Analiza mikrostrukture prolaznih fetalnih zona i segmenata bijele tvari ljudskoga mozga histološkim metodama i magnetskom rezonancijom [Microstructural analysis of transient fetal zones and white matter segments of human brain using histological methods and magnetic resonance imaging]

Žunić Išasegi, Iris (2019) Analiza mikrostrukture prolaznih fetalnih zona i segmenata bijele tvari ljudskoga mozga histološkim metodama i magnetskom rezonancijom [Microstructural analysis of transient fetal zones and white matter segments of human brain using histological methods and magnetic resonance imaging]. PhD thesis, Sveučilište u Zagrebu.

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Abstract

The development of human brain axonal pathways is a complex process where transitional fetal zones and white matter segments play an important role due to the various spatio-temporal frames of intense growth and the consequent specific sensitivity to the harmful factors during development. The aim of this thesis was to define the microstructural changes of the white matter segments, for the purpose of better correlation of MRI with clinical parameters in neurodevelopmental disorders. This study included postmortem brains (fetal/early postnatal period) treated with histological, immunohistochemical and MRI in vitro methods (40 samples in total). In vivo MR images were used in qualitative (12 fetuses in utero, 49 premature infants) and FA-ADC analysis at the (corrected) term-age (7 newborns, 52 premature infants) and at the second year of life (31 subjects). The histological/MRI analysis of the prenatal/perinatal development of the white matter segments reveals maturational specificity of the second white matter segment, especially the differences between premature and full term infants. The FA and ADC values follow the histological development of the segments, pointing to their differentiation in radial direction, from cerebral ventricles to pial surface, distinguishing groups of neonates between themselves and in comparison with the control group at the corrected term-age, with the tendency of reducing the differences towards the second year of life. Groups with and without perinatal lesions visible on structural MRI differ in the ADC values in the second year of life The most complex system of commissural, projection and associative fibers is present in the sagittal strata, characterized by particular MR signal intensity changes, which makes it the potential biomarker of perinatal neurorisk. Knowledge of histological/MRI development of the white matter segments has potential for application during routine brain imaging analysis.

Abstract in Croatian

Razvoj aksonskih puteva ljudskog mozga složen je proces gdje podjela na prolazne fetalne zone i segmente bijele tvari ima važnu ulogu zbog različitih vremensko-prostornih okvira intenzivnog rasta i posljedične specifične osjetljivosti na štetne čimbenike tijekom razvoja. Cilj rada je definiranje mikrostrukturalnih promjena segmenata bijele tvari, u svrhu jasnije korelacije MR-a i kliničkih parametara u nerorazvojnim poremećajima. Istraživanje uključuje postmortem mozgove (fetalno/rano postnatalno razdoblje) obrađene histološkim, imunohistokemijskim i in vitro MR metodama (ukupno 40 uzoraka), te ispitanike čiji su in vivo MR slikovni prikazi korišteni u kvalitativnoj (12 fetusa in utero, 49 nedonoščadi) i FA-ADC analizi u (korigiranoj) terminskoj dobi (7 novorođenčadi, 52 nedonoščadi) i drugoj godini života (31 ispitanik). Histološka/MR analiza prenatalnog/perinatalnog razvoja segmenata bijele tvari otkriva specifičnosti maturacije segmenta II bijele tvari, posebice različitosti između nedonoščadi i terminske novorođenčadi. FA i ADC vrijednosti prate histološki razvoj segmenata, ističući diferencijaciju razvoja segmenata bijele tvari u radijalnom smjeru od moždanih komora prema pijalnoj površini, razlikujući se između nedonoščadi međusobno i u odnosu na kontrolnu skupinu u terminskoj dobi, s tendencijom smanjivanja razlika u drugoj godini života. ADC vrijednosti u drugoj godini života razlikuju skupine s/bez perinatalnih lezija vidljivih na strukturnom MR-u. Najsloženiji sustav komisuralnih, projekcijskih i asocijativnih vlakana prisutan je u sagittal strata, što ga, uz specifične promjene intenziteta MR-signala, čini potencijalnim biomarkerom neurorizika. Poznavanje histološkog/MR razvoja segmenata bijele tvari ima potencijalnu primjenu tijekom rutinske analize mozga nedonoščeta.

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