Paul Shyn

The complex battle against cancer can be summarized in two steps: diagnosis and treatment. Paul Shyn, MD, associate radiologist and director of Cross-Sectional Interventional Radiology at BWH, seeks to improve both.

Shyn is primarily interested in destroying tumor cells by using different thermal or electrical technologies through a process known as ablation. He is actively collaborating with colleagues from other departments to develop better technologies to accomplish this.

Enhanced Needle Prevents Bleeding Complications

A cancer diagnosis often begins with a biopsy—a closer examination of extracted tissue suspected to be malignant. A clinician will perform this procedure if previous tests on that area of the body suggest some tissue cells may be abnormal. However, this procedure can sometimes cause significant bleeding in patients with risk factors for bleeding or in patients with certain types of tumors that are more prone to bleed.

“When you stick a needle into an organ to perform a biopsy, a bleeding complication is always a possibility,” said Shyn. “If you then stick that needle into a tumor, cancer cells can travel back along the needle track and create a new site for the tumor.”

To prevent this, Shyn has been working on developing improved prototypes of a cautery device that can be inserted into the needle used during a biopsy of the liver, spleen or kidney, for example, to prevent these complications from occurring.

Initially funded by the Brigham Innovation Hub (iHub), Shyn’s needle biopsy project has produced promising results thus far. He and his colleagues have developed a successful prototype and continue to modify it to maximize its effectiveness while minimizing its cost.

When bleeding occurs during a biopsy, clinicians face two options: remove the needle from the body without preventative measures or use a type of gel foam as a plug before removing the needle. The problem, however, with these plugs is that they are sometimes ineffective and cumbersome to use—two qualities that Shyn is avoiding in the development of this new needle prototype.

“There is no cautery on the market that’s small enough to fit through all biopsy needles,” said Shyn. “No instrument has been optimized for this purpose. This makes our design is unique.”

The Fusion of Imaging Techniques

Shyn’s second major project is centered on improving the technique of tumor ablation. When using thermal techniques to eradicate a tumor, radiologists must be sure that the entire tumor has been destroyed. To ensure this is the case and to minimize risk of recurrence, there must be a margin (in the shape of a ring around the tumor) of healthy tissue that is also destroyed. This margin is what Shyn and his colleagues want to view more clearly.

Current methods of viewing the ablation zone include combining previous imaging data and imaging data post-ablation. This method of fusing old and new studies of the same type of imaging, such as Magnetic Resonance Imaging (MRI) or positron emission tomography (PET), is limited by a host of problems, including misalignment of the two images, differences in the patient’s body position and even differences in the shape of the organ in the two images. Shyn and his team are developing a strategy by which they use a combination of PET and computerized tomography (CT) to get a better view without having to align “before” and “after” images.

“The idea is that we can use PET/CT imaging to see the margin by acquiring a single image,” said Shyn. “We can do this during a single breath hold. There’s no misalignment, and this method takes into account the patient’s position and circumstances on that specific day, at that specific moment.”

Using radioactive tracers, the combined PET/CT method results in imaging data that show the ablation zone, the margin and the tumor as three separate components. This is possible because of the radiotracer discrepancies between the tumor, margin and ablation zone, due to the tumor’s hypermetabolic properties, meaning that the tumor absorbs and concentrates more radiotracer than surrounding tissue.  The result is that in a successful ablation, the PET image shows a target appearance: high tracer uptake in the ablated tumor, low tracer activity in the margin and high tracer activity in the surrounding normal tissue. The ability to see the low activity margin completely surrounding the ablated tumor ensures a successful ablation.

“We’re also taking advantage of the fact that we’re getting two scans in one,” said Shyn. “The CT scan shows the anatomical detail and interventional devices while the PET scan shows metabolic information of the tumor. Tumors tend to light up quite intensely on these scans.” These advantages are helping with precise targeting of tumors for biopsy or ablation.

The next steps for both of Shyn’s projects will require collaboration from many departments. Shyn is collaborating with the Hematopathology Service of the Division of Surgical Pathology, which is also interested in reducing bleeding risks during procedures, on the needle biopsy project. Through his connections with iHub, Shyn was able to meet an engineer who is now working on the development of future prototypes for that project. He also connected with those involved in the process of patent development, something he is looking forward to in the future for this project. The PET/CT project for assessing the tumor ablation margin is moving forward with new corporate funding.