Usefulness of Shear Wave Elastography in Determining the Tumor Extent of Basal Cell Carcinomas.

Objectives: The purpose of this study was to investigate the value of shear wave elastography (SWE) in determining tumor extent of basal cell carcinomas (BCC), and thereby determine the optimal surgical margins (OSM).

Methods: 10 patients (40 surgical margins) with BCC were collected, the visual observation boundaries (VOB) were marked, and the SWE parameters of soft tissues were measured 1 mm intervals in "3, 6, 9, 12" clock directions, starting from VOB. Then tumors were resected with a 5 mm surgical margin outward expansion of VOB. All specimens were examined pathologically 1 mm intervals from VOB in four clock directions. With the positive margins furthest from the tumor as the real tumor boundaries (RTB) and the negative margins closest to the tumor as the optimal surgical margins (OSM). The SWE parameters were compared between these two groups.

Results: The elasticity ratio (E ) of average young's modulus between region of interest and adjacent normal soft tissue had statistically significant differences between groups (P = .000), while other parameters show no difference. The E of RTB and OSM were 1.22 ± 0.14 and 0.99 ± 0.07. The area under the ROC curve was .947. Taking 1.075 as the threshold of E for the diagnosis of tumor extent, the sensitivity, specificity and accuracy were 87.5%, 90.0% and 90.0%. The surgical margins designed according to OSM were better than those designed according to VOB + 5 mm (P = .000).

Conclusions: The E of SWE is helpful in determining tumor extent of BCC. This is beneficial for surgical margin designing.