Chest Imaging

Chest x-rays are routinely taken from the back to front. Usually a view from the side is also taken. Sometimes chest x-rays need to be taken with the person in a different position so that doctors can get a view of a specific area of the lungs or because the person cannot be placed in the usual position.

Chest x-rays provide a good outline of the heart and major blood vessels and usually can reveal a serious disorder in the lungs, the adjacent spaces, or the chest wall, including the ribs. For example, chest x-rays can show most pneumonias Overview of Pneumonia Pneumonia is an infection of the small air sacs of the lungs (alveoli) and the tissues around them. Pneumonia is one of the most common causes of death worldwide. Often, pneumonia is the final... read more , lung tumors Overview of Lung Tumors Lung tumors can be Noncancerous Cancerous All lung tumors require medical evaluation because even noncancerous tumors can cause problems if they grow and block breathing. The treatment of lung... read more , chronic obstructive pulmonary disease Chronic Obstructive Pulmonary Disease (COPD) (COPD), a collapsed lung Atelectasis Atelectasis is a condition in which all or part of a lung becomes airless and collapses. Blockage of the bronchial tubes is a common cause of atelectasis. Shortness of breath can develop if... read more (atelectasis), and air (pneumothorax Pneumothorax A pneumothorax is partial or complete collapse of the lung due to the presence of air between the two layers of pleura (thin, transparent, two-layered membrane that covers the lungs and also... read more ) or fluid (pleural effusion Pleural Effusion Pleural effusion is the abnormal accumulation of fluid in the pleural space (the area between the two layers of the thin membrane that covers the lungs). Fluid can accumulate in the pleural... read more ) in the pleural space (the space between the two layers of pleura covering the lung and inner chest wall).

Although chest x-rays seldom give enough information to determine the exact cause of the abnormality, they can help a doctor determine whether and which other tests are needed to make a diagnosis.

Computed tomography Computed Tomography (CT) Computed tomography (CT) is a type of medical imaging that combines a series of x-rays to create cross-sectional, detailed images of internal structures. In computed tomography (CT), which used... read more (CT) of the chest is a type of x-ray procedure that provides more detail than a plain x-ray. With CT, a series of x-rays is analyzed by a computer, which then provides several views in different planes, such as longitudinal and cross-sectional views. During CT, a substance that can be seen on x-rays (called a radiopaque contrast agent) may be injected into the bloodstream or given by mouth to help highlight certain abnormalities in the chest.

High-resolution CT and helical (spiral) CT are more specialized CT procedures. High-resolution CT may reveal more detail about lung disorders. Helical CT can provide 3-dimensional images.

Generally, CT scans are done after a person takes a deep breath (inhales). Sometimes, CT images are obtained after people inhale and then after they exhale to better look at small airways.

CT angiography CT angiography Computed tomography (CT) is a type of medical imaging that combines a series of x-rays to create cross-sectional, detailed images of internal structures. In computed tomography (CT), which used... read more uses a radiopaque contrast agent injected into an arm vein to produce images of blood vessels, including the artery that carries blood from the heart to the lungs (pulmonary artery).

CT angiography is usually done instead of nuclear lung scanning to diagnose blood clots in the pulmonary artery (pulmonary embolism Pulmonary Embolism (PE) Pulmonary embolism is the blocking of an artery of the lung (pulmonary artery) by a collection of solid material brought through the bloodstream (embolus)—usually a blood clot (thrombus) or... read more ). However, CT angiography may not be possible if a person has kidney disease, which can be worsened by the contrast agents, or allergies to the contrast agents Allergic-type contrast reactions Radiographic contrast agents are substances used to distinguish between internal structures in medical imaging, such as various types of x-rays and magnetic resonance imaging (MRI). During imaging... read more used.

Magnetic resonance imaging Magnetic Resonance Imaging (MRI) Magnetic resonance imaging (MRI) is a type of medical imaging that uses a strong magnetic field and very high frequency radio waves to produce highly detailed images. During an MRI, a computer... read more (MRI) of the chest produces highly detailed pictures that are especially useful when a doctor suspects blood vessel abnormalities in the chest, such as an aortic aneurysm Overview of Aortic Aneurysms and Aortic Dissection The aorta, which is about 1 inch (2.5 centimeters) in diameter, is the largest artery of the body. It receives oxygen-rich blood from the left ventricle of the heart and distributes it to all... read more .

MRI takes longer to do and is more expensive than computed tomography Computed Tomography (CT) of the Chest Chest imaging studies include X-rays Computed tomography (CT) CT angiography Magnetic resonance imaging (MRI) read more (CT). The resolution of MRI is lower than CT for diagnosing abnormalities in the lungs, and therefore MRI is not often used for chest imaging. Unlike CT, MRI does not use radiation.

Ultrasonography Ultrasonography Ultrasonography is a type of medical imaging that uses high-frequency sound (ultrasound) waves to produce images of internal organs and other tissues. During an ultrasound, a device called a... read more creates a picture from the reflection of sound waves in the body. Ultrasonography is often used to detect fluid in the pleural space (the space between the two layers of pleura covering the lung and inner chest wall). Ultrasonography can also be used for guidance when using a needle to remove the fluid.

