Quantitative MRI to review the affect of preterm delivery on the mind

Extremely premature babies who develop brain abnormalities in adolescence have subtle differences in white matter that can be detected by quantitative MRI, according to a new study published in the journal Radiology. The researchers hope to identify markers that can help detect these birth defects.

As survival rates of extremely preterm infants – less than 28 weeks of amenorrhea – have increased in recent decades, researchers are interested in the effects of this preterm birth on brain development, as it is generally agreed that this causes greater risks of brain abnormalities.

A study to better understand the effects of preterm birth on the brain

It’s a matter ofan American study published in the journal Radiology, led by Dr. Thomas M. O’Shea, from the University of North Carolina at Chapel Hill (USA). “Much of brain maturation occurs during the third trimester, when the fetus is in the nurturing environment of the uterus, specifies in the preamble. These premature babies do not fall into this category, so it seems likely that there are changes in brain maturation during this interval. »

Dr. O’Shea and colleagues at 14 academic medical centers across the United States began a study 20 years ago to better understand the effects of preterm birth. The study, known as the Extremely Low Gestational Age Newborn Environmental Influences on Child Health Outcomes (ELGAN-ECHO), has evolved over the years to include medical imaging experts such as Prof. Hernán Jara, Professor of Radiology at Boston University School of Medicine; in Boston (USA).

Quantitative MRI to highlight white matter abnormalities

For this new study, Prof. Jara, Dr. O’Shea and other ELGAN-ECHO researchers used quantitative magnetic resonance imaging (qMRI), a non-invasive technique that generates rich information about the brain without radiation. So they explored the brains of teenagers born very prematurely. “Quantitative magnetic resonance imaging on a large dataset allows us to identify small differences between populations that may reflect microstructural tissue abnormalities not visually observable from conventional magnetic resonance imaging,” continues Prof. Jara.

The researchers collected data from MRI scans at 12 different centers on teenagers ages 14 to 16. They compared images of atypically developing adolescents versus neurotypical youths, as well as girls versus boys. The comparison included in particular the assessment of brain volume. They also looked at lesser-used metrics such as proton density in the brain’s gray and white matter.

Abnormalities appear to be more present in girls than in boys

“What we wanted to do with qMRI was establish a biomarker that could help us distinguish preterm babies who were diagnosed with the disorder from those who did not,” continues the study’s lead author, Dr. Ryan McNaughton, mechanical engineer. Boston University student.

Of the 368 adolescents in the study, 252 developed neurotypically, while 116 had atypical development, showing differences in brain structure visible on qMRI, including subtle changes in white matter related to proton density, suggestive of a lack of free water.

“This may represent the tip of the iceberg, as the amount of free water is highly regulated in the brain,” explains Prof. Jara. The fact that this difference was observed more in women than in men may also be related to the known comparative resilience of women, as demonstrated by previous ELGAN-ECHO results as well as other studies. »

Use multidisciplinary expertise to link these outcomes to cognitive and psychological determinants

The researchers collected umbilical cord and blood samples at the start of the study. They plan to use them to look for correlations between qMRI results and the presence of toxic elements like cadmium, arsenic and other metals. The power of qMRI will allow them to study both the quantity and quality of myelin, which is important in cognitive development. They also want to recruit psychiatrists and psychologists to link qMRI results to intelligence, social cognition and other criteria.

“This project shows how researchers with different skills can work together to use qMRI as a predictor of psychiatric and neurocognitive outcomes,” says Dr. McNaughton. “The teamwork required to get to where we are now is incredible,” concludes Dr. O’Shea. I am very grateful to the families, nursing coordinators and everyone who made this possible. »

Bruno Benque with RSNA

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