December 1, 2006 New studies by radiologists have shown that MRI can be just as accurate as CT scans at helping radiologists diagnose pathologies such as cancer, cysts and kidney stones -- while carrying less risk, especially for pregnant women. The magnetic waves and radiofrequency energy used in MRI are a safer alternative to the potentially carcinogenic X-rays of CT scans, especially during gestation. CT scans are still much faster, but medical physicists are working on developing faster MRI machines.
CHAPEL HILL, N.C. -- It's hard enough being pregnant, but for some women, what happens during pregnancy can put their and their baby's life at risk. A simple scan at the hospital could increase the chance of developing cancer. Now, a new scan is making it safer for doctors to help pregnant women who are in pain.
Radiologist Richard Semelka is using MRI to help safely see inside a pregnant women, keeping the baby free from the risks of radiation.
"MRI uses magnetic waves and radiofrequency energy, and CT uses X-rays in order to generate the images," Dr. Semelka, of University of North Carolina Hospitals in Chapel Hill, tells DBIS.
CT scans increase cancer risks in both the baby and the mother, but now new studies show MRI is safer and just as accurate.
Dr. Semelka has diagnosed breast cancer, ovarian cysts, kidney stones, bowel problems and appendicitis with the MRI. He was able to see an enlarged appendix in one woman and remove it before it ruptured, saving her and her baby.
A CT scan takes about five minutes and MRI lasts for an hour, but doctors are working to create an faster MRI.
BACKGROUND: A new study from the University of North Carolina Hospitals in Chapel Hill shows that MRI is both safe and accurate for diagnosing pregnant women with acute pain in the abdomen and pelvis, surpassing the limits of both CT scans and ultrasound for this purpose. The researchers analyzed the MRIs of 29 pregnant patients who had been experiencing acute abdominal pain, and correctly diagnoses the cause of that pain in 28 of those cases. Some of the problems that can be diagnosed include acute appendicitis, fibroids, ovarian cysts, kidney stones, gall bladder problems, and problems with the fetus itself.
A NEW ALTERNATIVE: It can be difficult to diagnose acute abdominal pain in pregnant women because the enlarged uterus pushes organs out of their normal locations, so the pain is not in the usual place. There are also more possible causes for pain,. Today, CT scanning is normally used for diagnosing abdominal pain, but there is a risk of exposing the fetus to harmful ionizing radiation, increasing cancer risks in both fetus and mother. Ultrasound (sonography) doesn't use radiation, but its imaging potential is limiting. MRI is becoming a desirable option as the medical community and the public becomes more aware of the risks associated with radiation, particularly for pregnant women. The latest generation of MRI scanners has reduced the time needed to image a patient, so it is becoming possible to see what is actually happening inside the abdomen or pelvis.
ABOUT CAT SCANS: CAT (Computerized Axial Tomography) scans are similar to conventional X-ray imaging, but instead of imaging the outline of bones and organs, a CAT scan machine forms a full three-dimensional computer model of the inside of a patient's body. Doctors can even examine the body one narrow slice at a time. The X-ray beam moves all around the patient, scanning from hundreds of different angles, and the computer takes all that information to compile a 3D image of the body.
HOW MRI WORKS: Magnetic resonance imaging uses radiofrequency waves and a strong magnetic field instead of X-rays to provide clear and detailed pictures of internal organs and tissues. These radio waves are directed at protons in hydrogen atoms -- one of the most abundant atoms in the human body, because of the body's high water content. The waves "excite" the protons, and when they "relax," they emit strong radio signals. A computer can turn those signals into a high-contrast image showing differences in the water content and distribution in various bodily tissues. It is becoming increasingly popular as an alternative to traditional X-ray mammography for the early diagnosis of breast cancer because women aren't exposed to the same radiation they experience with X-rays.
The American Association of Physicists in Medicine contributed to the information contained in the TV portion of this report.
Editor's Note: This article is not intended to provide medical advice, diagnosis or treatment.