الفهرس 
IntroductionOnly 14 pages are availabe for public view
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Abstract
Fetal MRI is being increasingly used to assess for fetal CNS abnormalities .MRI has a better soft tissue contrast than ultrasound with by far better depiction of maturational stages of gray and white matter development than ultrasound. It has multiple planes for reconstruction and a large field of view . Similar to sonography, MRI does not expose patients to ionizing radiation, and there is no clinical or experimental evidence of teratogenic or other adverse fetal effects of MRI in pregnancy .On the other hand, MRI is cost-intensive and only available in a limited number of institutions. Few centers are experienced in the special technique of fetal MRI and the interpretation of fetal CNS anatomy and pathology. Fetal MRI is not a dynamic imaging method; the fetal skeleton and fetal motions can be better evaluated with ultrasound scan .Contraindications for MRI are metallic implants or shrapnel, severe claustrophobia,and obesity. Correct diagnosis depends on the quality of ultrasound and MRI images as well as on the quality of interpretation.
The aim of our work was to elaborate on sonographic & MRI prenatal diagnosis of various Fetal central nervous system malformations with comparison between the two modalities and focusing upon advantage of each.
Seventy pregnant females were enrolled in our study with their age ranging from 18 to 45 years for a total of 70 fetuses with gestational age ranging from 20 to 32 weeks. This study was conducted in our radiology department for pregnant females-with suspected or diagnosed U/S fetal CNS malformations- referred from the obstetrics & gynecology department. We performed fetal MRI to sonographically diagnosed fetal CNS malformations followed by postnatal brain MRI to 29 % of our cases (20 cases) who were traceable , non-terminated and live birth cases.
Eighty percent of the pregnant females in the study were older than 34 years old .That made an allusion that advanced maternal age could participate to the role of increased risk of congenital anomalies including CNS anomalies.
A spotlight had been put upon the possible risk factors in fetal CNS anomalies , where 66% of the cases in the study were found out to be nearly with parental positive consanguinity, while 60% of the total cases suffered perinatal maternal infection whether with or without fever, influenza like symptoms , hepatitis B/C . 12% of our cases skipped folic acid administration during pregnancy. Lastly; 22% of the cases in the study had history of breeding animals prenatally.
The CNS abnormality findings detected in the study had been illustrated, where the most detectable anomaly in the study was found out to be the hydrocephalus (70% of the cases) , whether isolated (38.5 %) or with other CNS associations (31.4 %). This was followed by the posterior fossa anomalies which accounted for 24.2 % of our cases & then the callosal dysgenesis which accounted for 14% of the cases, classified as isolated finding (2.8%) or associated with other CNS associations (11.2%).
In cases of VM , we compared degree of VM in ultrasound versus MRI, which revealed that VM measured in MRI was about 1-2 mm > that measured in U.S. without notable changing in the VM grade.
Fetal MRI additional abnormalities were yielded in 17 cases which constituted about 24% of our cases, more pronounced after 24 weeks GA. Callosal and septum pellucidum lesions were found out to be the most commonly detected additional abnormality accounting for 53% (subdivided as 29.4% constituting the only evident additional abnormality , while 23.6% as those with other fetal MRI additional abnormalities), followed by posterior fossa abnormalities (29.4%) & then cortical malformation (17.7%) accounted for major percent of the significant fetal MRI additional findings. Fetal MRI also changed sonographic diagnosis in about 4 cases (5.7%) and confirmed 70% of prenatal sonographically diagnosed cases in the study.
A conclusion was approached in the study concerning how presence of structural CNS abnormalities in hydrocephalic cases manipulate management rather than the degree of VM dilatation. where we found out that additional abnormalities in VM cases had high association with termination of pregnancy compared to isolated VM cases.
In addition to aiding in management and prediction of the neurodevelopmental outcome , fetal MRI additional abnormalities were noted to give a clue about the possibility of recurrence & the need for genetic testing in the diagnosed fetal brain malformations as well.
We also Compared between fetal MRI & prenatal U.S findings to those of postnatal MRI in 20 cases, where fetal MRI findings approached those of postnatal MRI to a great extent unlike those of prenatal U.S where variations were notable between them which render fetal MRI surpassing prenatal U.S regarding the complete precise fetal CNS malformation diagnosis.
Although the study revealed that fetal MRI is superior to ultrasound regarding the cortical malformations and periventricular abnormalities, the corpus callosal dysgenesis , the posterior fossa assessment , as well as the extension of the CNS tumours and cysts. On the other hand ,It also revealed that Prenatal ultrasound proved better in detection of intracranial calcifications, intra-tumoral vascularity as in the case of sacrococcygeal teratoma, fetal face with detection of cleft lips & bony abnormalities as in cranio-synostosis by means of surface rendering (skeletal mode) and associated extra-CNS bony dysplasias.