V. Pinto

Sonographic diagnosis of fetal cerebral ventriculomegaly: An update

Dilatation of the fetal cerebral ventricles (ventriculomegaly) is a generic sonographic sign that is common to several pathological entities carrying different prognoses. The main causes of fetal ventriculomegaly are aqueductal stenosis, Chiari II malformation, Dandy–Walker complex, and agenesis of the corpus callosum. Ventriculomegaly is easily recognized by ultrasound by measuring the atrial width. This simple measure allows the recognition of mild forms of ventricular dilatation and is used in screening for ventriculomegaly. However, although the diagnosis of ventriculomegaly is easy, the prenatal identification of the cause of ventricular dilatation is a more difficult task. For this purpose the evaluation of the posterior fossa in association with the visualization of the corpus callosum is useful. Research into the causes of ventriculomegaly is clinically useful, since the prognosis mainly depends on the etiology and on the presence of associated abnormalities. In this article the role of prenatal sonography in determining the cause of the ventriculomegaly is reviewed, as well as the prognostic value of the prenatal sonographic findings.

Comparison of six sonographic signs in the prenatal diagnosis of spina bifida.

Abstract Aims: To compare the diagnostic accuracy of sonographic signs that may be looked for in fetuses with spina bifida. Methods: Forty-nine fetuses affected by spina bifida were enrolled, at a gestational age of 18–28 weeks. The following sonographic signs were looked for: “lemon” sign, small cerebellum, effaced cisterna magna, small posterior fossa, ventriculomegaly and direct visualization of a spinal defect. Results: The “lemon” sign was present in 53%, a small cerebellum in 96%, an effaced cisterna magna in 93%, a small posterior fossa in 96%. Ventriculomegaly was present in 40/49 (81%) cases and was severe in 20 fetuses and borderline in the remaining 20. The spinal defect was missed in one fetus presenting the cerebellar and posterior fossa signs. In two fetusus, the myelomeningocele was present without cranial signs of Chiari II malformation and in both cases the defect was covered by intact skin. Conclusions: Our results confirm the usefulness of evaluation of the posterior fossa in the diagnosis of spina bifida, particularly in cases of small spinal defects that may be missed at ultrasound. Conversely, myelomeningocele covered by intact skin was not associated with the cranial signs of Chiari II malformation.

The specificity of ultrasound in the detection of fetal intracranial tumors.

AIMS To evaluate the specificity of ultrasound in identifying fetal brain neoplasms and its accuracy in the diagnosis of the tumors histological type. METHODS A retrospective evaluation of 7 cases of fetal brain tumors occurred at our unit in the period between January 92 and June 98 has been performed. All prenatal ultrasonographic diagnoses were compared with the postnatal findings on the aborted fetuses (post-mortem examination) or on the newborns (MRI or post-mortem examination). RESULTS In 6 out of 7 cases the antenatal ultrasonographic diagnosis of brain tumor was confirmed postnatally, in one case a supratentorial arachnoid cyst was mistaken for a teratoma with cystic components (86% specificity in the diagnosis of congenital brain neoplasms). Out of the 6 cases of suspected teratomas, one revealed to be a glioblastoma, one an arachnoid cyst and one a primitive neuroectodermal tumor. The prenatal diagnosis was confirmed in the case of choroid plexus papilloma. Prenatal ultrasonography was accurate in identifying the tumors histological type in the 57% of the cases. The diagnoses were not modified by the transvaginal scans performed in 2 cases. CONCLUSIONS Prenatal ultrasonography is a useful tool to identify any intracranial space-occupying lesion larger than 10 mm. In the present study it has shown an 86% specificity in the diagnosis of brain neoplasms. However the accuracy of ultrasound in diagnosing the tumors histological type was limited (57%).

Prenatal diagnosis and postnatal outcome of cardiac rhabdomyomas

Abstract Aims: To evaluate the sonographic appearance of suspected fetal cardiac rhabdomyomas and their evolution until delivery and in the postnatal period. Methods: The study group consisted of 6 patients at 23–37 weeks of gestation referred to our Ultrasonic Unit, between March 1992 and December 1998, for suspected fetal cardiac rhabdomyomas. Results: The cardiac tumors were single in three cases and multiple in the other cases. The size ranged from 11 to 47 mm. In two cases the tumors arose from the right ventricle, in one case from the interventricular septum and in three cases from the left ventricle. Five infants are alive and in satisfactory hemodynamic compensation, but three of them developed tuberous sclerosis. In two infants a regression in the maximum diameter of the tumor masses has been observed. One child underwent surgical treatment at the age of six months and the baby died after surgery. Conclusions: Two-dimensional and Doppler echocardiography are useful non invasive methods to diagnose fetal cardiac rhabdomyomas and to monitor their influence on the fetal cardiac function. However they do not allow us to recognize which fetuses presenting with features compatible with rhabdomyomas will develop tuberous sclerosis.

Prenatal Sonographic Imaging of an Immature Intracranial Teratoma

This article describes the prenatal sonographic diagnosis of a rare case of intracranial immature teratoma in a fetus at the 35th week of gestation which looked normal at previous examinations. At sonography a markedly enlarged fetal head containing a complex irregular mass and hydrocephalus was detected. Color Doppler examination of the mass showed intense vascularization with low resistance flows.

