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wileyonlinelibrary.com/journal/srt © 2019 John Wiley & Sons A/S. Skin Res Technol. 2020;26:148–149. Published by John Wiley & Sons LtdReceived: 8 May 2019
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Revised: 28 June 2019|
Accepted: 22 August 2019 DOI: 10.1111/srt.12769L E T T E R T O T H E E D I T O R
Can shear wave ultrasound elastography be a useful tool
for determining the tumor extent of basal cell carcinomas
pre‐operatively? A preliminary study
Dear Editor,
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
Age Gender Size (mm) Normal tissue stiffness (kPa) Border stiffness (kPa) Central stiffness (kPa) 63 E 8.3 × 3.0 23 33.7 37 65 E 6.2 × 3.4 54 82 117 67 E 6.5 × 2.7 27 41 81 66 E 10.8 × 4.0 13 14 18 51 E 11.0 × 5.0 50 67 80 72 E 31.0 × 7.0 34 75 157 42 K 7.5 × 4.5 44 68 113 65 E 13.7 × 2.6 15.8 25.9 46.8 82 E 9.0 × 1.9 35.0 46.1 106.7
Note: For all lesions, stiffness of center of BCC lesion is highest.
TA B L E 1 The measurements of central
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149 LETTER TO THE EDITORat the center of the lesions are higher than the values at the border of lesions. Similarly, values measured at the border of lesions are higher than values of perilesional normal skin (Figures 1 and 2). These data show an increase in tissue stiffness from normal skin to lesion center. Oncological use of elastography is based on the general observation that malignant tissues are stiffer than benign tissues. For instance, breast cancer tissue is stiffer than the surrounding normal breast tis‐ sue; therefore, elastography has been shown to be useful in the diag‐ nosis of breast cancer and to assess the extent of tumor.6 In previous studies, it was revealed that the tumor thickness of BCC measured by elastography using a color scale (not a quantitative measurement) cor‐ related better with the histological thickness than the B‐mode sonog‐ raphy.3 So, we claim that, as a result of the quantitative measurements by SWE at the different points near the border of BCC lesion seen on the gray scale of US, the most distant point where the tissue stiffness is harder than perilesional normal skin can be considered as the surgical
safe margin. Also, currently, there is no definitive stiffness value that can differentiate normal skin tissue from malign tissue. In future, if a “definitive stiffness value” which differentiates malignant BCC tissue from normal skin can be determined, the surgical safe margin will be easily demonstrated by SWE, pre‐operatively. We believe that this paper will lead to further studies on this subject.
CONFLIC T OF INTEREST
There is no conflict of interest.
Mehmet Unal1 Zeynep Gizem Kaya İslamoğlu1
Mehmet Öztürk2 Emine Uysal2 Necat İslamoğlu3
1Department of Dermatology, Faculty of Medicine, Selcuk University,
Konya, Turkey
2Department of Radiology, Faculty of Medicine, Selcuk University,
Konya, Turkey
3Van Research and Education Hospital, Department of Radiology, Van,
Turkey
Correspondence
Mehmet Unal, Department of Dermatology, Faculty of Medicine, Selcuk University, Selçuklu, Konya 42130, Turkey.
Email: dr.munal1101@gmail.com
ORCID
Mehmet Unal https://orcid.org/0000‐0002‐8964‐3314
Zeynep Gizem Kaya İslamoğlu https://orcid.
org/0000‐0002‐8141‐3186
REFERENCES
1. Cameron CM, Lee E, Hibler BP, et al. Basal cell carcinoma. J Am Acad Dermatol. 2019;80:321‐339.
2. Manea A, Crisan D, Badea AF, et al. The value of ultrasound diagnosis in the multidisciplinary approach of cutaneous tumours. Case report. Med Ultrason. 2018;1(1):108‐110.
3. Tanaka T, Tada Y, Ohnishi T, Watanabe S. Usefulness of real‐time tis‐ sue elastography for detecting the border of basal cell carcinomas. J Dermatol. 2017;44(4):438‐443.
4. Xiang X, Yan F, Yang Y, et al. Quantitative assessment of healthy skin elasticity: reliability and feasibility of shear wave elastography. Ultrasound Med Biol. 2017;43:445‐452.
5. Alfageme RF. Elastography in dermatology. Actas Dermosifiliogr. 2016;107(8):652‐660.
6. Bhatia KS, Yuen EH, Cho CC, Tong CS, Lee YY, Ahuja AT. A pilot study evaluating real‐time shear wave ultrasound elastography of miscella‐ neous non‐nodal neck masses in a routine head and neck ultrasound clinic. Ultrasound Med Biol. 2012;38(6):933‐942.
F I G U R E 1 Lesion evaluation via SWE [Colour figure can be
viewed at wileyonlinelibrary.com]
F I G U R E 2 T13 shows the stiffness of center of lesion; T12
shows the stiffness of peripheral region of lesion; T2 shows the stiffness of border between lesion and normal skin; and T1 shows the stiffness of normal skin [Colour figure can be viewed at wileyonlinelibrary.com]
