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Neuroimaging techniques have improved the understanding, diagnosis, and management of epilepsy. By providing excellent structural information, MRI is the technique of choice in evaluating patients with epilepsy. Functional imaging techniques, including MR spectroscopy, functional MRI, positron emission tomography, and single photon emission CT, permit noninvasive assessment of the epileptic substrate, its functional status, and neuroreceptors. The MRI-based techniques will potentially assume a greater role in the cost-effective workup of the patient. Currently, newer techniques such as magnetoencephalography, magnetic source imaging, and optical imaging are research tools.

Syphilis has become much more prevalent because of the dramatic increase in immunocompromised patients. The increase in immunocompromised patients is mainly secondary to AIDS. This article is put forth to refamiliarize the reader with syphilis, specifically neurosyphilis. The neurologic symptomatology and neuroimaging characteristics are presented so that one can recognize the findings and consider the diagnosis of neurosyphilis when confronted with a patient with AIDS.

Objective: Malignant neoplasms exhibiting mixed populations of neuronal and glial cells occurring in the cerebral hemispheres of young adults and children are well recognized, but rare. A confusing array of diagnostic terms has arisen. We describe two patients with such tumors and review the literature concerning these interesting cases., Patients: A 21-year-old man and a 5-year-old girl presented with large, cystic, intracerebral lesions on magnetic resonance images, which proved to be composite neoplasms exhibiting malignant neurons and astrocytes., Results: The 21-year-old man had a frontal lobe mass with enhancing and nonenhancing regions, which corresponded to cerebral neuroblastoma and anaplastic astrocytoma, respectively. The presence of occasional microtubules and rare primitive presynaptic processes, accompanied by antisynaptophysin immunoreactivity, established the neuronal nature of the cells in the enhancing region. The nonenhancing region was composed of a moderately cellular neoplasm of fibrillar astrocytes that were mitotically active. The 5-year-old girl presented with a left parietal lobe neoplasm, which histologically was composed of lobular proliferations of neuroblasts and glia. The neuroblastic populations exhibited evidence of maturation with small anaplastic cells, spindle-shaped cells, and large dysmorphic ganglion cells. The glial tumor showed both well-differentiated fibrillary astrocytes with microcysts and anaplastic populations with central necrosis and pseudopalisading., Conclusions: Present classification systems devised to describe mixed neuronal and glial tumors do not adequately encompass the diversity of morphologies presented by these two cases. We conclude that the terms cerebral neuroblastoma-anaplastic astrocytoma for case 1 and cerebral ganglioneuroblastoma-glioblastoma for case 2 are preferred because they convey useful clinical information by reflecting concepts already encompassed by the World Health Organization's classification system of tumors of the central nervous system.

Medial temporal sclerosis of the hippocampus and other lesions in the adjacent temporal lobe that can cause epilepsy are discussed in this article. The technical factors to consider to optimally image the hippocampus and criteria to diagnose medial temporal sclerosis are emphasized.

MR imaging sections of the hippocampus in different orthogonal planes are illustrated. Matching coronal slices in T2-weighted and gradient echo sequences allow a comparative evaluation of the intricate structure of the hippocampus and its relationship with adjacent structures. Techniques in volumetric assessment of the hippocampus are discussed in light of recent advancement in MR imaging.

Comprising the septal area and the subcortical nuclei, the septal region is gray matter structures with widespread projection systems and different neurotransmitters. Although their function is poorly understood, lesions of the septal nuclei result in a syndrome of hyper-reactivity, amnesia, and hypersexuality. The pathologic processes affecting the septal region are discussed.

The limbic system seems to be involved in the pathophysiology of neuropsychiatric disorders, including dementia, schizophrenia, affective disorders, and amnestic disorders. These findings are subtle and largely went undetected until the advent of modern neuroimaging. This article discusses some of the neuroimaging findings in these disorders.

The limbic system has a pivotal role in attention, memory, and the emotions. The limbic lobe comprises four C-shaped arches stretching from the medial surface of the frontal lobe to the temporal pole. The anatomic relationships are elegantly demonstrated by MR imaging. This article provides an overview of the development and complex anatomy of the limbic system.

