Fetal diffusion tensor quantification of brainstem pathology in Chiari II malformation.
OBJECTIVE
This prenatal MRI study evaluated the potential of diffusion tensor imaging (DTI) metrics to identify changes in the midbrain of fetuses with Chiari II malformations compared to fetuses with mild ventriculomegaly, hydrocephalus and normal CNS development.


METHODS
Fractional anisotropy (FA) and apparent diffusion coefficient (ADC) were calculated from a region of interest (ROI) in the midbrain of 46 fetuses with normal CNS, 15 with Chiari II malformations, eight with hydrocephalus and 12 with mild ventriculomegaly. Fetuses with different diagnoses were compared group-wise after age-matching. Axial T2W-FSE sequences and single-shot echo planar DTI sequences (16 non-collinear diffusion gradient-encoding directions, b-values of 0 and 700 s/mm(2), 1.5 Tesla) were evaluated retrospectively.


RESULTS
In Chiari II malformations, FA was significantly higher than in age-matched fetuses with a normal CNS (p = .003), while ADC was not significantly different. No differences in DTI metrics between normal controls and fetuses with hydrocephalus or vetriculomegaly were detected.


CONCLUSIONS
DTI can detect and quantify parenchymal alterations of the fetal midbrain in Chiari II malformations. Therefore, in cases of enlarged fetal ventricles, FA of the fetal midbrain may contribute to the differentiation between Chiari II malformation and other entities.


CONCLUSIONS
• FA in the fetal midbrain is elevated in Chiari II malformations. • FA is not elevated in hydrocephalus and mild ventriculomegaly without Chiari II. • Measuring FA may help distinguish different causes for enlarged ventricles prenatally. • Elevated FA may aid in the diagnosis of open neural tube defects. • Elevated FA might contribute to stratification for prenatal surgery in Chiari II.
Department of Biomedical Imaging and Image-guided Therapy, Medical University of Vienna, Waehringerguertel 18-20, 1090, Vienna, Austria. ramona.woitek@meduniwien.ac.at.
Ramona
R
Woitek
Department of Biomedical Imaging and Image-guided Therapy, Medical University of Vienna, Waehringerguertel 18-20, 1090, Vienna, Austria.
Daniela
D
Prayer
Department of Biomedical Imaging and Image-guided Therapy, Medical University of Vienna, Waehringerguertel 18-20, 1090, Vienna, Austria.
Michael
M
Weber
Department of Clinical Pathology, Medical University of Vienna, Vienna, Austria.
Gabriele
G
Amann
Department of Paediatrics and Adolescent Medicine, Medical University of Vienna, Vienna, Austria.
Rainer
R
Seidl
Department of Obstetrics and Gynecology, Medical University of Vienna, Vienna, Austria.
Dieter
D
Bettelheim
Department of Biomedical Imaging and Image-guided Therapy, Medical University of Vienna, Waehringerguertel 18-20, 1090, Vienna, Austria.
Veronika
V
Schöpf
Center for Anatomy and Cell Biology, Medical University of Vienna, Vienna, Austria.
Peter C
PC
Brugger
Department of Biomedical Imaging and Image-guided Therapy, Medical University of Vienna, Waehringerguertel 18-20, 1090, Vienna, Austria.
Julia
J
Furtner
Department of Biomedical Imaging and Image-guided Therapy, Medical University of Vienna, Waehringerguertel 18-20, 1090, Vienna, Austria.
Ulrika
U
Asenbaum
Department of Biomedical Imaging and Image-guided Therapy, Medical University of Vienna, Waehringerguertel 18-20, 1090, Vienna, Austria.
Gregor
G
Kasprian
D016880:Anisotropy; D001139:Arnold-Chiari Malformation / Q000175:diagnosis* / Q000196:embryology; D001933:Brain Stem / Q000473:pathology*; D056324:Diffusion Tensor Imaging / Q000379:methods*; D005260:Female; D005315:Fetal Diseases / Q000175:diagnosis*; D006801:Humans; D008297:Male; D011296:Prenatal Diagnosis / Q000379:methods*
Brainstem; Chiari II malformation; Diffusion tensor imaging; Fetus; Magnetic resonance imaging