Two-photon fluorescence microscopy may help diagnose skin cancer rapidly, accurately
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A novel imaging technique was associated with high sensitivity, specificity and accuracy in diagnosing nonmelanoma skin cancers, according to a study.
“We are interested in trying to improve clinical throughput and provide patients with a faster diagnosis,” Michael G. Giacomelli, PhD, of the department of biomedical engineering at the University of Rochester in Rochester, New York, and one of the authors of the paper, told Healio. “Biopsying patients, waiting days or weeks for lab results, and then rescheduling them if treatment is needed is time consuming and inefficient.”
Giacomelli added that processing and cutting slides is also “labor intensive.”
“With newer imaging technology we can potentially diagnose at the time of biopsy and then enable immediate treatment, and with much less labor,” he said. “Saving time and work would be good for everyone.”
The researchers noted that nonmelanoma skin cancers (NMSCs) are most commonly diagnosed through paraffin section histologic analysis of skin biopsy specimens.
Two-photon fluorescence microscopy (TPFM) may potentially allow for the diagnosis of NMSC and other conditions at the point of care. Giacomelli explained the approach.
“The core idea involves some complicated physics, but essentially near-infrared laser light is pulsed onto a point in the sample that has been stained with contrast agents that only absorb visible or UV light but not normally near-infrared light,” he said.
The technique also utilizes infrared light with shorter wavelengths to render images within a sample, according to Giacomelli.
“Because infrared light is not strongly absorbed except at the focus of the beam, TPFM can image through material more readily than other methods, and so is very effective at imaging fresh tissues and through blood and other material,” he said. “The laser can pulse millions of times per second and be scanned rapidly over the tissue generating HD images at video rate.”
In the comparative effectiveness pilot study, Giacomelli and colleagues examined 29 fresh biopsy specimens from confirmed NMSC lesions. TPFM was used to evaluate specimens immediately on site, and then the specimens were subsequently submitted for paraffin histology, producing co-registered images, according to the findings.
The study was conducted between October 2019 and August 2021.
The researchers used 12 of the co-registered image pairs as a training set, while 15 were used in a masked assessment by a licensed dermatologist. Two sets were excluded.
The outcomes of interest included the sensitivity, specificity and accuracy of TPFM for NMSC biopsies in comparison with paraffin histology.
Results showed that 14 of 15 samples in the evaluation set were identically diagnosed using both strategies.
TPFM was associated with 100% sensitivity (95% CI, 48%-100%), 100% specificity (95% CI, 69%-100%) and 100% accuracy (95% CI, 78%-100%) in diagnosing basal cell carcinoma.
For the squamous cell carcinoma samples, the novel approach yielded an 89% sensitivity (95% CI, 52%-100%), 100% specificity (95% CI, 54%-100%) and 93% accuracy (95% CI, 68%-100%).
Looking at overall NMSC diagnoses, TPFM carried a 93% sensitivity (95% CI, 66%-100%), 100% specificity (95% CI, 3%-100%) and 93% accuracy (95% CI, 68%-100%), according to the findings.
“I was not too surprised about the effectiveness of the technique,” Giacomelli said. “We had tested it with tumor samples from common skin cancers beforehand and screened a number of contrast agents for ones that would give high quality, easy to interpret images. After all that testing and preparation, we were confident that we could produce images that were very close to what is normally generated by conventional histology and so would give similar diagnoses.”
Giacomelli noted that imaging technology has advanced “enormously” in recent decades. “Newer techniques like TPFM have been very successful in the scientific study of cancer and other diseases because it enables rapid and high-resolution imaging of cells and tissue,” he said. “There is potential to improve treatment by taking these technologies from laboratory use to clinical use.”
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