Gliomatosis cerebri is a rare form of astrocytoma characterized by extreme infiltration of the brain structure in conjunction with a relative paucity of clinical findings. We describe the MRI findings in a patient with gliomatosis cerebri widely infiltrating the brain who presented with symptoms related to involvement of the optic nerves and chiasm. Contrast-enhanced MRI showed enlargement of the optic nerves and chiasm with pathological enhancement; T2-weighted images showed extensive infiltration of the brain by tumor. Histopathologic examination of the biopsy specimen showed anaplastic astrocytoma with gemistocytic predominance and a diagnosis of gliomatosis cerebri was reached.

Objective: The Single-Voxel Proton Brain Exam (PROBE/SV) is an automated MR spectroscopic technique. The purpose of this study was to investigate the use of PROBE/SV as a diagnostic tool in patients with primary brain tumors and to compare our findings with the known information obtained from conventional nonautomated MR spectroscopic techniques., Subjects and Methods: We used PROBE/SV to image 10 normal adults and 46 patients with primary brain tumors: 29 glioblastoma multiformes (GBMs), five anaplastic astrocytomas, and 12 low-grade astrocytomas. All studied were performed on a 1.5-T Signa unit. Average voxel sizes were 6-8 cm3. A corresponding point-resolved spectroscopy spectrum was obtained from normal-appearing brain parenchyma in each patient for comparison with the spectra from known areas of pathology., Results: In patients with low-grade gliomas (grades 1 and 2), we observed decreased N-acetylaspartate (12 of 12) and slightly increased choline (11 of 12) when we compared these metabolites with those in the spectra of patients' normal brains. This comparison in patients with GBM yielded markedly decreased N-acetylaspartate (29 of 29) and prominently increased choline (27 of 29). In the short TE spectra, we frequently saw lipid signal in high-grade tumors, especially in GBMs (12 of 20). We identified lactate peaks in high-grade tumors (anaplastic astrocytoma and GBM, 29 of 34) and also in low-grade tumors (four of 12). The creatine signal in all gliomas was slightly less than that of healthy brain tissue. The lowest N-acetylaspartate, choline, and creatinine levels in conjunction with the highest lactate levels were usually found in necrotic portions of high-grade tumors., Conclusion: PROBE/SV is a simplified MR spectroscopy technique that reduces setup time and provides automatic on-line data processing and display. The voxel location can be selected to focus on the area of interest and to minimize voxel contamination from unwanted tissue. The results from our experimentation with PROBE/SV in patients with brain tumors generally concur with published reports of tumor spectra obtained by conventional MR spectroscopic techniques. The ease and accuracy of this new technique make it a useful clinical tool in differentiating human brain tumor grades.

We aimed to determine the maximum tolerated dose (MTD) of 131I-labeled 81C6 in patients with leptomeningeal neoplasms or brain tumor resection cavities with subarachnoid communication and to identify any objective responses. 81C6 is a murine IgG monoclonal antibody that reacts with tenascin in gliomas/carcinomas but does not react with normal adult brain. 131I-labeled 81C6 delivers intrathecal (IT) radiation to these neoplasms. This study was a Phase I trial in which patients were treated with a single IT dose of 131I-labeled 81C6. Cohorts of three to six patients were treated with escalating doses of 131I (starting dose, 40 mCi; 20 mCi escalations) on 10 mg 81C6. MTD is defined as the highest dose resulting in serious toxicity in no more than two of six patients. Serious toxicity is defined as grade III/IV nonhematological toxicity or major hematological toxicity. We treated 31 patients (8 pediatric and 23 adult). Eighteen had glioblastoma multiforme. Patients were treated with 131I doses from 40 to 100 mCi. Hematological toxicity was dose limiting and correlated with the administered 131I dose. No grade III/IV nonhematological toxicities were encountered. A partial response occurred in 1 patient and disease stabilization occurred in 13 (42%) of 31 patients. Twelve patients are alive (median follow-up, > 320 days); five are progression free >409 days median posttreatment. The MTD of a single IT administration of 131I-labeled 81C6 in adults is 80 mCi 131I-labeled 81C6. The MTD in pediatric patients was not reached at 131I doses up to 40 mCi normalized for body surface area.

