The prevalence and the adding value of fetal MRI imaging in midline cerebral anomalies

Fetal corpus callosum abnormalities: Ultrasound and magnetic resonance imaging role

The corpus callosum (CC) is the major interhemispheric commissure and its abnormalities include agenesis, hypoplasia, and hyperplasia. The CC anomalies are typically related to other central nervous system (CNS) or extra-CNS malformations. The antenatal diagnosis of complete CC agenesis is easy after mid-trimester by ultrasound (US) even in the axial plane. The non-visualization of cavum septum pellucidum and colpocephaly are critical signs in the axial view. More subtle findings (i.e., hypoplasia and partial agenesis) might also be recognized antenatally. In this review, the focus was given on the prenatal diagnosis of CC abnormalities in US and magnetic resonance imaging.

Fetal brain imaging: A comparison between fetal ultrasonography and intra uterine magnetic resonance imaging (a systematic review and meta-analysis)

OBJECTIVE

The aim of this study was to compare ultrasound (US) and intra uterine MRI (IUMRI) of the brain in the diagnosis of fetal brain abnormalities.

METHODS

The present systematic review is done based on guidelines for preferred reporting items for systematic reviews and meta-analysis. All major articles comparing fetal US with IUMRI in fetuses with suspected brain abnormalities were qualified. Articles published before 2010 were excluded from the study. An I²  > 20% was considered as a sign of significant change. The statistical analysis was done using STATA -15 and Meta-Disk 1.4 applications.

RESULTS

Five articles were considered for meta-analysis. The sensitivity of US and IUMRI in diagnosing fetal abnormalities were 86% and 95%, respectively. The corresponding rates for specificity were 77% and 80%. IUMRI and US were concordant in 72.5% (95% CI: 68%-77%) of diagnoses. However, IUMRI added information in 21.7% of cases, while US added value was only 1.48.

CONCLUSION

Our results approved the good diagnostic performance of both US and IUMRI in confirming fetal brain normal development and emphasized that US is an appropriate screening technique in pregnancy. In cases of detected abnormalities in US, IUMRI is suggested as it was the most accurate imaging method and added information about the diagnosis in 22.2% of cases.

Diagnosis of central nervous system abnormalities: comparison of prenatal neurosonography and foetal magnetic resonance imaging findings

Magnetic resonance imagining (MRI) is gradually becoming the more preferred imaging modality in the evaluation of central nervous system (CNS) abnormalities rather than foetal ultrasonography (USG). The aim of this study was to compare the findings of prenatal neurosonography and foetal MRI. The study was a retrospective study analysing the records of 160 pregnant women who underwent both foetal MRI and USG due to suspicion of CNS abnormalities between 2008 and 2019. Indications for applying foetal MRI were neurosonography and foetal MRI findings. When the compatibility between MRI and USG results was examined in CNS abnormalities, it was found fully compatible in 61.3% of cases, partially compatible in 24.53% of cases, and not compatible in 14.5% of cases. When comparing prenatal neurosonography and foetal MRI findings, additional findings were reported in 16.9% of cases, and no additional finding was reported in 66.8% of cases. While normal anatomical findings were reported in 8.8% of the cases in MRI, the diagnosis made by neurosonography changed in 7.5%. Foetal MRI has more advantages than USG both in imaging the CNS abnormalities in more detail and in determining the accompanying additional anomalies.IMPACT STATEMENTWhat is already known on this subject: USG is a safe, practical and cost-effective primary imaging method that is widely used for foetal anomaly screening. However, there may sometimes be difficulties in evaluating the foetal brain structures due to foetal position which is unsuitable for imaging, extremely obese with a high body mass index, oligohydramnios and ossified foetal skull. For this reason, magnetic resonance imaging (MRI) is used as the most commonly used imaging method after USG in the evaluation of foetal anatomy, especially CNS.What do the results of this study add?: In our study, we saw that foetal MRI has more advantages than neurosonography in both seeing CNS abnormalities in more detail and recognising additional anomalies that may accompany.What are the implications of these findings for clinical practice and/or further research?: We have seen that besides neurosonography, foetal MRI can provide important information that can affect the clinical approach in pregnancy management by increasing the correct diagnosis in pregnancies with congenital CNS abnormalities. MRI: it is the best secondary imaging modality that can aid diagnosis in addition to neurosonography in the diagnosis of CNS abnormalities and in suspected cases. Therefore, foetal MRI should be used more widely in prenatal diagnosis.