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Purpose: To evaluate with respect to gestational age (GA) the effect of magnetic resonance (MR) imaging on changes in diagnosis, patient counseling, and case management regarding fetuses suspected of having central nervous system (CNS) anomalies., Materials and Methods: The authors compared images from 242 ultrasonographic (US) studies and 242 MR imaging studies of the CNS in 214 fetuses. Reference standards of postnatal physical examination, imaging, surgical, and autopsy findings were available in 171 (79.9%) fetuses. Referring physicians were surveyed on how MR imaging findings changed patient counseling or case management. Outcomes were compared with respect to GA. Statistical tests used were the Fisher exact test, Student t test, and analysis of variance., Results: Confirmatory US findings were normal in 69 fetuses. MR imaging findings changed diagnosis in 46 of 145 (31.7%) fetuses with abnormal US findings. The mean GA of 72 of 145 fetuses with changes in maternal counseling (25.9 weeks) was significantly greater than that in 73 of 145 fetuses without changes in maternal counseling (22.6 weeks, P <.01). The mean GA of the 46 fetuses with changes in diagnosis (26.3 weeks) was significantly greater than that of the 99 fetuses with no major change in diagnosis (23.3 weeks, P <.01). There were 27 of 145 changes in case management, with no significant difference in mean GA of fetuses with and those without changes in case management. In fetuses with abnormal US findings, MR images were used to decide to terminate the pregnancy (n = 13; mean GA, 20.1 weeks), continue the pregnancy (n = 4; mean GA, 19.2 weeks), direct the mode and/or location of delivery (n = 5; mean GA, 30.5 weeks), and direct perinatal care (n = 5; mean GA, 30.2 weeks)., Conclusion: When a CNS anomaly is detected or suspected at US, MR imaging may demonstrate additional findings that can alter diagnosis and case management. Changes in management are GA dependent., (Copyright RSNA, 2003)

Purpose: To elucidate further the magnetic resonance (MR) imaging appearance of fetal cerebral ventricles by comparing ultrasonographic (US) and MR images., Materials and Methods: A retrospective review of MR and US images was performed for 110 normal fetuses and 94 fetuses with central nervous system abnormalities to assess lateral ventricular morphology as having (a) a normal appearance, (b) mild, disproportionate dilatation of the occipital horns with overall preservation of ventricular morphology, (c) colpocephaly with or without normal orientation of the frontal horns, (d) abnormal orientation of the frontal horns without colpocephaly, (e) an angular appearance, (f) fused frontal horns, (g) global dilation, or (h) a distorted appearance. Ventricular morphology on US and MR images was compared and correlated with reference standard diagnoses., Results: US and MR imaging classifications were concordant in 145 of 188 (77%) examinations. Mild disproportion of occipital horns with respect to frontal horns was seen only on MR images. This ventricular configuration was present in eight of 110 normal fetuses and in 10 of 16 fetuses with isolated mild ventriculomegaly (P <.001). An angular configuration of the lateral ventricles, which is seen in fetuses with neural tube defects (NTDs), was present on review of MR images in 11 fetuses and on US images in one fetus. The ventricles of fetuses with NTDs and angular ventricles (3-12 mm) were significantly smaller than those of fetuses with NTDs and global dilatation of the ventricles (13-25 mm; P <.05)., Conclusion: Ventricular contours differ with differing diagnoses of central nervous system abnormalities.

The surge in the development of fast magnetic resonance (MR) techniques has revolutionized our ability to image the pregnant patient and the fetus. Fast MR imaging techniques provide excellent resolution for imaging the maternal and fetal anatomies without the need for sedation. This article addresses the use of fast MR imaging techniques in the evaluation of the pregnant patient for adnexal masses, pelvimetry, hydroureteronephrosis of pregnancy, and placenta accreta. In addition, fetal anomalies for which MR imaging has proved useful, such as ventriculomegaly, arachnoid cysts, and abdominal masses, are described.

