Ex vivo testing of basal cell carcinomas and melanomas with high-frequency ultrasound

The objective of this study is to significantly reduce the length of surgery for skin cancer patients by developing a diagnostic method to quickly distinguish cancerous from non-cancerous tissue. A common treatment for basal cell carcinoma and several melanomas is Mohs surgery, consisting of surgical resection of the tumor and successive resections of the surrounding tissues (margins). Because each excised specimen needs to be examined for cancerous margins, skin cancer surgery can last up to 4 hours. To rapidly evaluate Mohs surgical specimens, a high-frequency (20-80 MHz) ultrasound method, originally developed for testing breast cancer surgical specimens, was modified for smaller skin cancer tissues. The method uses a narrow-beam (1.5-mm diameter) probe, a broad-beam (6.35-mm diameter) transducer, an ultrasonic pulser-receiver, a digital oscilloscope, an aluminum test stage to hold the specimen, and a hybrid water immersion/contact approach to acquire highly accurate data. The method is currently undergoing a feasibility study on skin cancer surgical margins at the Huntsman Cancer Institute, Salt Lake City, Utah. Preliminary results from 16 patients show that the 20-80 MHz peak density values from the power spectra are consistent with those found in previous breast cancer margin studies.