Heliomar de Azevedo Valle

Statistical Analysis of High Frequency Ultrasonic Backscattered Signals from Basal Cell Carcinomas

A statistical approach was implemented in the study of histologic characteristics from ex vivo basal cell carcinomas, based on the properties of backscattered acoustic waves, for the purpose of evaluating the method as a diagnostic tool. The study was developed using an ultrasound biomicroscope working at a frequency of 45 MHz. The parameters examined were signal-to-noise ratio (SNR), and shape parameters from the Weibull (b(W)) and generalized gamma (c(GG) and υ(GG)) probability density functions. Twenty-seven carcinomatous skin samples were obtained from volunteer patients and classified into two groups (BCC1 and BCC2) based on the distribution patterns of their tumor nests; also, seven non-tumoral samples were used for comparative purposes. Significant differences between groups were obtained for all studied parameters. The successful differentiation between some tissue groups suggests its potential use for carcinoma characterization.

Study of superficial basal cell carcinomas and Bowen disease by qualitative and quantitative ultrasound biomicroscopy approach

In the present work the ultrasound biomicroscopy (UBM) technique is applied in the study of cutaneous cell carcinomas in vitro, including superficial basal cell carcinomas (BCC) and Bowen disease (BD) cases. The evaluation was made by qualitative observation of UBM images, and by quantitative computation of integrated backscatter coefficient (IBC), obtained with a system working at a central frequency of 45 MHz. The characteristic histological structures for each studied tumor type were well identified in the images. The IBC values observed in the two carcinoma types inside the affected region, were different between them, next to 10⁻⁴ [Sr⁻¹.mm⁻¹] for superficial BCC tissues, and to 10⁻⁵ [Sr⁻¹.mm⁻¹1] for BD tissues; moreover, in the deeper dermis (slight affected region) the backscatter was next to 10⁻³ [Sr⁻¹.mm⁻¹] for both tissue groups, and agrees with the values obtained for healthy skin both, in this study and in previous works. The results here obtained encourage the continuation of the work, with a higher number of samples, attempting to obtain more significant results.