Purpose: To describe the neuroimaging (Ct, MR, and single-photon emission CT [SPECT]) findings in a series of patients with chorea-ballismus associated with nonketotic hyperglycemia in primary diabetes mellitus and to correlate the imaging findings with the clinical presentation., Methods: The neuroimaging and clinical data from 10 patients with chorea-ballismus associated with nonketotic hyperglycemia in primary diabetes mellitus were evaluated. Family and drug histories, as well as other causes of chorea, were excluded. All 10 patients had CT, 5 also had MR imaging, and 3 had SPECT examinations. Three had follow-up CT and MR imaging studies, and MR findings were correlated with CT findings in 5 cases. Two experienced neuroradiologists, aware of the diagnosis but blinded to the clinical status of the patients, evaluated all images and reached a consensus as to the final interpretation., Results: CT studies in 9 of 10 patients showed a hyperdense putamen and/or caudate nucleus; in 1, the CT findings were normal. T1-weighted MR images in all 5 patients who had MR imaging (including the patient with a normal CT study) showed hyperintense lesions without significant T2 signal alternation at the basal ganglia. In all 3 of the patients who had SPECT studies of the brain, the scans revealed hypoperfusion at corresponding areas. All 3 follow-up studies depicted resolution of the lesions in the abnormal basal ganglia. Increased hypointensity on T2-weighted and gradient-echo T2*-weighted images was also observed in the sequential MR images. In all patients, the initial side of involvement correlated well with the neuroimaging findings. The chorea resolved within 2 days after treatment of the hyperglycemia in 9 patients., Conclusion: In patients with chorea-ballismus associated with nonketotic hyperglycemia in primary diabetes mellitus, CT and T1-weighted MR images show unilateral or bilateral lesions of the putamen and/or caudate. SPECT scans show hypoperfusion. These findings may be related to petechial hemorrhage and/or myelin destruction. Early recognition of these imaging characteristics may facilitate diagnosis of primary diabetes mellitus with hyperglycemia and prompt appropriate therapy.

We report two cases of papillary meningioma in children. The MRI appearance of this special type of meningioma is described for the first time. Both lesions were dura based and associated with cystic components. We review the literature pertaining to this type of meningioma and discuss the differential diagnosis of the MRI appearance. Because this is a malignant type of meningioma, early diagnosis and surgical intervention are important in the management of patients.

To assess the value of magnetic resonance imaging (MRI)-measured hippocampal volume in the detection of hippocampal sclerosis, we studied 28 patients undergoing anterior temporal lobectomy for medically intractable mesial temporal lobe epilepsy. Hippocampal volumetry and visual analysis of T2 signal change were performed using fast spin-echo T2-weighed MRI. Quantitative neuronal density measurements were performed in the resected hippocampal specimens. There was a significant correlation between MRI-measured absolute hippocampal volume (AHV) and neuronal density in CA1, CA2, and CA3 subfields (p < 0.0001, p < 0.01, and p < 0.05, respectively). Differential hippocampal volume (side-to-side volume difference) failed to detect bilateral atrophy in three patients, but the bilateral hippocampal atrophy was recognized by considering AHV in these patients. This study suggests that MRI-measured AHV can be of value in elevating patients with mesial temporal lobe epilepsy, especially when there is no side-to-side difference in hippocampal volumetry.

We present a case of a giant cell reparative granuloma of the frontoethmoidal region that had a large intracranial extraaxial component and was studied with MR. Although rare, giant cell reparative granuloma can be suggested in the correct clinical setting and when MR features suggest a fibrous lesion.

Cerebral phaeohyphomycosis is used to describe the rare clinical syndrome of cerebral infection caused by dematiaceous (i.e. pigmented olivaceous-brown) fungi. It usually presents as brain abscess. In view of the rarity of this fungal infection and its clinical importance, we report a case of cerebral phaeohyphomycosis caused by Xylohypha bantiana. The patient presented with a seizure attack. The MRI study revealed a ring-enhancing lesion with marked perifocal edema in right high frontoparietal junction of the brain. He underwent an initial craniotomy for removal of the lesion and a second craniotomy for recurrence of the lesion 3 months later. The diagnosis was based on successful cultivation of X. bantiana from the surgical specimen and on histopathology. The patient received antifungal drug therapy of 5-flucytosine and itraconazole. He has done well without any symptoms. We think complete surgical removal of the brain abscess combined with antifungal drug therapy is the best management for this rare fungal disease.

The MR images of a patient with cerebral amyloid angiopathy (a localized vascular deposition of amyloid without evidence of systemic amyloidosis) showed an extensive right temporoparietal lobe mass with frontal lobe extension that was slightly hypointense on T1-weighted images and heterogeneously hyperintense on T2-weighted images. No contrast enhancement was identified on MR imaging.

