| 1. |
- Vaz, Tania F., et al.
(author)
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Brain Extraction Methods in Neonatal Brain MRI and Their Effects on Intracranial Volumes
- 2024
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In: Applied Sciences. - : MDPI. - 2076-3417. ; 14:4
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Journal article (peer-reviewed)abstract
- Magnetic resonance imaging (MRI) plays an important role in assessing early brain development and injury in neonates. When using an automated volumetric analysis, brain tissue segmentation is necessary, preceded by brain extraction (BE) to remove non-brain tissue. BE remains challenging in neonatal brain MRI, and despite the existence of several methods, manual segmentation is still considered the gold standard. Therefore, the purpose of this study was to assess different BE methods in the MRI of preterm neonates and their effects on the estimation of intracranial volumes (ICVs). This study included twenty-two premature neonates (mean gestational age ± standard deviation: 28.4 ± 2.1 weeks) with MRI brain scans acquired at term, without detectable lesions or congenital conditions. Manual segmentation was performed for T2-weighted scans to establish reference brain masks. Four automated BE methods were used: Brain Extraction Tool (BET2); Simple Watershed Scalping (SWS); HD Brain Extraction Tool (HD-BET); and SynthStrip. Regarding segmentation metrics, HD-BET outperformed the other methods with median improvements of +0.031 (BET2), +0.002 (SWS), and +0.011 (SynthStrip) points for the dice coefficient; and −0.786 (BET2), −0.055 (SWS), and −0.124 (SynthStrip) mm for the mean surface distance. Regarding ICVs, SWS and HD-BET provided acceptable levels of agreement with manual segmentation, with mean differences of −1.42% and 2.59%, respectively.
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| 2. |
- Bajic, Dragan, et al.
(author)
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Asymmetric Development of the Hippocampal Region Is Common : A Fetal MR Imaging Study
- 2012
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In: American Journal of Neuroradiology. - 0195-6108 .- 1936-959X. ; 33:3, s. 513-518
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Journal article (peer-reviewed)abstract
- BACKGROUND AND PURPOSE: Hippocampal development is poorly understood. This study evaluated the normal development of the hippocampal region during the fetal period by using MR imaging. MATERIALS AND METHODS: MR images of 63 fetuses without intracranial pathology were reviewed independently by 2 radiologists with no knowledge of the fetal GA. Three MR images were performed postmortem and 60 in vivo. The progress of hippocampal inversion was analyzed in coronal sections, and the left and right sides of the hippocampal region were compared in every case. RESULTS: The fetuses in the postmortem examinations were at GWs 17-18 and in the in vivo examinations, at GWs 19-36. The hippocampal sulcus was open, bi- or unilaterally, in 39 fetuses. The oldest was at GW 32. The sulcus was closed at GW 21 at the earliest, unilaterally. In 26/63 fetuses (41%), the deepening or closure of the hippocampal sulcus or hippocampal inversion was asymmetric; in 23 fetuses, the right side developed faster. A shallow collateral sulcus was found earliest at GW 17. A deep collateral sulcus was visible earliest at GW 26 unilaterally, but in all fetuses from GW 31 onward, it was seen bilaterally. The orientation of the collateral sulcus was not related to the GA. CONCLUSIONS: There are wide individual temporal variations in the development and the inversion process of the hippocampal sulcus as well as in the formation of the collateral sulcus. Asymmetric development is common, and in most of the asymmetric cases, the right hippocampus develops faster.
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| 3. |
- Bajic, Dragan, et al.
