Journal of Medical Imaging and Radiation Oncology 59 (2015) 154–162



Isolated ventriculomegaly on prenatal ultrasound: What does fetal MRI add? Tejaswi Kandula,1 Michael Fahey,2 Rebecca Chalmers,3 Andrew Edwards,4 Paul Shekleton,3 Mark Teoh,3 Jenni Clark5 and Stacy K. Goergen2,5 1 2 3 4 5

Monash Childrens, Monash Health, Melbourne, Victoria, Australia Department of Paediatrics, School of Clinical Sciences, Monash University, Melbourne, Victoria, Australia Fetal Diagnostic Unit, Monash Health, Melbourne, Victoria, Australia The Ritchie Centre, Perinatal Services, Monash Health, Monash University, Melbourne, Victoria, Australia Monash Imaging, Monash Health, Melbourne, Victoria, Australia

T Kandula MBBS, FRACP; M Fahey MBBS, PhD, FRACP; R Chalmers MBChB, COGU, FRACOG; A Edwards MBChB, COGU, FRACOG; P Shekleton MBBS, COGU, FRACOG; M Teoh MBBS, COGU, FRACOG; J Clark RN; SK Goergen MBBS, MClinEpi, FRANZCR. Correspondence Clinical Adjunct Professor Stacy K Goergen, Monash Imaging, Monash Health, 246 Clayton Road, Clayton, Vic. 3168, Australia. Email: [email protected] Conflict of interest: The authors declare no actual or potential conflicts of interest in regard to the conduct or reporting of this study. Submitted 4 September 2014; accepted 19 December 2014. doi:10.1111/1754-9485.12287

Abstract Introduction: Cerebral ventriculomegaly is one of the most commonly detected fetal anomalies at the midtrimester ultrasound. Current evidence suggests that magnetic resonance imaging (MRI) is indicated when the isolated ventriculomegaly (IVM) on ultrasound is severe (>15 mm), but there is less agreement when IVM is mild or moderate (10–15 mm). The current study aimed to determine the frequency and nature of additional findings on MRI in IVM and their relationship to the severity of VM and gestational age. Methods: Data were gathered prospectively from all pregnant women with ultrasound-diagnosed IVM referred for MRI between November 2006 and February 2013. Cases with IVM and no other suspected cranial abnormality on a tertiary ultrasound performed at our institution, at or after 20 weeks gestation, were included. Results: Of the 59 fetuses with unilateral or bilateral IVM, additional findings were seen on MRI in 10 cases (17%) and half of these findings were identified in fetuses with mild IVM. Five of 40 (12.5%) fetuses with mild IVM had additional findings and 3/5 (60%) were potentially clinically significant. No additional abnormalities were identified in fetuses less than or equal to 24 weeks gestation with mild or moderate IVM. There was no statistically significant relationship between gestational age and additional findings on MRI in mild IVM. Callosal and septum pellucidum lesions, periventricular abnormalities and malformations of cortical development accounted for all of the significant additional findings. Conclusion: This study helps to inform referral of pregnant women with a fetus who has IVM for prenatal MRI. Key words: fetal imaging; magnetic resonance imaging; obstetric ultrasound; paediatric neuroimaging.

Introduction Aim To evaluate consecutive fetuses with ultrasound (US)detected isolated ventriculomegaly (IVM) at or after 20 weeks’ gestation that were referred for prenatal fetal


MRI (PMRI) following prenatal US performed in a tertiary referral centre in order to: 1 Measure the frequency of additional cranial abnormalities demonstrated by PMRI 2 Determine whether the occurrence of additional abnormalities was associated with

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Fetal MRI in ultrasound isolated ventriculomegaly

• the severity of ventriculomegaly (VM) • the latest gestational age (GA) at which IVM was demonstrated by US prior to PMRI • the GA at which PMRI was first performed 3 Describe additional findings demonstrated with PMRI and correlate these with post natal MRI or postmortem (PM) examinations.

