For over 200 years, physicians have tracked the growth of infant brains by measuring the circumference of infants’ heads. Enough of these measurements have been made that doctors can plot these measurements on percentile charts to get an indication of whether the infant’s brain is growing in a normal pattern and at a normal rate. These studies are helpful for observing the basics of growth rates, but they cannot tell doctors whether individual structures inside the brain are developing normally.
Magnetic resonance imaging (MRI) is a type of medical imaging that does not use ionizing radiation like ordinary x-rays and computed tomography (CT) do. Medical imaging that uses ionizing radiation is generally avoided in pediatric patients unless it’s necessary for diagnosis of an illness or injury. Researchers in the United States are now using MRI scans to create detailed atlases of information on how the individual structures within the brain grow in normal full-term newborns, premature infants, and children up through age six.
A Study by UCSD and the University of Hawaii
Researchers from the University of California, San Diego (UCSD) and the University of Hawaii recently published results of a study of MRI data on newborn brains in JAMA Neurology. The purpose of the investigation was to gather data and investigate how different regions of the brain develop based on gestational period, gender, and other factors during the first three months of life.
The study gave researchers a deeper understanding of how brain structure and function are related during the postnatal phase when the brain is developing at its most rapid pace. Researchers evaluated multiple brain regions in terms of size, growth rate, and asymmetry after performing MRI studies on sleeping infants. By amassing a detailed collection of measurements and images, researchers hope to learn to detect some of the earliest signs of neurodevelopmental disorders or of perinatal injury to the brain.
The first three months after birth are the most dynamic in terms of brain growth, and knowledge of the normally developing infant brain during this time has been limited. This study included MRI scans of 87 healthy newborns from 2007 through 2013. The longitudinal study included full-term and premature infants, with 39 boys and 48 girls.
The Brain in the First 90 Days of Life
Researchers examined 211 time points, and focused on cerebral structure development. Specific regions studied included the lateral ventricles, the hippocampus, the caudate, and putamen. Images were investigated for growth rates, volume, and asymmetry between the left and right halves of the brain.
They discovered that in a normal, full-term newborn, the brain grows on average 1% every day in the days immediately following birth. By the age of three months, however, brain growth slows to 0.4% per day. They also found that the brains of premature infants grew faster than full-term infants’ brains, but by 90 days of age, premature brains were still about 2% smaller than the brains of full-term infants at that age.
Gender did not appear to influence the cerebral structure of newborns at birth. However, at 90 days, male brains had grown by 66% on average, while female brains grew by 63%. During the first 90 days, the cerebellum, the part of the brain associated with motor control, grew fastest, more than doubling in size in both boys and girls. The hippocampus, an area of the brain linked with memory, grew at the slowest rate, gaining only an average of 47% in volume.
Asymmetries in the brain were also discovered during the first 90 days of life. Specifically, the right hippocampus was larger than the left. This was an unexpected finding, because previous studies had indicated that asymmetry in the hippocampus did not occur until early adolescence.
Future Studies Planned
The researchers plan to continue their studies of newborn brains using medical imaging. Future studies may incorporate measurements of the brains of infants of mothers who engaged in alcohol or drug use during pregnancy to determine any connections between substance use and infant brain volume and growth rates.
Boston Hospitals: Building Brain Atlases for a Child’s First Six Years
Researchers at several hospitals in Boston have also been compiling information to develop an atlas of the brain from birth through six years of age. In this study, however, researchers collected and examined MRI scans that had already been performed since the year 2006. Scans performed for a designated set of diagnoses were excluded, and gestational age was determined from patient records. The researchers identified what they called “potentially normative” MRI studies acquired after 2006 for patients under age 6 at the time of the scan.
Images were processed to remove skull imagery, and the resulting images were divided into 12 different age groups. For each age group, an unbiased atlas of age-specific brain data was created by averaging the geometry and intensity shown on the MRI scans of all subjects falling into the age group. The resulting atlas images were found to be in agreement with expert knowledge on the brains of children under six, and are expected to enhance clinicians’ ability to detect subtle brain abnormalities in children under age six. Future work will address whole-brain trends, tissue types, and individual brain structures.
The Importance of Expertise and Experience in Pediatric Radiology
Pediatric imaging is a radiology subspecialty that does not simply consider children as “smaller adults.” Not only must pediatric medical imaging take into account unique diseases of childhood, performing radiological medical imaging studies of children must also take into account the different needs of children versus adult patients. At SteleRAD, Drs. Arch, Fibkins, and Williams are pediatric subspecialty radiologists with the experience and expertise necessary to gain the most insight and relevance from medical imaging of pediatric patients.
SteleRAD is owned and operated by board-certified radiologists and adheres to the highest standards of excellence in medical imaging. SteleRAD’s doctors deliver timely, accurate medical imaging studies to hospitals, imaging centers, and physician groups in the South Florida region and elsewhere. With more than 40 years of combined experience, SteleRAD’s radiology group has improved the patient experience in South Florida. If you would like to learn more about SteleRAD’s pediatric medical imaging services, contact SteleRAD online or call 954-358-5250.