The imaging findings in a case of panamebic meningoencephalitis and in a case of granulomatous amebic encephalitis, two rare infections of the central nervous system caused by amebae, are presented and the world literature is reviewed. The brain CT findings in panamebic meningoencephalitis are nonspecific; our case showed diffuse edema. In the case of granulomatous amebic encephalitis, there was evidence of large arterial occlusions and MR demonstration of spinal cord infarctions.

Purpose: To identify the extent of hippocampal sclerosis in temporal lobe epilepsy with fast spin-echo MR and correlate it with histopathologic findings and surgical outcome., Methods: MR images of 30 patients with temporal lobe epilepsy and pathologically proved hippocampal sclerosis and 30 control subjects were obtained using a fast spin-echo technique with 4000/100/4 (repetition time/echo time/excitations), 16 echo train, 2- to 3-mm section thickness with interleave, 256 x 256 matrix, and 18-cm field of view. Criteria for MR diagnosis of hippocampal sclerosis included hippocampal atrophy diagnosed with MR volumetry and/or T2-weighted signal change. Hippocampal sectional areas were plotted, and T2 signal changes were topographically evaluated to identify the extent of hippocampal sclerosis, which was subsequently correlated with histopathologic findings and surgical outcome., Results: Hippocampal sclerosis was diffuse, involving both hippocampal head and body, in 96.7% of patients (29 of 30 patients). One patient had normal MR findings. Focal hippocampal sclerosis was not seen. Histopathologic findings of hippocampal sclerosis were present in all 29 patients who had abnormal MR findings. Eighty-six percent of patients (18 of 21 patients), who were followed for at least 1 year after temporal lobectomy, were seizure free (81%, 17 of 21 patients) or significantly improved (5%, 1 of 21 patients)., Conclusion: Fast spin-echo MR enables accurate definition of the extent of hippocampal sclerosis in patients with temporal lobe epilepsy. All cases of hippocampal sclerosis identified in this study involved the hippocampus diffusely. However, leaving the posterior portion of the hippocampus during surgery does not seem to be a major factor influencing surgical outcome.

We present a case of ethmoid mucocele occurring in a two-month-old child, and associated (presumably causally) with a benign fibroosseous lesion of the ethmoid bone. These two conditions may be more frequently associated than previously recognized; MR greatly facilitates their evaluation.

Purpose: To investigate the clinical significance of MR-defined asymmetry of the fornix and mamillary body for presurgical determination of the side of hippocampal sclerosis in patients with temporal lobe epilepsy., Methods: Fast spin-echo MR images were evaluated for evidence of an asymmetrically small fornix and mamillary body in 33 patients with pathologically proved hippocampal sclerosis (presurgical hippocampal sclerosis group), 7 patients who had undergone anterior temporal lobectomy (mean, 3 years from surgery) because of hippocampal sclerosis (postsurgical hippocampal sclerosis group), and 34 healthy subjects (control group). Fast spin-echo hippocampal volumetry was performed in each patient., Results: In the control group, 6% (2 of 34) of subjects had MR evidence of asymmetrically small fornix and none (0 of 34) of the subjects had asymmetrically small mamillary body. In the patient population, an asymmetrically small fornix was seen in 42% of presurgical hippocampal sclerosis group, 39% (13 of 33) ipsilateral, and 3% (1 of 33) contralateral, and in 71% of the postsurgical hippocampal sclerosis group (5 of 7), all ipsilateral. In the presurgical hippocampal sclerosis group, hippocampal atrophy measured with MR was more severe in patients with an ipsilaterally small fornix than in patients without. An asymmetrically small mamillary body was found ipsilaterally in 3% (1 of 33) of the presurgical hippocampal sclerosis group and in 57% (4 of 7) of the postsurgical hippocampal sclerosis group; all patients with an asymmetrically small mamillary body in the postsurgical hippocampal sclerosis group also had an asymmetrically small fornix on the same side., Conclusion: In presurgical hippocampal sclerosis patients, an asymmetrically small fornix can be seen ipsilaterally on the side of the hippocampal sclerosis; however, its low frequency, its association with severe hippocampal atrophy only, and the possibility of false-positive results limit its clinical usefulness in determining the side of the seizure focus. An asymmetrically small mamillary body is too rare to be used for presurgical location of hippocampal sclerosis. However, an asymmetrically small fornix and mamillary body are frequently seen on MR images after temporal lobectomy.

