CT and MRI
A minimally invasive procedure called a CT Scan is most often used in patients living with crohns disease in order to look into the abdomen. CT (computed tomography) is a newer radiological technology that is used for three-dimensional imaging of many areas of the body, but for Crohn’s patients specifically it is most often performed on the abdomen and pelvis.
Unlike an MRI (magnetic resonance imaging), which uses magnetic fields to obtain an image and does no harm to the subject, CT conveys relatively high doses of radiation. These doses are not above safe levels, but care must nonetheless be taken as cancer occurrence is thought to be linked with radiation exposure.
CT and MRI images may be taken with or without contrast. When contrast is used, CT scans most often utilize a barium contrast that is taken by mouth to illuminate the digestive tract, along with an intravenous injection of iodine, which aids the machine in achieving high image quality. An MRI scan will use oral contrast and/or intravenous dye as well, but agents such as manganese, ferric chloride, ferric ammonium citrate, and gadolinium are more conducive to MRI tests involving the abdomen.
Some people may have a sensitivity to any of these contrast agents and some have minor side effects, but all are generally safe for use in the average patient.
While MRI tends to be superior to CT in function, the fact is that CT is cheaper, tests can be performed faster, and it works in a wider field than MRI. Some patients who experience claustrophobia in the tight confines of an MRI machine do better in the wider ring used by most CT scans. Because MRI is a magnetic technology, image quality is benefitted from a more tightly enclosed space with the mechanical instruments closer to the patient’s body.
Both types of scans use multiple fields in different ways to bounce energy off the tissues of the body. They record thin slices of an image based on the return values of these fields and construct a two-dimensional, or more commonly, a three-dimensional image based on those values.
The costs of each test will obviously change over time, but an MRI may be anywhere from 20-60% more expensive than a CT scan.