Acute CT perfusion changes in seizure patients presenting to the emergency department with stroke-like symptoms: correlation with clinical and electroencephalography findings.

AIM: To determine acute computed tomography perfusion (CTP) changes in seizure patients presenting with stroke-like symptoms and to correlate those changes with clinical presentation and electroencephalography (EEG). MATERIALS AND METHODS: The medical records of all patients who presented to the emergency department with acute stroke-like symptoms and underwent CTP (n=1085) over a 5.5-year period were reviewed. Patients were included who had primary seizure as the final diagnosis, and underwent CTP within 3 hours of symptom onset. A subset of patients had a follow-up EEG within 7 days. The perfusion changes and EEG findings were compared between different clinical presentations. RESULTS: Eighteen of 1085 patients (1.7%) who underwent CTP following an acute stroke-like presentation were included. The abnormality on CTP was usually focal, unilateral hyperperfusion - increased relative cerebral blood flow (rCBF) and volume (rCBV) (n=14/18), which most often affected the temporal lobe. Those patients who presented with a motor or speech deficit (n=12) had a higher temporal lobe rCBV, and rCBF, and lower relative mean transit time (rMTT) compared to those with non-focal neurological deficit at presentation. Early EEG was available in 13 patients; a sharp-spike epileptiform EEG discharge pattern (n=5) was associated with higher temporal lobe ipsilateral rCBF and rCBV, and lower rMTT on admission CTP examination. CONCLUSION: Seizure patients who present with a unilateral motor or speech deficit most commonly have contralateral hyperperfusion in the corresponding eloquent brain regions on the acute-stage CTP examination. In such patients, epileptiform discharges on the early follow-up EEG are associated with ipsilateral hyperperfusion on the admission CTP.

Comparison of spin-echo and gradient-echo T1-weighted and spin-echo T2-weighted images at 3T in evaluating term-neonatal myelination.

SUMMARY: A prior clinical report of 3T MR imaging in subsequently healthy very premature neonates imaged at term-equivalent age found that both gradient recalled-echo-T1WI and spin-echo-T2WI showed higher rates of myelinated structures, compared with spin-echo-T1WI. The current study set out to assess those rates on the same sequences at 3T in term neonates and thus consisted of 16 term neonates with normal-appearing MR imaging findings who subsequently had normal findings at clinical follow-up. Two neuroradiologists independently assessed 19 structures in those infants on all 3 sequences. Gradient recalled-echo-T1WI showed a slightly higher rate of myelination (57.2%-72.4% of all structures) and interobserver agreement (κ = 0.546, P < .0001) than spin-echo-T2WI (58.2%-64.8%; κ = 0.468, P < .0001), while spin-echo-T1WI had the lowest myelination rate and agreement (25.0%-48.4%; κ = 0.384, P < .0001). Both observers noted that the following structures were myelinated in 88%-100% of patients on gradient recalled-echo-T1WI: the brachium of the inferior colliculus, decussation of the superior cerebellar peduncle, habenular commissure, medial lemniscus, pyramidal decussation, posterior limb of the internal capsule, and superior cerebellar peduncle; on spin-echo-T2WI, there was myelination in 88%-100% of the following structures: the brachium of the inferior colliculus, decussation of the superior cerebellar peduncle, inferior cerebellar peduncle, medial lemniscus, and posterior limb of the internal capsule. In conclusion, this study confirmed that similar to the findings in term-equivalent-age premature infants, myelination changes in term neonates may be best assessed on both gradient recalled-echo-T1WI and spin-echo-T2WI at 3T, and not on spin-echo-T1WI.

MRI in juvenile ALS: a patient report.

We describe the MR images of a patient with juvenile ALS. MRI of the brain showed bilateral hyperintensities along the corticospinal tracts extending from the corona radiata to the brainstem on T2-weighted images. These findings should be differentiated from the slight hyperintensities seen in the posterior limbs of the internal capsules in normal subjects.