We evaluated the utility of MR imaging in pediatric patients with acute and subacute spinal cord injuries. MR imaging of 22 pediatric patients with suspected traumatic spinal cord injuries was reviewed. MR findings were correlated with physical examination and compared to available radiographs and CT examinations performed at time of presentation. Twelve patients had abnormalities on MR imaging. Seven had spinal cord contusions; five contusions were hemorrhagic. Five of seven patients with cord contusion had normal radiographs and CT exams. Six patients with normal radiographs and CT examinations had abnormal MR studies revealing cord contusion, ligamentous injury, disc herniation, and epidural hematoma. MR is useful in initial evaluation of pediatric patients with spinal cord injuries and in prognosis of future neurologic function. In the setting of spinal cord symptomatology and negative radiographic studies, MR imaging should be performed. Surgically correctable causes of cord compression demonstrated by MR imaging include disc herniation, epidural hematoma, and retropulsed fracture fragments. The entity of spinal cord injury without radiographic abnormality is a diagnosis of exclusion which should only be made after radiologic investigation with radiographs, high-resolution thin-section CT, and MR imaging.

Brainstem gliomas are an important oncologic problem in the pediatric age group, constituting between 10 and 15% of childhood central nervous system neoplasms. A new classification scheme based on magnetic resonance imaging (MRI) has recently been proposed leading to speculation that gadolinium-DTPA-enhanced MRI may prove useful in defining the prognosis of subsets of patients with these tumors. We retrospectively reviewed gadolinium-DTPA-enhanced MRIs in 26 consecutive newly diagnosed pediatric patients (11 males, 15 females) from our institution between June 1988 and June 1994 with the diagnosis of diffuse brainstem glioma. The site, extent of invasion, T1 and T2 signals, and the pattern and the degree of contrast enhancement of the tumors were evaluated. We correlated the image features, clinical symptoms, and survival period in each patient. Seventeen tumors demonstrated contrast enhancement and 9 did not. The survival in the whole group ranged between 3 months and > 5 years with a median of 9 months. There was no statistical difference in the median survival between patients with or without contrast enhancement (11 versus 8 months).

Purpose: To describe imaging findings in the hippocampus in status epilepticus with fast spin-echo (SE) magnetic resonance (MR) imaging., Materials and Methods: Five patients with status epilepticus were examined with fast SE MR imaging, and the findings were correlated with neuropathologic observations of status epilepticus., Results: One patient with diffuse bilateral hippocampal and amygdalal abnormal hyperintensity died. In three patients with hippocampal abnormal hyperintensity and enlargement, hyperintensity and enlargement, follow-up fast SE MR images depicted decreased hyperintensity and swelling; one patient has remained seizure free at 6 months follow-up; a complex partial seizure disorder developed in two, and repeat images demonstrated hippocampal atrophy., Conclusion: T2-weighted fast SE MR images demonstrate reversible abnormal hyperintensity and swelling of the hippocampus and amygdala in patients with status epilepticus. Sequential fast SE MR imaging allows differentiation of this process from neoplasia and is useful in documentation of post-status epilepticus developments such as mesial temporal sclerosis.

Objective: Measurements of the volume of the hippocampus have been used preoperatively to determine the side of the hippocampus involved in patients with intractable temporal lobe epilepsy. However, the method used is time consuming and requires special training. The purpose of this study was to determine the validity of using measurements of the volume of the hippocampal body as a substitute for measurements of the volume of the whole hippocampus in patients with temporal lobe epilepsy., Subjects and Methods: The study group consisted of 33 patients with intractable temporal lobe epilepsy due to presumed hippocampal sclerosis and 30 control subjects. Of the 33 patients with intractable temporal lobe epilepsy, 30 had hippocampal sclerosis and three had normal findings on pathologic examination of the hippocampus. T2-weighted fast spin-echo images were used to determine hippocampal volumes. Volumes were calculated by summing the sectional areas of the entire hippocampus and of the hippocampal body. Correlation between the volume of the hippocampal body and the volume of the whole hippocampus was determined. The sensitivity and specificity of measurement of the volume of the hippocampal body for lateralizing the foci responsible for seizures in patients with presumed hippocampal sclerosis were compared with those of measurement of the volume of the whole hippocampus., Results: Significant linear relationships were noted between volumes of the hippocampal body and volumes of the whole hippocampus (p < .001). The sensitivity and specificity of measurements of volumes of the hippocampal body were identical to those of measurements of volumes of the whole hippocampus (87% and 100%, respectively)., Conclusions: Our results show that segmental MR measurements of the body of the hippocampus are as accurate as measurements of the whole hippocampus for lateralizing temporal lobe epilepsy before surgery. Because segmental measurements are less time consuming and require less experience to perform, they are considered the procedure of choice.

