New microscopy technique rapidly detects skin cancer tissue during
28 January 2014
The US National Institute of Biomedical Imaging and
Bioengineering has developed a microscopic technique to analyze and
remove cancerous tissue rapidly in the operating room,
removing the need for lengthy repeated tissue sampling and checking.
The technique, called strip mosaicing confocal microscopy, can dramatically reduce the length, inefficiency, and expense
of this procedure.
The common surgery for non-melanoma skin cancer, known as Mohs
surgery, typically achieves excellent results but can be a long
process, as the surgeon successively removes the tissue of concern
until the surrounding tissue is free of cancer. To determine whether
further tissue removal is necessary, the borders of the lesion must
be processed in a laboratory to check for residual cancer tissue, a
process that takes 20-45 minutes and is often repeated numerous
It can take one to three hours, or even longer depending on the
size and location of the lesion. The process is lengthy because
after a section of tissue is removed, it must be frozen and stained
so it can be examined to ensure the borders are clear of residual
tumour. Although highly effective, the current practice is labour
intensive for surgeons and assisting staff, as well as lengthy and
stressful for patients. The time spent by surgical personnel and
those analyzing the tissue in the lab increases the expense of the
procedure, which has been estimated to cost US$2-3 billion per year
in the US.
NIBIB-supported researchers led by Dr Milind Rajadhyaksha at
Memorial Sloan Kettering are using their expertise in optical
imaging to improve this common procedure. Optical imaging is a
technique that uses visible or near-infrared light to obtain
detailed images of organs, tissues, and cells. The investigators
developed a new pathological assessment technique using a type of
optical imaging called strip mosaicing confocal microscopy. It can
provide high resolution images during removal of basal cell and squamous cell carcinomas (non-melanoma skin cancers) and perhaps
other tumours of the skin.
The new technique uses a focused laser line that performs
multiple scans of the tissue to obtain image strips that are then
combined, like a mosaic, into a complete image of the excised
tissue. The process takes only 90 seconds and eliminates the need to
freeze and stain the tissue samples for analysis — a process that
takes 20-45 minutes.
Comparison of residual cancer detected with the new confocal imaging technique and the currently used freezing and staining technique. Source: Dr Milind Rajadyhyaksha, Memorial Sloan-Kettering Cancer Center.
The technique was tested on 17 patients with 34 tissue samples.
The overall image quality was excellent, with high resolution and
contrast, providing for good visibility of the epidermis and dermis.
Researchers compared the new technique against the Mohs approach
with its frozen section processing. The new technique achieved a
promising 94% in preliminary measures of sensitivity and specificity
for detecting skin cancer margins, which is comparable to the 'gold
standard' Mohs procedure. These preliminary results demonstrated
that the optical technique could potentially detect skin cancer
margins with the same accuracy as the conventional frozen section
The results of this study were obtained under laboratory
conditions; a clinical trial is now being conducted to demonstrate
the feasibility of using this technique in the clinical setting, the
ultimate goal of the research group.
Steve Krosnick MD, NIBIB director for the Program for
Image-Guided Interventions, explains the utility of the optical
system: “The technology is particularly well-suited for Mohs-trained
surgeons, who are experts at performing excisions and interpreting
images of tissue samples removed during the Mohs procedure. Image
quality, ability to make accurate interpretations, and time savings
will be key parameters for adoption of the system in the clinical
setting, and the current results are very encouraging.”
1. Larson B, et al. Detection of skin cancer margins in Mohs
excisions with high-speed strip mosaicing confocal microscopy: a
feasibility study (pages 922–926). British Journal of Dermatology,
Vol 169, issue 4, Oct-2013/ R01 EB012466