Basic X-ray examinations
X-ray methods remain the cornerstone of respiratory disease diagnostics. They allow not only for the initial detection of a problem, but also for dynamic monitoring of the disease course.
Radiography is one of the most informative and widely used primary imaging modalities.
- To obtain a complete picture, the examination is performed in several projections: anteroposterior, lateral, and oblique.
- On the resulting images, the physician analyzes in detail the state of the pulmonary parenchyma, the structure of the pulmonary roots, and the pulmonary pattern, which represents the aggregate of shadows from vascular and interstitial structures.
- A variant of radiography is fluorography, a method of producing small-format images used as a screening tool for mass population surveys.
Fluoroscopy has a unique functional advantage: the ability to assess the state of organs in real time (dynamically).
- During the examination, the physician studies how the lungs function during respiratory movements.
- The excursion (nature and amplitude of movements) of the diaphragm is evaluated.
- The state of the pleural sinuses and the anatomical position of the esophagus are checked.
Modern technical modernization of fluoroscopy includes displaying the image on a television monitor and using video recording. This significantly reduces the radiation dose to the patient and neutralizes the disadvantages inherent in classical fluoroscopy.
Tomography and contrast methods
When the capabilities of routine X-rays are insufficient, tomographic examinations are used to clarify the localization and nature of the detected pathology.
Classical tomography and computed tomography (CT) allow for the visualization of pathological densities and cavities at various depths, as well as a detailed evaluation of the tracheobronchial tree.
Advantages of computed tomography:
- Detection of small-sized pathological formations that are not visible on standard images.
- Discovery of deeply situated pathological lesions.
- High tissue differentiation: the ability to clearly visualize structures that are very close in X-ray density to the surrounding tissues.
Angiopulmonography is a specialized contrast method. Its principle involves injecting iodine-containing contrast agents directly into the patient's vascular bed (or, in some modifications, into the bronchi). The main target structures for such an examination are the vessels of the pulmonary circulation and the arteries of the bronchial tree. The method provides a clear map of the pulmonary vascular network.
Radionuclide methods (Scintigraphy)
In addition to traditional X-rays, radionuclide methods are actively used in pulmonology, providing valuable functional information.
The essence of scintigraphy consists of introducing special radiopharmaceuticals (isotopes) into the bloodstream. Their subsequent distribution in the respiratory organs is recorded using specialized scanners or a gamma camera. Isotopes such as technetium ($^{99}\text{Tc}$), gallium ($^{67}\text{Ga}$), xenon ($^{133}\text{Xe}$), indium ($^{133}\text{In}$), and phosphorus ($^{32}\text{P}$) are used in diagnostics.
Each isotope serves a specific diagnostic task:
- Technetium is used to assess perfusion (the quality of blood supply to the lung tissue).
- Xenon is used to assess regional pulmonary ventilation.
- Gallium helps determine proliferative activity in the interstitial tissue and lymph nodes.
Clinical examples of radionuclide diagnostics usage:
- When pulmonary embolism (PE) is suspected, scintigraphy reveals specific perfusion defects in the affected lung area.
- In active sarcoidosis, scanning records pronounced accumulation of the gallium isotope in intrathoracic mediastinal lymph nodes.
Briefly: answers to topical questions
What X-ray syndromes are characteristic of lobar pneumonia at the height of the disease?
Lobar pneumonia in the hepatization stage is characterized by intense homogeneous opacification of the lung tissue.
Main radiological signs:
- homogeneous opacification of a part or the entire segment of the lung, sometimes an entire lobe;
- in lobar involvement, the opacification may be sharply demarcated by the interlobar fissure;
- the air bronchogram sign is frequently observed;
- normal aeration is preserved in intact parts of the lung, and the pulmonary pattern is not enhanced in them.
What are the indications for magnetic resonance imaging (MRI) in pulmonology?
MRI in pulmonology is used according to the following evidence-based indications and tasks:
- for airway pathology: to differentiate bronchial wall thickening from mucus plugging, visually assess bronchiolar anomalies, and identify areas of air trapping;
- when pulmonary thromboembolism is suspected: chest MRI can be performed alongside spiral CT with CT pulmonary angiography;
- in systemic lupus erythematosus with clinical signs of pulmonary involvement: CT/MRI are used as auxiliary methods for clarifying the nature of the lesion and differential diagnosis;
- after resection of neuroendocrine tumors of the thymus and lungs: CT/MRI is performed after 3 months, followed by CT/MRI based on clinical indications.
What is the typical radiological picture of exudative pleurisy?
The typical radiological picture of exudative pleurisy manifests as intense homogeneous opacification in the lower, predominantly posterobasal regions of the lung field.
Key signs:
- the posterior costophrenic sinus is completely opacified;
- the contour of the diaphragmatic dome on the affected side is not differentiated and merges with the shadow;
- the upper boundary of the opacification may be indistinct or have an upward-sloping direction.
In encapsulated effusion, fluid accumulations on radiographs in anteroposterior and lateral projections can mimic a lung tumor. In pyopneumothorax, the fluid level becomes horizontal.
How to remember isotopes for scintigraphy: "Technetium for Blood flow (perfusion), Xenon for Oxygen (ventilation), Gallium for Granulomas (proliferation in sarcoidosis)."
Class and exam questions
The main advantage of fluoroscopy is the ability to assess organs dynamically (in real time). The physician can observe lung function during respiration and diaphragmatic excursion.
The main advantage of fluoroscopy is the ability to assess organs dynamically (in real time). The physician can observe lung function during respiration and diaphragmatic excursion.
Why is CT ordered if a standard X-ray has already been done?
CT has high tissue differentiation and allows for the detection of small formations or deeply situated lesions that are obscured by other tissues on a classical X-ray image.
How can diagnostic imaging help before bacterial culture results are ready?
The radiological picture often has specific features that allow the physician to clarify the etiology (cause) of the disease and prescribe treatment even before the laboratory provides culture or cytology results.
Which method detects pulmonary embolism (PE)?
To confirm PE, technetium scintigraphy is frequently used, allowing clear visualization of perfusion defects (areas of the lung deprived of blood supply).
What else to study on this topic
- Detailed analysis of pulmonary pattern structures (vascular and interstitial components)
- X-ray anatomy of the lung roots in health and disease
- Assessment of the state of the pleural sinuses in various projections
- Use of indium and phosphorus isotopes in pulmonology
- Technique of contrast bronchography
Master the entire topic in the "Propaedeutics" course
This is a summary. The course covers everything tested in classes and exams.
- Complete guide on "Diagnostic Imaging in Pulmonology" and 3,152 more pages on the subject
- Assignments and quizzes after every topic — just like in a colloquium
- AI tutor answers questions on the topic anytime
- 113 video lessons on the subject
Other topics in the "Respiratory System" section
Prepared by WhiteCoat Pro faculty in accordance with the medical school curriculum. For educational purposes only.