Bedside ultrasonography is sometimes done to diagnose pneumothorax Pneumothorax A pneumothorax is partial or complete collapse of the lung due to the presence of air between the two layers of pleura (thin, transparent, two-layered membrane that covers the lungs and also... read more .

Endobronchial ultrasonography (EBUS) can be used together with bronchoscopy Bronchoscopy Bronchoscopy is a direct visual examination of the voice box (larynx) and airways through a viewing tube (a bronchoscope). A bronchoscope, a thin viewing tube with a light, has a camera at the... read more to help guide doctors when they need to obtain a sample of lung tissue to look for cancer (needle biopsy Needle Biopsy of the Pleura or Lung A needle biopsy is a procedure in which a biopsy needle is inserted into the lung or through the membrane surrounding the lung (pleura) and is used to remove a piece of tissue for examination... read more ). In this case, the ultrasound probe is located on the bronchoscope to obtain images from inside the airways.

Nuclear lung scanning Radionuclide Scanning Radionuclide scanning is a type of medical imaging that produces images by detecting radiation after a radioactive material is administered. During a radionuclide scan, a small amount of a radionuclide... read more can be useful in detecting blood clots in the lungs Pulmonary Embolism (PE) Pulmonary embolism is the blocking of an artery of the lung (pulmonary artery) by a collection of solid material brought through the bloodstream (embolus)—usually a blood clot (thrombus) or... read more (pulmonary emboli) but has largely been replaced by CT angiography CT angiography Computed tomography (CT) is a type of medical imaging that combines a series of x-rays to create cross-sectional, detailed images of internal structures. In computed tomography (CT), which used... read more to diagnose this disorder. However, nuclear lung scanning may be done when CT angiography is not possible because a person has kidney disease, which can be worsened by the contrast agents, or allergies to the contrast agents used in CT. Nuclear lung scanning also may be used during the preoperative evaluation of people having part of their lung removed to treat lung cancer Lung Cancer Lung cancer is the leading cause of cancer death in both men and women. About 85% of cases are related to cigarette smoking. One common symptom is a persistent cough or a change in the character... read more or severe chronic obstructive pulmonary disease Chronic Obstructive Pulmonary Disease (COPD) Chronic obstructive pulmonary disease is persistent narrowing (blocking, or obstruction) of the airways occurring with emphysema, chronic obstructive bronchitis, or both disorders. Cigarette... read more (COPD) to see how well the rest of the lungs are functioning.

A nuclear lung ventilation/perfusion scan is noninvasive and fairly accurate but takes longer than CT angiography. A ventilation/perfusion scan is actually two scans, one that measures breathing (ventilation) and one that measures blood flow (perfusion). The tests are usually done together but can also be done separately.

For a lung perfusion scan, a tiny amount of radioactive substance is injected into a vein and travels through the pulmonary arteries to the lungs, where it outlines the blood supply of the lung.

In a lung ventilation scan, the person inhales a harmless gas containing a trace amount of radioactive material, which is distributed throughout the small air sacs of the lungs (alveoli). The areas where carbon dioxide is being released and oxygen is taken up can then be seen on a scanner.

By comparing the ventilation scan to the pattern of blood supply shown on the perfusion scan, doctors can usually determine whether a person has pulmonary emboli.

Pulmonary artery angiography (also called pulmonary artery arteriography) is done by injecting a radiopaque contrast agent directly into the pulmonary artery through a long, thin plastic tube (catheter) passed through a vein, into the heart and then into the pulmonary artery. After the contrast agent is injected, doctors use conventional x-rays to view the contrast agent in the lungs (angiography Angiography Angiography is a type of medical imaging that uses x-rays and a contrast agent to produce images of blood vessels. In angiography, x-rays are used to produce detailed images of blood vessels... read more ).

Angiography has traditionally been used most often when blood clots in the lungs (pulmonary embolism Pulmonary Embolism (PE) Pulmonary embolism is the blocking of an artery of the lung (pulmonary artery) by a collection of solid material brought through the bloodstream (embolus)—usually a blood clot (thrombus) or... read more ) was suspected, usually on the basis of abnormal lung scan results, and is still considered the most accurate test for diagnosing or excluding pulmonary embolism. However, angiography of the pulmonary arteries is usually done instead with CT angiography Computed Tomography (CT) Angiography of the Chest Chest imaging studies include X-rays Computed tomography (CT) CT angiography Magnetic resonance imaging (MRI) read more because pulmonary artery angiography, involving an injection directly into the large pulmonary artery, is more invasive.

PET scans are often combined with computed tomography (CT) scans Computed Tomography (CT) of the Chest Chest imaging studies include X-rays Computed tomography (CT) CT angiography Magnetic resonance imaging (MRI) read more to provide two different methods to visualize lung tumors.

Positron emission tomography Positron Emission Tomography (PET) Positron emission tomography (PET) is a type of medical imaging called radionuclide scanning. By detecting radiation after a radioactive material is administered, PET creates images that can... read more (PET) scanning may be used when cancer is suspected. This radiographic imaging technique relies on different metabolic rates of malignant (cancerous) compared with benign (noncancerous) tissues. Glucose molecules are combined with a compound that is visible using PET. These molecules are injected intravenously and accumulate in rapidly metabolizing tissue (such as in cancerous lymph nodes), making these tissues visible on PET scans. Benign growths usually do not accumulate enough molecules to be visible.