LAUSR

Basal cell carcinomas (BCC) are the most common keratinocytic tumor of the skin which are associated with significant morbidity and cost.1 The main treatment of BCC is surgical excision; therefore, determina‐ tion of tumor extent pre‐operatively is vital for an optimal excision.2 In order to evaluate tumor extent accurately, high‐frequency sonog‐ raphy, dermoscopy, and magnetic resonance imaging are commonly used.3 Shear wave ultrasound elastography (SWE) is a novel cost‐ef‐ fective diagnostic ultrasound (US) technique using acoustic radiation impulses to stress tissues and ultrafast US tracking techniques to mea‐ sure the speed of induced shear waves. Technically, SWE is superior to strain elastography (another form of elastography) due to its direct and quantitative estimation of Young's modulus and is not dependent on external compressions by the operator or other mechanical or physio‐ logic sources. SWE provides a dynamic visual display of tissue stiffness in a variety of clinical settings ranging from abdominal examination to visualization of small structures.4 In dermatology practice, it has been used for the assessment of the skin and adnexa.5 Pre‐operative pre‐ cise determination of tumor extent is important to detect appropriate surgical border and crucial to decrease the recurrence rate.3 The aim of this paper was to evaluate the usefulness of elastography in the assessment of tumor border of BCC and whether SWE can be used as a novel tool for determining surgical border pre‐operatively. In this study, we evaluated BCC lesions of 10 patients via SWE (Aplio 500 ultrasound machine‐Canon [formerly Toshiba] Medical Systems Corporation) using a linear array transducer (frequency 14 MHz). It provides a dynamic visual display of tissue stiffness in a variety of clinical settings ranging from abdominal examination to visu‐ alization of small structures. The highly accurate and reproducible tool provides fully integrated measurement and reporting. The 2D‐SWE map (left side) and quality mode (right side) were examined in split‐ screen mode. The quality mode, which is identified as the propagation mode (arrival time contour), is a mode in which reliable data are can be obtained when the lines are parallel and smooth, and the increase in distance between the lines is parallel to the increase in elasticity. Subsequently, a 1‐mm‐diameter region of interest (ROI) was used to take measurements at three different points in the sagittal plane. The ROI was placed by the examiner exactly in the center of the phantom target. Therefore, the depth from the phantom surface to the center of the ROI was the same in the same measuring series. The depth of the target was known (according to the manufacturer). All measurements were recorded for stiffness using the SWE (m/s)/ Young's modulus E (kPa). Tissue stiffness was measured for each lesion from three regions seen on the gray scale of US: first region is central lesion; second region was border of the lesion; and third region was perilesional normal skin. To reduce measurement error, every recording was repeated three times and the stiffness value was calculated by averaging the three measurements. A pad filled with an ultrasonic gel was used when the images were taken. A single radiologist conducted all evaluations. The measurements of central lesion, border, and perilesional normal skin are seen in Table 1. In all lesions, the stiffness values measured by SWE