الفهرس 
IntroductionOnly 14 pages are availabe for public view
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Abstract
The main purpose of prenatal diagnosis is to gather genetic, anatomical,
biochemical and physiological information about the fetus to detect potential
abnormalities that may have impacts both during the fetal period and after birth.
Thus, we can provide families with information, genetic counselling, and/or
therapeutic alternatives for any anomalies detected .
Ultrasonography (US) is the primary imaging modality for the evaluation of the
fetus. It is safe for both fetus and mother, is relatively inexpensive, allows realtime
imaging, and is readily available. However, US may be limited in cases of
oligohydraminos, large maternal body habitus, or complex fetal anomalies,
particularly when scanning is performed late in gestation. In these cases,
Magnetic resonance (MR) imaging appears as a good alternative imaging
modality that provide additional information that can improve diagnostic
accuracy and facilitate treatment decisions.
MRI examination allows a global evaluation of a case, through the analysis of
both anatomy of the district of interest and its possible disruption expressed by
modifications in signal intensity of parenchyma and affected organs.
MRI is definitely a valuable addition to the diagnostic list in the assessment of
fetal lung development, due its ability not only to provide detailed structural,
but also biochemical and functional information, which cannot be obtained by
ultrasound.
The main MRI techniques, used to analyze the process of the fetal lung growth
and abnormalities are MRI volumetry, assessment of signal intensities, and MR
spectroscopy .
Conclusion
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MRI can be used accurately for early diagnosis of different fetal anomalies
(Pulmonary hypoplasia, congenital diaphragmatic hernia, cystic adenomatoid
malformation, bronchogenic cyst, tracheal or bronchial atresia).
Fetal MRI might be useful in the evaluation of the signal intensity in lungs,
considering that some studies have indicated a relationship between the signal
intensity and the characterization of pulmonary hypoplasia. Lung volume
calculation has shown to be a better marker than the signal analysis in the
evaluation of pulmonary hypoplasia.
MRI is a method of choice for distinguishing congenital diaphragmatic hernia
from congenital cystic adenomatoid malformations.
In cases of congenital diaphragmatic hernias, the localization of the left hepatic
lobe plays a relevant role in the determination of the perinatal prognosis because
isolated “liver-up” and “liver-down” congenital diaphragmatic hernias are
related to a perinatal mortality rate of respectively 57% and 7%.
The additional use of other than T2-weighted sequences allows specifying fetal
tissue characteristics and may provide information related to functional qualities
of organs.
The knowledge gained about fetal lung fluid dynamics has led to the
development of new strategies in fetuses with congenital diaphragmatic (CDH).
The surgical technique of fetoscopic tracheal occlusion (FETO) is now
available to prenatally treat severe pulmonary hypoplasia in CDH.
Conclusion
162
Recent developments of new real-time sequences during free breathing without
cardiac triggering have established a potential role of MRI in the study of fetal
heart: MRI can study the morphology using steady-state free precession (True
FISP) sequences on sagittal, coronal and axial planes, orthogonally oriented to
the fetal diaphragm and allows to identify the viscero-atrial situs, the heart and
its axis. It is also possible to perform a dynamic study, through the acquisition
of cine-MR sequences with real-time steady state free precession (SSFP)
oriented according to the standard projections used in fetal echocardiographic
scanning. MRI can analyze the normal anatomy by transverse, long axis and
angulated views to visualize the principal cardiac planes.
However, the use MRI in evaluating fetal heart still reveals some diagnostic
limitations secondary to two typologies of factors: intrinsic and extrinsic.
The first intrinsic limitation concerns technical problems: it is still
necessary to develop the equipment in order to overcome some lacks such
as the low spatial and temporal resolution. Because of these limitations it
is not possible to reproduce or give direct information about valvular or
rate diseases.
The second extrinsic limitation is the still limited experience that is based
on the few data still available in the literature. Multicentric studies are
therefore necessary to acquire more experience, to construct biometric
reference limits and generate diagnostic guidelines.
In the immediate future the use of dedicated sequences, with potential pseudoangiographic
study, might open new horizons. Similarly the application of new
3T magnet field equipments might increase spatial resolution. New
possibilities of therapeutic treatments during prenatal period will undoubtedly
require further efforts to reach higher image quality.