Qian Li MD, Presenter: Nothing to Disclose

Anthony Edward Samir MD, Abstract Co-Author: Nothing to Disclose

To evaluate the strain sonoelastographic (SSE) appearances of stones in a phantom, and to establish whether SSE may accurately detect stone size as well as small stones/micro-calcifications without acoustic shadow.

A tissue-mimicking meat phantom with embedded stones was constructed. The stone length (minimum diameter) and width (maximum diameter) were obtained by physical measurements, gray-scale ultrasound measurements, and SSE measurements (Hitachi Preirus machine) in 4 groups with different depths. Measures of stone size and depth were described as mean±SD. p < 0.05 was considered statistically significant.

SSE showed 3 stable sonographic findings of the stone: front transitional region, hard region, and behind transitional region. Physically measured stone lengths and widths were 1.17-6.86mm and 1.30-11.15mm respectively. Sonographically measured stone depths in the 4 groups were: 9.00±1.44mm, 20.92±1.47mm, 32.99±1.29mm, and 41.53±1.83mm. SSE width correlated well with physical measurement in each group at different depths (r1=0.979, r2=0.988, r3=0.954, r4=0.970, p<0.05). Compared with the physical measurement, the differences of SSE width in each group were less than those of gray-scale width (0.03±0.68 vs. 0.44±0.38mm, -0.12±1.06 vs. 0.44±0.83mm, -0.20±0.73 vs. 0.44±0.67mm) or similar (0.42±0.61 vs. 0.36±0.38mm). SSE length correlated well with physical measurement in each group at different depths (r1=0.928, r2=0.954, r3=0.803, r4=0.726, p<0.05), especially when width<6.0 mm (r1=0.945, r2=0.955, r3=0.876, r4=0.836, p<0.05). Compared with the physical measurement, the differences of the SSE length were -0.36±0.87mm, 0.35±1.66mm, -0.42±1.19mm, and -1.28±1.09mm in each group. Non-shadowing stones 1 mm in size could be distinguished from similarly echogenic soft tissues on the basis of their typical sonoelastographic appearance.

This experiment demonstrated that stones have typical sonoelastographic findings, and that SSE can be used to accurately measure stone size, and measure stone size in regions of acoustic shadowing. SSE has the potential to enhance the diagnostic value of sonography in diseases that produce microcalcifications, such as carcinomas of the breast and thyroid.  

The large stiffness difference between soft tissues and stones/microcalcifications provides a plausible basis for strain sonoelastography to increase the sensitivity for these markers of pathology.

Li, Q, Samir, A, Detection and Characterization of Stones with Strain Sonoelastography – A Phantom Study.  Radiological Society of North America 2012 Scientific Assembly and Annual Meeting, November 25 - November 30, 2012 ,Chicago IL. http://archive.rsna.org/2012/12043872.html