Researchers from Washington University in St Louis, US, have developed a handheld device that accurately measures how deep a melanoma tumour extends into the skin, helping doctors easily make a prognosis before they treat the disease.
The researchers said the device uses lasers and sound waves applied directly onto the patient to gather diagnosis information about the melanoma tumour.
The findings have been published in the Optical Society’s journal, Optics Letters.
Lynn Cornelius, co-author of the study, said that the thicker the melanoma tumour is, the more likely it will spread and become deadlier.
Cornelius added that the device allows the doctors to measure the tumour during initial evaluation, helping them to determine the prognoses accurately and plan their treatment accordingly.
"Any type of tissue diagnosis at this point in time requires taking tissue out of the person and processing it and looking at it under the microscope."
The scientists said that high-resolution optical techniques cannot measure the tumour well and do not reach deep enough, since the skin emits light.
In order to measure the depth of tumour, a biopsy is required involving the removal of part of the tumour. If the tumour is in acosmetically sensitive area, the provisional measurements of the tumour depth may not be reliable, the researchers said.
Without proper knowledge of the depth of the tumour, doctors may need multiple surgeries, especially if they find that the tumour is deeper than they originally thought.
Co-author Lihong Wang said: "None are really sufficient to provide the two to 4mm penetration that’s at least required for melanoma diagnosis, prognosis or surgical planning."
The researchers use a photoacoustic microscopy method can accurately measure melanoma tumours directly on a patient’s skin.
Through the photoacoustic effect, the light is converted into vibrations while a laser beam shines into the skin at the site of a tumour.
Melanin, the skin pigment that’s also located in tumours, absorbs the light and transforms it into high-frequency acoustic waves.
Acoustic waves do not scatter in the way that light does while passing through skin. In the process, the cells with tumours will produce more melanin than the surrounding healthy skin cells to find the exact depth.
The device can also provide a three-dimensional image of the affected cells through the acoustic waves.
Image: The motor, translation stage, ultrasonic transducer, and optical fibers are all incorporated in this handheld probe for easy operation. Photo: courtesy of Yong Zhou.