- Email: [email protected]
Fetal central nervous system anomalies: ultrasound and magnetic resonance imaging (MRI)
S76
Ultrasound in Medicine and Biology
The objective is to demonstrate the basic ultrasound (US) technique, normal findings, and typical pathologic conditions of spinal US in infancy, and to present the established indications for the sonographic evaluation of the neonatal and infant spinal canal. Furthermore, the future potential using modern US methods such as mmode, harmonic imaging, extended field of view US, and threedimensional US will be discussed. After defining the technical prerequisites, the application technique will be demonstrated. All major sonographically accessible pathologies of the neonatal and infant spine will be mentioned and related to normal US findings; however, fetal spinal US will not be included. Typical pathologic US findings will be related to other imaging such as plain film and MRI, when applicable. The clinical value as well as the restrictions and pitfalls of spinal US in infancy will be discussed. As neonates and infants offer an exclusive view through the non- or poorly ossified bones to the spinal canal, spinal US is a valuable technique for evaluating spinal canal pathology. Being an easy applicable, non-invasive and non-ionizing imaging technique, US has become the first-line imaging method for evaluating newborns or infants with suspected spinal cord disease. In general, spinal US offers a comprehensive and reliable diagnosis in most conditions, and thus represents an ideal screening tool in risk populations; however, in some situations, plain film, CT, and MRI still are indicated and necessary.
Fetal central nervous system anomalies: Ultrasound and magnetic resonance imaging (MRI) Bulas D, Radiology, Children’s National Medical Center, Washington, DC Sonographic assessment of fetal CNS anomalies can be challenging. In the first trimester, major anomalies such as anencephaly can be identified. By the second trimester, abnormal BPD and HC measurements may suggest a CNS abnormality. Ventricles should measure less than 10 mm at the atria. Ventriculomegaly may be secondary to atrophy (hydrancephaly, porencephaly), dysgenesis (holoprosencephaly, ACC), or hydrocephalus (increased CSF formation, decreased resorption, obstructed flow). The most common etiology for ventriculomegaly is spinal bifida. Evaluation of the fetal spine and cerebellum allows detection in 95% of cases. The posterior fossa, including cerebellum and cisterna magna should be examined closely for possible Chiari or Dandy Walker malformation. Encephaloceles or meningoceles should be searched for. The fetus should be examined for additional anomalies. Functional review including hand clenching, foot position, and swallowing provides additional information. Transvaginal and 3-D sonography may improve brain, spine, and face visualization. Amniocentesis should be offered. If additional anomalies or abnormal chromosomes are present, the prognosis is poor. With mild ventriculomegaly and no associated anomalies, outcome may be less severe. However, neurological abnormalities have been noted in up to 20% of these cases. Examination of the fetal brain can be limited due to overlying skull, fetal lie, maternal body habitus, and oligohydramnios. With rapid sequences available, MRI can image the fetus in any plane in the second and third trimester without sedation. While long-term studies are not available concerning fetal MRI exposure, no studies to date have demonstrated an effect on fetal growth. Due to its superior imaging of the cerebral cortex, corpus callosum, and posterior fossa, MRI can confirm or clarify a diagnosis. When cranial anomalies are complex, neurosurgeons and neuroradiologists are comfortable interpreting the images, providing additional expertise for family counseling. MRI can be helpful in documenting normal fetal CNS anatomy. Due to the changing sulcation pattern, MRI provides an additional parameter in the assessment of gestational age.
