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Fast MR Imaging of Fetal Central Nervous System Abnormalities¹

¹ From the Departments of Radiology (D.L., T.S.M.) and Obstetrics and Gynecology (D.L., G.W.), Beth Israel Deaconess Medical Center, 330 Brookline Ave, Boston, MA 02215; Department of Radiology, Children’s Hospital, Boston, Mass (R.R.R.); and Department of Radiology, Lucille Salter Packard Children’s Hospital at Stanford, Palo Alto, Calif (P.D.B.). Received July 10, 2002; revision requested August 23; final revision received April 27, 2003; accepted May 5. Supported by a National Institutes of Health grant, National Institute of Neurologic Disorders and Stroke, NS 37945. Address correspondence to D.L. (e-mail: dlevine@caregroup.harvard.edu).

View larger version (179K): [in a new window]   Figure 1. Coronal MR image in a fetus with subependymal hemorrhage at 18 weeks of gestational age. The patient was referred to our institution because the fetus had an enlarged cisterna magna that appeared normal at confirmatory US. Half-Fourier single-shot RARE MR image (echo spacing of 4.2 msec, echo time of 60 msec, echo train length of 72, one signal acquired, 2.8-mm section thickness, 21 x 24-cm field of view, 192 x 256 matrix, 19-second sequence duration, and section acquisition of 420 msec) shows an area of low signal intensity (arrow) in the left subependymal region. This finding was confirmed on all images. Subependymal hemorrhage in utero has unknown clinical importance. The baby had normal US findings in the head at birth and is developing normally. This is an example of a fetus with normal confirmatory US findings with an MR imaging finding that changed the diagnosis but not case management, since the patient continued the pregnancy, and peripartum care was not affected.

View larger version (164K): [in a new window]   Figure 2. Coronal MR image in a fetus with tuberous sclerosis at 33 weeks of gestational age. US images (not shown) demonstrated multiple cardiac rhabdomyomas. Half-Fourier single-shot RARE MR image (echo spacing of 4.2 msec, echo time of 60 msec, echo train length of 72, one signal acquired, 3-mm section thickness, 30 x 40-cm field of view, 128 x 256 matrix, 20-second sequence duration, and section acquisition of 420 msec) shows multiple small subependymal tubers (arrows). These were not visualized at US (or on MR images obtained at 22 weeks [not shown]). This is an example of a fetus strongly suspected of having a CNS abnormality despite normal US findings with an MR finding that changed diagnosis but not case management, since the patient continued the pregnancy.

View larger version (169K): [in a new window]   Figure 3a. Fetus with ventriculomegaly, absent corpus callosum, Dandy-Walker malformation, and hemorrhage at 25 weeks of gestational age. (a) Transverse US image demonstrates enlarged cisterna magna with splayed cerebellar hemispheres, consistent with Dandy-Walker malformation (D). The lateral ventricle is enlarged with an enlarged choroid plexus (arrow), which suggests hemorrhage. (b) Transverse and (c) sagittal half-Fourier single-shot RARE MR images (echo spacing of 4.2 msec, echo time of 60 msec, echo train length of 72, one signal acquired, 4-mm section thickness, 22.5 x 30-cm field of view, 192 x 256 matrix, 16-second sequence duration, and section acquisition of 420 msec) demonstrate the Dandy-Walker malformation (D) and multiple regions of porencephaly (arrowheads) due to spontaneous ventriculostomies. The corpus callosum is not visualized. This is an example of a fetus with abnormal US findings of the CNS with additional MR imaging findings that changed maternal counseling but not case management, since the patient continued the pregnancy. Postnatal diagnosis was acrocallosal syndrome.

View larger version (117K): [in a new window]   Figure 3b. Fetus with ventriculomegaly, absent corpus callosum, Dandy-Walker malformation, and hemorrhage at 25 weeks of gestational age. (a) Transverse US image demonstrates enlarged cisterna magna with splayed cerebellar hemispheres, consistent with Dandy-Walker malformation (D). The lateral ventricle is enlarged with an enlarged choroid plexus (arrow), which suggests hemorrhage. (b) Transverse and (c) sagittal half-Fourier single-shot RARE MR images (echo spacing of 4.2 msec, echo time of 60 msec, echo train length of 72, one signal acquired, 4-mm section thickness, 22.5 x 30-cm field of view, 192 x 256 matrix, 16-second sequence duration, and section acquisition of 420 msec) demonstrate the Dandy-Walker malformation (D) and multiple regions of porencephaly (arrowheads) due to spontaneous ventriculostomies. The corpus callosum is not visualized. This is an example of a fetus with abnormal US findings of the CNS with additional MR imaging findings that changed maternal counseling but not case management, since the patient continued the pregnancy. Postnatal diagnosis was acrocallosal syndrome.

