Imaging tests utilize medical equipment that takes pictures of the body, showing what is occurring on the inside. There are several different imaging tests that may be done during diagnosis and staging of lung cancer.1
During diagnosis, doctors will look for any lung nodules or masses on the images. Lung nodules, also called pulmonary nodules, are small round or oval shaped growths. They are smaller than 3 centimeters. Growths larger than 3 centimeters are called a mass, and these are more likely to be cancerous (malignant). Nodules may be malignant or benign (not cancerous). In fact, over 90% of lung nodules that are smaller than 2 centimeters are benign and can be caused by infections, inflammation or a non-cancerous abnormal growth. Larger and more irregularly shaped nodules are more likely to be malignant.2
Chest X-Ray
The chest x-ray is most often the first imaging test used to identify any abnormal areas in the lungs. X-ray machines use a type of electromagnetic radiation to send particles through the body and capture the image of the body on a computer or film. Dense structures, such as bone, appear white, while muscle, fat, and fluid appear in shades of gray. A chest x-ray takes an image of the chest, lungs, heart, large arteries, ribs, and diaphragm.4
Lung nodules appear as spots on a chest x-ray. The size and shape of the nodule, as well as its location, are evaluated. Larger nodules and nodules in the upper portions of the lungs are more likely to be cancerous.2
CT Scan
Computed tomography (CT) scans use special x-ray equipment to make cross-sectional views of the inside of the body. The patient lies flat on a table while the CT scanner rotates around the body, taking pictures at different angles or in a spiral pattern. Modern CT scans create three-dimensional (3-D) pictures of the inside of the body, enabling doctors to view small abnormalities.1,4
CT scans can provide further views of any nodules found on x-ray, or lung nodules may be first identified on a CT scan. CT scans are more accurate and can provide more detail on the shape, size, location and density of nodules compared to chest x-rays.2
PET Scan
Positron emission tomography (PET) scans are also used in diagnosing lung cancer as they can provide additional information on whether a nodule is benign or malignant. Prior to the scan, the patient is given an intravenous (IV) injection of a radioactive substance called a tracer. The tracer is absorbed into organs and other parts of the body. Cancerous cells, which have a higher metabolism rate than healthy cells, absorb more of the tracer, making them easily identifiable on the images. During the scan, the patient lies flat on a table, which slides into a large tunnel-shaped scanner. The computer creates 3-D images on the monitor. Most PET scans are performed in conjunction with a CT scan and the combined scan is called a PET/CT scan.1,2,4
Bone Scan
Bone scans can be used during the staging of lung cancer to determine if the cancer has spread to the bones, generally when other imaging doesn’t offer clear results. Prior to the bone scan, the patient is given an intravenous (IV) injection of a radioactive substance called a tracer. The images capture how much of the radioactive tracer collects in the bones, which helps identify changes in the bones. These changes may represent spread of cancer to the bone.4
Brain MRI
Magnetic resonance imaging (MRI) is a test that uses powerful magnets and radio waves to generate pictures of the internal structures of the body. MRI is often used to view the brain and surrounding nerve tissues and is one of the tools that can be used during staging of lung cancer to determine if the cancer has spread to the brain.4