Background Mid-trimester US at 19–22 weeks’ gestation is performed to screen for fetal structural abnormalities.1 Cerebral VM, defined as a maximum lateral ventricular atrial diameter greater than 10 mm, is one of the most commonly identified abnormalities2 and is a marker for increased risk of chromosomal abnormality, infection and malformations.3 PMRI has been used to improve diagnosis of fetal structural abnormalities identified or suspected on US and to screen fetuses with genetically high risk of brain abnormalities but normal US.4–6 As the severity of VM increases, so does occurrence of associated abnormalities and adverse neurodevelopmental outcome, even when other abnormalities are absent.7,8 Additional abnormalities are found on US when VM is severe in about 60% of fetuses9,10 and in those with borderline VM (10–12 mm) in 6–76%.3,9 Prognosis for fetuses with VM and associated abnormalities depends on type and severity of the associated abnormalities and presence of chromosomal or genetic abnormality or prenatal infection. The classification of VM has varied in published studies, but mild (10–12 mm), moderate (>12–15 mm) or severe (>15 mm) is a commonly accepted categorisation. Fetal outcome when VM is isolated (IVM) is determined by severity; mild IVM is associated with a normal neurodevelopmental outcome in 90–100% of cases.9,10 Although there appears to be good agreement between US and PMRI about the degree of VM, additional structural abnormalities have been demonstrated by MRI in 5–44% of cases when US demonstrated IVM.11–19 The few studies that have analysed the additional diagnostic information provided by PMRI in the setting of IVM on midtrimester US have been heterogeneous in design. Variations in the performance of prenatal US in the community vs. tertiary referral centre; prenatal screening for TORCH (toxoplasmosis, rubella, cytomegalovirus, herpes) infections and/or amniocentesis to exclude fetal infection and major chromosomal abnormalities; GA at the time of PMRI; performance of postnatal imaging; PM; and/or clinical follow to validate PMRI findings as well as variable documentation and analysis of additional findings by GA of the fetus or degree of IVM make it difficult to provide clear practice recommendations regarding which fetuses with IVM at what stage of gestation are most likely to have additional useful information provided by PMRI.

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Patients and methods Consecutive pregnant women referred for clinically indicated PMRI between November 2006 and February 2013 at the discretion of the Fetal Diagnostic Unit (FDU) of our institution, because of US-detected IVM, were the subjects of this study. The FDU at our institution is a level 1 referral centre for our state for fetal diagnosis and therapy and is situated in a teaching hospital affiliated with a university department of obstetrics and gynaecology. Institutional Human Research Ethics Committee approval was granted to allow access to the medical records of our patients in order to obtain information about postnatal imaging, PM examinations, results of amniocentesis and TORCH testing. Informed consent to access these records was not obtained from patients. All patient data were de-identified and stored in a password protected database accessible only to the principal investigators.

Inclusion criteria 1 US-diagnosed IVM (one or both ventricles measuring 10 mm or more in maximum diameter on an axial US image at the level of the ventricular atrium) on prenatal US performed at or after 20 weeks’ GA. VM was defined as mild (10–12 mm), moderate (>12– 15 mm) or severe (>15 mm). VM was classified as symmetric or asymmetric, with asymmetric VM defined as enlargement of a single ventricle or ventricular enlargement that was discordant by 3 mm or more. 2 US performed at our institution by our fetal diagnostic unit obstetrician sonologists.

Exclusion criteria Patients were excluded from the study if the PMRI could not be completed due to patient refusal or if the diagnosis of suspected IVM in a patient referred from another institution or practice was not confirmed when the US was repeated at our institution. Technically suboptimal MRI was not an exclusion criterion as long as sufficient images were acquired for diagnostic purposes, and a written report on the examination was provided by the interpreting radiologist.

