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 GeneticsMount Sinai Hospital Departments of Medical Imaging, Prenatal Diagnosis & Medical Genetics and Obstetrics & Gynaecology

The University of Toronto, Ontario, Canada

Check for signs of fetal life

Normal cardiac signal void

Signal dropout from fetal cardiac activity

PurposeMost 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.

Suggested reading•Saguintaah M. Couture A. Veyrac C. Baud C. Quere MP. MRI of the fetal gastrointestinal tract. Pediatric Radiology. 32(6):395-404, 2002 Jun.•Coakley FV. Hricak H. Filly RA. Barkovich AJ. Harrison MR. Complex fetal disorders: effect of MR imaging on management--preliminary clinical experience. Radiology. 213(3):691-6, 1999 Dec.•Levine D. Barnewolt CE. Mehta TS. Trop I. Estroff J. Wong G. Fetal thoracic abnormalities: MR imaging. Radiology. 228(2):379-88, 2003 Aug.•Shinmoto H, Kuribayashi S. MRI of fetal abdominal abnormalities. Abdom Imaging. 2003 Nov-Dec;28(6):877-86.•Coakley FV, Glenn OA, Qayyum A, Barkovich AJ, Goldstein R, Filly RA. Fetal MRI: a developing technique for the developing patient. AJR Am J Roentgenol. 2004 Jan;182(1):243-52.•Zaretsky MV. Ramus RM. Twickler DM. Single uterine axial fast acquisition magnetic resonance fetal survey: is it feasible?. Journal of Maternal-Fetal & Neonatal Medicine. 14(2):107-12, 2003 Aug.•Caire JT. Ramus RM. Magee KP. Fullington BK. Ewalt DH. Twickler DM. MRI of fetal genitourinary anomalies. AJR. American Journal of Roentgenology. 181(5):1381-5, 2003 Nov.•Chen CP. Shih JC. Huang JK. Wang W. Tzen CY. Second-trimester evaluation of fetal sacrococcygeal teratoma using three-dimensional color Doppler ultrasound and magnetic resonance imaging. Prenatal Diagnosis. 23(7):602-3, 2003 Jul.

Materials and MethodsRetrospective 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 amniotic fluid volume.

ConclusionFollowing on from the previous poster, we demonstrate a practical guide for the analysis of the rest of the fetus (non-CNS), including how to perform the biometric measurements, and examples of normality and basic abnormalities.

Oligohydramnios & no signal dropout – fetal death in utero

Normal “swirling” appearance of amniotic fluid

Check fetal number, chorionicity, amnionicity & presentation

Two placentas (P) with membrane (M)

Dichorionic diamniotic twins Breech presentation Cephalic presentation

Fetal head opposite bladder Fetal head adjacent to bladder

Motion artefact from fetusAbnormal cardiac signal void

Check amniotic fluid volume – subjective assessment is most reliable

No fluid visible around fetus Fluid completely surrounding fetus

Oligohydramnios Polyhydramnios

Check placental location and attachment

Placenta (P) covering internal os (O) Attached directly to myometrium Invaded into myometrium Invaded through serosa

Biometry (see CNS poster)

Esophageal atresia

Congenital diaphragmatic hernia

Congenital high airway obstruction

Normal situs Normal levocardia Normal aortic archAbdominal circumference

Normal stomachH-type tracheo-esophageal

fistula

Pulmonary hypoplasia secondary to oligohydramnios

Normal lower limbs & feet

Bladder outlet obstruction

Normal 3-vessel cord

Horseshoe kidney

Normal handsNormal arm

Exomphalos

Normal kidneys - sagittal

Normal bladder sagittal

Normal gallbladder

Normal kidneys - axial

Normal bladder axial

Debris in stomach

Normal liver Liver hemangioma

Check the kidneys & bladder

Check lungs & diaphragms

Check stomach, liver, gallbladder

Check the umbilical cord and its insertion

Check the extremities – presence of four limbs plus hands & feet

Check situs – work out which side is fetal left/right BEFORE checking internal organs

Maternal Tarlov cystXYXX

Genitalia – sex can be helpful in diagnosis

Physiological hydronephrosis

Maternal structures – make sure of no serious pathology

Correct level = true axial through junction of portal veins

Aortia passes left of trachea on same side as stomach

Cardiac silhouette to left of thorax Shepherd’s crook-shaped flow void

Diaphragms should clearly divide thorax from abdomen

Diaphragms inverted, lungs enlarged and increased signal

Diaphragm incomplete, stomach (S) & bowel (B) in chest

Lungs small and abnormally low signal

Normal diaphragms

Placenta previa Placenta accreta Placenta increta Placenta percreta

Gastroschisis

Talipes

Check the stomach, usually ovoid or biconcave and seen to change size during scan

Normal liver should be low signal on SSFSE

No stomach seen during scan, polyhydramnios

Small (not absent) stomach, with polyhydramnios

Fetus may swallow blood in amniotic fluid from placental abruption or amniocentesis

Often seen, usually ellipsoid Abnormal low signal liver on T2* sequences

Check for focal parenchymal abnormalities

“Neonatal” hemochromatosis

Check the fetal genitalia Don’t confuse penis (P) & cord (C)

XY

Check the maternal kidneys Check the maternal spine

Placenta anterior, no previa

Renal pelvis should not measure >5mm AP at any age

Renal length (mm) = age (weeks) approximately

Renal tissue seen crossing the midline

Normally ovoid or bean-shaped.

Should be seen to fill and empty during scan. If not seen, wait and re-scan.

Enlarged bladder (B) reaching umbilicus, urinary ascites (A)

from renal rupture

Make sure there is a proximal and distal component

Make sure hands are present Only assess for talipes if foot is away from uterine wall

Feet are clearly both inverted with respect to the body (B)

Two arteries (smaller) and one vein (larger)

Bowel (B) & liver (L) outside fetus, membrane-covered

Loops of bowel outside of fetus, cord inserts to side

normalNormal amniotic fluid volume

B

L

B

Normal cord insertion

Abdominal wall suface should be complete

B

A

P C

SB

PP

M

P

O

Multicystic dysplastic kidneys

Kidneys enlarged with multiple small cortical cysts

Erum Manif absent KUB

Oligohydramnios, neither kidney present, adrenals are

clearly seen however

Renal agenesis