How OCT Works

What is Optical Coherence Tomography (OCT)?

A high-resolution imaging technology

Optical Coherence Tomography (OCT) is a non-invasive, optical imaging technique that produces ultra-high-resolution images of subsurface tissue structures.

OCT is similar to ultrasound but uses light instead of sound. It is a powerful tool for visualizing suspicious tissue microstructures and features like blood vessels, ducts, and glands. While new to oncology, clinicians have relied on high-resolution OCT imaging for decades to inform their clinical decisions. OCT was developed at MIT in the 1990s and has been widely used in clinical settings ranging from ophthalmology (retina) and interventional cardiology (vessel plaques) to dermatology (skin lesions). Perimeter is the first to use this technology in the operating room for visualizing the margins of excised tissue.


Light interactions reveal different tissue characteristics

A single beam of light is directed at the tissue specimen and rapidly moved/translated across the desired scan area. Light that is reflected back from the tissue specimen down from a depth of 2 mm is transformed into an OCT image.


Very dense features will reflect the light completely:

  • Calcifications
  • Surgical clips, wires


Less dense features allow light to pass through them:

  • Adipose tissue
  • Cysts


Denser features cause the light to scatter:

  • Fibrous tissue


Each light beam captures a single depth profile of a specific area. This single image is called an axial A-scan. As the beam of light moves across the tissue in a line, it generates a long sequence of A-scans that can be compiled into a two-dimensional image known as a B-scan. A series of B-scans can then be stacked to form a three-dimensional image volume.

Optimized for Margin Visualization

OCT provides cross-sectional, microscopic images of tissues down to 2 mm depth, with 10x greater image resolution than
standard x-ray and ultrasound, and 100x greater resolution than MRI.

How OCT compares to other imaging technologies in resolution and penetration depth.

OCT optimal structures visualization capability.

Clinical Resources You Might Be Interested In

OCT gives you the power to see more

Traditional imaging technologies like X-ray do not have the resolution needed to visualize margins at the cellular level, and all residual disease cannot be detected in the cavity by sight or palpation. Surgeons need advanced technology support in the OR to optimize clinical decision making.

Patient-centered decision-making for cavity shaves

Research shows that Optical Coherence Tomography (OCT) technology has the potential to increase confidence that the tumor has been excised with sufficient margins or to indicate that taking additional tissue is advisable prior to closing.

Continue Exploring

Benefits to Surgeons

See It In Action

Ready to learn more about Perimeter?

Get Started