Ultrasound Med Biol. 2021 Oct 23:S0301-5629(21)00407-5. doi: 10.1016/j.ultrasmedbio.2021.09.011. Online ahead of print.
ABSTRACT
Soft tissue stiffness provides relevant information on plantar foot status. Therefore, appropriate monitoring of foot elasticity could be useful for diagnosis, treatment or health care of people with complex pathologies such as a diabetic foot. In this work, a feasibility study of reverberant shear wave elastography (RSWE) applied to plantar soft tissue was performed. Shear wave speed (SWS) measurements were estimated at the plantar soft tissue at the first metatarsal head, the third metatarsal head and the heel from both feet in five healthy volunteers. Experiments were repeated for a test-retest analysis with and without the use of gel pad using a mechanical excitation frequency range between 400 and 600 Hz. Statistical analysis was performed to evaluate the reliability of the SWS estimations. In addition, the results were compared against those obtained with a commercially available shear wave-based elastography technique, supersonic imaging (SSI). The results indicate a low coefficient of variation for test-retest experiments with gel pad (median: 5.59%) and without gel pad (median: 5.83%). Additionally, the values of the SWS measurements increase at higher frequencies (median values: 2.11 m/s at 400 Hz, 2.16 m/s at 450 Hz, 2.24 m/s at 500 Hz, 2.21 m/s at 550 Hz and 2.31 m/s at 600 Hz), consistent with previous reports at lower frequencies. The SWSs at the plantar soft tissue at the first metatarsal head, third metatarsal head and heel were found be significantly different (p < 0.05), with median values of 2.42, 2.16 and 2.03 m/s, respectively which indicates the ability of the method to differentiate between shear wave speeds at different anatomical locations. The comparison results indicate better elastographic signal-to-noise ratios with RSWE than SSI because of the artifacts present in the SWS generation. These preliminary results indicate that an RSWE approach can be used to estimate foot elasticity, which may have great potential to better evaluate changes in foot.
PMID:34702642 | DOI:10.1016/j.ultrasmedbio.2021.09.011
