Mesothelioma Diagnosis: Could a New Way of Reading MRIs Replace Surgical Biopsy?

A new way of evaluating MRI images may eventually make more invasive ways of diagnosing mesothelioma unnecessary. That assertion is being made by a multi-disciplinary team of Belgian doctors who have just published an article on the new technique.

Malignant pleural mesothelioma grows on the pleural lining that encases the lungs. Magnetic Resonance Imaging (MRI) is one of the imaging techniques (along with PET and CT) that doctors use to help diagnose the disease and determine patient prognosis. Radiologists assessing these MRI images typically look for two visual markers for mesothelioma – pleural thickening and shrinking of the lung.

But scientists from the departments of radiology, thoracic surgery, pneumology and pathology at the University Hospitals Leuven in Leuven, Belgium say a third technique called pleural pointillism may be even more effective at spotting mesothelioma. The so-called “pointillism sign” is an area of hyper-intense spots on the pleura that can be seen on a type of MRI image called a diffusion-weighted image. Diffusion-weighted MRI imaging reveals tissue characteristics based on the diffusion of water molecules in tissue.

To test the value of looking for the pointillism sign on these images, the doctors performed PET/CT and MRI imaging (including diffusion-weighted MRI) on 100 consecutive patients suspected of having pleural mesothelioma. To confirm their mesothelioma, these patients also had either open or minimally invasive tissue biopsies, which is the primary way in which mesothelioma is currently diagnosed.

Of the 100 patients screened, 57 were found to have mesothelioma, 10 had another type of cancer, and 33 had benign tumors. “A total of 78 patients received a correct diagnosis (benign vs. malignant) on the basis of mediastinal pleural thickening and 66 patients on the basis of shrinking lung,” reports Dr. Johan Coolen, the study’s lead investigator.

But the pleural pointillism evaluation turned out to be even more accurate than either of those methods. Eighty-eight patients were correctly diagnosed with either cancer or benign disease when radiologists looked for the pointillism sign on their diffusion-weighted MRI images. Dr. Coolen and his colleagues conclude that the pointillism approach performed “substantially better” than evaluations of either pleural thickness or shrinking lung and “might obviate unnecessary invasive procedures for malignant pleural mesothelioma”.

The study is published in a recent issue of the journal Radiology.

Source:

Coolen, J et al, “Malignant Pleural Mesothelioma: Visual Assessment by Using Pleural Pointillism at Diffusion-weighted MR Imaging”, September 19, 2014, Radiology, Epub ahead of print.