PMRI technique The MRI was carried out on a 1.5T Siemens Avanto MRI scanner (Erlangen, Germany) using an eight-channel six-element body matrix coil in conjunction with a 24-element phased array spinal coil. Sedation was not routinely administered to subjects unless repeated attempts at image acquisition were substantially degraded by motion. In this situation, up to 1 mg of midazolam was given to the pregnant woman as a statim


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dose into an antebrachial superficial vein. The PMRI was performed as close as practicable to the prenatal US. The PMRI images were prospectively interpreted by one of two radiologists with 7 and 3 years’ experience, respectively, in the interpretation of PMRI and longer experience with paediatric neuroimaging interpretation. Measurement of lateral ventricular diameter was made on each side at the widest point of the trigone of the lateral ventricle on the relevant axial T2 HASTE image. The choroid plexus is poorly visualised on T2 HASTE MR images and thus was not used as a landmark for taking this measurement as it is with US. The radiologists were aware of the US findings at the time of interpretation.

Data collection and analysis Measurement of ventricular size at the time of the latest US (if multiple US exams were performed) preceding PMRI was recorded as was the GA at the time of this US. Findings on PMRI and the GA at the time of PMRI were recorded (if multiple PMRI exams were performed, the result of the first one was recorded for the purpose of this study). 1 Occurrence of additional findings was categorised by GA (20–24/40, 25–35/40 and >35/40) as well as severity of IVM at the time of the latest US preceding the PMRI. Fisher’s exact test was used to determine, at a 95% level of significance, if there was:

2 a relationship between additional findings at PMRI and GA 20–24 /40 compared with 25/40 or more when VM was mild and 3 a relationship between additional findings at PMRI and degree of VM (mild vs. moderate – severe) when GA was 20–24 weeks. Specialist counselling of the pregnant patients, whose fetuses were our study subjects, was carried out both before and after the PMRI. Amniocentesis to determine the presence of aneuploidy was offered but not performed in all cases, depending on maternal consent. Maternal screening for TORCH infections was similarly performed variably at the discretion of the FDU. Information about the performance and results of TORCH screening and amniocentesis as well as pregnancy outcome, postnatal imaging and PM examinations was collected, where available, from the patient medical records for the pregnant women, fetuses and infants. PM examinations were performed by a fetal/neonatal pathologist with over 20 years’ experience in the performance of fetal and neonatal PM examinations in the context of terminated pregnancies, stillbirth and neonatal death. No formal neurodevelopmental assessment was conducted on live born infants.

Results Fifty-nine fetuses were diagnosed with unilateral or bilateral VM but no other sonographically detected cranial abnormality between November 2006 and February 2013 (Figs 1–6). There were 53 singleton and six twin

Fig. 1. Occurrence of additional abnormalities stratified by GA at PMRI and severity of IVM on US. VM, isolated ventriculomegaly on prenatal ultrasound.


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Fetal MRI in ultrasound isolated ventriculomegaly

Fig. 2. (a and b) Agenesis of the corpus callosum with absent septum pellucidum at 22 weeks’ gestation. The arrow indicates the fornices. Severe isolated ventriculomegaly was identified on ultrasound at 22 weeks. Diagnosis confirmed at postmortem.

pregnancies. All of the twin pregnancies had a single fetus affected with IVM, and this single fetus in each twin pregnancy was included in our sample of 59. Median GA at US was 26 weeks (interquartile range (IQR) 24–31 weeks) and at PMRI was 28 weeks (IQR 25.2–32 weeks). Maternal serum screening for TORCH infections was performed in 36 pregnancies including 62.5% (25/40) of fetuses with mild VM, 66% (8/12) of those with moderate VM and 42.8% (3/7) of those with severe IVM. Amniocentesis was performed in 18 of 59 fetuses including 25% (10/40) with mild, 33% (4/12) with moderate and 57.1% (4/7) with severe IVM. Of the 10 fetuses with additional abnormalities found on PMRI, 6/10 had no amniocentesis and the other four had a normal karyotype and 5/10 had no maternal TORCH screen and in the other five the result was normal. There were four terminations of pregnancy in our cohort and three fetal deaths in utero. Two terminations were in the setting of severe VM and additional findings on prenatal MRI, the third as one of a twin pregnancy with severe IVM and the last one also as one of a twin pregnancy with moderate isolated asymmetric VM on US

