Researchers Use 3D Mapping to Measure Growth and Folding Patterns in Pre-Term Babies’ Brains

3D printing has been used often in pediatric surgeries, but it’s also been put to work in difficult medical cases where a baby hasn’t even been born yet. A collaborative research team based at Washington University in St. Louis (WUSTL) has tested a new method, using 3D technologies, that could be used to make new diagnostic tools capable of measuring the growth and folding patterns of a baby’s brain in the third trimester of pregnancy.

A baby’s brain goes through very rapid development in utero during the third trimester, as the cerebral cortex grows its surface area and starts to fold. According to previous research, the details of this vital and quick growth can vary from baby to baby, as this process is very individualized. Minor folds are a little randomly shaped and distributed, but major ones can form important landmarks in the baby’s brain.

Philip Bayly

“One of the things that’s really interesting about people’s brains is that they are so different, yet so similar. We all have the same components, but our brain folds are like fingerprints: Everyone has a different pattern,” explained Philip Bayly, the Lilyan & E. Lisle Hughes Professor of Mechanical Engineering at WUSTL’s School of Engineering & Applied Science. “Understanding the mechanical process of folding—when it occurs—might be a way to detect problems for brain development down the road.”

When cortical folding is disrupted, it can lead to emotional and cognitive disorders, and even though many people have studied the processes that produce both normal and abnormal folding, not much is known about them other than the fact that third trimester rapid expansion plays a part. It would be helpful to be able to take accurate measurements of the growth pattern during this period, but so far efforts have not yielded much success. But this research team is hoping to help.

The researchers published an online paper on their findings, titled “Dynamic patterns of cortical expansion during folding of the preterm human brain,” in PNAS; co-authors include Kara E. Garcia, Emma C. Robinson from Imperial College London and King’s College London, Dimitrios Alexopoulos, Donna L. Dierker, Matthew F. Glasser, Timothy S. Coalson, Cynthia M. Ortinau, Daniel Rueckert from Imperial College London, Larry A. Taber, David C. Van Essen, Cynthia E. Rogers, Christopher D. Smyser, and Bayly.

According to the abstract, “In this study, we propose a unique method to estimate local growth from sequential cortical reconstructions. Using anatomically constrained multimodal surface matching (aMSM), we obtain accurate, physically guided point correspondence between younger and older cortical reconstructions of the same individual. From each pair of surfaces, we calculate continuous, smooth maps of cortical expansion with unprecedented precision. By considering 30 preterm infants scanned two to four times during the period of rapid cortical expansion (28–38 wk postmenstrual age), we observe significant regional differences in growth across the cortical surface that are consistent with the emergence of new folds. Furthermore, these growth patterns shift over the course of development, with noninjured subjects following a highly consistent trajectory. This information provides a detailed picture of dynamic changes in cortical growth, connecting what is known about patterns of development at the microscopic (cellular) and macroscopic (folding) scales. Since our method provides specific growth maps for individual brains, we are also able to detect alterations due to injury.”

3D mapping technology is used often to give people a more accurate look at underwater scenes and busy streets in cities around the world, but it can also be very useful in terms of getting a closer look at the organs inside our bodies.

Engineering doctoral student Kara Garcia worked with other researchers at the university’s School of Medicine in order to get 3D MRI images, scanned by Associate Professor of Neurology Christopher Smyser, MD and his pediatric neuroimaging team, of the brains of 30 pre-term infants. During the period of rapid brain expansion, which normally occurs between 28 and 30 weeks, the babies had been scanned two to four times each.

The team then used a new computer algorithm to get accurate point-to-point correspondence between cortical reconstructions of the same infant at younger and older ages; these two surfaces allowed the team to calculate accurate maps of the expansion.

By using a minimum energy approach to compare the surfaces of the babies’ brains at different times, the team was able to see some small differences in the folding patterns.

“The minimum energy approach is the one that’s most likely from a physical standpoint. When we obtain surfaces from MR images, we don’t know which points on the older surface correspond with which points on the younger surface,” Bayly said. “We reasoned, that since nature is efficient, the most likely correspondence is the one that produces the best match between surface landmarks, while at the same time, minimizing how much the brain would have to distort while it is growing.

“When you use this minimum energy approach, you get rid of a lot of noise in the analysis, and what emerged were these subtle patterns of growth that were previously hidden in the data. Not only do we have a better picture of these developmental processes in general, but doctors should hopefully be able to assess individual patients, take a look at their pattern of brain development, and figure out how it’s tracking.”

The findings could result in measurement tools that would be very helpful in neonatal intensive care units, as they could alert doctors and nurses early on to development disorders in premature infants which could affect them later in life.

Bayly explained, “You do also find folding abnormalities in populations that have cognitive issues later in life, including autism and schizophrenia. It’s possible, if medical researchers understand better the folding process and what goes on wrong or differently, then they can understand a little bit more about what causes these problems.”

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[Source: Medical Xpress / Images: University of Washington in St. Louis]