Images courtesy of Lennard A Nadalo, MD
Images courtesy of Lennard A Nadalo, MD
Author
Lennard A Nadalo, MD
Clinical Professor, Department of Radiology
University of Texas Southwestern Medical School
Consulting Staff
Envision Imaging of Allen and Radiological Consultants Association
Dallas, Texas
Disclosure: Lennard A Nadalo, MD, has disclosed no relevant financial relationships.
Editor
Lars Grimm, MD, MHS
House Staff
Department of Internal Medicine
Duke University Medical Center
Durham, North Carolina
Disclosure: Lars Grimm, MD, MHS, has disclosed no relevant financial relationships.
Reviewer
Jose Varghese, MD
Associate Professor of Radiology
Boston University School of Medicine
Boston, Massachusetts
Disclosure: Jose Varghese, MD, has disclosed no relevant financial relationships.
These films show a normal posteroanterior (PA) and lateral chest x-ray. The chest x-ray is one of the most common imaging tests performed in clinical practice, typically for cough, shortness of breath, chest pain, chest wall trauma, and assessment for occult disease. Standard x-rays are performed with the patient standing facing an x-ray film or digital cassette, 6 feet away from an x-ray tube. The tube fires x-rays through the patient from back to front, ie, posterior to anterior (PA).This reduces the magnification of the heart and other anterior mediastinal structures that are situated close to the film in the PA position. Other factors to consider for a good quality chest x-ray are centering (the trachea should be equidistant between the clavicular heads), penetration (the spine should be just transparent through the cardiac density), and inspiratory effort (at full inspiratory effort, the anterior end of the right 6th rib should point mid-way along the right hemidiaphragm).
In the intensive care unit and emergency department, chest x-rays are often taken with the film placed behind the patient and the x-ray tube in front of the patient because the patient is lying down (supine), or barely sitting up (semi-erect). In these situations, the x-rays pass through the patient from front to back, ie, anterior to posterior (AP). Because the heart is an anterior structure, x-rays diverge as they pass through the remainder of the chest cavity to hit the film that is behind the patient, leading to artificial magnification of the heart. This AP semi-upright chest x-ray demonstrates mild cardiomegaly in a 93-year-old patient that has been magnified secondary to the AP projection.
Whatever technique is used to obtain the study, interpretation of a chest x-ray requires a careful, systematic examination of the entire film. It is a good practice to first review the chest x-ray without any history, and then look at the x-ray again when you know something about the patient. Many mnemonics have been described to help remember a good search pattern, but a common one is ABCDEF. The A stands for airways, B for bones, C for cardiomediastinal silhouette, D for diaphragm, E for expanded lungs/everything else, and F for foreign objects. The airway, or trachea, should be midline without any deviation or stenosis after taking into account any rotational variations. This AP supine portable film demonstrates an obvious opacification of the entire left chest (2 double-headed arrows). This may be due to either filling (such as due to effusion) or volume loss (such as due to lung collapse). The key finding in this case is that the trachea is deviated toward the left (red arrow), indicating loss of volume in the left chest. If the left chest was filled with fluid, the heart and the trachea would most likely remain in the midline or become displaced toward the right.
Bone fractures (aBcdef) can be easily overlooked on a chest radiograph. With digital x-rays, manually altering the window and level settings can be helpful to make fractures more obvious. It is important to closely examine the ribs, clavicles, and visualized bones of the shoulders. This AP supine chest x-ray was obtained during the initial resuscitation of a multiple trauma victim. There is generalized decreased density in the left chest suggestive for a pneumothorax, although the pleural margin of the lung is not seen. There are multiple left rib fractures, which can be identified by the step-off pattern to the normally smooth rib margins (black arrows). Large metal artifacts (blue arrows) are parts of the trauma transportation system. They are not in the patient.
