Nanoparticles can reveal lung disease

Measuring the structures of the lungs is difficult. Not even chest x-rays can reliably capture changes in the alveoli, the lung’s smallest components. The new measurement method, AiDA – Airspace Dimension Assessment – can provide more answers about precisely those smallest tissue structures in the lung.

The method has been used on more than 800 participants. The method has also been compared with established techniques such as chest x-rays, pulmonary function tests and MRI scans with hyperpolarised gas.

Madeleine Petersson Sjögren, one of the researchers who studied and evaluated the technique, has now presented her results in a thesis on aerosol technology. She says:

“Our results show that the method can be used to identify pathological changes in the lung. The method is fast and provides results that, according to our research, match those of more advanced methods of measuring the structure of the lung.”

The number of particles that get stuck reflect the structure of the lung

The method is based on the knowledge that nanoparticles move in a particular way in air, and the fact that the tissue structure differs between healthy and sick lungs.

“By inhaling a low concentration of nanoparticles and measuring the number that get stuck, we can calculate distances inside the lung which is a measure of how large the cavities in the lungs are. That distance can reveal whether there are pathological changes or not,” says Madeleine Petersson Sjögren.

In a healthy lung, the alveoli are small, well-defined and have short distances between the tissue parts. As a result, there is a lot of surface area on which the particles can get stuck, which means that few particles are exhaled. In a diseased lung, the opposite is the case:

“If you have emphysema, the alveoli are broken down and you get larger cavities in the lung. That means there is less surface area on which the particles can get stuck, resulting in more particles being exhaled.”

In a healthy lung, the alveoli are small, well-defined and have short distances between the tissue parts. As a result, there is a lot of surface area on which the particles can get stuck. If you have emphysema, the alveoli are broken down and you get larger cavities in the lung. That means there is less surface area on which the particles can get stuck. Illustration: Johanna Rydeman/Pexels

The structure of the lung is changed when we contract lung diseases, but according to Madeleine Petersson Sjögren these changes can be difficult to identify using conventional methods such as x-rays and pulmonary function tests.

“Since today’s methods of lung diagnosis are often insufficiently sensitive to changes in the deepest parts of the lung where diseases such as emphysema take hold, the disease has often progressed by the time it is discovered, making it more difficult to restrict.”

A quick examination – and no radiation

As well as the method being able to reveal serious illness at an early stage, it is also quick to conduct and does not entail any significant discomfort for the patient.

“An examination takes around fifteen minutes and the number of particles the patient inhales is comparable to the concentration present in the air in our day-to-day environment,” says Madeleine Petersson Sjögren, whose research also compared the technique with other methods of measurement such as chest x-ray and MRI scans using hyperpolarised gas.

“The results from the various methods of measurement match – that suggests that AiDA could be a useable method for early diagnosis of pulmonary disease,” says Madeleine Petersson Sjögren.

Other advantages she can see are that the method does not expose the patient to radiation, as with chest x-rays, and that the technique could be made widely available. MRI technology is more advanced, but inaccessible and expensive – it is only present at a few sites around the world.

May be useful for other lung diseases

Globally, the third-largest cause of death is Chronic Obstructive Pulmonary Disease, COPD, with emphysema often part of the illness.

“If emphysema of the lung can be discovered at an early stage, the opportunities for restricting the progress of the disease are greater,” says Madeleine Petersson Sjögren.

She also hopes that other pulmonary diseases can be diagnosed using the method in the future:

“In the future we would like to investigate whether the method can be used to identify other pulmonary diseases, such as fibrosis and asthma, for example.”