Pulmonary scintigraphy is one of the non-invasive procedures and is a nuclear medical, imaging test method to assess the circulation and ventilation of the lungs. Even the smallest circulatory disorders can be visualized via a gamma camera, which makes them indispensable for the diagnosis of pulmonary embolism.
Pulmonary scintigraphy is used in addition to the diagnosis of pulmonary embolism in various lung diseases and malformations. It also has the advantage that it can also be used to calculate blood flow between the lungs to assess surgical risks and predict lung lung tissue removal.
A lung scintigraphy is composed of various techniques that can be combined with each other:
In ventilatory scintigraphy, a radioactive noble gas, usually 133Xenon, must be inhaled and exhaled by the patient. The body does not absorb noble gases. During inhalation and exhalation, the gamma camera records 3 images (three-phase scintigraphy): image 1 is taken by inhalation, image 2 by the distribution of the gas in the lungs and image 3 by the exhalation of the gas. The gas distribution indicates the ventilation in the respective area. With this technique, it should be determined whether the air flow is obstructed or the extensibility of the lung is limited. However, it is technically complex and the patient must breathe in and out at the right moment.
In inhalation scintigraphy, the smallest radiolabelled particles of a carrier are finely vaporized or aerosolized into the patient's breathing air. It is usually used before a perfusion scintigraphy because it can be compared to the ventilation and blood flow of the lungs. The doctor can thus also recognize the original symptoms and initiate the right therapy with these findings.
In perfusion scintigraphy, the patient is given intravenous injections of radiolabelled protein components that migrate via the veins into the lungs. Where the circulation is disturbed, less radioactive particles are visible. In the distribution of the radioactive particles, the posture of the patient during the injection of importance. In healthy people, lower-lying lung areas are imaged more strongly due to gravity, while in pulmonary hypertension (increased blood pressure in the lungs, all areas are imaged uniformly.
If there is a suspicion of a life-threatening embolism due to a blood clot, perfusion scintigraphy is usually the first choice and is combined with an X-ray thorax.
It can also detect right-left shunts in the pulmonary circulation, where blood is pumped into the body via a connection between the pulmonary and systemic circulation without supplying oxygen from the lungs. Normally, the radioactive particles remain in the lungs and are broken down again via the lungs. In a shunt, however, they migrate into the systemic circulation and are excreted through the kidneys with the urine. About the blood volume, which flows through the kidneys per minute, the computer can calculate the volume and extent of the shunt.
In the case of lung cancer, before and after the operation, the inhalation scintigraphy is combined with perfusion scintigraphy in order to be able to assess the function of the lung or the remaining lung portion before and after the operation and to be able to give a prognosis after the operation.
A lung scintigraphy with gallium citrate allows the assessment of cartilaginous scaffold diseases and inflammatory processes in the lungs and finds particular application in the study of a pneumoconiosis or tuberculosis. Also, pneumonia and pulmonary infarction can be detected faster by lung scintigraphy than with other examination methods.
Side effects are rather rare with a lung scintigraphy, at most there is the risk of a low radiation exposure by the radioactive drugs used, which is considerably lower than the normal radiation exposure in one year. There are no known interactions with other drugs. In intravenous injection, mild allergic reactions may sometimes occur to the protein components. In the case of existing protein allergy, it must be considered whether lung scintigraphy makes sense in this case. Patients who need to take blood thinners (eg marcumar) should reckon with a small rebleeding at the injection site.
Nuclear medical examinations such as pulmonary scintigraphy can also be carried out with restrictions in pregnancy, but here primarily a healthy development of the child counts. Possible side effects and risks should be carefully weighed and discussed with the pregnant woman. Possibly. the dose can be reduced. Nursing women should not breastfeed 48 hours after nuclear medicine examinations.
For pulmonary scintigraphy, no special preparation is necessary and patients should not appear sober. Patients suffering from asthma should take bronchodilator drugs before the examination. The costs are covered by the statutory health insurance.
As pulmonary scintigraphy is associated with few risks and side effects, it is a highly recommended method for the examination of the circulation and ventilation of the lungs and for the diagnosis of pulmonary embolism the best examination procedure. There are only slight limitations in the significance of chronic obstructive pulmonary disease (COPD).