The cardiomediastinal silhouette (abCdef) must be evaluated for size, contour, and orientation. Remember that the heart will appear larger on an AP vs a PA chest radiograph. This PA upright chest x-ray is from a young woman who presented with chief complaints of severe bone pain and fever. The size of the pericardial outline (double-headed white arrow) is markedly increased. The cardiac-to-chest width ratio (or cardiothoracic ratio) should be less than 55%. This ratio was calculated to be greater than 60% in this patient. The central pulmonary vessels are dilated (black arrows). An infusion port catheter is noted overlying the right chest (yellow arrow). This patient has sickle cell anemia and was in sickle cell "crisis" when this examination was performed. An echocardiogram excluded a pericardial effusion. The cardiomegaly in this case was caused by severe chronic anemia.
This AP semi-upright chest x-ray is from a middle-aged woman who presented with mid upper abdominal to lower chest pain. Multiple "masses" were identified on the radiograph. The heart is enlarged but there is no evidence of acute heart failure. A mass (white arrow) is noted overlying the cardiac silhouette that was proven to be a large hiatus hernia. The right paratracheal "mass" (black arrow) was proven to be torturous right carotid and subclavian vessels. The patient’s chest pain was later proven to be caused by coronary artery disease.
Careful evaluation of the diaphragm (abcDef) should reveal clear margins and sharp costophrenic angles bilaterally. When the diaphragmatic border is obscured, it indicates an adjacent disease process. This PA film is taken from a child with chest pain, cough, and fever. It shows increased density of the left lower lung (consolidation) with a loss of the outline of the left hemidiaphragm (black arrows). There is increased density along the lateral chest with loss of costophrenic angle visualization (blue arrow). This pattern is consistent with a left lower lobe pneumonia.
The diaphragms should normally have a smooth rounded contour. This PA and lateral upright chest x-ray was obtained as a part of the evaluation of child who was experiencing wheezing, chest pain, and acute shortness of breath. The PA radiograph on the left demonstrates depression and flattening of the diaphragms (yellow arrows). On the lateral radiograph there is an increase in the anterior-to-posterior chest diameter (double-headed black arrow). These findings are consistent with air-trapping in a case of acute asthma.
Many radiologists reserve review of the expanded lungs until the end of the survey (abcdEf). The lungs should be well aerated without focal or diffuse areas of opacification. In this AP supine portable chest x-ray there is a sharply defined margin of the right lower lobe density (black arrows) with loss of the outline of the right hemidiaphragm (white double-headed arrow) due to lower lobe atelectasis. An endotracheal tube tip is at the level of the clavicular heads (yellow arrow) and a nasogastric tube is coiled in the stomach below the left hemidiaphragm (red arrow). Sudden onset of lower lobe atelectasis is often associated with trauma, surgery, and conditions that reduce the level of consciousness of the patient.
Bilateral, fluffy-appearing infiltrates are the hallmark of significant pulmonary edema. This AP supine chest x-ray from an afebrile patient in severe respiratory distress demonstrates a gray, almost homogeneous, density of the lower lungs (black arrow), which indicates the accumulation of fluid in the alveolar spaces. Note the normal size of the heart. This was a case of noncardiogenic pulmonary edema. Atelectasis is seen in the left lower lobe (white arrow).
This PA upright chest x-ray was obtained to evaluate a young patient with night sweats and weight loss. There was no history of smoking. The examination demonstrates left upper lobe consolidation (yellow arrows) with a thick walled cavity containing an air-fluid level (black arrow). The recognition of an air-fluid level is much more likely when using an upright technique. Thick-walled cystic masses in the chest may represent lung tumors with central necrosis but, on a global scale, tuberculosis remains the most common cause of lung cavitation.
