Shear Wave Elastography Acquisition Parameters May Bias Shear Wave Velocity Measurements

To determine the effects of acquisition parameters on measured shear wave velocity (SWV) in reference phantoms.

SWV were measured on three phantoms of certified SWV 0.794 m/s (Phantom 1), 1.711 m/s (Phantom 2) and 2.500 m/s (Phantom 3). Parameters examined were depth, location, region of interest (ROI) size, transducer type, pitch, frame rate and one-shot mode. Measurements were repeated 10 times for different levels of each parameter at 1.8 MHz and 2.5 MHz transducer frequency on both Canon Aplio i700 and i800 systems. Statistical analyses were performed using linear mixed models with Holm test for multiple comparisons.

There was an interaction between acquisition depth and phantom stiffness (p < 0.001) with 1 cm of depth increasing SWV by 0.037 and 0.012 m/s in Phantoms 1 and 2 but decreasing SWV by -0.049 m/s in phantom 3. Lateral acquisition box location had increased SWV compared to the middle location (left 0.048 m/s, right 0.065 m/s, p < 0.001). ROI size (10 mm, 0.002 m/s, p = 0.846) had no statistically significant effect on SWV. Transducer type at 2.5 cm depth had no significant effect on SWV (linear 0.038 m/s, p = 0.049). Diff pitch setting of 2 had lower SWV (-0.030 m/s, p = 0.002). Frame rate had no statistically significant effect on SWV (1 frame per second increasing SWV by 0.037 m/s, p = 0.025). One-shot mode had higher SWV than continuous mode by 0.042 m/s (p < 0.001).

Acquisition parameters can have statistically significant effects on measured SWV and may bias measured SWV due to cumulative effects.