DIAGNOSTIC IMAGING TESTS
Imaging tests are the first step towards diagnosing mesothelioma. Doctors use scans produced by imaging tests to guide the diagnostic process in the right direction.
Scans obtained from imaging tests show doctors where the tumor or buildup of fluid is located in the patient’s chest or abdomen. Some tests can even show how far a mesothelioma tumor has spread.
Because mesothelioma can easily be mistaken for other cancers, the visual information provided by imaging tests help steer doctors towards an accurate diagnosis. Learn more about how mesothelioma is diagnosed in our free guide.
X-ray: The First Step
An x-ray is usually the first imaging test doctors use when a patient comes to them with symptoms. If a doctor suspects that symptoms point to a disease, they will order an x-ray to get a better look at what might be causing them.
To begin the procedure, a patient stands between an x-ray machine and a special screen. The machine passes a safe level of electromagnetic rays through the patient’s upper body and into the screen, which captures an image showing bones, organs and other structures of the body.
The x-ray image also shows any abnormalities that may indicate the presence of mesothelioma. Signs pointing to mesothelioma include small, scattered nodules (bumps) in the lining of the lung and the buildup of excess fluid.
X-rays are useful as a first step in the diagnostic process, but do have one major drawback. Serious fluid buildups show up on x-rays a large white or gray mass and can hide other signs that are stronger visual indicators of mesothelioma. For example, large pleural effusions in patients with advanced-stage mesothelioma can hide pleural thickening or tumors in the lining of the lungs.
If an x-ray provides the doctor enough visual evidence to suspect mesothelioma, they will most likely order a CT scan for further confirmation.
CT Scans Provide a Clearer Picture
A CT scan provides more detail than an x-ray because it produces a 3D image of a patient’s body. This allows doctors to see behind fluid buildups that usually block other important visual signs of mesothelioma, like pleural thickening or tumors, in an x-ray.
The imaging process begins when the patient lies down on a table over which the CT scanner is attached. As the patient passes through the scanner, the machine rotates. Each rotation creates an x-ray scan, commonly called a slice, of the patient’s chest and abdominal area. The x-ray slices are then fed into a computer, which takes the snapshots and arranges them into a 3D image.
Some CT scans use a contrast material that helps the scanner differentiate between organs and body structures. This material differentiates between abnormalities, like smaller mesothelioma tumors, and regular organs a bit better. Doctors will usually inject the contrast material intravenously (into a vein) or have the patient drink it a few hours before the procedure.
CT scans work better than x-rays because they show how far the mesothelioma has metastasized (spread) throughout the chest or abdominal cavity. Having this visual information about the cancer’s metastasis, or cancer stage, is important. The stage of mesothelioma determines the type of treatment a patient can receive.
PET Scans Show Metastasis
Specialists prepare for a PET scan by injecting a safe, radioactive chemical into the patient’s bloodstream. The chemical, commonly called a tracer, is attracted to cells that produce a lot of energy, like cancer cells.
The process is similar to a CT scan. After the patient lies down on a table, they are passed through an imaging machine connected to a specialized camera. The camera is modified to pick up which organs or areas of the body collect most of the tracer chemical. Since the tracer is attracted to cells that produce a lot of energy, the image shows where high energy cancer cells are located.
Since PET scans only show the where the most tracer fluid was collected, they are an excellent tool for determining how far mesothelioma has spread. PET scans are often paired with CT scans to provide doctors with the most accurate view of a patient’s body: a 3D image that shows where even the smallest mesothelioma tumors are located.
MRI Scans Help Prepare for Surgery
An MRI scan produces a detailed image of the body’s internal organs and structures. It can detect very slight variations or abnormalities, like mesothelioma, within the body. Unlike an x-ray or CT scan, an MRI doesn’t use radiation to produce an image.
During the procedure, the patient lies on a movable table that is slid into a large tube surrounding by a large, circular magnet. The magnet spins around the tube, creating a strong magnetic field that causes cells in the body to give off special signals. These signals are picked up by the machine and produce a detailed image of the body’s organs and structures.
Usually, the entire procedure requires the patient to pass through the machine several times so that the radiologist can obtain the best, most detailed image of the upper torso. The entire procedure typically takes about 25 – 50 minutes.
The detail produced by an MRI helps doctors determine if a patient is a candidate for surgery. It is also a very useful scan for patients with peritoneal mesothelioma. The abdomen contains many organs in a relatively small space, making it difficult for x-rays or CT scans to produce a detailed image.
Imaging Tests Guide the Diagnostic Process
Doctors rely on scans produced by imaging tests to locate the suspected mesothelioma tumor. They also use imaging tests to visually determine how far the tumor has spread.
Imaging tests provide visual evidence that doctors can use as a guide for further diagnosis. They do not, however, provide enough information about mesothelioma to confirm a diagnosis. Because mesothelioma can be mistaken for other cancers, an accurate diagnosis requires further testing by an experienced mesothelioma specialist.
1. Computed Tomography (CT) Scan of the Body. (n.d.). Retrieved September 5, 2014, from http://www.webmd.com/a-to-z-guides/computed-tomography-ct-scan-of-the-body.
2. Positron Emission Tomography (PET). (n.d.). Retrieved September 5, 2014, from http://www.webmd.com/a-to-z-guides/positron-emission-tomography.