Volume 29, Number 5S, 2003
Advances in adult transcranial duplex ultrasonography Bartels E, Department of Clinical Neurophysiology, University of Goettingen, Neufahrn, Germany Transcranial color-coded duplex ultrasonography enables the visualization of basal cerebral arteries through color-coding the flow velocity information. The purpose of this presentation is to demonstrate the technique for examining intracranial arteries, veins and cerebral parenchyma, and to present typical pathological findings in occlusive disease, in vascular malformations, cerebral venous thrombosis as well as in cerebral parenchyma disorders. Additionally, the advantages of echo contrast agents in the evaluation of cerebrovascular disease will be shown. Of particular clinical relevance is an occlusion of the middle cerebral artery (MCA). An early diagnosis in patients with cerebral ischemia is crucial for the therapeutic strategy— especially in the decision for a thrombolysis. Sonographic diagnosis of occlusion of a cerebral artery can be made when a color-coded signal cannot be obtained at depths of insonation corresponding to that artery, although neighboring arteries can be imaged well. Criteria for the sonographic diagnosis of MCA occlusion in the axial plane include lack of detectable flow in the MCA, a good visualization of the ipsilateral posterior cerebral artery, and detection of the collateral flow. In patients with acute stroke, contrast enhancement is valuable, especially in those patients whose baseline scans are not of good quality. In such a situation, it is important for further diagnostic steps and for therapy to be able to determine whether failure to visualize a cerebral vessel is due to methodological problems or to an occlusion of a cerebral artery. Using echo-contrast agents (Levovist, Sonovue), it is possible to obtain more detailed information about the anatomical course of the cerebral arteries. Additionally, new techniques, such as harmonic imaging combined with use of echo contrast agents for the ultrasonic assessment of a cerebral parenchyma in patients with cerebral ischemia will be discussed. The potential of the different cerebral perfusion imaging techniques in acute stroke patients with decompressive craniotomy will be presented.
HOT TOPICS IN ABDOMINAL DOPPLER Evaluation of TIPS Teefey SA, Mallinckrodt Institute of Radiology, St. Louis, MO Acute or recurrent variceal hemorrhage is the most common indication for TIPS placement. Although the immediate technical success rate of placing a TIPS is approximately 90%, the frequency of TIPS stenosis and occlusion is fairly high. Duplex and color Doppler sonography has been shown to be an excellent means to evaluate and follow patients with stents. Various Doppler perimeters can be used to diagnose shunt malfunction including peak systolic velocity within the stent, the difference between the maximum and minimum velocity in the stent, temporal change in the stent velocity, velocity in the main portal vein, flow direction in the left and right portal vein branches, peak systolic velocity in the hepatic artery, and flow direction in the draining hepatic vein. Each of these perimeters will be discussed during this lecture to assist the participant in better understanding how to diagnose TIPS malfunction.
Role of Doppler in the diagnosis and follow-up of abdominal vascular disease Pellerito J, Radiology, North Shore University Hospital, Manhasset, NY
Ultrasound in Medicine and Biology
The objective is to demonstrate the basic ultrasound (US) technique, normal findings, and typical pathologic conditions of spinal US in infancy, and to present the established indications for the sonographic evaluation of the neonatal and infant spinal canal. Furthermore, the future potential using modern US methods such as mmode, harmonic imaging, extended field of view US, and threedimensional US will be discussed. After defining the technical prerequisites, the application technique will be demonstrated. All major sonographically accessible pathologies of the neonatal and infant spine will be mentioned and related to normal US findings; however, fetal spinal US will not be included. Typical pathologic US findings will be related to other imaging such as plain film and MRI, when applicable. The clinical value as well as the restrictions and pitfalls of spinal US in infancy will be discussed. As neonates and infants offer an exclusive view through the non- or poorly ossified bones to the spinal canal, spinal US is a valuable technique for evaluating spinal canal pathology. Being an easy applicable, non-invasive and non-ionizing imaging technique, US has become the first-line imaging method for evaluating newborns or infants with suspected spinal cord disease. In general, spinal US offers a comprehensive and reliable diagnosis in most conditions, and thus represents an ideal screening tool in risk populations; however, in some situations, plain film, CT, and MRI still are indicated and necessary.