Purpose: To compare fast screening and conventional magnetic resonance (MR) imaging for the detection of occult dysraphic myelodysplasias in children and young adults., Materials and Methods: A retrospective case-control study included 101 patients (mean age, 4.9 years; range, 1 day to 26 years) suspected of having occult lumbosacral dysraphism. Sixty case patients had myelodysplastic lesions (19 filar lipoma, 14 syringomyelia, 10 intradural lipoma, eight dermal sinus, five diastematomyelia, five lipomyelomeningocele, two caudal regression syndrome); 41 control patients had no dysraphic lesions; 17 patients had associated renal anomalies. Two neuroradiologists reviewed MR images from conventional and fast screening protocols. Diagnostic performance parameters included sensitivity, specificity, and area under the receiver operating characteristic curve (Az value)., Results: The sensitivity of conventional and fast screening MR studies was 97.1% and 98.5%, respectively, the specificity was 90.9% and 84.8%, respectively. The Az value was 0.973 for the fast screening and 0.976 for the conventional MR studies (P = .83). Interobserver agreement was very good for fast screening images (kappa = 0.68) and excellent for conventional images (kappa = 0.75). For renal anomalies, the Az value was 0.786 and 0.853 for fast screening and conventional MR imaging, respectively (P = .28)., Conclusion: Conventional three-plane lumbosacral MR imaging in children and young adults suspected of having occult dysraphism provides better diagnostic information than does fast screening two-plane MR imaging because of its higher specificity and interobserver agreement.

Purpose: To establish the appearance of normal fetal cortical development in utero and compare it with the appearance of abnormal cortical development., Materials and Methods: Magnetic resonance (MR) images of the brain in 53 normal and 40 abnormal fetuses at 14-38 weeks gestational age (GA) were reviewed. The GAs at the time of MR imaging visualization of the fissures or sulci were compared with the GA guidelines based on neuroanatomic studies., Results: In normal fetuses, the sulcation landmarks appeared on MR images in the order predicted by using anatomic studies, with a 0-8-week lag in the MR imaging visualization of the sulci compared with the reported time of visualization of the sulci in anatomic specimens. When landmarks were grouped by range of GAs, the expected MR imaging sulcation landmarks in the group with younger GAs than the actual GA were seen in 50 of 53 (94%) normal fetuses, in five of nine fetuses (56%, P < .05) with isolated mild ventriculomegaly, and in 24 of 31 fetuses (77%, P < .05) with other CNS anomalies., Conclusion: Normal fetal cortical maturation at MR imaging follows a predictable course that is slightly delayed compared with that described in neuroanatomic specimens. This maturation is often further delayed in fetuses with CNS abnormalities.

Purpose: To evaluate the normal appearance of fetal anatomy, the conspicuity of fetal organs, the reproducibility of images, and the limitations to image quality with the use of half-Fourier, single-shot rapid acquisition with relaxation enhancement (RARE) magnetic resonance (MR) imaging., Materials and Methods: Fifty-four fetuses of 49 pregnancies underwent MR imaging with the half-Fourier, single-shot RARE technique. Two reviewers attempted to identify 47 organs and anatomic regions in each fetus. Organ or region conspicuity, image quality, and the limitations of image quality were graded., Results: Fetal anatomy was well depicted in fetuses over 20 weeks in gestational age. Fetal imaging was limited by gestational age of 20 weeks or less usually owing to the small size of the organ or region being evaluated and, less frequently, by motion., Conclusion: Half-Fourier, single-shot RARE MR imaging provided a detailed and reproducible evaluation of normal fetal anatomy, which can be used as a standard of reference in MR imaging of fetal anomalies.

Purpose: To evaluate fetuses with sonographically suspected central nervous system anomalies to determine the frequency with which obstetric magnetic resonance (MR) imaging adds clinically useful information to that provided by ultrasonography (US)., Materials and Methods: US and MR images and diagnoses in 18 pregnant women were reviewed and compared by two radiologists. Postnatal physical examination and imaging findings and fetal autopsy results were standards. Referring physicians were questioned as to how the additional information provided by MR imaging changed patient counseling., Results: In 10 (55%) patients, MR imaging demonstrated 11 additional findings. These findings were agenesis of the corpus callosum (n = 4), cerebellar hypoplasia (n = 2), cortical cleft (n = 2), polymicrogyria (n = 1), porencephaly (n = 1), and partial agenesis of the septi pellucidi (n = 1). In seven (39%) patients, additional information provided by MR imaging altered counseling. In one case of suspected agenesis of the corpus callosum, diagnosis at MR imaging was at least partially incorrect., Conclusion: US and MR imaging are complementary imaging methods in the evaluation of high-risk pregnancy. When a central nervous system anomaly is suspected at US, MR imaging may demonstrate additional findings that can alter patient counseling.