Bilateral periventricular nodular heterotopia with mental retardation and syndactyly in boys: a new X-linked mental retardation syndrome.

Bilateral periventricular nodular heterotopia (BPNH) is a recently recognized malformation of neuronal migration, and perhaps proliferation, in which nodular masses of gray matter line the walls of the lateral ventricles. Most affected individuals have epilepsy and normal intelligence with no other congenital anomalies. A striking skew of the sex ratio has been observed because 31 of 38 probands have been female, and one gene associated with BPNH was recently mapped to chromosome Xq28. We report three unrelated boys with a new multiple congenital anomaly-mental retardation syndrome that consists of BPNH, cerebellar hypoplasia, severe mental retardation, epilepsy, and syndactyly. Variable abnormalities included focal or regional cortical dysplasia, cataracts, and hypospadius. We hypothesize that this syndrome involves the same Xq28 locus as isolated BPNH, and we review the expanding number of syndromes associated with BPNH.

Differences in the gyral pattern distinguish chromosome 17-linked and X-linked lissencephaly.

BACKGROUND: Classical lissencephaly or "smooth brain" is a human brain malformation that consists of diffuse agyria and pachygyria. Two genes associated with classical lissencephaly have recently been cloned-LIS1 from chromosome 17p13.3 and XLIS (also called DCX) from Xq22.3-q23. OBJECTIVE: We performed genotype-phenotype analysis in children with lissencephaly associated with mutations of different genes. METHODS: We compared the phenotype, especially brain imaging studies, in a series of 48 children with lissencephaly, including 12 with Miller-Dieker syndrome (MDS), which is associated with large deletions of LIS1 and other genes in the region, 24 with isolated lissencephaly sequence caused by smaller LIS1 deletions or mutations, and 12 with isolated lissencephaly sequence caused by XLIS mutations. RESULTS: We found consistent differences in the gyral patterns, with the malformation more severe posteriorly in individuals with LIS1 mutations and more severe anteriorly in individuals with XLIS mutations. Thus, mutations of LIS1 are associated with a posterior-to-anterior gradient of lissencephaly, whereas mutations of XLIS are associated with an anterior-to-posterior gradient. We also confirmed differences in severity between MDS and ILS17. Hypoplasia of the cerebellar vermis proved to be more common with XLIS mutations. CONCLUSION: It is often possible to predict the gene mutation from careful review of brain imaging studies.

X-linked malformations of neuronal migration.

Malformations of neuronal migration such as lissencephaly (agyria-pachygyria spectrum) are well-known causes of mental retardation and epilepsy that are often genetic. For example, isolated lissencephaly sequence and Miller-Dieker syndrome are caused by deletions involving a lissencephaly gene in chromosome 17p13.3, while many other malformation syndromes have autosomal recessive inheritance. In this paper, we review evidence supporting the existence of two distinct X-linked malformations of neuronal migration. X-linked lissencephaly and subcortical band heterotopia (XLIS) presents with sporadic or familial mental retardation and epilepsy. The brain malformation varies from classical lissencephaly, which is observed in males, to subcortical band heterotopia, which is observed primarily in females. The XLIS gene is located in chromosome Xq22.3 based on the breakpoint of an X-autosomal translocation. Bilateral periventricular nodular heterotopia (BPNH) usually presents with sporadic or familial epilepsy with normal intelligence, primarily in females, although we have evaluated two boys with BPNH and severe mental retardation. The gene for BPNH has been mapped to chromosome Xq28 based on linkage studies in multiplex families and observation of a subtle structural abnormality in one of the boys with BPNH and severe mental retardation.

A categorical course curriculum for radiology residencies.

A categorical course curriculum was introduced at Brooke Army Medical Center to focus the content of daily conferences and lectures according to radiology subspecialties. Our goal was to improve the traditional uncoordinated conferences and apprenticeship approach to resident learning. After one-year's experience, resident performance has improved, and residents and staff greatly prefer this style of teaching. The format has been adopted.

