Radiographs, most often called x-rays, produce shadow-like images of bones and certain organs and tissues. They can show some organs and soft tissues, but MRI and CT scans often give better pictures of them.
Another contrast study, an intravenous pyelogram (MVP), uses a special dye to look at the structure and function of the urinary system (ureters, bladder, and kidneys). For instance, in the past, angiography was often used to help learn the stage or extent of cancer, but now CT and MRI scans are most often used to do this.
A special tube inside the x-ray machine sends out a controlled beam of radiation. After passing through the body, the beam hits a piece of film or a special detector.
Tissues that block high amounts of radiation, such as bone, show up as white areas on a black background. Soft tissues block less radiation and show up in shades of gray.
Other than removing metal objects that might interfere with the picture, no special preparation is needed before having a standard x-ray. Always be sure to tell your health care provider whether you have allergies to iodine or have had problems with contrast materials in the past.
You’ll need to remove jewelry or other objects that might interfere with the image. You’ll be asked to sit, stand, or lie down, depending on the body part to be x-rayed.
Your body is put against a flat box or table that holds the x-ray film. The technologist then moves the machine to aim the beam of radiation at the right area.
You may have special shields put over parts of your body near the area being x-rayed so that they’re not exposed to the radiation. Usually the technologist leaves the room to operate the machine by remote control.
For a chest x-ray in people who can ’t stand, the film is put under them and the picture is taken from the front. You’ll need to hold your breath and lie still while the picture is taken quickly.
Contrast studies Angiography: You’ll be asked to not eat before this test. You will lie still on a table as the skin over the injection site is cleaned and numbed.
A tiny cut will be made so the catheter (thin plastic tube) can be put into a blood vessel (usually the artery at the top of the thigh) and slid in until it reaches the area to be studied. Firm pressure might be needed on the catheter site for a while to make sure it doesn’t bleed.
You’ll also need to lie flat and keep your leg still for up to several hours. Magnetic resonance angiography (MRA) is an MRI study of the blood vessels.
Intravenous pyelogram (MVP): You’ll probably be asked not to eat or drink anything for about 12 hours before this test, and you must take laxatives to clean out your bowel. Another series of x-rays is taken over the next 30 minutes or so to get pictures of the dye as it moves through the kidneys and out of your body.
Pressure may be applied to the belly to help make the image clearer. Once the dye has reached the bladder, you’ll be asked to pass urine while another x-ray is taken.
Lower GI series (barium enema): Your diet may be restricted for a few days before this test. Then liquid barium is put into your bowel through a small, soft tube placed in your rectum.
Upper GI series: You will probably be asked to not eat or drink for 8 to 12 hours before this test. You will lie down and be strapped to a tilting table while a series of x-rays are taken as the barium coats your esophagus and stomach.
You’ll need to swallow the barium mixture a few times during the test. You might also be asked to swallow baking soda crystals to create gas in your stomach.
Venography : As you lie still on a table, the skin over the vein to be used is cleaned and numbed. The contrast dye is put in to make the veins show up on the x-ray, and a series of x-ray pictures is taken.
Extra fluids may be given through the catheter to help wash the dye out of your body. Firm pressure may be needed on the site for a while to make sure it doesn’t bleed.
The contrast material may cause nausea, vomiting, flushing, itching, or a bitter or salty taste. In rare cases, people can have a severe allergic reaction to the contrast material that affects their breathing and blood pressure.
There’s also a small risk of damage to the blood vessel from the catheter, which could lead to internal bleeding. A hematoma (a large collection of blood under the skin) may develop where the catheter was put in if pressure is not kept on the site long enough.
Intravenous pyelogram (MVP): The contrast dye sometimes causes some people to have flushing, mild itching, or a bitter or salty taste. In rare cases, people have a severe reaction to the contrast material and need emergency treatment.
Lower GI series (barium enema): The test can be uncomfortable. The barium contrasts material will make your stools a light color for a few days after the test and may cause constipation.
Your arm or leg (where the catheter is put in) may feel numb during the test. In rare cases, people can have a severe allergic reaction to the contrast material that affects their breathing and blood pressure.
There’s also a small risk of damage to the blood vessel from the catheter, which could lead to internal bleeding. A newer technology, called digital radiology, produces pictures on computer screens rather than on film.
