Conventional radiology – such x-ray, ultrasound, computed tomography (CT) scan or magnetic resonance imaging (MRI) – simply shows how a part of the body looks. We as physicians then study and determine normal or abnormal function based on the appearance of those images. For example, if your child has a severe cough and fever your doctor may order a chest x-ray to look for pneumonia. If the lungs appear to be normal on the x-ray, we assume they are normal.
Nuclear radiology involves studying how an organ functions. Images from nuclear radiology are typically not as detailed as those from a CT or MRI scan, but give us a different type of information. When you combine the two types of information together – from conventional and nuclear images – you get a much better overall view of what is ailing a child in order to craft an improved, more informed treatment.
What technology is used?
PET (Positron Emission Tomography) is a technique within nuclear radiology in which an image of a radioactive dye (previously intravenously injected into the body) is produced. PET scanning is a sensitive mechanism to identify a site of infection or inflammation, monitor the effects of chemotherapy on many cancers, detect a seizure-focus in the brain of an epilepsy patient and can even help diagnose Alzheimer’s disease in adults.
As mentioned above, imaging is optimized when conventional and nuclear radiology combine forces. As CT scanners became faster and decreased in cost, PET/CT scanners, a combination camera capable of producing both anatomic and physiologic resolution simultaneously, were developed. This advance in the detail of information obtained by a PET/CT scanner has been shown to be much more accurate in evaluating patients than the information previously obtained by a separate PET-only or CT-only scan.
Similar to PET/CT, there is now PET/MRI. Although there can be an overlap with the information gained, each imaging technique has its optimal uses. PET/ MRI is ideal for imaging the nervous system, specifically the brain and spinal cord, as well as organs, such as the liver and bone marrow. It also significantly decreases the radiation exposure to a patient, estimated at up to a 40% reduction.
What technology does Texas Children’s Hospital have?
Texas Children’s Hospital installed our very own PET/MRI and PET/CT scanners in April of 2013, becoming one of the first hospitals in the world to have both. We are also the first free-standing children’s hospital in North America to do so. We are on the forefront of creating protocols for radiation reduction for our pediatric patients – and this is another step towards that standard.
Although the PET/CT has existed for over a decade the PET/MRI is brand new, so we are proceeding with cautious optimism. We recognize the need to ensure the diagnostic accuracy and influence on treatment before implementing PET/MRI into clinical practice. Therefore, at this time we are offering these scans only when a PET/CT has been ordered, as part of a research study to confirm effectiveness and necessity.
The main theme among our team at Texas Children’s Hospital is continued vigilance and research. We have confidence that PET/MRI will have a big impact on pediatric imaging. We and our pediatric patients are very fortunate to have this technology right here in Houston.