View larger version (125K): [in a new window]   Figure 3c. Fetus with ventriculomegaly, absent corpus callosum, Dandy-Walker malformation, and hemorrhage at 25 weeks of gestational age. (a) Transverse US image demonstrates enlarged cisterna magna with splayed cerebellar hemispheres, consistent with Dandy-Walker malformation (D). The lateral ventricle is enlarged with an enlarged choroid plexus (arrow), which suggests hemorrhage. (b) Transverse and (c) sagittal half-Fourier single-shot RARE MR images (echo spacing of 4.2 msec, echo time of 60 msec, echo train length of 72, one signal acquired, 4-mm section thickness, 22.5 x 30-cm field of view, 192 x 256 matrix, 16-second sequence duration, and section acquisition of 420 msec) demonstrate the Dandy-Walker malformation (D) and multiple regions of porencephaly (arrowheads) due to spontaneous ventriculostomies. The corpus callosum is not visualized. This is an example of a fetus with abnormal US findings of the CNS with additional MR imaging findings that changed maternal counseling but not case management, since the patient continued the pregnancy. Postnatal diagnosis was acrocallosal syndrome.

View larger version (157K): [in a new window]   Figure 4a. Early second-trimester fetus with either hydranencephaly or holoprosencephaly. (a) Transverse US image in the fetal head with measurements that correlate with 13 weeks of gestational age. Calipers and dotted area denote head circumference. The abdomen and femur length in this fetus correlated with size at 14 weeks (not shown), and the age according to menstrual dates was 16 weeks. The intracranial anatomy could not be assessed at either transabdominal or transvaginal US because of maternal body habitus. (b) Transverse half-Fourier single-shot RARE MR image (echo spacing of 4.2 msec, echo time of 60 msec, echo train length of 72, one signal acquired, 5-mm section thickness, 26 x 35-cm field of view, 128 x 256 matrix, 19-second sequence duration, and section acquisition of 420 msec) of the fetal head shows only a small amount of tissue centrally (arrow). This is an example of MR imaging findings that changed case management in that the patient decided to terminate the pregnancy on the basis of MR imaging findings.

View larger version (165K): [in a new window]   Figure 4b. Early second-trimester fetus with either hydranencephaly or holoprosencephaly. (a) Transverse US image in the fetal head with measurements that correlate with 13 weeks of gestational age. Calipers and dotted area denote head circumference. The abdomen and femur length in this fetus correlated with size at 14 weeks (not shown), and the age according to menstrual dates was 16 weeks. The intracranial anatomy could not be assessed at either transabdominal or transvaginal US because of maternal body habitus. (b) Transverse half-Fourier single-shot RARE MR image (echo spacing of 4.2 msec, echo time of 60 msec, echo train length of 72, one signal acquired, 5-mm section thickness, 26 x 35-cm field of view, 128 x 256 matrix, 19-second sequence duration, and section acquisition of 420 msec) of the fetal head shows only a small amount of tissue centrally (arrow). This is an example of MR imaging findings that changed case management in that the patient decided to terminate the pregnancy on the basis of MR imaging findings.

View larger version (123K): [in a new window]   Figure 5a. Cerebrocerebellar malformation with kinked midbrain. (a, b) Transverse half-Fourier single-shot RARE MR images (echo spacing of 4.2 msec, echo time of 60 msec, echo train length of 72, one signal acquired, 3.5-mm section thickness, 22.5 x 30-cm field of view, 128 x 256 matrix, 16-second sequence duration, and section acquisition of 420 msec) in the fetal head show ventriculomegaly (*) and a small cerebellum (arrows). (c) Sagittal MR image shows a kinked midbrain (arrowhead). US images (not shown) demonstrated only ventriculomegaly and the small cerebellum. This is an example of an MR imaging finding that changed case management. The midbrain finding was not visualized at US. Because of the severe cerebral dysgenesis, the patient decided to terminate the pregnancy.

View larger version (127K): [in a new window]   Figure 5b. Cerebrocerebellar malformation with kinked midbrain. (a, b) Transverse half-Fourier single-shot RARE MR images (echo spacing of 4.2 msec, echo time of 60 msec, echo train length of 72, one signal acquired, 3.5-mm section thickness, 22.5 x 30-cm field of view, 128 x 256 matrix, 16-second sequence duration, and section acquisition of 420 msec) in the fetal head show ventriculomegaly (*) and a small cerebellum (arrows). (c) Sagittal MR image shows a kinked midbrain (arrowhead). US images (not shown) demonstrated only ventriculomegaly and the small cerebellum. This is an example of an MR imaging finding that changed case management. The midbrain finding was not visualized at US. Because of the severe cerebral dysgenesis, the patient decided to terminate the pregnancy.

View larger version (109K): [in a new window]   Figure 5c. Cerebrocerebellar malformation with kinked midbrain. (a, b) Transverse half-Fourier single-shot RARE MR images (echo spacing of 4.2 msec, echo time of 60 msec, echo train length of 72, one signal acquired, 3.5-mm section thickness, 22.5 x 30-cm field of view, 128 x 256 matrix, 16-second sequence duration, and section acquisition of 420 msec) in the fetal head show ventriculomegaly (*) and a small cerebellum (arrows). (c) Sagittal MR image shows a kinked midbrain (arrowhead). US images (not shown) demonstrated only ventriculomegaly and the small cerebellum. This is an example of an MR imaging finding that changed case management. The midbrain finding was not visualized at US. Because of the severe cerebral dysgenesis, the patient decided to terminate the pregnancy.

View larger version (18K): [in a new window]   Figure 6. Graph of the effect of gestational age on decisions in case management during pregnancy. Data points indicate individual fetuses. Circled data points indicate fetuses that underwent autopsy, surgery, or postnatal imaging follow-up.