RSNA: Ultrasound technique could open doors for skin cancer imaging

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CHICAGO—High-frequency ultrasound with ultrasound elastography successfully delineated the extent of and was able to provide quantitative differentiation among a variety of benign and malignant skin lesions, according to clinical study presented Tuesday at the Radiological Society of North America (RSNA) meeting. The researchers believe that this analysis will make headway for using imaging techniques to assess skin lesions.

“Radiologists have scanned basically all the areas of the body, except for the skin. Skin is superficial—we see it all the time—and yet, there have not been any imaging studies to evaluate skin cancer,” said lead author and study presenter Eliot L. Siegel, MD, vice chairman of the radiology department at the University of Maryland in Baltimore.

The growing annual incidence of skin cancer should make new techniques incredibly relevant, according to Siegel, who cited the American Cancer Society statisics that one in five Americans will develop skin cancer and about one million Americans develop basal cell carcinoma annually.

He added that neither radiology nor dermatology employ imaging to assess or manage skin cancer patients.

The researchers prospectively imaged 40 patients with proliferative malignant neoplasms or benign skin lesions utilizing an ultra-high frequency sonography system. They assessed the elastographic properties of these lesions. “Elastography identifies cancer based on skin elasticity, and harder skin was associated with cancer,” Siegel said.

In an interview, Siegel also pointed out that the technology is already available on the market, so it will not mean additional costs to hospitals. “The technology is already capable of assessing strain ratio. It simply hasn’t been used for skin imaging, but has been used in breast and thyroid imaging,” he said.

Siegel and colleagues quantified the physical interaction of the tissue with ultrasonic waves in the 14 to 16 MHz range using a color-coding schema to reflect its physical elasticity. They then calculated the ratio of elasticity between adjacent normal skin and each skin lesion.

The researchers found that cystic lesions demonstrated high levels of elasticity while malignant lesions were relatively “hard” with a very low level of elasticity.

Based on the imaging results, the ratio of normal skin to skin lesions ranged from 0.04 to 0.3 for cystic skin lesions, 0.4 to 5 for benign proliferative lesions such as intradermal nevi or benign histiocytosis, and a ratio above 10 was characteristically seen in malignant lesions. The investigators confirmed the imaging findings histopathologically.

The high-frequency ultrasound imaging and elastographic analysis visualized and quantified the elasticity of the skin and superficial soft tissue lesions with 100 percent accuracy, Siegel said.

In addition to being able to accurately diagnosis cancer and cancer type, the imaging technique may also assist dermatologists with patient management.

“Dermatologists tend to biopsy any lesions that seem visually suspicious for disease,” said co-author and co-presenter Bahar Dasgeb, from the department of dermatology at Wayne State University in Detroit. “Consequently, many benign lesions are needlessly biopsied in order to avoid the risk of missing a potentially deadly melanoma.”

The technique also allows for accurate characterization of the extent and depth of the lesion.

“The visualized portion of a skin lesion can be just the tip of the iceberg, and most dermatologists operate blindly beyond what they can see on the surface,” said Siegel, adding that this new technique enables physicians to get “size, shape and extent of the lesion prior to biopsy.”

Siegel noted that he and his colleagues are currently pursuing larger, prospective trials, to further assess the technique’s predictive value.