d Original Contribution QUANTITATIVE SONOGRAPHY OF BASAL CELL CARCINOMA HANNA PIOTRZKOWSKA-WROBLEWSKA,* JERZY LITNIEWSKI,* ELZBIETA SZYMANSKA, y and ANDRZEJ NOWICKI* *Department of Ultrasound, Institute of Fundamental Technological Research, Warsaw, Poland; and y Dermatology Clinic, CSK MSWiA Hospital, Warsaw, Poland (Received 16 January 2014; revised 29 October 2014; in final form 23 November 2014) Abstract—A 30-MHz ultrasonic scanner was used to collect B-scan images together with appropriate radiofre- quency echoes from diseased and healthy skin regions of patients with diagnosed basal cell carcinoma and pre-cancerous lesions (actinic keratosis). Radiofrequency data were processed to obtain the attenuation coefficient and statistics of the backscattered echo signal determination (K-distribution and effective density of scatterers [EDS]). The attenuation coefficient was significantly higher for patients with basal cell carcinoma than for healthy patients. Also, the pre-cancerous skin lesions had increased attenuation. The averaged EDS values for cancer lesions were significantly lower than those for pre-cancerous lesions and healthy skin. The successful differentia- tion between the tissue groups examined suggests the potential value of the attenuation coefficient and EDS for carcinoma characterization. (E-mail: hpiotrzk@ippt.pan.pl) Ó 2015 World Federation for Ultrasound in Medicine & Biology. Key Words: Quantitative ultrasound, High frequency, Human skin, Skin lesions, K-distribution, Attenuation coefficient, Tissue characterization. INTRODUCTION Basal cell carcinoma (BCC) is the most common cuta- neous malignancy, representing 80% of all skin cancer cases. BCC arises from the basal cells of the epidermis. Although BCC is not associated with significant mortal- ity, the associated morbidity and therapeutic costs are an increasing burden to the health care system. BCC cases are rather easily diagnosed, but a substantial number of cases require biopsy because of their similarity to other cutaneous neoplasms, both benign and malignant, making the BCC direct diagnosis ambiguous. Basal cell carcinoma can develop from pre- cancerous growths like an actinic keratosis (AK), as well as from unchanged skin. According to Cham (2013), it is estimated that up to 50% of the population is affected by AK. The difficulty in predicting the evolution of this kind of lesion makes AK very dangerous. It may not be a threat to the health and life of the patient for a long period, but at some point it can vanish or transform into cancer. Foster et al. (2000) reported that although ultrasound (US) has the capability to image fine features in the skin, such as sweat gland ducts, hair follicles and veins, the diagnostic ability of skin images to reveal specific pathol- ogies is limited. It is difficult to differentiate between benign and malignant lesions using B-scan images (Fornage et al. 1993) because both types of lesions appear hypo-echogenic compared with healthy skin. Another study indicated that both scar tissue and malignant mela- noma could appear similar in US scans (Turnbull et al. 1995). Thus, biopsy is still the gold standard in final diag- nosis of skin cancer; however, quantitative ultrasound can provide additional information that is potentially helpful in lesion assessment and screening tests. First, quantitative studies of skin lesions in vivo us- ing ultrasound have mostly been limited to parameters that could be computed directly from images, recorded by using commercially available 20-MHz systems. For instance, changes in skin echogenicity (mean pixel amplitude, which is proportional to the mean backscatter amplitude) and skin thickness have been found to be related to photo-aging of the skin (Gniadecka and Jemec, 1998). The degree of acoustic shadowing, measured as the ratio of echogenicity of the retrocessional dermis to that of the perilesional dermis, was found to be Ultrasound in Med. & Biol., Vol. 41, No. 3, pp. 748–759, 2015 Copyright Ó 2015 World Federation for Ultrasound in Medicine & Biology Printed in the USA. All rights reserved 0301-5629/$ - see front matter http://dx.doi.org/10.1016/j.ultrasmedbio.2014.11.016 Address correspondence to: Hanna Piotrzkowska-Wroblewska, Department of Ultrasound, Institute of Fundamental Technological Research, ul. Pawinskiego 5 b, 02-106 Warsaw, Poland. E-mail: hpiotrzk@ippt.pan.pl 748