Lung Imaging – Keeping the Respiratory System Healthy

Many people have damaged or suboptimally functioning lungs. One reason is age because the capacity of our respiratory system gradually decreases over time, while unhealthy and modern lifestyle choices play another role in this setting. An accurate diagnosis and subsequent treatment are vital to protect this life-sustaining organ. Modern imaging solutions help physicians and patients understand what happens inside the lungs.

Obstructive or restrictive lung diseases, pulmonary edema, atelectasis, pneumothorax, inflammation or tumors: there are many diseases that can affect our respiratory system. Modern medicine offers a variety of imaging types and modalities that allow physicians to look inside the air passages and lungs to detect structural or functional changes. Even after a diagnosis has been made, imaging remains an important tool during treatment. A chest (thorax) x-ray (radiograph) is one of the most commonly performed diagnostic lung examination.

Another diagnostic procedure that uses radiation is lung scintigraphy. To help diagnose or rule out a blood clot in the lungs (or pulmonary embolism), radioactive material, so-called radiopharmacons, radionuclides or tracers are being used. This makes the metabolic process inside the body visible because the tracer disintegrates and releases gamma rays. Nowadays, this procedure has largely been replaced by computed tomography (CT). This special x-ray procedure provides more detailed information. The split-image procedure creates two-dimensional cross-sectional images or slices of organs and tissues, indicating the different densities in shades of gray. The computer then uses this to generate a 3D model and thus creates a spatial representation of the organ. Lung cancer is one of the most common and often deadliest cancers. To be able to make a diagnosis as early as possible, the U.S. has used a new method for some time. Some doctors in other countries - including Germany – prefer to use a screening program using low-dose computed tomography. Professor Hans-Ulrich Kauczor, Medical Director, Department of Diagnostic and Interventional Radiology at the Heidelberg University Hospital is among these physicians. In an interview with MEDICA.de he explains the advantages of this early screening test: "A low-dose CT scan should deliver less than two millisieverts of radiation exposure and ought to be done without a contrast medium. A conventional CT scan exposes the patient to approximately five millisieverts. It is used to investigate suspected lung cancer and requires the administration of a contrast medium."

Not all common medical imaging types and modalities are equally suited for a look inside the lungs. Magnetic resonance imaging (MRI) is a more time-consuming method and more expensive than a CT scan and hasn’t become popular as a diagnostic test for lung disorder until much later. It has some clear advantages: no x-rays and better image quality - always an objective of medical research. The patient is placed inside a scanner tube in a magnetic field in which the body’s hydrogen atoms are excited by radio wave impulse to produce a weak signal. It is recorded by the device antennas and used to compute the images. Abnormalities appear in lighter color against the dark low water content lungs.

This is not a routine method, but it is especially well-suited to examine pregnant women and children. This is a standard procedure at the Radiologie Darmstadt, a clinical facility that routinely offers this method to its patients.

Diagnostic ultrasound, also known as sonography or echography, is a similar technique that doesn’t expose patients to radiation. The versatility of this procedure is yet another advantage. Although not all lung diseases can be visualized by ultrasound since the air in the organ can interfere with the result, the fluid-filled space between the lungs and the chest cavity can still be very accurately examined. Approximately 60 percent of the relevant pleural surface is visible, which can show tumors or disease-related changes.

All in all, a look inside the lungs is an elaborate, albeit necessary process. Time is always an important factor in this setting as well. To identify the boundaries of the respiratory system from surrounding other organs, tissues, and structures requires between 200 and 500 computed tomographic images. The problem is that they require subsequent manual markings, which can take up to six hours. In an interview with MEDICA.de, Dr. Anja Braune and Professor Marcelo Gama of the University Hospital Carl Gustav Carus Dresden explain how an optimized computer program is now able to do this in only a few seconds and describe what students of the Institute of Medical Informatics at the Brandenburg University of Technology Cottbus-Senftenberg contributed to this process.

Due to their characteristics, the lungs are not particularly well-suited for imaging modalities. The circulating air and constant movement of the chest and rib cage don’t make things easy for medicine. Nevertheless, modern, high-quality and technologically advanced techniques make it possible to carefully examine this vital organ. The current state of medicine indicates that the field of pneumology is also on the right track to prevent unnecessary harmful steps and minimize risks to patients. No doubt, the limits of what’s feasible have not been reached yet in this area.