CASE REPORT
Diagnosis of Vein of Galen Aneurysmal Malformation Using Fetal MRI Li-Xia Zhou,1 Su-Zhen Dong,2 and Ming-Feng Zhang3* Purpose: To present three fetal vein of Galen aneurysmal malformations (VGAMs), which were diagnosed through magnetic resonance imaging (MRI), and highlight these cardiovascular findings. Materials and Methods: We retrospectively reviewed three fetuses with VGAM at 31, 32, and 33 weeks of gestation. Feeding arteries and draining veins were observed by MRI. Secondary changes in the brain and high-output heart failure caused by high blood flow in the lesion were evaluated. Two fetuses were born, and neonatal MRI was performed. One fetus was terminated. Results: A characteristic dilated structure in the midline of the brain presented in each fetus. The arteriovenous fistula led to anatomical brain changes such as in the hydrocephalus, dilated feeding vessels (one or more), jugular vein, and/ or superior vena cava. Substantial brachiocephalic vessel dilation was observed in two fetuses. Following parturition, one baby had neonatal asphyxia and sinus thrombosis, and MRI revealed hypoxic-ischemic encephalopathy. Cardiomegaly was detected in all three cases. Conclusion: With a large field of view, fetal MRI can observe brain VGAM, as well as the heart and affected large vessels. It can determine hydrocephalus, ischemia, intracranial hemorrhage, and sinus thrombosis. Providing such information on the infant’s entire body can aid clinicians in determining the most appropriate treatment. J. MAGN. RESON. IMAGING 2016;00:000–000
Level of Evidence: 4
V
ein of Galen aneurysmal malformations (VGAMs) are the most common dural sinus malformations in fetuses and neonates.1 These malformations form between the 6th and 11th week of gestation. Due to the fistula between the cerebral arteries and deep draining veins of the brain, the median prosencephalic vein, a precursor to the vein of Galen, becomes significantly enlarged and aneurysmal.2,3 In this study we present three fetal VGAMs diagnosed through MRI.
Materials and Methods Study Subjects The Ethics Committee of the Second Affiliated Hospital of Hebei Medical University approved this study. Written informed consent and permission for imaging were obtained from all mothers. Between January 2007 and June 2013, three cases of prenatally diagnosed VGAM through fetal ultrasound and MRI in our hospital were reviewed. Two fetuses were born, and neonatal MRI was
performed again to evaluate the VGAM and the brain. Chest radiography was used to observe the cardiac function. One fetus was terminated at 35 weeks of gestation.
Magnetic Resonance Imaging Prenatal MRI was performed using a 1.5T unit (Achieva Nova Dual; Philips Medical Systems, Best, The Netherlands) with 33 mT/m gradients and a sixteen-channel SENSE XL Torso coil. Fetal nonenhanced MRI was performed. Section thickness, 7 mm; spacing, 2 mm; T2-weighted imaging (T2WI) included two sequences: a balanced turbo field echo (B-TFE) sequence and a single-shot turbo spin echo (SSTSE) sequence. T1-weighted imaging (T1WI) was applied by a single-shot turbo fast echo sequence. Diffusionweighted imaging (DWI) sequence was also performed. Two fetuses were born, and neonatal brain MRI and chest radiography were performed. Brain MRI used a 1.5T unit (Signa EchoSpeed; GE Medical Systems, Milwaukee, WI) with 33 mT/m gradients. Imaging sequences included T1WI, T2WI, and DWI.
View this article online at wileyonlinelibrary.com. DOI: 10.1002/jmri.25478 Received Aug 1, 2016, Accepted for publication Aug 29, 2016. *Address reprint requests to: M.-F.Z., Department of Rheumatology, Second Hospital of Hebei Medical University, 215 West Heping Road, Shijiazhuang, 050000, China. E-mail:
[email protected] From the 1Department of Medical Imaging, Second Hospital of Hebei Medical University, Shijiazhuang, China; 2Department of Radiology, Shanghai Children’s Medical Center, Shanghai Jiaotong University School of Medicine, Shanghai, China; and 3Department of Rheumatology, Second Hospital of Hebei Medical University, Shijiazhuang, China Evidence level: 4 The first two authors contributed equally to this work.
C 2016 International Society for Magnetic Resonance in Medicine V 1
Journal of Magnetic Resonance Imaging
FIGURE 1: Brain MRI of a 31-week fetus with VGAM (case 1). Case 1: A 31-week fetus with VGAM. A round mass lesion, midline, occupied the cistern between hemispheres. Mass size was 60 3 52 3 57 mm with sharp margin, accompanied hydrocephalus. A,B: Fetal MRI B-TFE sagittal and coronal view images show the dilated vein with heterogeneous low signal (arrows). C: T1WI axis view shows the mass in mild high intensity (arrow). D: DWI shows no ischemic signal in the brain parenchyma, and the mass was a low signal indicating no thrombus and hemorrhage (arrow). E: Dilated carotid arteries and jugular veins were seen (arrows). F: The heart was enlarged on the fetal MRI B-TFE sequence (arrow).
