MR Imaging of the Fetus in utero II: A Practical Guide to Systematic Analysis - ….. and the rest (non-CNS)

A Robinson, S Blaser, S Pantazi, A Toi, D Chitayat, M Gundogan, G Ryan The Hospital for Sick Children Departments of Diagnostic Imaging and Clinical & Metabolic Genetics Mount Sinai Hospital Departments of Medical Imaging, Prenatal Diagnosis & Medical Genetics and & Gynaecology The University of Toronto, Ontario, Canada

Purpose Biometry (see CNS poster) Check situs – work out which side is fetal left/right BEFORE checking internal organs Check the kidneys & bladder Most of our examinations are performed for CNS indications, with which most neuroradiologists should feel comfortable. However these examinations also include a variable amount of non-CNS anatomy with which neuroradiologists might feel less comfortable, but which should be reviewed routinely also, and not simply glossed over or even worse ignored.

Materials and Methods Retrospective analysis of was performed in over 190 consecutive fetal MR examinations performed for CNS and non- CNS indications. Analysis included, but was not limited to, evaluation of thoracic and abdominal situs, lung parenchyma, diaphragms, liver and gallbladder, stomach, kidneys (including biometry), bladder, cord insertion, cord vessels, placental site and morphology, and volume. Abdominal circumference Normal situs Normal levocardia Normal aortic arch Normal kidneys - axial Multicystic dysplastic kidneys Normal kidneys - sagittal Horseshoe kidney

Conclusion Correct level = true axial through Aortia passes left of trachea on Cardiac silhouette to left of thorax Shepherd’s crook-shaped flow Renal should not Kidneys enlarged with multiple Renal length (mm) = age Renal tissue seen crossing the Following on from the previous poster, we demonstrate a practical guide for the analysis of the rest of the fetus (non- junction of portal veins same side as stomach void measure >5mm AP at any age small cortical cysts (weeks) approximately midline CNS), including how to perform the biometric measurements, and examples of normality and basic abnormalities. Check for signs of fetal life Check lungs & diaphragms

A

B S ErumRenal Manif agenesis absent KUB Normal bladder axial Normal bladder sagittal Bladder outlet obstruction B Normal diaphragms Congenital high airway Congenital diaphragmatic Pulmonary hypoplasia Oligohydramnios, neither Normally ovoid or bean- Should be seen to fill and Enlarged bladder (B) reaching obstruction hernia secondary to oligohydramnios Normal cardiac signal void Abnormal cardiac signal void Motion artefact from fetus kidney present, adrenals are shaped. empty during scan. If not umbilicus, urinary ascites (A) clearly seen however seen, wait and re-scan. from renal rupture Diaphragms should clearly divide Diaphragms inverted, lungs Diaphragm incomplete, stomach Lungs small and abnormally low Signal dropout from fetal Oligohydramnios & no signal Normal “swirling” appearance thorax from abdomen enlarged and increased signal (S) & bowel (B) in chest signal cardiac activity dropout – fetal death in utero of amniotic fluid Check the extremities – presence of four limbs plus hands & feet Check fetal number, chorionicity, amnionicity & presentation Check stomach, liver, gallbladder

P P

M B

Normal arm Normal hands Normal lower limbs & feet Talipes H-type tracheo-esophageal Dichorionic diamniotic twins Breech presentation Cephalic presentation Normal stomach Esophageal atresia fistula Debris in stomach Make sure there is a proximal Make sure hands are present Only assess for talipes if foot Feet are clearly both inverted and distal component is away from uterine wall with respect to the body (B) Two (P) with membrane (M) Fetal head opposite bladder Fetal head adjacent to bladder Check the stomach, usually No stomach seen during scan, Small (not absent) stomach, Fetus may swallow blood in ovoid or biconcave and seen with polyhydramnios amniotic fluid from placental to change size during scan abruption or Check the umbilical cord and its insertion Check amniotic fluid volume – subjective assessment is most reliable

L

B

Normal liver Normal gallbladder “Neonatal” hemochromatosis Liver hemangioma Normal 3-vessel cord Normal cord insertion Exomphalos Gastroschisis Oligohydramnios Normal amniotic fluid volume normal Polyhydramnios Normal liver should be low Often seen, usually ellipsoid Abnormal low signal liver on Check for focal parenchymal Two arteries (smaller) and one Abdominal wall suface should Bowel (B) & liver (L) outside Loops of bowel outside of signal on SSFSE T2* sequences abnormalities vein (larger) be complete fetus, membrane-covered fetus, cord inserts to side No fluid visible around fetus Fluid completely surrounding fetus

Check placental location and attachment Genitalia – sex can be helpful in diagnosis Maternal structures – make sure of no serious pathology Suggested reading

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