A 32-month-old child presented in status epilepticus (SE) involving the left side of the body. Fast spin-echo magnetic resonance imaging (FSE-MRI) with hippocampal volumetry performed < or = 24 h after the seizure showed increased T2 signal of the right hippocampus, but no atrophy. Complex partial seizures (CPS) appeared at age 33 months, and three more episodes of SE occurred between 33 and 37 months of age. Follow-up FSE-MRI at 34 and at 45 months of age demonstrated progressive hippocampal atrophy with resolution of the increased T2 signal. Her CPS became intractable and, at age 51 months, she underwent right temporal lobectomy. In the ensuing 5 months, she has had only one major motor seizure. This case demonstrates that acute increased hippocampal T2 signal intensity can occur soon after SE and hippocampal sclerosis (HS) may become evident within months in the setting of recurrent early childhood SE. This observation may support the hypothesis that early childhood SE can lead to HS. Furthermore, this case suggests that years of temporal lobe CPS may not be necessary for development of HS.

Terminal syringohydromyelia is a cystic dilatation of the lower third of the spinal cord. The authors describe its incidence and characteristics, its frequent association with occult spinal dysraphism, and its clinical significance and need for surgical treatment. All 143 cases of occult spinal dysraphism treated at the Duke University Medical Center between 1972 and 1992 were reviewed. A terminal syrinx was found in 24 (27%) of the 90 cases that were evaluated by magnetic resonance (MR) imaging. In contrast three (6.2%) of 48 cases evaluated by myelography and postmyelographic computerized tomography had a syrinx documented. The relative radiographic severity of the different syringes was estimated by using measurements of the syrinx and spinal cord on the MR images, classifying the cysts into large and small. Large syringes were frequently symptomatic, commonly presenting with pain, motor and sensory deficits of the lower extremities, scoliosis, and bowel and bladder dysfunction. Terminal syringohydromyelia with occult spinal dysraphic lesions was most often associated with tethered spinal cord from a tight filum terminale in the presence of an anorectal anomaly (67% of cases), meningocele manqué (54%), and diastematomyelia (38%). An infrequent association was seen with other spinal cord anomalies. The results of surgical management of terminal syringohydromyelia were analyzed, highlighting the necessity and effectiveness of shunting the large cysts, especially in the setting of a progressive symptomatology. Of the 11 patients with shunts who underwent MR imaging, 10 showed either complete or significant resolution of the syrinx; all five patients who had presented with pain (mainly back pain) showed complete resolution of the pain after shunting; finally, one-third of patients with shunt placement had significant postoperative improvement in their neurological examination, whereas none worsened. It is stressed that terminal syringohydromyelia is an important pathological entity that should be considered in patients with occult spinal dysraphism, and treated surgically when clinically or radiographically significant.

Conventional treatment for medulloblastoma includes surgical resection followed by craniospinal irradiation, with the potential risk of subsequent radiotherapy-induced secondary neoplasms. We report a 23-year-old woman previously irradiated nine years earlier for a cerebellar medulloblastoma who developed a new enhancing lesion in the primary radiation field four weeks following completion of high dose chemotherapy with bone marrow transplantation for recurrent disease. Resection of this lesion revealed a low grade glioma with no evidence of recurrent medulloblastoma.

The limbic system refers to the part of the brain that is involved in emotional expression and in cognitive and somatomotor control systems; it most likely also has a significant role in the pathogenesis of certain dementias, neuropsychiatric disturbances, and seizure disorders. This system, as originally defined, has no clear anatomic boundaries. Limbic regions of the telencephalon include a continuous medial zone of cortical regions, including the hippocampal formation; a perihippocampal zone, including the cingulate gyrus, prefrontal region, and perirhinal region; along with subcortical areas, including the septum pellucidum and the amygdala. A distinguishing characteristic of the limbic region is that it is highly interconnected and appears to form the only major route for information transfer between the neocortex and the hypothalamus. With the multiplanar capability and resolution of MR imaging, the individual parts of the limbic system and the diseases that affect them can be studied. In this review, we discuss MR imaging of the diseases that affect this system.