Resolution improvements in in vivo 1H NMR spectra with increased magnetic field strength.

The measurement of cerebral metabolites using highly homologous localization techniques and similar shimming methods was performed in the human brain at 1.5 and 4 T as well as in the dog and rat brain at 9.4 T. In rat brain, improved resolution was achieved by shimming all first- and second-order shim coils using a fully adiabatic FASTMAP sequence. The spectra showed a clear improvement in spectral resolution for all metabolite resonances with increased field strength. Changes in cerebral glutamine content were clearly observed at 4 T compared to 1.5 T in patients with hepatic encephalopathy. At 9.4 T, glutamine H4 at 2.46 ppm was fully resolved from glutamate H4 at 2.37 ppm, as was the potential resonance from gamma-amino-butyric acid at 2.30 ppm and N-acetyl-aspartyl-glutamate at 2.05 ppm. Singlet linewidths were found to be as low as 6 Hz (0.015 ppm) at 9.4 T, indicating a substantial decrease in ppm linewidth with field strength. Furthermore, the methylene peak of creatine was partially resolved from phosphocreatine, indicating a close to 1:1 relationship in gray matter. We conclude that increasing the magnetic field strength increases spectral resolution also for 1H NMR, which can lead to more than linear sensitivity gains.

The normal and abnormal genu of the corpus callosum: an evolutionary, embryologic, anatomic, and MR analysis.

PURPOSE: To define the normal and abnormal genu of the corpus callosum by examining its evolution and embryology and by analyzing its normal and abnormal appearance on MR images. METHODS: A reference line was drawn from the mamillary body through the anterior commissure and corpus callosum-the MAC line. This line was used to evaluate the genu in adult mammal brains, in human fetal brains, on MR images of 1800 patients with normal corpora callosi, and on MR images of 113 patients with callosal anomalies. RESULTS: In primates, increased frontal lobe size is associated with an anteriorly shifted genu. In human fetal development, the anterior body of the corpus callosum develops before the definitive genu. The normal human genu always projects in front of the MAC line. In none of the 113 patients with callosal anomalies was there only a normal genu. CONCLUSIONS: The human corpus callosum develops bidirectionally, not from front to back. The MAC line is a useful frame of reference to study the evolution and embryology of the genu and to distinguish the normal from the abnormal genu of the human corpus callosum.

The lamina rostralis: modification of concepts concerning the anatomy, embryology, and MR appearance of the rostrum of the corpus callosum.

PURPOSE: To study the anatomy and embryology of the lamina rostralis, and to determine whether the rostrum is, as frequently stated, the last section of the corpus callosum to develop. METHODS: The rostrum was analyzed in dissected adult brains and on MR studies in 300 patients with a normal corpus callosum and in 84 patients with a hypogenetic corpus callosum. MR images of intact fetuses and photographs of dissected fetal and adult vertebrate brains were also analyzed. RESULTS: The rostrum extends from the genu to the upper end of the lamina terminalis and consists of two sections: a thick beaked segment and the thin lamina rostralis, which blends posteriorly with the lamina terminalis. During fetal development the lamina rostralis changes from a semivertical to a semihorizontal orientation. Many hypogenetic corpora callosi have a semivertical lamina rostralis. A rudimentary beaked segment can be present without a normal genu. CONCLUSIONS: The rostrum is not the last segment of the corpus callosum to develop. Rather, the lamina rostralis segment of the fetal rostrum is already present before the genu and splenium develop. Additionally, the beaked segment of the rostrum develops concurrently with maturation of the genu.

Brain damage from perinatal asphyxia: correlation of MR findings with gestational age.

