Fluorescence Lifetime Imaging (S. Janssen/H. de Rooster)

Dogs and cats that are diagnosed with cancer at an early stage are often advised surgery. This remains one of the best possible treatments for cancer patients in whom no metastases have been detected. During surgery, surgeons aim to remove the entire tumor mass to reduce the risk of recurrence. However, since surgeons rely on their own vision and touch during surgical procedures, and our vision and touch does not allow us to detect all small cancer cells, new techniques are being explored to assist surgeons.

One promising development is the use of contrast agents that act as little guides and make cancer cells visible that would otherwise be undetectable to the naked eye. These contrast agents help us achieve this by emitting light, which can then be detected using specialized camera systems. This technique is known as Fluorescence-Guided Surgery.

Despite these advances, contrast agents can still accumulate in areas other than the cancerous tissue itself. Therefore, it remains difficult to determine where the cancerous tissue stops as surgeons can further only base themselves on their vision and touch. In this study, we aim to use a novel imaging technique during surgery to determine whether it can help surgeons better distinguish between contrast agent present in cancer cells and contrast agent present in other tissues, such as inflamed tissue. This is achieved by focusing on the cellular environment of the contrast agent. This technique is called macroscopic Fluorescence Lifetime (FLT) imaging.

WHAT IS FLUORESCENCE LIFETIME IMAGING?

To understand FLT Imaging, it is important to first define the term fluorescence. Fluorescence is the physical property of a molecule or contrast agent to absorb light of a specific wavelength and then emit light of another wavelength.

With traditional Fluorescence Imaging, we measure the amount of light emitted by the contrast agent. In contrast, Fluorescence Lifetime Imaging does not focus on the amount of light emitted but rather on the time it takes for the molecule to emit this light. This time is extremely short (less than one nanosecond) but depends on the environment in which the molecule or contrast agent is located. Because the FLT of a contrast agent is dependent on the environment in which it is in, this allows us to differentiate the presence of the contrast agent in cancer tissue from its accumulation  in healthy tissue.

THE OBJECTIVES OF THIS STUDY

Thanks to promising results from our preclinical studies, we can now proceed with a clinical study in dogs and cats. Any patient scheduled for surgical tumor removal, with an additional margin of healthy tissue removed according to standard surgical protocols, may participate in this study.

The goal of this study is to confirm whether the use of this imaging technique during surgery provides adds value in completely removing cancer compared to current Fluorescence Imaging techniques. We will use the contrast agent Indocyanine Green (ICG), which has already been approved for various applications in both veterinary and human medicine by the European Medicines Agency.

PARTICIPATION IN THE PROJECT

By participating in this study, your dog or cat with cancer—who has already been scheduled for surgery or will be scheduled for surgery—will gain access to a new imaging technique that increases the chances of complete cancer removal. Additionally, your pet will be among the first to benefit from a promising application that will only become available for humans at a later stage.

For this study, your pet must arrive at the faculty the day before surgery, preferably on an empty stomach in case sedation is necessary.  Since the contrast agent requires 24 hours to accumulate in the tumor, it will be administered the day before the procedure. After administration, you and your pet can return home or your pet can remain hospitalized.

The next day, you will check in at the surgical department for the tumor removal. During and after the surgery, several images will be taken of the tumor and surrounding tissue.

A TOKEN OF APPRECIATION

As a token of appreciation for participation in this study, the pathological evaluation of the cancerous mass will be covered by the research project. The pathology results will be shared with you and your veterinarian as soon as they become available. There are no additional costs compared to other patients undergoing surgery without participating in the clinical study.

Your participation will provide crucial information on the use of Fluorescence Lifetime Imaging for intraoperative guidance during cancer surgery.

ANY QUESTIONS? 😊

For more information, please contact the main investigator, veterinarian Simone Janssen (simone.janssen@ugent.be), or Prof. Hilde de Rooster (hilde.derooster@UGent.be). For referrals, please email chirurgie.khd@ugent.be