The midsagittal view of the fetal brain: a useful landmark in recognizing the cause of fetal cerebral ventriculomegaly.

Abstract Aim: To evaluate the positive predictive value of the midsagittal view of the fetal brain in recognizing the cause of ventriculomegaly diagnosed with traditional axial scan. Methods: Fifty-eight pregnant women, referred to our Center following a generic diagnosis of ventriculomegaly have been evaluated: 38 had marked and 20 had borderline ventriculomegaly. The fetal brain was scanned by the midsagittal view using a transabdominal probe in fetuses in breech presentation or transverse lie and a transvaginal probe in fetuses in cephalic presentation. The possible cause of ventriculomegaly was postulated by combining the findings of the corpus callosum/cavum septi pellucidi complex with those of the posterior fossa. The prenatal diagnoses were compared with the anatomical specimens of aborted fetuses or with postnatal neuroimaging. Results: The prenatal diagnoses were confirmed in 54/58 cases (PPV 93.1%). In the marked ventriculomegaly group, one case of partial agenesis of the corpus callosum was mistaken for a complete agenesis. In the group of borderline ventriculomegaly, two cases of partial agenesis of the corpus callosum were confused with a complete agenesis, while one case of suspected isolated ventriculomegaly was diagnosed after birth as partial agenesis of the corpus callosum. Conclusions: The sagittal scan of the fetal brain is a useful source of information and allows the contemporary view of both corpus callosum and posterior fossa, where various typical sonographic findings are present in ventriculomegaly.

Cavum veli interpositi cyst: prenatal diagnosis and postnatal outcome

The cavum veli interpositi (CVI) is a space within the double‐layered tela choroidea of the third ventricle. Occasionally, this space is fluid‐filled and sonographically visible as an interhemispheric anechoic cyst. Because of its rarity, the incidence of CVI cyst is undetermined and the outcome of affected individuals has been found to be variable. The aim of this study was to report our experience of the sonographic findings and outcome of fetuses affected by CVI cysts.

3‐M syndrome: a prenatal ultrasonographic diagnosis

The ultrasonographic imaging of a fetus affected by 3‐M syndrome is described. This is a primordial dwarfism with low birthweight, short stature, facial dysmorphism and normal mental development. The biparietal diameter and head circumference were in accordance with the gestational age at 18 weeks. The femur and tibia lengths were on the fifth centile and the radius, ulna and humerus lengths were below the fifth centile. A second scan at 22 weeks showed slowing of growth of all long bones, with the femur, tibia, fibula, humerus, radius and ulna lengths further below the fifth centile. The pregnancy was terminated and postmortem examination confirmed the prenatal diagnosis. The differential diagnosis of skeletal dysplasias characterized by a slow growth of long bones is discussed and the conclusion reached that the detection of shortened long bones (below the fifth centile) is the only ultrasonographic finding of 3‐M syndrome. Copyright

Fetal Subependymal Cysts with Normal Neonatal Outcome

The authors report the prenatal sonographic diagnosis of subependymal cysts, confirmed by in utero MRI, in an apparently uneventful pregnancy. The sonographic appearance of the lesions, the obstetric management and the postnatal follow-up to one year are described. Special attention is paid to prenatal factors of neurological morbidity, rather than intrapartum and postnatal, thus emphasizing the importance of early and sequential evaluation of the developing fetal brain. Diagnosis, clinical significance and outcome of prenatal subependymal cysts are necessary for parental counselling and obstetric management. Furthermore, the detection of a prenatal brain injury may have remarkable medico-legal implications.

OP03.05: Prenatal diagnosis and outcome of cavum veli interpositi cysts

Objectives: To evaluate the feasibility and the processing time using off-line analysis of 3D brain volumes to perform basic as well as detailed, targeted, fetal neurosonogram. Study design: Three dimensional fetal brain volumes were obtained in 20 consecutive healthy fetuses that underwent routine anatomical survey at 20 to 23 post menstrual weeks. Grey scale and power Doppler volumes of the fetal brain were acquired in the axial, coronal and the sagittal planes using trans-abdominal and transvaginal approaches, respectively. Off-line analysis of each volume was performed by two of the authors in a blinded fashion. Initially, a list containing the basic structures, as defined by ISUOG and AIUM guidelines, complete with intra-cranial biometrical measurements was attempted. Subsequently, we attempted to identify a list of CNS structures recommended by ISUOG guidelines for fetal neurosonogram. Additional structures that were selected by the authors were also sought (see * in table). The feasibility of obtaining diagnostic quality images was evaluated. The processing times of volume acquisition as well as the off-line analysis were recorded. Results: Volume acquisition time was 3–6 sec/volume and a mean processing time of 9.5 and 11 minutes to complete both the ‘basic’ and the ‘detailed’ neurosonogram was recorded by the two examiners, respectively. The feasibility of obtaining diagnostic quality images of the different structures is displayed in the table. Conclusions: Off-line analysis of fetal 3D brain volumes at 20–23 weeks of gestation can identify all the structures necessary to complete a detailed fetal neurosonogram. This approach may provide several potential advantages such as a short processing time, increased safety due to shorter dwell time, increased patient through-put, and the ability to obtain off-site expert consultation if necessary.