MR scans of 25 patients who suffered asphyxia at known gestational ages were reviewed retrospectively. The gestational ages of the patients at the time of asphyxia ranged from 24 to 46 weeks. The MR pattern of brain damage in patients with prolonged partial asphyxia was seen to evolve in a predictable manner corresponding to the known maturation of the brain and its vascular supply. Patients at 24- and 26-weeks gestational age had irregularly enlarged ventricular trigones with minimal periventricular gliosis. Patients at 28-34 weeks had variably dilated ventricles with periventricular gliosis. The 36-week neonate had mild cortical and subcortical atrophy and gliosis superimposed on deep white matter and periventricular gliosis. Term neonates had significant cortical and subcortical gliosis and atrophy in the parasagittal watershed areas. Postterm neonates (44-46 weeks) showed cortical and subcortical watershed gliosis and atrophy with sparing of the immediate periventricular region. Two children suffered cardiocirculatory arrest; their scans revealed a different pattern of brain damage, demonstrating primarily brainstem, thalamic, and basal ganglia involvement. MR appears to be a powerful tool in the assessment of brain damage resulting from perinatal asphyxia that gives important clues to the time and nature of the asphyxia.

Pathogenesis of intracranial lipoma: an MR study in 42 patients.

Intracranial lipomas are uncommon lesions whose development remains poorly understood. To clarify the anatomic and embryologic features of intracranial lipomas, we retrospectively reviewed the MR scans of 42 patients with 44 intracranial lipomas. Interhemispheric lipomas were the most common, accounting for 45% of cases. The remainder of the lesions were clustered in the quadrigeminal/superior cerebellar (25%), suprasellar/interpeduncular (14%), cerebellopontine angle (9%), and sylvian (5%) cisterns. Fifty-five percent of the lesions were associated with brain malformations of varying degrees. Intracranial vessels and nerves were noted to course through 16 (36%) of the lesions. The relative frequencies of the locations of the lipomas correspond to the temporal sequence of dissolution of the meninx primitiva, the mesenchymal anlage of the meninges. This finding supports the concept of lipoma formation as a result of abnormal persistence and maldifferentiation of the meninx. This embryologic concept of the development of intracranial lipomas explains the high frequency of callosal and other brain hypoplasias. Intracranial lipomas are neither hamartomas nor true neoplasms; rather, they are congenital malformations.

MR imaging of rhombencephalosynapsis: report of three cases and review of the literature.

We describe the clinical and MR findings in three cases of rhombencephalosynapsis, a rare congenital malformation of the posterior fossa consisting of vermian agenesis or severe hypogenesis, fusion of the cerebellar hemispheres, and apposition or fusion of the dentate nuclei. Associated anomalies include hydrocephalus, fusion of the inferior colliculi, deficiency or absence of the septum pellucidum, and hypoplasia of the anterior commissure. Fourteen previous cases of rhombencephalosynapsis have been reported including Obersteiner's first report in 1914. The clinical presentation is variable, ranging from early death to variable degrees of cerebellar dysfunction and developmental delay. Patients may reach young adulthood. We report three additional cases and provide radiographic (MR) images of this unusual anomaly detected during life. Diagnoses in three children with rhombencephalosynapsis were made on the basis of MR findings. To our knowledge, this is the first report of this disorder being diagnosed in living patients.

MR imaging of reversible cyclosporin A-induced neurotoxicity.

Neurotoxicity is a recognized complication of cyclosporin A (CsA) therapy in patients undergoing organ transplantation. It is most commonly manifested by fever, seizures, and altered mental status. Cortical blindness and speech and motor disturbances can also occur. Changes seen in cerebral white matter on imaging studies are nonenhancing areas of hypoattenuation on CT and T2 prolongation on MR. We report three cases of CsA-induced neurotoxicity in which reversible changes were observed in the cerebral white matter. In the first patient, CsA neurotoxicity occurred 1 week following orthotopic liver transplantation. In the second patient, CsA neurotoxicity coincided with an episode of severe systemic hypertension 4 weeks after cardiac transplantation. The third patient experienced seizures 1 month after heart/lung transplantation for cystic fibrosis. A current theory postulates a relationship between diminished serum cholesterol and CsA neurotoxicity. This theory, however, does not satisfactorily address all cases of CsA neurotoxicity. In particular, serum cholesterol measurements were normal in cases 2 and 3 and probably were normal in case 1, despite diminished cholesterol levels preoperatively. Although the matter of CsA-induced neurotoxicity remains unresolved, we suggest that endothelin, a newly described neuropeptide that causes intense vasoconstriction and that has been implicated in cerebral vasospasm, may potentiate CsA-induced damage to endothelium and promote CsA neurotoxicity.