Contrast angiography is the standard means of diagnosing spinal dural arteriovenous fistulas. We present a patient in whom a spinal dural arteriovenous fistula was demonstrated on phase contrast MR angiography.

Lesions of the central skull base, most notably the sphenoid bone, commonly originate from the endocranial soft tissues. Although most commonly identified with pituitary macroadenomas, skull base erosion, destruction, and remodeling may be seen with a variety of congenital, neoplastic, cystic, vascular, and inflammatory lesions involving the sellar and parasellar soft tissues.

Magnetic resonance imaging features of a rare pineal region yolk sac tumor found in a 31-year-old man with a history of previously treated embryonal cell carcinoma of the testicle are presented. No specific magnetic resonance imaging features that definitely differentiate yolk sac tumor from other pineal region tumors could be found. However, in individuals with a previously established testicular germ cell tumor, a metastatic or secondary primary germ cell tumor should be suspected when there is a newly diagnosed pineal region mass. Serum tumor markers are helpful in confirming the diagnosis of a germ cell tumor.

Cephalocervical fibromuscular dysplasia is an uncommon vascular disease that affects less than 1% of the population. Although often an incidental finding, patients may present with transient ischemic attacks, cerebral infarctions, or subarachnoid hemorrhage. Fibromuscular dysplasia is usually diagnosed in the fourth or fifth decade of life; it occurs in women more often than in men and in whites more frequently than in blacks. The purpose of this essay is to illustrate the broad spectrum of neuroimaging findings seen on CT scans, MR images, and angiograms of patients with cephalocervical fibromuscular dysplasia. The value of MR imaging in distinguishing tubular fibromuscular dysplasia from arterial dissection and arterial hypoplasia is demonstrated.

A patient had severe hydrocephalus and diffuse leptomeningeal enhancement on MR which mimicked leptomeningeal spread of a primary brain tumor. The leptomeningeal enhancement resolved completely after decompression of the hydrocephalus. Data suggest that the leptomeningeal enhancement is caused by vascular stasis induced by the hydrocephalus.

Objective: The purpose of this study was to evaluate the usefulness of diffusion-weighted echoplanar MR imaging in the examination of high-grade brain gliomas compared with that of conventional spin-echo (SE) or fast spin-echo (FSE) MR imaging. We hypothesize that diffusion-weighted MR imaging may enable us to differentiate various tumor components on the basis of differences in the diffusion of water., Subjects and Methods: Conventional SE and FSE MR images were obtained in 10 patients with high-grade brain glioma. Diffusion-weighted echoplanar MR images were obtained with a head gradient coil capable of providing diffusion-weighted imaging along the cephalocaudal axis. Using SE and FSE MR images as a baseline, we evaluated the diffusion-weighted MR images for usefulness in distinguishing tumor components on the basis of differences in diffusion., Results: Areas of tumor that showed significant enhancement on T1-weighted SE MR images obtained after injection of contrast material were markedly hyperintense on diffusion-weighted images and had a lower apparent diffusion coefficient (ADC) than the ADCs for nonenhancing tumor and peritumoral edema. Cystic or necrotic portions of tumor showed the most signal suppression on diffusion-weighted images and were associated with the highest ADCs. On T2-weighted FSE MR images, areas of hyperintensity observed in white matter oriented parallel to the direction of the diffusion gradient could be differentiated into two patterns on the basis of findings on diffusion-weighted images: areas that showed marked signal suppression with a higher ADC, most likely representing areas of predominantly peritumoral edema, and areas that showed a lesser degree of signal suppression with similar but slightly lower ADCs than those of edema, most likely representing areas of predominantly nonenhancing tumor., Conclusion: Diffusion-weighted echoplanar MR imaging is a useful technique for examining high-grade cerebral gliomas. It enabled us to differentiate various components of the tumor (e.g., enhancing, nonenhancing, cystic, or necrotic) and to distinguish areas of predominantly nonenhancing tumor from areas of predominantly peritumoral edema when the abnormality was located in the white matter aligned in the direction of the diffusion-weighted gradient. Diffusion-weighted echoplanar MR imaging appears to be a powerful tool in the characterization of brain neoplasms.

Chédiak-Higashi syndrome (CHS) is a rare autosomal recessive disorder postulated to result from lack of regulation of fusion of the primary lysosomes. In this report we present the MR and CT features of the brain in a patient with known CHS. These findings include diffuse atrophy of the brain with diffuse periventricular decreased density identified with CT, as well as increased signal on the T2-weighted images and lack of enhancement on the T1-weighted images in the periventricular and corona radiata regions.