The size and contrast of the pictures can be digitally adjusted to make them easier to read, and they can be sent to computers in other medical offices or hospitals. From the WebMD Archives April 8, 2005 -- When the news that Peter Jennings had lung cancer hit earlier this week, many WebMD users asked why doctors don't use chest X-rays to diagnose lung cancer at an early stage, when it's more treatable.
WebMD turned to cancer expert Harold Burstein, MD, assistant professor of medicine at Harvard Medical School in Boston, for the answer. The vast majority of lung cancer cases are caused by smoking, ” Burstein tells WebMD.
Chest X-rays are inadequate for diagnosing lung cancers at an early stage, when they are more treatable. “By the time lung cancers are discovered on chest X-ray, the tumor is often too far advanced to allow the patient to be cured with surgery or radiation therapy.
The hope was that these CT scans would be able to find smaller, earlier cancers without leading to further unnecessary tests. “A variety of recent studies in the U.S. and Japan have suggested that high-resolution CT scans can often detect lung cancers.
However, he explains that these were small, early studies that were not able to answer the questions of whether CT scans can actually save lives. Continued Burstein says a recent analysis of potential lung cancer screening tests shows there is inadequate data to recommend widespread lung cancer screening at this time.
Chest X-rays are seen in shades of gray and require interpretation by a radiologist trained to spot abnormalities. Any abnormal growth in the lung will appear on a chest X-ray as a relatively consolidated area of light gray.
A chest X-ray alone cannot confirm if a lung nodule, mass, shadow, neoplasm, or lesion is cancer or something more benign, like a cyst or scar. Pneumonia, which commonly occurs with symptomatic lung cancer, can easily conceal a tumor as pus and mucus start to clog the airways.
Even after the TB infection resolves, any remaining spots on the lungs may be presumed to be scarring and left investigated. It is not uncommon for someone to be told that a chest X-ray is normal only to find out, months or years later, that cancer is present.
In such cases, this typically only comes to light when advanced symptoms (such as wheezing, unintended weight loss, or the coughing up of blood) develop. While this may suggest negligence is the sole cause of missed diagnoses, chest X-rays fundamentally have limitations, particularly when it comes to detecting certain types and sizes of lung cancer.
Research published in Diagnostic and Interventional Radiation reported that 45% to 81% of missed lung cancers occurred in the upper lobes where clavicles and other structures obscure the view. Generally speaking, tumors smaller than 1.5 cm (3/5 inch) are more likely to be missed on a chest X-ray than larger ones.
In addition, many of the symptoms of lung cancer, such as shortness of breath or fatigue, are non-specific and easily attributed to things like age or obesity. There are surprisingly few recent studies looking at the actual incidence of missed diagnoses of lung cancer, but the research that has been done is sobering.
This not only makes the disease more difficult to manage but significantly reduces a person's survival time. Computed tomography (CT) scans take multiple X-ray images and combine them in dimensional “slices” so that abnormalities in the lungs can be seen more clearly.
Sputum cytology involves coughing up phlegm so that the sample can be checked for cancer cells in the lab. Lung biopsy, involving the extraction of suspicious tissues by needle or other methods, is ordered if a CT scan suggests cancer.
If cancer is diagnosed, other tests will be performed to stage and grade the tumor so that the appropriate treatment can be delivered. Positron emission tomography (PET) scans are less commonly used for the initial diagnosis of lung cancer and are considered more useful for the staging of the disease.
A study published in JAVA involving 150,000 people at high risk of lung cancer reported that four years of annual chest X-rays did nothing to alter the death rate in the group. It is in this population of adults that screening can significantly reduce the risk of advanced malignancy and premature death.
According to interim guidance from the U.S. Preventive Services Task Force (USP STF), annual low-dose chest CT scans are recommended if you meet all the following criteria: Used according to these guidelines, CT screening could reduce the lung cancer death rate by 20% in the United States.
Although the consensus among health officials is that the risks of annual CT screening in other groups outweigh the benefits, a 2019 study in the Journal of Thoracic Oncology suggests otherwise. According to the researchers, low-dose CT screening in non-smokers detected a significant number of cancers in the early stages that would have otherwise been missed.
As reassuring as a “normal” result may seem, don't allow it to give you a false sense of security if the cause of persistent symptoms remains unknown or if the diagnosis you were given can 't explain them.