and severe asymmetric IVM on PMRI performed at 24 weeks gestation. PM examinations were available in two of these cases. Two of the fetal deaths were in the setting of twin pregnancies (one with twin–twin transfusion syndrome) and the third with mild IVM and placental insufficiency on pathological examination. Degree of US-detected ventricular enlargement in our subjects and its relationship to ventricular size on PMRI is documented in Table 1. Three out of 59 patients (5.1%) had US-diagnosed VM but normal-sized ventricles and no other abnormality on cranial MR. The median difference between ventricular size on US and MRI was

Table 1. Severity of ventriculomegaly on ultrasound and PMRI in 59 study subjects

MR normal – mild MR moderate MR severe

US mild n = 40

US moderate n = 12

US severe n=7

26 11 3

3 6 3

0 1 6

Fig. 3. (a–c) Periventricular nodular heterotopia. US at 36 weeks’ gestation demonstrates severe isolated ventriculomegaly. MRI at 37 weeks demonstrates subependymal heterotopic nodules within the occipital horns of the lateral ventricles. Postnatal MR (c) confirms this finding. The male infant did not have FLNA or another identified gene mutation and maternal cranial MR was normal.

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Fig. 4. (a–e) Hemimegalencephaly. Moderate IVM on 29/40. Axial T2 HASTE images from MRI at 31/40. Figure parts a–c demonstrate enlargement of the right calvarium and cerebral hemisphere, enlarged subarachnoid spaces, oversulcation in the right occipitotemporal region and ‘herniation’ of the occipital lobe to the left (arrow). Postnatally (d and e), this child had a hemihypertrophy syndrome affecting the limbs and body and the predominant posterior quadrant dysplasia.

1 mm (IQR 0.3–2.2 mm). In 17/59 (28.8%) the severity of VM was greater on PMRI than on US and in 4/59 (6.8%), it was less. The occurrence of additional findings by severity of IVM is presented in Table 2. Of the 59 fetuses, 10 (17%) had

additional findings on PMRI, and this was more common in fetuses with severe than with mild or moderate IVM. Of the 59 fetuses, 23 had ‘gold standard’ correlative postnatal imaging with MRI or a PM examination and an additional 16 had cranial US performed as neonates.

Table 2. Additional findings on PMRI by severity of ventriculomegaly: clinical importance and correlation with gold standards

Additional findings on MR Additional findings with actual/potential clinical significance Cases with additional findings on MRI confirmed with PN MRI or PM Total cases with PN gold standard study – PM or PN MRI Total cases with any post natal study – PM/PN MRI/PN US

US mild n = 40

US moderate n = 12

US severe n = 7

5 (12.5%) 3 (7.5%) 2 11 (27.5%) 25 (62.5%)

1 (8.3%) 1 (8.3%) 1 6 (50%) 8 (66.7%)

4 (57.1%) 4 (57.1%) 4 6 (85%) 6 (85%)

MRI, magnetic resonance imaging; PM, post-mortem; PN, postnatal; US, ultrasound.


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Fetal MRI in ultrasound isolated ventriculomegaly

Fig. 5. (a–c) Germinolytic/subependymal cysts. Mild IVM diagnosed on US at 35 weeks. MR demonstrated bilateral germinolytic cysts (a). Postnatal imaging confirms this finding (b and c). Postnatal testing for CMV and metabolic disorders, including alpha glutaric aciduria, was negative and the infant developmentally normal when assessed by a paediatric neurologist at 6 weeks.

