing to up to 35% of female infertility cases, and highlighting the critical need for effective tubal patency diagnostics. Hysterosalpingo-contrast sonography (HyCoSy) is a noninvasive ultrasound technique for assessing fallopian tube patency, crucial in infertility diagnostics. Despite its advantages over x-ray and laparoscopic methods, its clinical use is limited due to operator dependence and the need for specialized training. However, existing ultrasound phantoms lack compatibility with microbubble-based contrast agents, restricting their effectiveness for HyCoSy training.

This study presents a low-cost, anatomically representative ultrasound phantom of the female reproductive system designed to support contrast agent infusion.

The phantom replicates the uterus and fallopian tubes using tissue-mimicking materials with acoustic and mechanical properties approximating human muscle and serous membrane tissues. Fabrication was performed using 3D-printed molds. Materials were selected and characterized based on density, Young's modulus, acoustic velocity, and attenuation slope, and compared with literature-reported physiological ranges. Reproducibility was assessed through multiple independent fabrications, and statistical analysis was conducted to evaluate inter-batch variability.

Among 15 tested material formulations, muscle-mimicking sample 6 exhibited a Young's modulus of 24.3 ± 4.8 kPa, an acoustic velocity of 1550 ± 5 m/s, and an attenuation slope of 0.055 ± 0.002 dB/mm/MHz-closely matching reported values for human muscle tissue (13-32 kPa, 1547 m/s, 0.05-0.054 dB/mm/MHz, respectively). Serosa-mimicking sample 15 showed a Young's modulus of 60.7 ± 7.3 kPa, velocity of 1598 ± 5 m/s, and attenuation slope of 0.079 ± 0.002 dB/mm/MHz, closely aligning with reported ranges for serous tissue (50-500 kPa, 1575-1595 m/s, 0.048-0.157 dB/mm/MHz). Computed tomography and B-mode ultrasound confirmed the structural integrity and formation of internal cavities in the phantom, while fluorescence and ultrasound imaging demonstrated effective retention of contrast agents during microbubble infusion. Both B-mode and non-linear contrast ultrasound imaging enabled clear visualization of the uterine and tubal structures.

The phantom demonstrates validated mechanical and acoustic properties that closely match those of human muscle and serosa, supporting its suitability for illustrating core principles of HyCoSy, including contrast agent infusion and tubal visualization. The low cost and structural reproducibility of the model make it a practical option for simulation-based radiology training.