Foreign bodies (abcdeF) -- namely support hardware -- can greatly complicate a chest radiograph, but each item must be individually identified to ensure proper positioning. This AP supine chest x-ray was taken of a patient with multiple sites of trauma. Two right chest tubes and 1 left chest tubes are present (white arrows). The tip of the endotracheal tube (yellow arrow) is noted to be in line with the air in the trachea and above the carina. The ideal position is between the clavicular heads and the carina. The nasogastric tube is seen overlying the stomach (black arrow). The ECG wires and leads crossing the chest represent visual distractions that can lead to diagnostic errors. All wires and tubes that are outside the patient should be carefully repositioned to the side of the patient before taking the x-ray. In some cases, repeat radiographs are required to confirm line or tube positioning.
Portable chest radiographs are notorious for poor patient positioning, often with the patient significantly rotated to one side. It is important to rely on landmarks to ensure appropriate tube positioning. This AP supine portable chest x-ray was obtained during cardiopulmonary resuscitation of a woman who had been intubated on an emergency basis before transfer to the emergency department. The tip of the endotracheal tube is to the far right (red arrow) from the actual midline position of the trachea (broken blue arrow). The trachea (appearing as a lucent column of air) may be shifted from midline secondary to patient positioning (rotation) or disease process. The stomach is seen distended with air. This is an example of esophageal endotracheal tube placement. Although the endotracheal tube was repositioned following this examination, the patient died after an unsuccessful cardiopulmonary resuscitation.
Central lines are commonly placed in critically ill patients. Chest radiographs are used to ensure proper positioning and to rule out complications during placement. The ideal location for the tip of a central line is at the cavoatrial junction, which is where the superior vena cava meets the right atrium. This allows for the infusion of large volumes of fluids or medications. Lines that are placed without the aid of fluoroscopy must have placement confirmed before they can be used. This AP chest radiograph shows a left-sided central line that has crossed midline and is likely within the right subclavian vein (arrows). An endotracheal tube is also noted.
The exact position of central lines may be confusing when there are multiple overlapping lines. This AP portable chest x-ray demonstrates a right internal jugular venous line and a right subclavian venous line. Following the course of each catheter from insertion to the tip shows the tip of the subclavian line in the lower superior vena cava (white arrows) and the tip of the internal jugular line in the right atrium (black arrows). There is a theoretical risk of arrythmogenic activity if the line is within the right atrium so it should be withdrawn.
Serious complications from central line placement are fortunately uncommon. This AP supine portable chest x-ray was obtained to evaluate chest pain and shortness of breath after a left subclavian line placement. A large left pneumothorax has occurred (double-headed yellow arrow). There is clear visualization of the left lung margin (black arrows). The distal tip of the venous line is noted in the superior vena cava (red arrow). Because of the proximity of the left lung apex to the left subclavian vein, pneumothorax is a recognized risk for central line placement. The patient also has an endotracheal tube. The tip (white arrow) is noted to be above the carina and below the position of the clavicles.
A pacemaker is one of the common devices encountered on a chest x-ray. The usual location for a pacemaker is the anterior left upper chest wall (black arrow). Pacemakers may have either 1 or 2 leads. The wires connecting the pacemaker to the intracardiac electrodes must be intact (yellow arrow). The typical position of the cardiac electrodes is in the right ventricle (red arrow) for a single lead, and also in the right atrium for a dual-lead pacemaker. It is important to compare the electrode position to that in previous studies because an electrode may become dislodged.
Images courtesy of Lennard A Nadalo, MD
Author
Lennard A Nadalo, MD
Clinical Professor, Department of Radiology
University of Texas Southwestern Medical School
Consulting Staff
Envision Imaging of Allen and Radiological Consultants Association
Dallas, Texas
Disclosure: Lennard A Nadalo, MD, has disclosed no relevant financial relationships.
Editor
Lars Grimm, MD, MHS
House Staff
Department of Internal Medicine
Duke University Medical Center
Durham, North Carolina
Disclosure: Lars Grimm, MD, MHS, has disclosed no relevant financial relationships.
Reviewer
Jose Varghese, MD
Associate Professor of Radiology
Boston University School of Medicine
Boston, Massachusetts
Disclosure: Jose Varghese, MD, has disclosed no relevant financial relationships.
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