When surgeons excise a tumor, the challenge is always to remove the neoplasm with good margins while preserving as much of the healthy surrounding tissue as possible. To make sure that everything appropriate has been removed, pathologists look at the frozen sections and later at the full slices of samples taken during surgery. The preparation of the slides, imaging, and analysis takes so much time that patients often have to be closed up before results come in. Revision surgeries are therefore common and associated worries, costs, and time lost are great.
What if you could bring high quality microscopy to the operating room? SamanTree Medical, a Swiss firm, is trying to do that with its Histolog Scanner, a new device that doesn’t require complex processing while helping surgeons to guarantee the best outcomes. Bastien Rachet, PhD, the CEO and Co-Founder of the company, was kind enough to answer our questions about SamanTree’s technology and what it can mean for surgical care.
Medgadget: Your company has developed a digital microscopy scanner that can be used within the operating room. Can you tell us why this capability is important?
Bastien Rachet, PhD: For cancer surgeries, in particular breast conserving surgery and skin Mohs surgery, it is crucial to control that the borders of the surgical specimen are free from cancer. Tissue microscopy is the unchallenged reference for such margin assessment. However, it traditionally requires extensive tissue processing (fixing, paraffin embedding, slicing, glass mounting) that makes it incompatible with use in the operating room.
The Histolog Scanner now brings tissue microscopy at the cellular detail, the gold standard for margin assessment, within the operating room. It does not replace the final assessment done by the pathologist after the surgery, but instead empowers the surgeon with unprecedented control over its specimen margins intraoperatively. The Histolog Scanner serves the need for surgeon to close his or her patient with the greatest possible confidence that the margin will be confirmed clean by the pathologist later on.
Medgadget: What were the technical challenges that had to be overcome to build the Histolog Scanner?
Rachet: The first challenge relates to the nature of the specimen. In surgery you are dealing with a thick piece of large size and random shape. On top of that, the specimen needs to be preserved for further detailed testing in pathology. The objective was to propose an accurate image-based assessment, working directly with the fresh surgical resection and not requiring specialized staff.
The second challenge is the time and consequently ease of use, as surgeon’s and OR time are key factors in patient safety and treatment cost.
Therefore, our solution shall provide access to high-resolution microscopy without requiring the processing of the sample onto microscope slides.
There’s a broad continuum of image resolution through the spectrum of imaging techniques, but when it comes to subcellular resolution for tissue morphology inspection, good imaging quality comes with a preparation of thin slices (thinner than your hair) on microscope slide.
Our solution is based on the well-established technique of confocal microscopy, widely used in research when it is about high resolution and high contrast imaging on thick specimen. Of course, resolution aside, heavy research microscopes available today would fail on the above-mentioned challenges (ease of use and time constraint), so we had to entirely redesign the optical principle in order to deliver a device much more alike to a flatbed scanner for paper copy machine, but still based on a confocal imaging principle.
Medgadget: Can you give us a summary of how your technology works and what was achieved to overcome the challenges that you mentioned?
Rachet: To overcome the speed issue inherent with confocal microscopy, we have developed and patented a massively parallel approach leading to a breakthrough imaging modality. Instead of scanning one laser beam at the time and mosaicing small images, the Histolog Scanner scans several tens of thousands at once.
To be ready for imaging, the surgical specimen is simply immersed in a fluorescence contrast agent and rinsed. The full surgical specimen is directly placed on the imaging window by the surgeon, there is no need for fixing, nor embedding, nor glass mounting. As a result, you get an immediate digital image of the entire specimen to zoom and pan. Somehow, we are the google maps of fresh tissue microscopy!
With the Histolog Scanner, a 4cm x 4cm specimen surface morphology is revealed within seconds, and the subcellular resolution is below the minute. This is unprecedented microscopy performance in terms of time to image on large area, and as simple to handle as a paper scanner.
Medgadget: Our audience is mostly clinical, so we’d like to know how the Histolog Scanner would be used in the OR? Would it require a separate trained operator and/or a pathologist to be present?
Rachet: The Histolog Scanner is an adjunctive tool for the surgeons to better control their surgical margins. A simple two-hour training allows the surgeon and/or surgeon assistant to be autonomous and comfortable in operating the device. The software interface, which is used to acquire, manage and visualize the images, is directed with a touch screen.
It is state of the art that surgeons can use this imaging modality to control their margins. Beyond that, we are very much interested by the impact for the pathology workflow of this new imaging modality, as the documentation of the specimen made in the course of surgery can be shared with the pathologist.
Medgadget: How quickly can a tissue sample go from excision to being analyzed on the screen?
Rachet: Two minutes! The excised specimen is ready for imaging in one minute only. High resolution image, covering a 4cm x 4cm surface, is acquired in less than one minute. The surgeon is directly handling the specimen on top of the imaging window. For example, it will take approx. 5 minutes to prepare the surgical specimen and check 4 of its sides.
Another example, in breast lumpectomy, the complete mapping of the full surface of a typical specimen is expected to be done in less than 10 minutes.
Medgadget: Can you give us a glance at the history of SamanTree Medical and how you came to lead the company?
Rachet: First thing first, history serves the future and SamanTree Medical is now fundraising to scale-up manufacturing, launch the Histolog solution v2.0 and further develop the product pipeline.
On the brief history side, I was leading advanced microscopy projects for life science research at EPFL (Swiss Federal Institute of Technology) when I met Davor who introduced me to the medical needs in cancer surgery. We understood through the pioneer work of the company MaunaKea Technology how confocal microscopy can carry a tremendous added value for the cancer surgery area. At that time, I was co-inventor on a new imaging method for fast tissue examination and I was getting my first entrepreneurial experience. When I met Etienne it became clear that he was the one to turn this research prototype into a performing medical device. The seed was planted for a great venture. Finance being always the key, it took several detour to mature our project, but 3 years ago we met the right investors to seriously deliver on our development plan.
In 2014 we spun-off from the EPFL, at this stage we were 4 people developing a first version to validate the proof of concept on animal tissues. Today we have our first CE product, and we are about to release the version upgraded for breast cancer surgery. We confirmed the ease of use and integration into surgery workflow with surgeons and the clinical studies showed that we are matching the quality of the gold-standard microscopy slide imaging for cancer detection. This is a major change to come in how intraoperative assessment is perceived by surgeons today, and we are excited to be leading that!
Link: SamanTree Medical…
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