Impact of Optical Biopsy on Medical Imaging

Optical biopsy uses an imaging technique called optical coherence tomography (OCT) to produce subsurface, cross-sectional images of an object. Frost & Sullivan has analyzed the optical biopsy market, and has published reports capturing the innovations in this space.

The term biopsy has Latin origins, as most medical terms do. Biopsies are crucial confirmatory tests that involve excision of tissue or other biological samples (Bios meaning “life”) for microscopic examination (Opsis meaning “to see”). While this has been in practice for centuries, it has gained prominence in the last few decades, and is now central to cancer diagnoses. In fact, the test has become so common that the reportage about its prevalence in medical diagnoses is extremely unstructured. An article published in the Journal of the American Medical Association in 2016 estimated that more than 1.6 million breast biopsy tests are ordered every year in the United States. Other articles present estimates for other tests (e.g., 1.3 million prostate biopsies and 2.3 million skin biopsies). What is clear, however, is that tens of millions of pieces of tissue (every procedure excises a few tissue samples) are obtained every year for the purpose of better inspection.

What is often left unsaid is that not all of these samples test positive for cancer. While this is good news for patients, it also means that if there was a better way to study tissue in situ, these procedures could be avoided. What’s more, the time, cost and effort, the pain and discomfort, and the emotional trauma of the biopsy prescription and the wait for results can all be avoided. With optical biopsy, this is possible. Optical biopsy uses light to create cross-sectional images of the tissue sample without the need to excise it. Optical biopsy, fittingly, uses light to “see life.”

Optical biopsy uses an imaging technique called optical coherence tomography (OCT) to produce subsurface, cross-sectional images of an object. OCT is highlighted as a special imaging modality because other approaches that use light capture only surface images (consider the photos we take on our mobile phones). Digital cameras and medical imaging modalities such as endoscopy use visible light whose wavelength is between 400 and 700 nanometers. However, as the wavelength of light increases (between 750 and 1,400 nanometers), so does its ability to penetrate samples. OCT uses near-infrared light that penetrates the surface, creating cross-sectional scans within a light-scattering medium such as biological tissue. This technique is similar in principle to how ultrasound imaging works.

Also similar to ultrasound imaging, OCT is non-ionizing radiation and therefore safe for patients; indeed, OCT does not even require the physical contact that ultrasound needs. The procedure has no need for dyes or contrast agents, or special patient preparation. While the imaging output is two-dimensional and black-and-white, digital image processing can stitch the slices into a 3-D color output.

Frost & Sullivan has analyzed the optical biopsy market, and has published reports capturing the innovations in this space. Some of the notable companies and their OCT-based products are presented here.

NinePoint Medical, Inc. (Bedford, Mass.)

NinePoint Medical is among the few companies to develop OCT-based imaging tools for gastrointestinal imaging. Its flagship product, NVision VLE (short for volumetric laser endomicroscopy), employs an advanced OCT technology that not only enables rapid image acquisition, but also high-resolution images—two attributes that usually do not go hand-in-hand. NVision’s endoscopic probe consists of a laser scanner ensconced in a balloon catheter. The scanner swivels within the balloon as the probe itself moves along the esophagus, collecting thousands of cross-sectional images. To put things in perspective, NVision VLE’s OCT probe can scan an area that is 6 cm long and 2 cm in diameter, and image up to a depth of 3 mm, in 90 seconds. This represents a field of vision of nearly 10,000 mm2, as opposed to the pinpoint field of vision offered by other endomicroscope systems, and an image resolution of 10 microns.

Mauna Kea Technologies (Paris, France)

Mauna Kea is a pioneer in probe-based confocal laser endomicroscopy (pCLE), a procedure that provides microscopic imaging through an endoscopy probe. Its Cellvizio platform builds pCLE capabilities into conventional endoscopy probes so that clinicians have three types of possible “views”: a conventional white light endoscopy view of the target’s external physiology, microscopic imaging for tissue-level information, and subsurface imaging for cellular-level diagnosis—all this in real time and at the point of care. Its pCLE probes are trademarked as Miniprobes and are available for applications as diverse as gastroenterology, colorectal imaging, pancreatic cancer diagnosis, urology, and pulmonary imaging.

The Cellvizio platform has also made its foray into image guidance and navigation during surgical procedures. The company’s latest product, CelioFlex ultra-high definition confocal probes, has received the U.S. Food and Drug Administration 510(k) clearance for use in robot-assisted surgical procedures. Earlier this month, the product also received the CE mark for marketing in Europe. 

Compact Imaging, Inc. (Mountain View, Calif.)

Compact Imaging is an early-stage technology company that is developing wearable and smart imaging devices based on its proprietary imaging platform for medical and non-medical applications. Its patented Multiple Reference OCT (MRO) technology is a miniaturized OCT module that can be fitted onto mobile phones, wearable devices and even eyeglasses to impart subsurface scanning capabilities. Compact Imaging is aiming to build MRO into systems for applications such as ophthalmic imaging (diagnosing age-related macular degeneration and diabetic retinopathy), optometric testing, and non-invasive blood glucose monitoring. The company is also interested in exploring applications beyond health care: integrating the MRO into mobile phones and finger scanners for improved biometrics and personal identification. The MRO technology’s ability to penetrate the skin’s surface means that instead of merely scanning a fingerprint (which can be counterfeited) a person’s subdermal structures such as tissue form and sweat glands can be used for personal identification.

The Road Ahead

Optical biopsy is a useful tool, and its importance has been recognized by the clinical community. The number of markets that it caters to has been steadily increasing, to now include advanced applications including surgical planning and neurology. However, the true potential of OCT is that its impact is not confined to medical diagnoses. OCT finds applications in non-destructive testing, quality control of pharmaceutical drugs, and homeland security. Interestingly, these areas are the mainstays of industrial radiology. OCT could well be a safer, better and cheaper alternative.

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