Preliminary assessment of turbo spectroscopic imaging for targeting in brain biopsy.

BACKGROUND AND PURPOSE: Brain biopsy remains an integral and necessary component in the diagnosis of brain lesions. We assessed the ability of turbo spectroscopic imaging (TSI) to provide a physiologically based target for tissue sampling. METHODS: TSI was performed in 26 anesthetized patients immediately before MR-guided brain biopsy. In 10 patients, single-voxel spectroscopy was performed on the TSI-indicated target and correlated with the TSI findings. Biopsy samples were taken from the imaging and spectroscopically defined target(s) under MR guidance, and pathologic findings were compared with preoperative spectra. RESULTS: TSI alone provided a definitive target based on a region of elevated choline in 17 of 21 patients in whom a neoplasm was confirmed. The remaining four neoplasms exhibited relatively low metabolic levels and were difficult to distinguish from the five cases of radiation necrosis seen in this study. TSI findings were in qualitative agreement with those obtained at single-voxel spectroscopy, although TSI spectra exhibited more contamination. Quantitative spectral analysis of TSI data is limited by low spectral resolution. CONCLUSION: TSI is helpful for determining an appropriate biopsy target in heterogeneous lesions. Coupling TSI targeting with conventional imaging and intraoperative confirmation of needle positioning resulted in a 100% diagnostic success rate and increased the clinician's confidence in the histologic findings.

Pallister-Hall syndrome: clinical and MR features.

A 4-month-old boy with polydactyly and bifid epiglottis was found to have a large sellar and suprasellar mass. When the diagnosis of Pallister-Hall syndrome was made, conservative management was elected. When the patient was 2 years old, the tumor had grown proportionally with the patient, and he was developing appropriately. Although rare, this entity is important to recognize not only for clinical diagnosis but also for appropriate management and genetic counseling.

Posterior reversible encephalopathy syndrome: utility of fluid-attenuated inversion recovery MR imaging in the detection of cortical and subcortical lesions.

BACKGROUND AND PURPOSE: Posterior reversible encephalopathy syndrome (PRES) is typically characterized by headache, altered mental functioning, seizures, and visual loss associated with imaging findings of bilateral subcortical and cortical edema with a predominantly posterior distribution. Our goal was to determine whether fluid-attenuated inversion recovery (FLAIR) imaging improves the ability to detect subtle peripheral lesions of PRES, as compared with conventional MR techniques. METHODS: Sixteen patients with clinical and imaging findings consistent with PRES were studied. Thirteen patients had undergone transplantation and had cyclosporin A neurotoxicity. Fast-FLAIR images were compared with spin-echo proton density- and T2-weighted images. RESULTS: FLAIR imaging improved diagnostic confidence and conspicuity of the T2 hyperintense lesions of PRES, typically in the subcortical white matter of the parietooccipital regions bilaterally. On all 23 abnormal MR studies, FLAIR was judged superior to proton density- and T2-weighted images for the detection of PRES in the supratentorial brain. In a mean of 6.7 of 23 studies, FLAIR findings prompted a raise in the grade of disease severity. FLAIR also showed cortical involvement in 94% of patients with PRES and in a mean of 46% of the total lesion burden. In four cases, subtle lesions were virtually undetectable without FLAIR. Brain stem or cerebellar disease was encountered in 56% of patients. CONCLUSION: FLAIR improves the ability to diagnose and detect subcortical and cortical lesions in PRES as compared with proton density- and T2-weighted spin-echo images. We therefore believe that FLAIR should be performed in patients with suspected PRES to allow more confident recognition of the often subtle imaging abnormalities.

