Magnetic Resonance Imaging (MR or MRI)
Functional MRI (fMRI)
MR technology allows physicians to see the anatomic structure of the body's organs and tissues. Functional MR (fMR) enables physicians to see how the body functions. An fMRI is performed on a conventional MRI unit that consists of a very large magnet and uses a safe, non-invasive magnetic field and radiofrequency waves to take pictures of the brain while it is working. The technique measures changes in blood flow all over the brain. In this way, the fMRI scan allows us to see what areas of the brain are activated during a specific activity. For example, by having people perform simple tasks during the scan (such as moving digits or limbs) we can see which part of the brain controls those tasks.
At Boston Children's Hospital, fMR scans are used to provide additional information used for treatment planning for neurological disorders such as epilepsy, brain tumors, brain injury, mental retardation, autism, and learning disabilities. Read here about the fMR simulator that prepares kids for research studies. The hospital's Dream magazine also looks at fMR.
Image Fusion and Post-Processing
The Advanced Image Analysis Laboratory in the Radiology Department at Boston Children's Hospital allows radiologists, nuclear medicine physicians, and referring clinicians to maximize information gained from computed tomography (CT), magnetic resonance imaging (MRI), and nuclear medicine exams. The three-dimensional models, fused images, and other advanced post-processing methods improve patient care by aiding diagnosis, treatment planning and surgical intervention. The images can also be used for patient-friendly explanations and answering research questions.
‘Try-Without Sedation’ and ‘Feed and Wrap’ programs
We routinely offer cooperative children ages 4-6 years the chance to try undergoing their MRIs without sedation after a pilot program showed that most of them can do so successfully with proper preparation and distraction. Movement will cause the MRI images to be blurry, so we use a variety of techniques to help children lie still, such as listening to music or watching videos during the exam with special goggles and headphones. Motion-reduction sequences are also used to improve the quality of the images. Our Child Life Specialist helps to prepare children and families before and during the MRI to make the visit as safe, pleasant and comfortable as possible.
Additionally, we perform "feed and wrap" imaging of sleeping, unsedated newborns, ages 0 to 3 months. Our custom made 32-channel head coils for newborns and six month olds improve signal to noise and our ability to accelerate image acquisition.
Children in the 3 months to 4 years age group rarely undergo an MRI without sedation or anesthesia. A recent Catalyst funded grant is allowing us to focus on preparing children between the ages of 6 months and 1 year for a non-sedated MRI. Additionally, in collaboration with the Gaab Laboratory, we are developing distraction techniques to make improvements in this area for the 3 months to 4 years age group.
Motion Mitigation and Accelerated Image Acquisition
Movement during the MRI will cause the images to beblurry. Motion mitigation sequences track the head motion of a patient and readjust the image acquisition to account for a child’s movement during the scan. These are not yet commercially available, yet we use them routinely.
We also have custom made 32-channel head coils for newborns and six month olds to improve signal to noise and our ability to accelerate image acquisition.
MRI Imaging to Reduce Exposure to Radiation from CT Exams
In order to limit exposure to radiation, we are performing MRI studies for exams that were previously routinely imaged by CT. For example, IBD studies and ventricular size checks are now being performed using MRI, resulting in a decreased lifetime cumulative radiation dosage. Additionally, some airway (sleep apnea) exams are being obtained with MR instead of CT.
MR tractography uses data sets from diffusion weighted images to show white matter organization and orientation of white matter fibers in the brain. Tractography is helpful for preoperative planning and understanding seizure propagation in epilepsy and other brain disorders. In the future, it may also be able to play a role in evaluating how the brain as a whole is connected, and how such connectivity is altered in certain disease states.
Magnetoencephalography (MEG) monitors neural activity by recording magnetic fields in the brain. Current MEG devices are only available in adult sizes. In collaboration with the National Science Foundation, we are designing and building the first whole head MEG system for infants and children aged 0 to 3 years. This system will have the technical capabilities needed for monitoring neural activity in young patients.
Encephalographic MRI (eMRI) is a research technique that combines advanced magnetic resonance imaging (MRI) and electroencephalography (EEGs) in an attempt to more directly image the electrical changes in the brain than was previously possible. Early results demonstrate fast eMRI responses that correlate well with epilepsy spikes on the EEG. Work is now directed at trying to use eMRI to help with surgical planning for epilepsy patients. More generally, eMRI may prove to be a powerful tool for understanding the origin and spread of abnormal electrical activity in the brain in various epilepsy syndromes, both during wakefulness and sleep.