The nature of the additional findings on PMRI are listed in Table 3. Three of the five cases of additional findings in mild IVM were thought to be clinically significant, with the potential to change the prenatal counselling offered to the parents. All of the additional findings in moderate and severe IVM were considered to be clinically significant.

VM was asymmetric in 36 (61%) cases. There was no difference in the likelihood of additional findings in asymmetric and symmetric VM (Table 4). There were no additional findings on PMRI in fetuses with mild-moderate IVM on US between 20 and 24 weeks (Table 5). A significant difference in the occurrence of additional findings with moderate to severe compared with mild IVM was not found for fetuses with US-diagnosed IVM at 20–24 weeks (P = 0.25). There was also no significant difference in additional findings between fetuses with mild IVM on US when PMRI was carried out at 20–24/40 GA compared with those with PMRI >25/40 (P = 0.61).

Follow-up in fetuses with no additional findings on PMRI (Table 6) Of the 49 fetuses who had IVM on both prenatal US and PMRI, 31/49 (63.2%) had postnatal studies. In 15/49 (30.6%), this was US only, in 10/49 (20.4%) MRI only, 5/49 (10.2%) had both US and MRI and 1/49 (2%) had a PM. Seven of these 31 fetuses had additional abnormalities shown postnatally. In one case of hemispheric infarction, the abnormality clearly had developed after PMRI (Fig. 6).


Fig. 6. ADC map from MRI performed on day 8, demonstrates acute left frontoparietal cortical infarction following perinatal cardiac surgery, but no other abnormality. This was not evident on prenatal MRI at 29 weeks that demonstrated only isolated ventriculomegaly and is likely to have occurred intra- or postoperatively.

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Our study has demonstrated that fetal cranial MRI, performed at or after 20 weeks in fetuses with IVM on prenatal US performed in a tertiary referral centre yielded additional abnormalities in 17% (10) of 59 fetuses, and half of these additional findings were identified in fetuses with mild IVM. There are relatively few published studies designed to determine the additional diagnostic value of PMRI in


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Table 3. Nature of additional findings on PMRI relative to severity of VM, gestational age (GA) of latest US and earliest PMRI Finding

Small subependymal/germinal matrix haemorrhage Absent septum pellucidum Germinolytic cysts Periventricular cysts – connatal Foramen of Monro hamartoma – father with tuberous sclerosis complex Hemimegalencephaly – posterior quadrant dysplasia Absent septum pellucidum – postnatal septooptic dysplasia Periventricular nodular heterotopia Agenesis of the corpus callosum, occipital lobe cortex abnormal Agenesis of the corpus callosum

Table 4. Occurrence of additional findings on PMRI in symmetric vs. asymmetric IVM Symmetric n = 23

Asymmetric n = 36

Cases with additional findings 4 (17.4%) 6 (16.7%) Asymmetry defined as 3 mm or more discrepancy if both ventricles enlarged OR enlargement of one lateral ventricle (10 mm or more) but normal diameter of the other ventricle.

the fetus with IVM on prenatal US performed at or after 20 weeks of gestation. A Medline search enabled us to identify nine studies published in the English language since 2002.11–19 Two studies, Salomon et al. in 200612 and Parazzini et al. in 2012,19 addressed all key methodological domains by including only ‘low risk’ fetuses with negative TORCH screening results and absence of aneuploidy who had prenatal US performed in a tertiary referral centre. Both studies documented PMRI findings

Table 5. Additional findings on PMRI stratified by GA at latest US prior to PMRI and severity of IVM at time of this US Degree of US VM Mild (40) Moderate (12) Severe (7)




0/9 0/1 3/6

4/30 1/11 0

1/1 0 1/1

VM severity

Gestation at US (weeks)

Gestation at MRI (weeks)