Posterior fossa venous angiomas with drainage through the brain stem.

PURPOSE: To describe 11 cases of posterior fossa venous angiomas with drainage through the brain stem. METHODS: Eleven cases of posterior fossa venous angioma with drainage through the brain stem were evaluated using MR. Correlation with known routes of venous drainage for the cerebellum and brain stem is made. RESULTS: Six of the 11 venous angiomas were found in the cerebellum, four in the brain stem; one involved both the cerebellum and brain stem. The cerebellar venous angiomas drained to subependymal veins about the fourth ventricle and dorsal pons. These then connected with an enlarged transmesencephalic or transpontine vein, to drain anteriorly to the anterior pontine veins. The brain stem angiomas had variable drainage depending on location. Evidence of hemorrhage was seen in five cases. CONCLUSION: Cerebellar and brain stem venous angiomas have several potential routes of drainage, including an enlarged vein traversing the pons, midbrain, or medulla. A knowledge of the normal venous anatomy of this region helps to understand the occurrence of these uncommon routes of venous drainage.

MR imaging of Kallmann syndrome, a genetic disorder of neuronal migration affecting the olfactory and genital systems.

PURPOSE: We report the MR findings in nine patients with clinical and laboratory evidence of Kallmann syndrome (KS), a genetic disorder of olfactory and gonadal development. In patients with KS, cells that normally express luteinizing hormone-releasing hormone fail to migrate from the medial olfactory placode along the terminalis nerves into the forebrain. In addition, failed neuronal migration from the lateral olfactory placode along the olfactory fila to the forebrain results in aplasia or hypoplasia of the olfactory bulbs and tracts. Patients with KS, therefore, suffer both reproductive and olfactory dysfunction. METHODS: Nine patients with KS underwent direct coronal MR of their olfactory regions in order to assess the olfactory sulci, bulbs, and tracts. A 10th patient had MR findings of KS, although the diagnosis is not yet confirmed by laboratory tests. RESULTS: Abnormalities of the olfactory system were identified in all patients. In particular, the anterior portions of the olfactory sulci were uniformly hypoplastic. The olfactory bulbs and tracts appeared hypoplastic or aplastic in all patients in whom the bulb/tract region was satisfactorily imaged. In two (possibly three) patients, prominent soft tissue in the region of the bulbs suggests radiographic evidence of neurons that have been arrested before migration. CONCLUSIONS: Previous investigators of patients with KS used axial MR images to demonstrate hypoplasia of the olfactory sulci but offered no assessment of the olfactory bulbs. In the present study we used coronal images to show hypoplasia of both olfactory sulci and bulbs. In addition, we found what we believe to be the radiologic correlate of arrested neuronal migration in KS.

Cerebral palsy: MR findings in 40 patients.

PURPOSE: We used MR to retrospectively analyze the brains of patients suffering from cerebral palsy, our aim being to determine MR's role in the assessment of brain damage and the relationship of pre-, peri-, and post-natal events to cerebral palsy. METHODS: Forty patients (aged 1 month to 41 years) underwent MR scanning and findings were correlated with clinical histories in all cases. RESULTS: Review of MR scans of 11 patients who had been born prematurely revealed findings of periventricular white matter damage, indicative of hypoxic-ischemic brain injury (82%), the chronology of which was difficult to determine. Among 29 patients who had been born at term, three major patterns emerged: (1), gyral anomalies, suggestive of polymicrogyria, consistent with mid-second trimester injury; (2), isolated periventricular leukomalacia reflecting late second- or early third-trimester injury; and (3), watershed cortical or deep gray nuclear damage, consistent with late third-trimester, perinatal or postnatal injury. In 16 (55%) of 29 patients born at term, MR findings of intrauterine brain damage were observed; in over half of these cases MR revealed developmental anomalies, which is nearly twice the rate reported in prior studies employing CT. CONCLUSIONS: Our results support a growing consensus that cerebral palsy in term infants is often the result of prenatal factors, and less commonly related to the perinatal period.