Medically Reviewed By
Karen Ritter, RN BSN
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Important Facts About Imaging Tests for Mesothelioma
- There are multiple imaging tests used to diagnose mesothelioma, but none of them are definitive enough to diagnose it. A biopsy is the only definitive test to diagnose mesothelioma.
- The first test used is an X-ray, followed by a CT scan, PET scan and MRI scan.
- None of the scans cause pain for the patient. Some are better at detecting pleural mesothelioma than peritoneal mesothelioma.
- The length of the process varies for each type of test but it is important in getting a diagnosis of mesothelioma and other cancers.
How Are Scans Used for Mesothelioma?
Mesothelioma imaging tests collect detailed visuals of a patient’s lungs, heart or abdomen. They are essential for doctors to make determinations about the likelihood of mesothelioma cancer and can help with early detection. Doctors also use these tests for an early analysis of treatment options.
The two most common types of mesothelioma are pleural mesothelioma (lining of the lung cavity) and peritoneal mesothelioma (lining of the abdominal cavity). Malignant pleural mesothelioma is the most common mesothelioma. All four tests can help with either type of the disease. A third, much rarer type is pericardial mesothelioma, which is a cancer of the sac around your heart. For this cancer, you’ll undergo an echocardiogram, which is an ultrasound of the heart. A fourth type is called testicular mesothelioma, and it’s the rarest form.
What Are the Tests for Mesothelioma?
There are four tests used for mesothelioma. If you suspect you have this cancer, you will almost certainly undergo one of them:
- Computed tomography (CT) scan
- Positron emission tomography (PET) scan
- Magnetic resonance imaging (MRI) scan
X-rays and CT scans are the most common imaging tests used for mesothelioma. However, some tests aren’t as effective as others for different types of mesothelioma. CT scans, for example, aren’t effective in detecting peritoneal mesothelioma because gas in the intestines can be mistaken for tumors.
How to Measure the Accuracy of Scans
Imaging scans are measured by sensitivity, specificity and accuracy. These three measurements are similar but determined with different formulas all incorporating:
- True positive (the test says the patient has the cancer when they do)
- True negative (the test says the patient doesn’t have the cancer when they don’t)
- False positive (the test says the patient has the cancer when they don’t, which is how doctors misdiagnose mesothelioma)
- False negative (the test says the patient doesn’t have the cancer when they do)
Doctors want either a true positive or true negative result for a test to be effective. False positives and false negatives can cause significant stress and strain on patients. A false positive leads to unnecessary further testing. A false negative causes the patient to think they don’t have cancer when in fact they do and need treatment right away.
Other measurements of imaging scans are sensitivity, specificity and accuracy. These can rule out other conditions.
Sensitivity is the rate of how well the test detects cancer compared to everyone with the disease. The formula is: true positives divided by true positives plus false negatives. The rate is the percentage of people accurately told they have the cancer compared to the total number with the cancer.
Specificity is the rate of how well the test can distinguish someone with cancer versus someone without the cancer, or how well the test can determine if someone is healthy. The formula is: true negatives divided by true negatives plus false positives. So the rate is the percentage of people accurately told they don’t have cancer.
Accuracy is the ability for a test to determine if a patient has or doesn’t have the cancer, at a rate of the total number of cases. The formula is: true positives plus true negatives, divided by all results using the test (true positives, true negatives, false positives and false negatives). So the rate is the number of people accurately told they either have or don’t have mesothelioma.
X-ray for Mesothelioma
An X-ray uses electromagnetic beams to collect two-dimensional images inside your body. X-rays examine all parts of the body, including the chest and abdomen. This is usually the first step in the diagnostic process.
An X-ray helps doctors determine if there is an anomaly in the patient’s lungs, abdomen or heart. X-rays of the chest or abdomen can show fluid buildup around the organs. This fluid may indicate the presence of mesothelioma.
About X-rays for Mesothelioma
- Pre-procedure: None needed
- Post-procedure: More images may have to be taken at a later time
What is the procedure time?
Approximately 15 minutes
Does it hurt?
CT Scan for Mesothelioma
A CT scan generates detailed three-dimensional images of the body. This test uses X-rays and computer technology to gather multiple images of the same organ at different angles. These images are merged to create a cross-sectional image of bones, blood vessels and tissue.
The patient lays down on a table as they slowly enter the cylinder, which is referred to as the “donut.” The result provides evidence of tumors or tissue abnormalities.