Results Case 1 The first case was a 28-year-old woman who was referred to our hospital for fetal evaluation due to the diagnosis of a large brain cyst by prenatal ultrasound at 31 weeks of gestation. MRI revealed a round mass lesion at the midline. The mass size was 60 3 52 3 57 mm, with a sharp margin. The lesion had a low signal on the SSTSE sequence and a high intensity on the B-TFE sequence. Mild-high intensity was observed in T1WI. The mass compressed the aqueduct of the Sylvius, leading to the hydrocephalus. Bilateral posterior cerebral arteries and the transverse sinus were dilated. Jugular veins were expanded and cardiomegaly associated with a cardiac to thoracic area (CA/TA) ratio, which was recorded at 0.43 (Fig. 1). This fetus was terminated at 35 weeks of gestation. Autopsy was permitted by the parents, and confirmed. 2
Case 2 A 35-year-old pregnant woman presented with a fetus at 32 weeks of gestation. The flow void of the VGAM was clearly shown on the B-TFE sequence. The VGAM was rich with blood feeding consisting of multiple feeding arteries. The transverse sinus and jugular veins were dilated bilaterally. The heart was enlarged with a CA/TA ratio of 0.51 (Fig. 2). The fetus was born at 38 weeks. Enlarged intracranial veins of the VGAM were detected by computed tomography (CT) and MRI. Prenatal and neonatal hydrocephalus was also observed. Three hours after birth, the infant was noted to be tachypneic, and radiographic evidence of cardiomegaly persisted (Fig. 3). An echocardiogram demonstrated a dilated right ventricle with possible pulmonary hypertension. Thrombocytopenia and intractable heart failure led to multiorgan failure. The baby died 38 hours after birth. Volume 00, No. 00
Zhou et al.: VGAM Imaging
FIGURE 2: MRI images of a 32-week fetus with VGAM of case 2. Case 2: A 32-week fetus. A: An enlarged venous pouch as precursor of the vein of Galen; the median prosencephalic vein (arrow) can be seen on B-TFE image as black signal. B,C: Bilateral transverse sinus and sigmoid sinus also enlarged (arrows). B: Dilated arteries including bilateral anterior and posterior choroidal arteries and the anterior cerebral arteries were also shown (white arrows). D: On T1WI, the VGAM showed mild high signal (arrow). E: There was no thrombus and ischemia detected on DWI (arrow). F: Bilateral jugular veins dilated (arrows). G: The heart was notably enlarged (arrow).
FIGURE 3: The neonatal images of case 2 with brain CT/MRI and chest radiography. The neonatal images of case 2. A: The dilated vein was high intensity on the CT image (arrow), but MRI showed low signal indicating no thrombus (thick arrows in B–E). No ischemia was shown on DWI (D). Multiple dilated arteries (thin arrows in E–F) and a vein (thin arrows in E–F) could be seen onT2WI (E) and MRA (F). G: Chest radiography showed evidence of cardiomegaly.
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FIGURE 4: Brain MRI of a 32 weeks fetus with VGAM (case 3). Case 3: A 32-week fetus. A,B: A dilated venous sac (arrows) and a fistula can be seen between the vein and the left posterior choroidal vessels. C: The basal artery was enlarged (arrow). The supratentorial ventricles were mildly dilated. D: Part of the VGAM was high signal on T1WI (arrow). E: The brachiocephalic vessels (arrow). F: The heart was mildly enlarged (arrow) and a small pleural effusion could be observed on T2WI.
FIGURE 5: Neonatal images of case 3 with brain CT/MRI and chest radiography. The fetus of case 3 was born full term as a smallfor-gestational-age. Sinus thrombosis was seen on CT and MRI (arrows in A,B,D). C: An ischemic lesion was seen on DWI (arrow). E: Chest radiographic indicated cardiac enlargement.
Zhou et al.: VGAM Imaging
Case 3 A 29-year-old pregnant woman presented with a fetus at 33 weeks gestation. The enlarged midline venous sac at the location of the vein of Galen was represented by a dilated median vein of the prosencephalon. The left posterior choroidal artery was dilated, and a fistula could be observed between the artery and the dilated venous sac. The heart was mildly enlarged. A little pleural effusion could also be observed on T2WI (Fig. 4). This fetus was born full-term as small-for-gestational-age with neonatal asphyxia and sinus thrombosis. Neonatal MRI revealed hypoxic-ischemic encephalopathy, and the flowing void signal disappeared in the sinus of the VGAM, including its branches. Chest radiography of the newborn was normal (Fig. 5). The baby survived, and was treated with a 2-year follow-up period.
Discussion Prenatal diagnosis of VGAMs is usually made during the third trimester. Color Doppler ultrasonography is the most often used modality for exploring the fetus.4 Fetal MRI has become superior to color Doppler ultrasonography in the diagnosis of VGAM in recent years.5 It was easier to observe the VGAM artery blood supply and affected veins on SSTSE images (black blood sequences). In addition, SSFP imaging (white blood sequence) permits the cardiac chambers and vessels to be clearly imaged.6 In our three cases, high T1WI signals before and after birth were not necessarily due to thrombus in the abnormal vein, but more likely caused by the fast blood flow into the vessel. However, in the last case the newborn had a high signal on both T1WI and T2WI, which indicated venous thrombosis. Substantial brachiocephalic vessel dilation was observed in all three cases. High-output fetal cardiac failure can result from the large arteriovenous shunt that exists with VGAM cardiomegaly and fetal hydrops may ensue with the development of heart failure, and adrenal hemorrhage can also complicate VGAM in fetuses with severe heart failure.7 Fetal MRI can observe brain VGAM, as well as the heart and affected large vessels. It may provide the basis of some intracranial complications, such as cerebral hemorrhage,
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ischemia and venous sinus thrombosis, and system complications such as serous cavity effusion and fetal hydrops. This can aid the obstetrician and neurologist in their corresponding diagnosis and treatment.8 In addition to VGAM, other neonatal cerebral vascular anomalies such as arteriovenous malformation or fistula can also be found. Digital subtraction angiography (DSA) is the gold standard in diagnosis and safety of treatment.9 Some new MRI technique such as arterial spin labeling (ASL) imaging may be used to assess the blood flow change of VGAM in the future.10
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