(author)
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Development of the hippocampal region demonstrated on fetal MRI : A preliminary report
- 2011
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In: NRJ Digital. - 2239-7493. ; 1:12, s. 555-557
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Journal article (peer-reviewed)abstract
- Coronal slices of three fetal MRIs performed post mortem and 37 performed in utero, all without intracranial pathology, was assessed. Progress of the hippocampal inversion was analyzed, the left and right sides were compared and occurrence of the collateral sulcus was revealed. The fetuses in the post mortem examinations were at gestation weeks (GW) 17-18 and in the in utero examinations at GW 19-35. The symmetric development of the hippocampal sulcus was revealed in 26 subjects and asymmetric in 14. The non-ovoid hippocampal formation could be evaluated at GW 24 at earliest and an ovoid hippocampus at GW 29. The collateral sulcus could be recognized at GW 17 in post mortem and at GW 22 in in utero examinations. From GW 29 onwards it was seen in all fetuses and it was symmetric in all but one case. Evaluation of the hippocampi is difficult on fetal MRI, especially in in utero examinations. The hippocampal development is not fulfilled at GW 21 as presumed. There is a wide temporal variation in the development of the hippocampal region, and the developmental process does not progress simultaneously in the right and left side of the same individual.
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| 4. |
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| 5. |
- Canto Moreira, Nuno, et al.
(author)
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Measurements of the normal fetal brain at gestation weeks 17 to 23 : a MRI study
- 2011
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In: Neuroradiology. - : Springer Science and Business Media LLC. - 0028-3940 .- 1432-1920. ; 53:1, s. 43-48
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Journal article (peer-reviewed)abstract
- INTRODUCTION: To obtain measurements of the normal fetal brain before 24 weeks of gestation (GW), a deadline for medical decisions on fetal viability in a large number of countries. METHODS: We retrospectively reviewed 70 normal MR examinations of fetuses aged GW 17 to 23. The fronto-occipital diameter, the cerebral bi-parietal diameter, the transverse cerebellar diameter, the vermian height, and antero-posterior diameter were measured. RESULTS: The median, maximum, and minimum values for each parameter were displayed for each individual GW. CONCLUSION: The recorded data might contribute to a better assessment of fetal health by providing normal boundaries for the brain growth.
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| 6. |
- Canto Moreira, Nuno
(author)
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MRI Studies of the Fetal Brain and Cranium
- 2012
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Doctoral thesis (other academic/artistic)abstract
- Ultrasound is the primary modality for fetal imaging, but Magnetic Resonance Imaging nowadays has a valuable complementary role as it often reveals findings that alter pregnancy management. Knowledge on some clinically relevant areas of the normal fetal development is still lacking, and this was the aim of this project. We wanted 1) to obtain reference MRI data of normal brain measurements before 24 gestation weeks (GW), 2) to study the development of the hippocampus, 3) to study the development of the ear and 4) to test the ability of MRI for evaluating the lip and palate. For this, we retrospectively analysed a database with 464 in vivo and 21 post mortem fetal MRI examinations. Study I evaluated a series of 70 normal fetuses. A table of normal brain measurements from 17 to 23 GW was built, the first in the literature that includes ages below 20 GW. Study II focused on the evolution of the hippocampus from 18 to 38 GW by evaluating 3 post mortem and 60 in vivo MRI examinations. Our results suggested this area to develop later and more asymmetrically than previously thought. Study III analysed a series of 122 normal MRI in vivo and 16 MRI post mortem. We described the development of the fetal ear in vivo for the first time in the literature, realizing that the value of MRI is limited by the size of the structures evaluated. In study IV, 60 brain-targeted MRI examinations of 55 normal fetuses and 5 fetuses with orofacial clefts were blindly reviewed by two readers, focusing on the lips and palates. Our results suggest a high accuracy of MRI in the evaluation of this area, regardless of fetal age or previous ultrasound findings. This thesis brings new knowledge on the normal development of the fetal brain and cranium.
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| 7. |
- Canto Moreira, Nuno, et al.
