ALBUQUERQUE – A long-wave infrared system distinguished malignant and benign skin lesions with a sensitivity of 96.97% and a specificity of 78.05%, with skin biopsies used as a benchmark, in a pilot study of 74 patients.
The results "suggest the technique is promising as a noninvasive screening tool" and merits continued research and development to improve sensitivity, specificity, and statistical confidence, reported Stephen Myers, Ph.D., of Skinfrared, and his associates.
Recent advances in infrared technology have led to the development of imaging devices that noninvasively detect tumors, based on differential thermal properties of malignant versus healthy tissue. The long-wave infrared detection device used in the pilot study was designed to identify thermal signatures of suspicious lesions and surrounding skin after the application of a temperature stimulus, Dr. Myers said at the annual conference of the Society for Investigative Dermatology.
In the United States skin cancers are diagnosed more often than all other cancers combined, noted Dr. Myers, but screening for them "requires the skill of a highly trained dermatologist," who must assess a range of morphologic characteristics. "This is a rather subjective approach that causes many biopsies to be performed on benign lesions," Dr. Myers added.
To test the device, investigators at the University of New Mexico, Albuquerque, Dermatology Clinic offered patients with suspicious skin lesions the option of being evaluated with the infrared device before undergoing biopsy.
The device has infrared and visible cameras, as well as a registration marker, a cold air source, and a computer and software to guide image acquisition and analysis, Dr. Myers said. Investigators placed the registration marker near the skin lesion of interest, captured a visible image of the lesion, and then took a 15-second baseline thermal image sequence. After cooling the lesions and surrounding skin to 10° C, they measured and compared 3-minute thermal recovery rates for the lesion and surrounding skin.
Participants averaged 55 years of age, and 53% were male. A total of 102 suspicious lesions were tested. Based on biopsy results, 55% were benign, 34% were basal cell carcinomas, 7% were squamous cell carcinomas, and 4% were melanomas, Dr. Myers reported. The receiver operating curve – calculated to assess the test’s ability to classify skin lesions – had an area under the curve of 95.3% (95% confidence interval, 90.0-99.0). Using biopsy results as a benchmark, the infrared device had a sensitivity of 96.97% and a specificity of 78.05%, Dr. Myers said.
The study was supported by the National Science Foundation and Skinfrared, which makes the device. Dr. Myers is an employee of Skinfrared.