Prenatal Diagnosis of a Vein of Galen Aneurysmal Malformation with Fetal MR Imaging Study

We read with interest the article by Jones et al (1), in which the authors describe their experience in diagnosing and treating 13 children with vein of Galen aneurysmal malformation (VGAM) during a 14-year period. Their experience confirms that children with VGAM presenting during the neonatal period have a generally much worse prognosis than do those presenting later in childhood. Only two of the eight patients who presented during the neonatal period achieved normal or near-normal outcomes; five died, and one experienced significant impairment. Neonatal presentation with congestive heart failure is frequent with these malformations; if they are diagnosed prenatally, early delivery by means of cesarean section may be proposed to enable more effective cardiac evaluation and management. However, the authors also emphasize that only four cases among the 13 were diagnosed prenatally, and despite the increased use of routine prenatal sonography in recent years, they identified no trend toward a greater number of prenatal diagnoses. We would like to point out that fetal MR imaging may play a role for prenatal diagnosis of VGAM and to emphasize its value for appropriate management of these cases.

In 1995, we had experience with one such case. A 34-year-old gravida 2, para 0 woman was referred at 38 weeks and 5 days of gestation for evaluation of a routine sonography-detected anechoic intracranial lesion. Doppler ultrasonography revealed turbulent blood flow within the lesion, 20 mm in diameter, situated in the midline, and a possible diagnosis of VGAM was suggested (Fig 1). Intrauterine MR imaging was performed without curarization or sedation on a 1.0-T superconducting unit (Magnetom Impact; Siemens, Erlangen, Germany). It confirmed the diagnosis of VGAM and showed otherwise normal brain parenchyma, without hydrocephalus (Fig 2). Fetal echocardiography showed slight cardiomegaly and slightly distended superior cava, brachiocephalic, and internal jugular veins. After 2 days, a male infant weighing 2860 g was delivered by cesarean section. Apgar scores were 9 at 1 min and 9 at 5 min; echocardiography showed no signs of congestive heart failure. Postnatal MR imaging and MR angiography were performed with the patient under narcosis at 35 days (not shown) and at 75 days of life (Figs 3 and 4); the child’s clinical condition remained good, and his development was normal. At 6 months of life, he underwent digital angiography and graded catheter embolization, which were performed during a 4-month period. For these procedures, the child was referred to another institution; therefore, no information is provided herein. The result was occlusion of 80% of the VGAM. At 7-year follow-up, the patient’s physical and psychomotor development was normal.

Fig 1.

Ultrasonogram and color Doppler sonogram from the case of a 34-year-old gravida 2, para 0 woman who was referred at 38 weeks and 5 days of gestation.

A, Routine ultrasonogram shows an intracranial echo-free area.

B, Color Doppler sonogram shows turbulent blood flow within the lesion (courtesy of Dr. G. Ciotti, Department of Obstetrics, Children’s Hospital “G. Salesi,” Ancona, Italy).

Fig 2.

Fetal MR images obtained at 38 weeks and 5 days of gestation (body coil; fast low angle shot 2D; 44/10 [TR/TE]; flip angle, 40 degrees; section thickness, 5 mm; field of view, 380 mm; matrix, 192 × 256).

A, Midsagittal view of the fetal brain shows a distended midline vascular structure; the brain parenchyma appears otherwise normal, and there is no ventricular dilation.

B, Axial view.

Fig 3.

Postnatal midsagittal T1-weighted spin-echo MR image obtained at 75 days of life (500/15; section thickness, 5 mm; field of view, 230 mm; matrix, 220 × 256) shows an interhemispheric vascular malformation at the level of the posterior third and splenium of the corpus callosum, flowing into a markedly distended vein of Galen and into the straight sinus.

Fig 4.

Postnatal MR angiograms obtained at 75 days of life.

A, Arterial flow (fast imaging with steady-state free precession 3D, magnetization transfer-tilted optimized nonsaturating excitation, 44/10).

B, Venous flow (fast low angle shot 2D, 40/10). Although turbulent flow through the vein of Galen makes it impossible to directly show it, the images indirectly show the malformation via its arterial supply and the venous flow into the straight sinus.

Although ultrasonography is the imaging technique of choice for assessment of fetal CNS abnormalities, intrauterine MR imaging has several advantages over it (2) and provides additional information that can aid in the management of these cases. Its use for revealing VGAM has rarely been reported (3–5). In fetuses with ultrasonographic findings consistent with VGAM, complementary MR imaging enables correct diagnosis, allows for better evaluation of the lesion, and aids in decision making, which also depends on an accurate assessment of the condition of the brain parenchyma. Elective early cesarean delivery can enable optimal care of the baby’s cardiac function, minimizing the risks related to the sudden diversion of flow through the malformation at birth. Importantly, monitoring with postnatal MR imaging and MR angiography can also help in understanding the right time to perform treatment. Prompt postdelivery embolization may not be the best management option. In their article, Jones et al note that embolization during the first few weeks of life is unlikely to result in good outcomes and that endovascular treatment should be delayed, if possible, for several months. Thanks to the absence of congestive heart failure, the child whose case we reported had treatment delayed for 6 months, and he eventually achieved a good outcome. His case also confirms that graded embolization procedures may provide the best results in these cases and that incomplete obliteration of the lesion may be ideal (1, 6).