Purpose: To determine clinical predictors useful in differentiation of surgical lesions from medically treated disorders and the role of neuroimaging in children with headache. MATERIALS' AND METHODS: In a 4-year retrospective study, 315 patients with headache and no known neurologic disorder underwent brain magnetic resonance (MR) imaging. Sixty-nine patients also underwent brain computed tomography (CT). Clinical data were correlated with findings from MR imaging and CT and the final diagnosis by means of logistic regression., Results: Thirteen (4%) patients had surgical space-occupying lesions. Seven independent multivariate predictors of a surgical lesion were identified. Sleep-related headache and no family history of migraine were the strongest predictors. Other predictors included vomiting, absence of visual symptoms, headache of less than 6 months duration, confusion, and abnormal neurologic examination findings. A positive correlation between number of predictors and risk of surgical lesion was noted (P < .0001). No difference between MR imaging and CT was noted in detection of surgical space-occupying lesions, and there were no false-positive or false-negative surgical lesions detected with either modality on the basis of clinical follow-up., Conclusion: Children at high risk on the basis of these criteria usually require neuroimaging, while children at low risk may be safely followed up clinically without neuroimaging.

A three-dimensional registration and alignment algorithm was developed to align single photon emission computed tomography examinations and magnetic resonance images. Operators manipulated images interactively with real-time visual feedback, with use of both internal and surface features to achieve accurate alignment. Operators aligned five brain phantom examinations (accuracy, 1.6 pixels; consistency, 0.7 pixels) and eight patient brain examinations (consistency, 0.5 pixels).

The authors analyzed the clinical and imaging findings in 30 consecutive pediatric, adolescent, and young adult patients who underwent MR imaging because of atypical features of idiopathic scoliosis. Atypical clinical and plain radiographic features included early onset (n = 4), rapid progression (n = 19), pain (n = 17), other neurologic symptoms or signs (n = 12), associated syndromes (n = 4), a convex left thoracic or thoracolumbar curve (n = 18), a kyphotic component (n = 7), and pedicle thinning (n = 4). MR imaging demonstrated 17 abnormalities in 11 patients: lumbar disk protrusions (n = 1), patulous intradural space (dural ectasia) (n = 3), hydrosyringomyelia (n = 7), Chiari I malformation (n = 5), and cord astrocytoma (n = 1). Significant associations with abnormal MR imaging findings were shown for patients with pain, weakness, abnormal neurologic findings, and atypical curvatures. Furthermore, there was a striking association of convex left thoracic or thoracolumbar scoliosis with hydrosyringomyelia (six of seven cases). On the basis of these results, "atypical" spinal curvatures at radiography and "atypical" clinical features should prompt performance of additional diagnostic studies.

Signal intensity of blood products on proton-density- and T2-weighted images obtained with spin-echo (SE) and fast SE (FSE) sequences was evaluated in 15 patients with central nervous system hemorrhage to determine the extent of differences between the two techniques when signal loss from magnetic susceptibility effects in hemorrhagic lesions is considered. Within operator-defined regions of interest, signal intensity of hemorrhage, iron-containing nuclei, white matter, scalp fat, and noise was measured along the phase-encoding direction. Hemosiderin, deoxyhemoglobin, and iron-containing nuclei had slightly higher signal intensity on FSE images than on SE images, but the differences were not statistically significant. Signal intensity of methemoglobin was similar with both sequences, whereas that of scalp fat was higher on FSE images. Signal intensity measurements for most tissues studied were comparable, but the signal-to-noise ratios with FSE imaging were less than those with SE imaging. Although paramagnetic blood products may show slightly higher signal intensity with FSE imaging, contrast with the two sequences was comparable and lesion conspicuity was nearly identical.