News
Author: Eric Zachary Berkowitz, MD
Mt Sinai Medical Center, New York, NY
Title: The Use of High Frequency High Resolution Ultrasound Prior to Mohs Surgery
Co-Authors: Ellen Marmur MD, Josh Zeichner, MD, Mohammad Al-Hadab, MD, Jodi Siskind, MS, Brian Fuchs, BA, Connie Phillips-Jones, RN, MSN
Purpose: The use of ultrasound (US) to examine and assess the skin is a relatively new technology. Ultrasonography utilizes the echoes of sound waves to create images of soft tissue anatomy. The object of this study is to explore the clinical application and use of high frequency high resolution ultrasound in Mohs micrographic surgery. Additionally, the study will evaluate the ability to accurately determine lesion depth and width of tumor borders in order to reduce the number of surgical stages and possibly leading to a smaller defect.
Design: Single center study of twenty patients scheduled for Mohs surgery with lesions on flat surfaces (chest, back, extremities and face). The investigator will demarcate and document clinical estimation of the first stage. Ultrasound images will then be taken and depth and diameter will be documented, extirpation of tumor and histological analysis will be performed using standard Mohs technique. Statistical analysis will be performed via a Student‘t’ test for differences.
Summary: The effectiveness of the ultrasound within the context of Mohs surgery and Mohs stages, the tumor size that was predicted by the ultrasound in comparison to clinical evaluation had interesting results. Of the twenty-two patients, 6 patients or 27% of the patients had ultrasound measurements that were either similar or smaller than the initial clinical measurement of the tumor (2/6 were Squamous Cell Carcinoma - SCC and 4/6 were Basal Cell Carcinoma - BCC) but, required multiple stages of Mohs surgery (2-4 stages). This indicates that the initial ultrasound measurements predicted a smaller cancer when in reality the cancer was larger. Alternatively, another subset of the study, 6/22 or 28% of patients were found to have larger ultrasound measurements of their cancer (4/6 were SCC and 2/6 were BCC) when compared to the clinical measurement, yet histologically only required one Mohs stage. It is difficult to say which measurement is more accurate in this case; it may be implied, that in this situation the clinical is more accurate because the US prediction was larger than the clinical measurement and still only one Mohs stage was needed. Therefore, if you had taken the stage according to the US measurement it would have been larger than necessary. Finally, in 12/22 or 54% of patients, the ultrasound measurements were smaller than the clinical measurements, but the tumor still only required one stage of Mohs for complete extirpation. The scenario does not enable us to determine which method is more accurate.
A paired 2-sided t-tests testing for differences between clinical and US widths and lengths was performed and found: width: t=-2.189 (p=0.040) length: t=-1.427, (p=0.168) indicating that there is a significant difference between the widths found from clinical assessment vs. ultrasound; implying that the widths found clinically tend to be larger. Conversely, there was no significant evidence to suggest a difference between the lengths found from clinical assessment vs. the ultrasound.
Conclusion: The use of high frequency ultrasound using 20 MHz transducers has been established for the noninvasive imaging of skin tumors. We found that it has the ability to detect a more precise measurement of the width of a cancer enabling it to be used adjunct for preoperative planning with regard to surgery, especially in areas where there is a need to preserve normal skin.