Scientists from St Petersburg University have created a device that causes fluorescence of the parathyroid glands during surgery

The adoption of such technology will make it possible to increase the quality of endocrine operations and reduce the number of post-surgery complications with minimal costs.

Hundreds of thousands of people in the world suffer from thyroid disorders of varying severity. On average, about 150,000 operations on this organ are performed annually in the United States, and there are about 50,000–60,000 of them in Russia. The world leader in the number of thyroid operations has become the Pirogov Clinic of High Medical Technologies of St Petersburg University. In 2018, specialists from the Department of Endocrinology and Endocrine Surgery Department performed more than 5,500 surgical interventions.

One of the most common complications that can occur after thyroid operations (up to 30–67% of all operations) is hypoparathyroidism – the decreased function of the parathyroid glands. In 30% of cases, the complication is temporary, but in about 12% it becomes chronic.

There are currently no effective ways to prevent the development of hypoparathyroidism. Existing methods of dealing with these complications are based mainly on the experience of the surgeon and delicate surgical technique.

Viktor Makarin, head of the Outpatient Department, the Pirogov Clinic of High Medical Technologies of St Petersburg University, Candidate of Science (Medicine) 

The surgeon noted that the main cause of complications associated with the parathyroid glands is, as a rule, damage to their blood supply or their accidental removal. This leads to a decrease in the level of parathyroid hormone in the blood and the onset of specific symptoms: formication; numbness, up to convulsions; and respiratory failure.

That is why the possibility of reliable identification of the parathyroid glands is a pressing challenge of modern endocrine surgery, emphasised Viktor Makarin.

The methods that are used today in medicine to better identify the parathyroid glands give insufficient results or are very expensive. For example, there is a technology of intraoperative gamma scanning with Technetril. It makes it possible to get imaging data on the parathyroid glands in about 30% of cases. However, this technique uses expensive equipment and radioactive drugs, so it can hardly be promising, the researchers say. Other imaging techniques for the parathyroid glands are associated with the introduction of dyes or photosensitiser into the patient's body that can visually highlight organs by changing their colour or making them glow.

To cause fluorescence of tissues, two methods are used. Each of them is being studied and improved by scientists in the framework of the project. One of them is already known to science. This is the introduction of an agent into the patient's body that stimulates the production of protoporphyrin IX, which is an effective photosensitiser. For this, 5-Aminolevulinic acid is used. It initiates the active production of protoporphyrin in the parathyroid gland, while in the thyroid gland this process is much weaker.

Up to now, studies have been carried out with a visual assessment of the fluorescence intensity of the parathyroid glands after introduction of 5-aminolevulinic acid. It has had a number of limitations and in some cases has not given a true picture.

For the first time, the scientists and doctors from St Petersburg University have managed to objectify and quantify the intensity of the fluorescence of the parathyroid glands after the introduction of 5-aminolevulinic acid using a laser device.

The laser beam of the device determines the intensity of the fluorescence emitted in a certain range. Then, using the receiver, the information is encoded and displayed on a computer screen. The development of such a method will make it possible to identify the parathyroid gland with maximum accuracy. This will significantly increase the identification and preservation of the parathyroid glands during surgery.

‘One of the drawbacks of the created system is the use of 5-aminolevulinic acid. The price of one dose of the agent for the production of protoporphyrin IX is currently about 20,000 roubles. This potentially makes the fluorescence technique significantly more expensive for patients as well as for medical institutions,’ explained Viktor Makarin.

At present, the scientists and doctors from of St Petersburg University have switched to the second method of fluorescence of the parathyroid glands. They have carried out research into autoluminescence, when the luminescence from tissues is estimated without the use of expensive fluorescent agents. A laser system to identify autofluorescence of the parathyroid glands was first developed in Russia. It makes it possible to obtain spectral data of the luminescence intensity just during the operation without the introduction of additional dyes. The scientists from St Petersburg University are also exploring for the first time the possibility to predict possible post-surgery complications based on the obtained luminescence spectra of the operated glands. This will lay the foundation of a new direction in endocrine surgery – paramonitoring.

The undoubted advantage of the project is that the prospective studies are a reality. They are planned to be carried out in close cooperation between the Research Park and the Clinic of High Medical Technologies of St Petersburg University with the ability to fully test the methods under development in real operating conditions.

Alexey Kurochkin, a co-head of the project, Director of the Centre for Optical and Laser Materials Research of the St Petersburg University Research Park, Candidate of Physics and Mathematics

The device prototype is currently ready. In the near future it is planned to be tested in the operating room. One of the advantages of the device is its small size. It does not clutter up the space and does not stand in the doctors’ way during the operation.

Next year, the scientists are planning to complete the work on the project and present a finished and tested model of the device. The project team see as the main goal of their work the improvement of the quality of thyroid operations throughout the country. In the near future, they will prepare technical and methodological procedures for equipping leading multi-field hospitals and clinics in Russia with the innovative device.