Ultrasound elastography accurately spots skin cancer

In an ironic twist for radiology, effective imaging of skin cancers has just been accomplished by none other than the imaging modality in closest contact with the skin: ultrasound.

“We in radiology have scanned basically the entire body, but not the skin, which seems like it should be superficial and accessible to imaging,” said lead investigator Dr. Eliot L. Siegel, vice chairman of radiology at the University of Maryland School of Medicine in Baltimore.

Tuesday at the 2009 RSNA meeting Siegel unveiled results of a study that, for the first time, looked at the utility of ultrasound elastography for identifying skin cancers.

Findings suggest that high-frequency ultrasound with elastography has the potential to measure the extent and depth of skin lesions as well as reduce the number of unnecessary skin biopsies.

Siegel and colleagues used high-frequency ultrasound with elastography to evaluate 40 patients with either benign or malignant skin lesions. They found malignant lesions are dramatically less elastic than nonmalignant skin. The elasticity ratios recorded by the investigators ranged from 0.04 to 0.3 for benign lesions to 10 and higher for malignant lesions.

According to Siegel, skin cancer will develop in one in five people in the U.S. The American Cancer Society finds that more than one million cases are diagnosed each year. Melanoma is the most deadly, but it is highly curable if detected early. Ultrasound with elastography could provide clear details of the skin without biopsy, Siegel said.

“Melanoma has increased precipitously from 1935 to 2010,” Dr. Siegel said. “This makes it even more important to differentiate melanoma from other skin cancers.”

According to coauthor Dr. Bahar Dasgeb, a dermatologist at Wayne State University in Detroit, current dermatology assessment of lesions is purely visual. That could change thanks to elastography.

“If lesions have anything that catches the eye of the dermatologist, it’s biopsied,” she said. “Elastography can help determine the nature of the lesion before a potentially unnecessary biopsy is ordered.”

Ultrasound hardware with a frequency between 14 and 16 MHz is relatively common and currently available clinically. To streamline and better perfect ultrasound with elastography, technology with the ability to image at a higher frequency and the capability to compute elasticity ratios must be developed, Siegel said.

“We believe ultrasound seems to better and more accurately detect skin cancer. It has tremendous potential,” Siegel said.