Iodine fluid, or radiocontrast (contrast), can improve visibility within the body on the scans. Patients either drink the iodine fluid or receive an injection into their veins.
CT scans are the primary imaging technique for a patient with suspected pleural mesothelioma. One study showed pleural thickening was evident in 94% of pleural mesothelioma patients who underwent a CT. Pleural effusion occurred in 74% of those patients.
This test had a reported sensitivity of 53%, specificity of 100% and accuracy of 68%. This means:
- 53% of the positive mesothelioma cases were detected with this test
- 100% of people without the cancer were accurately told they didn’t have it thanks to the test
- 68% of people, either with or without peritoneal mesothelioma, were given an accurate diagnosis based on a CT test
About CT Scans
- Pre-procedure: Patients drink or receive an IV of a contrast liquid so images can be seen clearly
- Post-procedure: More images may be taken at a later time
What is the procedure time?
Between 15 and 60 minutes, with some preparation time needed if the patient takes a contrast fluid
Does it hurt?
PET Scan for Mesothelioma
A PET scan determines how organs or systems in the body are functioning. They detect the presence of cancers in target areas of the body.
Doctors insert a small dose of a radioactive sugar into the body. Cancerous cells absorb sugar, so this radioactive substance serves as a tracer. A small camera takes a picture of the radioactive energy in the body. The cancerous cells appear brighter in the image.
This radiopharmaceutical is usually injected into the bloodstream. Images are collected in the same way CT scans are, through a rotating cylinder that gathers images from all angles.
PET scans can show the presence of tumors and help with staging. The radioactive tracer can show if the cancer has metastasized. Patients can leave and resume their normal day after the test is over. According to one study, PET scans are 89% accurate in distinguishing between malignant mesothelioma and a benign disease.
PET scans for mesothelioma had scores of 86-92% for sensitivity, 83-89% for specificity, and 87-89% for accuracy. This means:
- Up to 92% of the positive mesothelioma cases were detected with this test
- Up to 89% of people without mesothelioma were accurately told they didn’t have it
- Up to 89% of people, either with or without mesothelioma, received an accurate diagnosis
About PET Scans
- Pre-procedure: 1 hour before, a radiopharmaceutical material is injected
- Post-procedure: A second CT scan may be performed to collect more detailed images
What is the procedure time?
What is the procedure time? Between 45 and 90 minutes, most of which is for the radioactive sugar to travel through your body
Does it hurt?
MRI for Mesothelioma
An MRI scan creates a complex detailed image of the soft tissue in a specific area. A mesothelioma MRI can reveal the exact location of tumors.
MRI scans do not involve radiation or X-rays. They create the image with magnets. MRI scans are primarily used for staging mesothelioma and creating a treatment plan.
Patients lay down a table and slowly enter a cylinder, where a magnetic field gathers images. Patients must remain still to provide clear pictures.
About MRI Tests
- Pre-procedure: None Needed
- Post-procedure: A second MRI scan may be performed to collect more detailed images
What is the procedure time?
Between 40 and 80 minutes, depending on the size of the area scanned
Does it hurt?
Top Cancer Centers
Brigham and Women's Hospital
Moffitt Cancer Center
UCLA Medical Center
Los Angeles, CA
Why Are Mesothelioma Tests So Important?
Imaging tests are typically the first step in diagnosing mesothelioma. Patients experiencing symptoms of mesothelioma are examined to find abnormalities in the body. Mesothelioma is difficult to diagnose because the cancer appears like other conditions.
These tests can reveal the presence of tumors in the patient, but they cannot determine the exact disease or if the tumors are malignant. Surgical procedures determine if the tumors are mesothelioma.
While mesothelioma tests are an important diagnostic tool, they aren’t the most important. Seeing a specialist is imperative for patients showing symptoms and to receive a mesothelioma diagnosis.
Following mesothelioma tests, patients should either get a blood test for mesothelioma or a biopsy. A biopsy is the only way to confirm a mesothelioma tumor. Mesothelioma blood tests allow doctors to analyze the blood for abnormal cells.
This disease is hard to diagnose and often confused with other types of cancer, such as adenocarcinoma or lung cancer. A tissue biopsy is the only way to diagnose mesothelioma. Connect with a mesothelioma specialist at a cancer center to get an accurate mesothelioma diagnosis.
Sources & Author
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- Part 1: Simple Definition and Calculation of Accuracy, Sensitivity and Specificity. Archives of Academic Emergency Medicine. Retrieved from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4614595/. Accessed: 03/28/2022.
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