Mild Mild Mild Mild Mild Mod Severe Severe Severe Severe

25 25 35 28 25 29 21 36 22 22

26 28 36 30 25 31 22 37 23 22

by GA of the fetus and severity of IVM on US and presented the results of clinical follow-up, postnatal imaging and PM for fetuses with and without additional findings. Salomon et al. studied fetuses with IVM using PMRI at or after 30 weeks of gestation regardless of the GA at US diagnosis. Additional findings were identified in five of 106 (4.7%) fetuses with mild (10–12 mm) IVM and 6/36 (16.7%) with IVM >12 mm. PM or postnatal MRI in these 11 cases confirmed the PMRI findings, and clinical follow-up to delivery in the remaining 131 cases was unremarkable with the exception of a single unexplained fetal death in utero. In all 11 cases, the additional abnormalities (white matter abnormalities likely to be attributable to infection or ischaemia; subependymal heterotopias; a short, thin corpus callosum; an occipital cephalocele; and frontal cortical abnormality) could be regarded as of actual or potential clinical significance. Parazzini et al. reported the results of PMRI in 179 ‘low risk’ fetuses that were 21–35 weeks’ gestation at PMRI with mild (10–12 mm) IVM, negative maternal TORCH screening and no aneuploidy. Additional findings were identified in 19.5% of fetuses, but these findings were considered to be of clinical importance in only two (1.1%) – one with absence of the septum pellucidum and the other with subependymal heterotopia. Although 87% of the 179 had clinical follow-up, only 11% had postnatal MRI or PM correlation. It is possible that Salomon et al. identified a higher proportion of fetuses with additional

Table 6. Results of follow up in 49 fetuses with no additional findings on PMRI

Postnatal study Additional findings

US only


MRI only


No PN imaging

15 Hypogenesis of the corpus callosum (1) GMH (1)

5 Connatal cysts (1) Extensive MCA territory infarction likely postnatal (1)

10 Hypogenesis of the corpus callosum (1) Enlarged third ventricle (1) Thinning of periventricular white matter (1)



GMH, germinal matrix haemorrhage; MCA, middle cerebral artery; MRI, Postnatal cranial MRI; PM, post-mortem; US, postnatal cranial US.


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Fetal MRI in ultrasound isolated ventriculomegaly

abnormalities than did Parazzini et al. by performing PMRI later and including fetuses with more severe IVM. We were unable to demonstrate a statistically significant difference between the 20- to 24-week cohort and fetuses of more advanced GA when VM was mild with regard to the likelihood of additional findings on PMRI. It is possible that this is the result of small sample size, and these are the interim results of an ongoing prospective study. Similar to previous studies, we found that a large proportion of our subjects with severe IVM on US had additional findings on PMRI. Morris et al.15 and Griffiths et al.14 found 58% and 57% of the fetuses with severe VM had additional findings on PMRI. It seems appropriate, therefore, for all fetuses with VM >15 mm, even if isolated, to have PMRI. Although it may be argued that prognostic counselling for neurological outcome in fetuses with IVM that is severe on US will not be changed by performing PMRI, our study has shown that by demonstrating specific additional structural abnormalities such as subependymal heterotopia, agenesis of the corpus callosum, absent septum pellucidum and hemimegalencephaly, additional important information may be gained that can inform parental counselling about clinical outcome, likelihood of recurrence and performance and interpretation of genetic testing. Limitations of our study include lack of TORCH screening in five of the 10 cases with additional findings and lack of amniocentesis for chromosomal abnormality in six of these 10. However, one of the five infants without antenatal TORCH testing had normal results on postnatal TORCH. This infant was the only one whose PMRI findings, germinolytic/subependymal cysts, were consistent with those seen in TORCH infections. No postnatal clinical evidence of chromosomal aneuploidy was present in any of the subjects who did not have prenatal karyotyping. We may have underestimated the additional diagnostic value of PMRI because we had no fetuses with lissencephaly, which often presents with only mild IVM at the midtrimester screening US and is diagnosable by 24 weeks of gestation with PMRI. Righini et al.20 have shown MRI can demonstrate polymicrogyria at less than 24 weeks’ gestation and we had no such cases in our study. We were unable to achieve follow-up imaging in all patients with IVM on PMRI so it is possible that we missed additional findings in these cases. In those who did receive follow-up, additional findings were not major malformations and with the exception of hypogenesis of the corpus callosum, possibly or definitely developed after the PMRI was performed. Finally, we did not systematically assess the effect of fetal MRI on decision making by patients or clinicians as a part of this study. However, the greater diagnostic specificity of MRI enables more accurate counselling with regard to postnatal outcome, making for more informed decisions and discussion by patients and those providing medical care to the pregnant woman and fetus.

