Accuracy during the diagnosis phase is vital for determining if someone has cancer, which cancer they have, and how to treat the disease. The importance is magnified for peritoneal mesothelioma because patients need to begin treatment immediately. The speed of the tumors’ growth and spread makes beginning treatment or having surgery a significant part of defeating the cancer diagnosis.

Imaging scans are a major part of diagnosing peritoneal mesothelioma, like they are for most other cancers. However, there are a few imaging scans doctors and cancer hospitals can choose to use during the diagnostic process.

Which imaging tests are best for detecting and staging peritoneal mesothelioma?

A new report in the medical journal Abdominal Radiology investigated how often each of the three main imaging scans are used, along with their accuracy and sensitivity, for peritoneal mesothelioma. Two of the co-authors, Dr. Kiran Turaga and Dr. Hedy Lee Kindler, are peritoneal mesothelioma specialists.

 

How to Tell if Someone Has Peritoneal Mesothelioma

Before visiting the doctor to undergo tests, patients usually notice symptoms related to a disease. For peritoneal mesothelioma, signs of the disease usually manifest in the abdominal region.

Some of the peritoneal mesothelioma symptoms are:

  • Abdominal pain
  • Unexplained weight loss
  • Decreased appetite
  • Ascites (fluid buildup in the peritoneum)

The peritoneum is the thin layer of tissue and fluid where peritoneal mesothelioma forms. This layer wraps around the abdominal cavity, acting as a protective lining for all the tissue and organs within the abdomen.

As tumors form in this lining, fluid bunches together into pockets and pushes the peritoneum out. The lining presses against the stomach, which can cause pain. Ascites also causes noticeable bulging of the stomach region.

Imaging scans for peritoneal mesothelioma may detect ascites visually.

 

Which Imaging Scans Do Doctors Use for Peritoneal Mesothelioma?

The four common imaging scans for peritoneal mesothelioma are:

  • X-ray
  • CT scan
  • PET scan
  • MRI scan

An X-ray is a two-dimensional look at tissues and bone structures inside the body. X-ray sends electromagnetic radiation to create images.

An X-ray is usually one of the first scans patients receive during the mesothelioma diagnosis steps. However, a single X-ray is far from enough evidence to formally diagnose someone with peritoneal mesothelioma – or even give doctors a firm idea that the cancer exists in a patient.

CT scan, or computed tomography scan, combines multiple X-ray scans of your body taken at different angles. Computer technology creates cross-sectional slicing of bones, tissue linings and blood vessels. This type of imaging scan is essentially a more detailed form of X-rays, specifically creating multiple scans to create a more complex and full image of the tissue and bone structure.

PET scan, or positron emission tomography scan, uses a radiotracer to allow light to create images from within the body. This type of imaging scan provides a closer, three-dimensional look at the tissue linings. While CT scans and X-rays provide non-moving looks at the body, a PET scan gives a visual at the cellular level.

Mesothelioma doctors usually insert a radioactive drug, called a tracer, via an IV into the patient’s arm. The tracer travels through the blood and collects in organs and tissue. A tunnel-shaped scanner takes images based on tracer signals, and a computer transfers the images into three-dimensional looks.

MRI scan, or magnetic resonance imaging scan, is the most complex type of imaging test available. This is usually the last type of scan used during the diagnostic process and either confirms what other scans indicate or clarifies a question for doctors. This scan can also help with staging, as it provides the most detailed look at a body area and can detect how much tumors have spread.

MRI scans use magnetic fields and computer-created radio waves to form three-dimensional looks at the body. Athletes who tear ligaments require an MRI scan to confirm their injury. Similar to a PET scan, an MRI scan uses a tunnel-shaped object to send images back to a computer. Patients must remain still while inside the cylinder.

 

How to Measure Each Imaging Test for Peritoneal Mesothelioma

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)
  • 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, either causing them to undergo further testing when not necessary or delaying needed treatment by assuming they don’t have the cancer.

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 peritoneal mesothelioma.

 

Study Analyzes Accuracy of Imaging Scans for Peritoneal Mesothelioma

Doctors from University of Chicago Medicine, and other hospitals, analyzed 582 studies involving diagnostic procedures for peritoneal mesothelioma. The goal was to detect which imaging scans were best for detecting peritoneal tumors in patients – and which were best for staging the cancer.

The imaging test used most often in these studies was CT scan. Approximately 55% of diagnoses involved CT scans for patients. Imaging tests need to differentiate between two or more cancers. Peritoneal mesothelioma can appear like peritoneal carcinomatosis, ovarian cancer and other malignancies.

One of the studies reviewed reported CT scans had a sensitivity of 53%, specificity of 100% and accuracy of 68%. This means:

  • 53% of the positive peritoneal 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 scan imaging test

PET scans had better results, albeit not used as often so the sample size is lower. PET imaging tests, per two studies’ reports, had scores of:

  • 86-92% for sensitivity
  • 83-89% for specificity
  • 87-89% for accuracy

Another study found MRI scans were most accurate in staging peritoneal mesothelioma via the peritoneal cancer index (PCI). The PCI is a staging system that scores each region of the abdominal cavity based on the amount of tumors in the area. An MRI scan likely provides the best visual of the entire abdominal region and therefore the best scope of disease spread.

MRI scans also were better than other imaging tests at revealing ascites (fluid buildup in the peritoneal cavity), peritoneal tissue thickening, pleural plaques and tumor dimension. These symptoms and signs can differentiate peritoneal mesothelioma from other diseases and help in staging.

The authors concluded CT scans are used most often but PET and MRI scans are promising for peritoneal mesothelioma tests.

“Future studies should compare the effectiveness of these modalities,” the authors wrote.

    Sources & Author

Devin Goldan image

About the Writer, Devin Golden

Devin Golden is the content writer for Mesothelioma Guide. He produces mesothelioma-related content on various mediums, including the Mesothelioma Guide website and social media channels. Devin's objective is to translate complex information regarding mesothelioma into informative, easily absorbable content to help patients and their loved ones.

Guide Packet Desktop Ad

Want to learn more?

Try Our Free Guide to Fighting Mesothelioma

Get in depth knowledge about your diagnosis & the best treatments.

Learn More
Guide Packet Mobile Ad

    Sources & Author

Picture of Devin Golden

About the Writer, Devin Golden

Devin Golden is the content writer for Mesothelioma Guide. He produces mesothelioma-related content on various mediums, including the Mesothelioma Guide website and social media channels. Devin's objective is to translate complex information regarding mesothelioma into informative, easily absorbable content to help patients and their loved ones.