Computed Tomography (CT)
Computed tomography (CT) is an imaging technology that uses a combination of x-rays and computer synthesis to generate more sophisticated and detailed pictures of the internal structures of our body than conventional x-rays are capable of producing. CT is considered the “gold standard” imaging test for the diagnosis of a variety of conditions, including malignant mesothelioma, because of the richly-detailed nature of the images it creates.
CT scans are produced by a CT scanner, a complex, technologically-advanced imaging machine that utilizes a rotating x-ray beam to take multiple x-rays of specific areas of the body, all from slightly different angles. These individual pictures are then fused into a single image, which gives a rich anatomical map of the area imaged. These scans provide a detailed view of the interior landscapes of our body and can achieve much higher resolution than can x-rays—especially when it comes to the imaging of soft tissues, such as the pleurae. CT’s images are high enough in resolution that “differences between tissues that differ in physical density by less than 1% can be distinguished [Wikipedia].
High resolution is what gives CT its value in the diagnosis of pleural mesothelioma and peritoneal mesothelioma. Whereas x-ray cannot properly visualize the pleurae and other aspects of the lung parenchyma, CT is able to accurately visualize these structures and to distinguish normal from malignant tissues. There are a number of difficulties in the imaging assessment of mesothelioma, so there is not a definitive guarantee that CT will identify the malignancy, but the necessary resolution is available for this purpose and in most cases, an experienced radiologist should be able to identify the disease.
The primary difficulty with identifying the disease is due to its unique infiltration pattern and the morphological form that it typically presents with. Unlike many cancers that present as a single tumor with clear boundaries between the malignancy and the surrounding tissues, mesothelioma’s typical presentation is a diffuse spread of malignant tissue throughout a surface area. Instead of an individually-identifiable tumor, mesothelioma is most often seen as a “sheath-like” layer of cancerous cells that grow atop tissue structures. The complexity of the surfaces it grows along, such as the chest wall, the lung and peritoneum, combined with its own unique form, can complicate proper assessment of the disease’s presence and/or status. However, as indicated above, an experienced radiologist should be able to accurately answer these questions.
Even though CT is effective for imaging cancers and other conditions, it utilizes ionizing radiation to function, so care must be taken in limiting a patient’s exposure to excess radiation. Some people have called for regular full-body screenings using CT, but the high levels of radiation that are necessary have prevented this from occurring. CT’s most important use is still for specific diagnostic purposes, such as it’s used for mesothelioma and lung cancer, and this will likely continue for the future.