DR. MANU JAIN, Optical Imaging Specialist at Memorial Sloan
Kettering Cancer Centre (MSKCC) Department of Dermatology provides great
insight on the advantages of Reflectance Confocal Microscopy (RCM) for the
diagnosis of skin cancers, in vivo.RCM is a form of in vivo microscopy— “histopathology-like” diagnosis without doing a biopsy. It offers several advantages over conventional light microscopy, including imaging of tissue in vivo and ability to provide bedside diagnosis. In addition to its applications in dermatology it can also be applied for oral cancers. Meanwhile, we call this application ‘optical biopsy’. Microscopy is actually what's paving the way for digital imaging in dermatology. Before this it was the naked eye and magnifying lens.
THE POWER OF LIGHT
As ultrasound is recognized for being non-invasive and
radiation free, so is optical imaging – gathering cellular and nuclear
epidermal and superficial dermal information through the use of LIGHT and
laser. It penetrates the skin to reach an
estimated 200 micron in depth - good enough in dermatology to diagnose skin
cancers like melanoma, basal cell carcinoma, and squamous cell carcinoma.
Because most tumors that appear originates at the dermo-epidermal junction
(around a hundred-micron depth from skin surface). In addition to morphological
and cellular details, RCM also provides
information on the dynamic phenomenon of the
blood flow very clearly.
Dr. Jain joined MSK four years ago, but this technology has
been used primarily for research prior
to her joining in the USA. The engineering team at MSK (headed by Dr. Milind Rajadhyaksha) helped design this machine in
collaboration with Caliber ID (Rochester, NY) 20+ years ago. Few years ago, RCM acquired a category I current
procedural terminology (CPT) reimbursement codes
(96931–96936) by the US Centers for Medicare and Medicaid Services (CMS) [1]. However,
there are limited expert readers of RCM in the US. To bridge this gap, Dr. Jain
teaches and trains her residents in the dermatology and dermatopathology. She
is has started her own annual CME accredited confocal courses at Memorial Sloan
Kettering Cancer Center. She is also the Vice-president of recently formed
American Confocal Group.
This innovation relies solely on reflectiveness of various
tissue structures in the skin, illuminating and magnifying images by relying on
the light planes. “Your skin is like a mirror and when you shine light on the
mirror, whatever absorbs all the light becomes dark and whatever reflects all
the light appears bright”.
"I think it could be interesting to explore the option
of combining confocal microscopy with ultrasound because ultrasound can give us
the doppler information and also the depth is a very good with ultrasound…
which we miss with confocal microscopy.
So that would be really great. Like they have done with confocal and
optical coherence tomography."
Her professional
focus is to teach RCM to dermatologists and dermatopathologists. For the large institutions, it’s fairly
affordable and cost-effective as it takes only 15 minutes or 20 minutes to do
one lesion. That means a patient gets
scanned and diagnosed at the same time. This saves a lot of time for the
patient at the end of the day because the patient doesn't have to wait for the
biopsy report for week.
According to Dr. Jain's original bedside diagnosis study,,
RCM has shown remarkable sensitivity (~90%) and specificity (~70%) in hands of
a novice, within a short interval of 16 months [2] , for skin cancers.. Several studies reported RCM imaging to
achieve sensitivity of 70–92% and specificity 84–88% for melanocytic lesions
[3] and sensitivity of 100–92% and specificity 85–97% for non-melanocytic skin
lesions . . "As an example, we’re examining a patient's new mole with
confocal microscopy and if we are suspicious that it might be melanoma, we can
use dermoscopy and confocal together to improve the accuracy of diagnosis.
Although the sensitivity of RCM has not much changed over
dermoscopy but the specificity is two times superior—translating into marked
decrease in benign biopsies.
Thanks to the developmental expertise of Dr. Milind
Rajadhyaksha (member of the faculty of Memorial Sloan Kettering Cancer Center),
the IN VIVO CONFOCAL MICROSCOPY is fast becoming the new standard in dermal
non-invasive imaging. Originally
conceptualized with his mentors at MD Anderson (renowned physicist Dr. Robert
Webb and dermatologist/laser pioneer Dr. Rox Anderson), the team sought better
ways to detect skin cancers while reducing the need for biopsies in real time
at the bed-side. At the time, biopsy and
pathology were the standard approach for detecting and diagnosing skin
lesions. The demand for advancing
diagnostic imaging was a call from the 5 million+ new cases diagnosed in the US
each year and another million cases detected in Europe, UK, Australia, other
regions of the world.
Milind (as he prefers to be called) described how the RCM
works in simplified terms: “We start with a bright light source… in our case
it's a laser. We focus the laser down to
a very tiny spot inside the skin and we move the spot around in 2 dimensions so
we create essentially a plane of illumination by moving that spot. Imagine
having a flashlight which you point at a wall and now you move the flashlight
back and forth, sideways and up and down until you can illuminate the entire
wall. Similarly, we ‘paint’ a single
plane within tissue with focused laser spot and we collect light from each
location that the spot illuminates and that we can use that to produce an
image. You can essentially create an image or a picture of a single layer of
cells or layer of tissue within skin.”
Milind states having built the original laboratory bench top
portion in the early 1990’s and continued the expansion of the technology with
MSKCC since 2005. He has been involved with advancing both the IN vivo (means
directly on the patient) and the EX vivo microscope (referring to any fresh
tissue that has been removed from the patient, ie. biopsy) to do faster imaging
over large areas. Besides looking at skin cancers, this technology is set up
over a mic top with a probe that can allow for imaging inside the oral cavity
looking for oral cancers. “We've done a lot of work in imaging to guide
treatment, surgeries and to guide laser ablations at Memorial for more than a
decade.”
References:
1) Current Procedural Terminology, Professional Edition. Chicago IL: American Medical Association; 2016. The preliminary physician fee schedule for 2017 is available at https://www.cms.gov/Medicare/Medicare-Fee-for-Service-Payment/PhysicianFeeSched/PFS-Federal-Regulation-Notices-Items/CMS-1654-P.html
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