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Radiology
Magnetic Resonance Imaging in Obstetrics
Built from Obstetric Imaging
What’s inside
9 sections · 123 slides
Overview
- Fetal magnetic resonance imaging: what it is
- Fetal regions assessed by MRI
Role of MRI alongside ultrasound
Why a second imaging test is asked for, and when
- Limitations of obstetric ultrasound
- Advantages of MRI over ultrasound
- Diagnostic gain of adding MRI to ultrasound
- American College of Radiology guidance on fetal MRI
- Referral pathway to a fetal MRI
- Prerequisites for performing and reading a fetal MRI
- Timing of the examination
Technique and sequences
The magnet, the sequences, and what each one shows
- Magnetic field strength: 1.5 T and 3 T
- Ultrafast acquisition and fetal motion
- Fast T2-weighted sequences
- Echoplanar T2-star imaging
- T1-weighted gradient-echo sequences
- Diffusion-weighted imaging
- Functional MRI sequences
- MRI sequence families in fetal imaging
- Signal on T2- versus T1-weighted images
The fetal brain
Normal maturation, and the malformations MRI is asked to settle
- Why MRI performs well in the fetal brain
- Normal brain development as a moving target
- Germinal matrix and white matter signal
- Neuronal migration and the five-layered pattern
- Normal fetal brain maturation on coronal T2 images
- Cortical folding of the fetal brain at 36 weeks
- Analysis of sulcation and cerebral biometry
- Common indications for fetal brain MRI
- Cortical development and the Sylvian sulcus
- Disorders of cortical development
- Undermigration: lissencephaly type 1 and heterotopia
- Subependymal nodules of tuberous sclerosis
- Subependymal nodules in a fetus with tuberous sclerosis
- Overmigration: lissencephaly type 2
- Polymicrogyria
- Normal lateral ventricles through gestation
- Ventriculomegaly: definition and significance
- Causes of ventriculomegaly
- Structural causes of ventriculomegaly
- The corpus callosum on fetal MRI
- Normal corpus callosum and posterior fossa at 31 weeks
- Ultrasound clues to callosal abnormality
- Spectrum of callosal abnormalities
- What MRI must exclude in callosal dysgenesis
- Complete agenesis of the corpus callosum at 31 weeks
- Holoprosencephaly
- Normal posterior fossa development
- Enlarged retrocerebellar fluid space
- Dandy-Walker malformation and its mimics
- Dandy-Walker malformation in a 33-week fetus
- Acquired brain lesions: causes
- Intracranial signs of prenatal infection
- Ischemic and hemorrhagic brain injury
- Vein of Galen malformation
- Fetal intracranial tumours
- Arachnoid cysts
Spine, thorax and lungs
Neural tube defects, lung lesions and diaphragmatic hernia
- Fetal spine: limitations of ultrasound
- Neural tube defects and spinal masses
- Fetal lung abnormalities
- What MRI adds in fetal lung lesions
- Normal fetal lung signal on T2
- Cystic lung lesions and sequestration
- Bronchial atresia
- Congenital diaphragmatic hernia: what MRI answers
- Left congenital diaphragmatic hernia at 28 weeks
- From diaphragmatic defect to postnatal prognosis
- Lung volume measurement in diaphragmatic hernia
- Fetal endoscopic tracheal occlusion
- How tracheal occlusion enlarges the fetal lung
- Diffusion MRI of the fetal lung
Face, abdomen and urinary tract
Airway masses, bowel obstruction, abdominal wall and uro-MRI
- Fetal face and neck masses
- Cleft lip and palate
- Gastrointestinal tract: when MRI is added
- Meconium and MRI colonography
- Normal fetal bowel on T1-weighted images
- Distal bowel atresia in a 29-week fetus
- Abdominal cystic masses
- Abdominal wall defects
- Genitourinary anomalies and the value of MRI
- What uro-MRI can analyse
- Dilated urinary tract on uro-MRI at 33 weeks
- Complex urogenital anomalies
Heart and skeleton
Where echocardiography and ultrasound still lead
- Fetal heart: role of MRI
- Advances in fetal cardiovascular MRI
- Skeletal dysplasia
The placenta
Abnormal invasion, and functional imaging of placental physiology
- The normal placenta on MRI
- Placenta accreta spectrum
- MRI features sought to document accreta
- Placenta praevia with and without accreta
- Placenta accreta on sagittal T2
- Diffusion imaging of the placenta
- BOLD, arterial spin labeling and contrast-enhanced placental MRI
- Functional placental MRI techniques
- Gadolinium and the status of placental functional MRI
Other applications and safety
Postmortem imaging, labour, twins, and what is known about risk
- Virtuopsy: imaging as an alternative to autopsy
- MRI in labor and delivery
- Monochorionic twins: why the brain is at risk
- Brain injury after death of a co-twin
- Safety of the magnetic field in pregnancy
- Gadolinium contrast in pregnancy
- What the referring physician needs to know
- Composition of the fetal MRI team
- 1.5 T
- Key points
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- Obstetric Imaging: Fetal Diagnosis and Care, 2nd Edition