(author)
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Superficial Siderosis : A Case Report
- 2011
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In: Medicina (Kaunas). - 1010-660X .- 1648-9144. ; 47:6, s. 320-322
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Journal article (peer-reviewed)abstract
- Superficial siderosis of the central nervous system is the result of chronic recurrent hemorrhages (e.g., arteriovenous malformations, tumors, or trauma), which leads to the accumulation of cytotoxic hemosiderin and presents with hearing loss, cerebellar dysfunction, and myelopathy. This article presents a clinical case of an 11-year-old boy in whom the diagnosis of medulloblastoma was established. He underwent surgery, and after a few years, he began to complain of hearing loss. Magnetic resonance imaging revealed the cause of the hearing disturbance. The aim of this article is to review the recent literature related to the etiology, clinical and radiologic features of superficial siderosis, emphasizing the role of magnetic resonance imaging.
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| 8. |
- Canto Moreira, Nuno, et al.
(author)
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The ear in fetal MRI : what can we really see?
- 2011
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In: Neuroradiology. - : Springer Science and Business Media LLC. - 0028-3940 .- 1432-1920. ; 53:12, s. 1001-1008
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Journal article (peer-reviewed)abstract
- INTRODUCTION: The aim of this study was to investigate the ability to depict the components of the ear on brain-oriented fetal MRI studies. METHODS: Retrospective evaluation of the ear in MRI studies was performed post-mortem in 16 fetuses ranging from 15 to 22 gestation weeks (GW), and in 122 examinations in vivo of fetuses ranging from 20 to 38 GW. The cochlea, vestibular apparatus, middle ear, and external auditory canal were separately graded according to the components that were delineated. RESULTS: The components of the inner and middle ear were fully delineated in 100% of the post-mortem examinations, but the external auditory canals were only seen in only 25%. In the in vivo group, the imaging detail was much lower. Cochlear turns could be identified in 75% of the fetuses, the vestibule and the lateral semicircular canals in 72% andossicles in 70%. Before 25 GW, the ability to identify these individual parts was 50%, 30%, and 33%, respectively, and above it was 89%, 93%, and 90% . In most cases, the external auditory canals could only be seen after 29 GW. CONCLUSION: In fetal MRI studies in vivo, it is possible to depict the components of the ear in the majority of the fetuses, in such a manner as to exclude major malformations. However, MRI might not provide enough detail to rule out pathology of the ear before 25 GW, this being a critical age for pregnancy management in many countries.
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| 9. |
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| 10. |
- Canto Moreira, Nuno, 1962-, et al.
(author)
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Visualisation of the fetal lip and palate : is brain-targeted MRI reliable?
- 2013
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In: The Cleft Palate-Craniofacial Journal. - : Sage Publications. - 1055-6656 .- 1545-1569. ; 50:5, s. 513-519
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Journal article (peer-reviewed)abstract
- Introduction: The purpose of the study was to evaluate the ability of brain-targeted MRI to assess the anatomy of the fetal upper lip and palate.Methods: Two independent readers made a blind retrospective review of 60 MRI of fetuses of 20 to 38 gestational weeks (GW). Fifty-five fetuses had normal post-natal follow-up. Five fetuses had oro-facial anomalies at post-natal follow-up, including five cleft lips (two bilateral, three unilateral), four cleft primary palates (two bilateral, two unilateral) and two cleft secondary palates.The upper lip, primary palate, secondary palate and nasal septum were scored into four levels, from evidently normal to evidently abnormal. In case of a suspected pathology, the readers attempted a diagnosis.Results: Interobserver agreement (weighted kappa) was 0.79 for the upper lip, 0.70 for the primary palate, 0.86 for the secondary palate, and 0.90 for the nasal septum. The scoring levels of the readers did not change significantly across gestational age.The readers identified 100% of all pathological cases. The normality was correctly scored in 96-100% of the normal lips and primary palates and in 93-97% of the normal secondary palates depending on the reader. A deviated septum was only scored in two fetuses with unilateral cleft palates.Conclusion: MRI in experienced hands seems reliable for assessment of the fetal lip and palate, even in brain-targeted examinations. Attention should therefore be paid to the lip and palate in all fetal MRI examinations, since unsuspected clefts may be revealed.
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