MRI and PET Scans
with Loralie Ma, MD
How are MRI and PET images taken?
A thorough diagnosis is important for obtaining the best treatment results. Magnetic resonance imaging (MRI) and positron emission tomography (PET) scans both help physicians get an accurate picture of a patient’s condition. “We are able to put everything together through the MRI and PET scans and completely stage a patient and evaluate the extent of their disease before we treat them,” says Loralie Ma, MD, Medical Director of Medical Imaging of Baltimore at GBMC.
MRI is used for imaging all parts of the body, including soft tissue, bones and joints. The test is particularly useful for imaging the brain and spine. “We image the feet, head and everything in between,” says Dr. Ma. “MRI is a bit different from other diagnostic tests because it does not use radiation – it uses electromagnetic energy.”
An MRI scan typically takes about half an hour, during which the patient is placed into an MRI scanner. “We take images at the beginning of the scan and sometimes inject contrast dye and do post-contrast images,” says Dr. Ma. “Radiologists are the specialists who read the test results. A lot of times we are looking for cancer and with an MRI we can see the location of the disease. In other cases we may be looking for the cause of pain or trauma. For example, if the patient has knee pain, we may look for a meniscus, cartilage or ACL tear.” Results from MRI tests are usually available within 24 hours.
In most cases, PET scans are used to diagnose patients who are suspected to have cancer or to stage patients who have already been diagnosed with cancer. “During a PET scan, the patient is injected with a radiotracer that goes through the body’s bloodstream and is taken up by the body’s tissues,” says Dr. Ma. “Radiologists are able to tell if cancer is present because cancerous tissue takes up more of the radiotracer than other tissues in the body. We are able to see where the cancer is, and if and where it has spread.”
PET scans are typically done in conjunction with a computerized tomography (CT) scan. “From a PET scan we are able to tell where a cancer hot spot is and combined with a CT scan, we are able to tell exactly where the cancer is in the patient’s body,” says Dr. Ma. Results from the combined PET-CT scan are generally available within 24 hours.
When patients come to GBMC, they are able to receive comprehensive services at one location. “We have a team approach that includes input from many specialists,” says Dr. Ma. “Our approach helps ensure patients receive the most optimal treatments for their conditions and we have everything available on one campus.”