Magnetic resonance imaging (MRI) is becoming the method of choice for evaluation of central nervous system tumors. However, the sensitivity of this modality raises concern that new lesions in patients previously diagnosed with a brain tumor may not necessarily represent recurrent disease. We report a patient previously treated with surgery, radiotherapy, and chemotherapy for a medulloblastoma who developed a new lesion in the floor of the fourth ventricle. Histologic review following excision revealed an arteriovenous malformation.

Objective: With the increased survival of patients with severe immunosuppression, it has become more important to recognize the various forms of cerebral and craniofacial aspergillosis. Currently, only small series of patients with this infection have been described; the radiographic diagnosis of cerebral and craniofacial aspergillosis has varied and has been relatively nonspecific. The purpose of our study was to identify neuroimaging patterns in patients with cerebral and craniofacial aspergillosis. Recognition of radiographic patterns of aspergillosis may facilitate earlier radiologic diagnosis and prompt therapy., Materials and Methods: The imaging and clinical data of eight immunosuppressed patients with cerebral aspergillosis and one patient each with aspergillosis of the orbit, paranasal sinus, and calvaria were evaluated retrospectively. All patients were at risk of developing infection by virtue of poorly controlled diabetes or other types of congenital or acquired immunosuppression (e.g., steroids, chemotherapy). Patients were selected for study if the diagnosis of aspergillosis was established by means of biopsy or autopsy and CT scanning or MR imaging was available for review. CT scans and MR images were compared by two experienced neuroradiologists, who were aware of the diagnosis of aspergillosis, to see if common radiographic patterns could be identified that could be used as predictors of this type of infection., Results: Five patients with cerebral aspergillosis had multiple ring-enhancing lesions consistent with abscesses. Characteristic findings were multiple lesions, an irregular ring of contrast enhancement, and hypointensity of the ring on T2-weighted MR images. Three patients had cortical and subcortical hypodensities on CT scanning or hyperintensities on MR imaging consistent with cerebral cortical and subcortical infarction. Two of these three had superimposed hematoma formation. Three patients had craniofacial aspergillosis. One patient each had enhancing mucosal thickening of the paranasal sinus with secondary intracranial dural enhancement, abnormal enhancement of the optic nerve and sheath with infiltrating enhancing soft tissue within the intraorbital fat, and an enhancing diploetic lesion of the calvaria with underlying dural enhancement., Conclusion: Three different neuroimaging patterns of cerebral aspergillosis were identified in immunosuppressed patients. The first pattern was multiple areas of hypodensity on CT scans or hyperintensity on T2-weighted MR images involving the cortex and/or subcortical white matter consistent with multiple areas of embolic infarction. This pattern could be seen with or without superimposed hemorrhage, identified as hyperdensity on CT scans or as hyperintensity on T1-weighted MR images. The second pattern was multiple intracerebral ring-enhancing lesions consistent with abscesses. The ring was irregular and of low signal on T2-weighted MR images. The third pattern was dural enhancement associated with enhancing lesions in the adjacent paranasal sinus structure or calvaria or dural enhancement of the optic sheath with associated optic nerve and intraorbital fat enhancement. Recognition of these three patterns of aspergillosis in immunosuppressed patients may lead to more effective diagnosis and treatment planning.

Maximum intensity projections are the currently accepted method of displaying Magnetic resonance angiography (MRA) data. In this study, we introduce a modified surface rendering method for displaying this same MRA data. The system we have developed is designed to reconstruct three-dimensional (3D) images of vasculature using standard magnetic resonance images. A workstation was used for post-processing that is readily available and inexpensive. Software was written to process the original images and control the commercially available surface rendering algorithm while performing the reconstruction. The standard surface rendering technique was modified by including several velocities of blood flow in the reconstruction. These velocities were assigned varying degrees of translucency, which allow flow information to be included in the reconstructed images. Six subjects were examined using this technique and the images were compared with those from other imaging modalities. This surface rendering method has been shown to produce clearer and more comprehensible images of complex vasculature, both for radiologists, and for physicians of other disciplines. Its success is based on improvements in computing techniques and in acquisition of vascular MR images. The method shows great potential, and with future clinical trials, the true uses of this method will be discovered or confirmed.