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Future work should assess the utility of PMRI for the fetus with mild nonresolving VM demonstrated at or after 24 weeks’ gestation that has had negative results on testing for TORCH infections and aneuploidy. The yield of follow-up MRI after 26 weeks when an earlier PMRI is normal, apart from IVM, requires further evaluation. Consideration should be given to review of current clinical practice guidelines relating to additional testing of the fetus with IVM on midtrimester screening US, to incorporate use of PMRI.

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resonance imaging in the evaluation of isolated mild ventriculomegaly. J Ultrasound Med 2004; 23: 519–23. Salomon L, Ouahba J, Delezoide A, Vuillard E, Oury J, Sebag G, Garel C. Third-trimester fetal MRI in isolated 10- to 12-mm ventriculomegaly: is it worth it? BJOG 2006; 113: 942–7. Ouahba J, Luton D, Vuillard E, Garel C, Gressens P, Blanc N, Elmaleh M, Evrard P, Oury J. Prenatal isolated mild ventriculomegaly: outcome in 167 cases. BJOG 2006; 113: 1072–9. Griffiths PD, Reeves MJ, Morris JE, Mason G, Russell SA, Paley MNJ, Whitby EH. A prospective study of fetuses with isolated ventriculomegaly investigated by antenatal sonography and in utero MR imaging. AJNR 2010; 31: 106–11. Morris JE, Rickard S, Paley MNJ, Griffiths PD, Rigby A, Whitby EH. The value of in-utero magnetic resonance imaging in ultrasound diagnosed fetal isolated cerebral ventriculomegaly. Clin Radiol 2007; 62: 140–4.

16. Benacerraf BR, Shipp TD, Bromley B, Levine D. What does magnetic resonance imaging add to the prenatal sonographic diagnosis of ventriculomegaly? J Ultrasound Med 2007; 26: 1513–22. 17. Manfredi R, Tognolini A, Bruno C, Raffaelli R, Franchi M, Pozzi Mucelli R. Agenesis of the corpus callosum in fetuses with mild ventriculomegaly: role of MR imaging. Radiol Med 2010; 115: 301–12. 18. Yin S, Na Q, Chen J, Li-Ling J, Liu C. Contribution of MRI to detect further anomalies in fetal ventriculomegaly. Fetal Diagn Ther 2010; 27: 20–4. 19. Parazzini C, Righini A, Doneda C, Arrigoni F, Rustico M, Lanna M, Triulzi F. Is fetal magnetic resonance imaging indicated when ultrasound mild isolated ventriculomegaly is present in pregnancies with no risk factors? Prenat Diagn 2012; 32: 752–7. 20. Righini A, Parazzini C, Doneda C, Avagliano L, Arrigoni F, Rustico M, Consonni D, Re TJ, Bulfamante G, Triulzi F. Early formative stage of human focal cortical gyration anomalies: fetal MRI. AJR 2012; 198: 439–47.

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Isolated ventriculomegaly on prenatal ultrasound: what does fetal MRI add?

Cerebral ventriculomegaly is one of the most commonly detected fetal anomalies at the midtrimester ultrasound. Current evidence suggests that magnetic...
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