Fetal central nervous system anomalies: Ultrasound and magnetic resonance imaging (MRI) Bulas D, Radiology, Children’s National Medical Center, Washington, DC Sonographic assessment of fetal CNS anomalies can be challenging. In the first trimester, major anomalies such as anencephaly can be identified. By the second trimester, abnormal BPD and HC measurements may suggest a CNS abnormality. Ventricles should measure less than 10 mm at the atria. Ventriculomegaly may be secondary to atrophy (hydrancephaly, porencephaly), dysgenesis (holoprosencephaly, ACC), or hydrocephalus (increased CSF formation, decreased resorption, obstructed flow). The most common etiology for ventriculomegaly is spinal bifida. Evaluation of the fetal spine and cerebellum allows detection in 95% of cases. The posterior fossa, including cerebellum and cisterna magna should be examined closely for possible Chiari or Dandy Walker malformation. Encephaloceles or meningoceles should be searched for. The fetus should be examined for additional anomalies. Functional review including hand clenching, foot position, and swallowing provides additional information. Transvaginal and 3-D sonography may improve brain, spine, and face visualization. Amniocentesis should be offered. If additional anomalies or abnormal chromosomes are present, the prognosis is poor. With mild ventriculomegaly and no associated anomalies, outcome may be less severe. However, neurological abnormalities have been noted in up to 20% of these cases. Examination of the fetal brain can be limited due to overlying skull, fetal lie, maternal body habitus, and oligohydramnios. With rapid sequences available, MRI can image the fetus in any plane in the second and third trimester without sedation. While long-term studies are not available concerning fetal MRI exposure, no studies to date have demonstrated an effect on fetal growth. Due to its superior imaging of the cerebral cortex, corpus callosum, and posterior fossa, MRI can confirm or clarify a diagnosis. When cranial anomalies are complex, neurosurgeons and neuroradiologists are comfortable interpreting the images, providing additional expertise for family counseling. MRI can be helpful in documenting normal fetal CNS anatomy. Due to the changing sulcation pattern, MRI provides an additional parameter in the assessment of gestational age.
Volume 29, Number 5S, 2003
Advances in adult transcranial duplex ultrasonography Bartels E, Department of Clinical Neurophysiology, University of Goettingen, Neufahrn, Germany Transcranial color-coded duplex ultrasonography enables the visualization of basal cerebral arteries through color-coding the flow velocity information. The purpose of this presentation is to demonstrate the technique for examining intracranial arteries, veins and cerebral parenchyma, and to present typical pathological findings in occlusive disease, in vascular malformations, cerebral venous thrombosis as well as in cerebral parenchyma disorders. Additionally, the advantages of echo contrast agents in the evaluation of cerebrovascular disease will be shown. Of particular clinical relevance is an occlusion of the middle cerebral artery (MCA). An early diagnosis in patients with cerebral ischemia is crucial for the therapeutic strategy— especially in the decision for a thrombolysis. Sonographic diagnosis of occlusion of a cerebral artery can be made when a color-coded signal cannot be obtained at depths of insonation corresponding to that artery, although neighboring arteries can be imaged well. Criteria for the sonographic diagnosis of MCA occlusion in the axial plane include lack of detectable flow in the MCA, a good visualization of the ipsilateral posterior cerebral artery, and detection of the collateral flow. In patients with acute stroke, contrast enhancement is valuable, especially in those patients whose baseline scans are not of good quality. In such a situation, it is important for further diagnostic steps and for therapy to be able to determine whether failure to visualize a cerebral vessel is due to methodological problems or to an occlusion of a cerebral artery. Using echo-contrast agents (Levovist, Sonovue), it is possible to obtain more detailed information about the anatomical course of the cerebral arteries. Additionally, new techniques, such as harmonic imaging combined with use of echo contrast agents for the ultrasonic assessment of a cerebral parenchyma in patients with cerebral ischemia will be discussed. The potential of the different cerebral perfusion imaging techniques in acute stroke patients with decompressive craniotomy will be presented.
HOT TOPICS IN ABDOMINAL DOPPLER Evaluation of TIPS Teefey SA, Mallinckrodt Institute of Radiology, St. Louis, MO Acute or recurrent variceal hemorrhage is the most common indication for TIPS placement. Although the immediate technical success rate of placing a TIPS is approximately 90%, the frequency of TIPS stenosis and occlusion is fairly high. Duplex and color Doppler sonography has been shown to be an excellent means to evaluate and follow patients with stents. Various Doppler perimeters can be used to diagnose shunt malfunction including peak systolic velocity within the stent, the difference between the maximum and minimum velocity in the stent, temporal change in the stent velocity, velocity in the main portal vein, flow direction in the left and right portal vein branches, peak systolic velocity in the hepatic artery, and flow direction in the draining hepatic vein. Each of these perimeters will be discussed during this lecture to assist the participant in better understanding how to diagnose TIPS malfunction.
Role of Doppler in the diagnosis and follow-up of abdominal vascular disease Pellerito J, Radiology, North Shore University Hospital, Manhasset, NY