Purpose: Superficial venous malformations are slow-flow vascular malformations that present throughout life. This prospective study was conducted to evaluate the prevalence of coexistent developmental venous anomalies, occult vascular malformations, or other associated cerebral anomalies in patients with superficial venous malformations of the head and neck.Methods: Eighty patients with superficial venous malformations of the head and neck had clinical evaluation, computed tomography (CT) before and after contrast administration, and noncontrast T-1- and T-2-weighted magnetic resonance imaging (MRI). Postcontrast. T-1-weighted imaging was performed in some patients (n = 6), as were magnetic resonance angiography (MRA) using two-dimensional phase contrast techniques (n = 8) and time-of-flight techniques (n = 1), and four-vessel angiography (n = 24).Results: Coexistent developmental venous anomalies (DVAs) were present in 21 (26%) of the 80 patients and were clinically silent in all 21 patients. No other cerebral vascular anomaly was depicted. Intradiploic extension of the superficial venous malformation was observed in 11 patients, and lytic bone lesions were seen in 6, In one man, a meningoencephalocele was associated with DVA. III one woman, an orbital meningocele Tvas present. CT detected a venous malformation in association with cerebellar hypoplasia in one additional case, and in association with an arachnoid cyst in another.Conclusion: Our study of patients with venous malformations of the head and neck revealed a higher prevalence of DVAs of the cerebral nervous system in these patients than is usually observed in the general population. A majority of the concurrent DVAs were situated in the posterior fossa, The concurrent DVAs were more common when the venous malformations were extensive, invading the face unilaterally or bilaterally.
Purpose: To obtain quantitative information on regional cerebral metabolic dysfunction in early Parkinson disease (PD).Methods: Twenty-two patients with PD who displayed predominantly or exclusively unilateral symptoms and 13 age-matched control subjects were studied with positron emission tomography (PET) using F-18-deoxyglucose (FDC).Results: Metabolic asymmetry in the lenticular nucleus was 7.8%: the nucleus contralateral to the more affected side was hypermetabolic compared with the other side and compared with the normal lenticular nucleus. The caudate was unaffected. Thalamic metabolism was bilaterally elevated by 13% compared with the control subjects. The cortex generally showed a small metabolic asymmetry in the opposite direction (contralateral hypometabolism). The lenticular asymmetry decreased with disease duration, whereas the cortical asymmetry increased (became more negative).Conclusion: These results support current theories of the effects of PD on neural pathways. The changes with disease duration help to bridge the gap between differing reports in early and advanced PB.
Purpose: To correlate the magnetic resonance imaging (MRI) findings in patients with visual field defects with findings on visual field measurement.Methods: The study included 25 patients with a variety of visual field defects secondary to intracranial lesions, including cerebral infarction, hemorrhage, primary or metastatic brain tumors, arteriovenous malformation (AVM), acute disseminated encephalomyelitis (ADEM), presumed vasculitis, and lobectomy were evaluated using MRI. Four parts of the posterior visual pathways (PVPs) were identified, including the optic tract, the lateral geniculate body (LGB), the optic radiation, and the striate cortex. In each case, the involved regions of the PVPs were correlated with the four parts according to MRI findings, and MRI findings were subsequently compared with expected visual field defects. In patients who showed discrepancies between MRI findings and expected visual field defects, the causes were evaluated.Results: Coronal MRI was useful and could delineate the relationship between the lesion and the PVPs in most cases. The patients were divided into two groups: those with MRI findings consistent with the visual field defects and those with MRI findings inconsistent with the visual field defects. In 16 patients, the locations of the lesions on MRI correlated well with the classically stated visual field defects, although some discrepancies were observed in the remaining 9 patients. In the nine patients in which MRI findings were inconsistent with the visual field defect, reversible ischemic changes in the occipital lobe infarct, perifocal edema with tumor, and optic tract lesion were considered to be the causes of the discrepancies. Occasionally, no visual field defect could be detected because of technical problems with routine visual field measurement.Conclusion: MRI was useful for evaluating patients with PVP abnormalities and the relationship between the lesion and the PVPs. The discrepancies between MRI findings and visual field defects may be caused by pathologic processes of the lesions and technical problems associated with visual field measurement.
Purpose: To examine cerebrospinal fluid (CSF) dynamics and pressure gradients at obstructions of the spinal canal, and to introduce for consideration a new hypothesis for the origin and growth of spinal cord cysts/syringomyelia. This new hypothesis is based on the presence of increased intramedullary pressure; a medullary-arachnoid pressure dissociation; and filling of the cyst by extracellular fluid.Methods: Six patients with posttraumatic syringomyelia, seven patients with Chiari I malformations, and three patients with spinal block were examined with pulse-gated magnetic resonance imaging.Results: The patients with posttraumatic syringomyelia had increased systolic and diastolic CSF velocities at the posttraumatic stenosis, indicating an increased intramedullary pressure gradient at and distal to the stenosis. In patients with Chiari I malformations, systolic volume conduction through the foramen magnum was maintained. This may indicate an increased systolic pulse pressure in the spinal subarachnoid space (SAS).Conclusion: The new hypothesis explains the development of syringomyelia, regardless of its etiology, according to two general principles. First, spinal cord cysts are caused by and formed by mechanical distension of the cord. Second, the cysts are filled by extracellular fluid from the microcirculation of the cord, not by CSF. Increased extracellular fluid in the distended cord may precede cyst formation. Four mechanisms for the mechanical distension of the cord must be considered: 1) increased intramedullary pressure gradients occur at and just distal to obstructions of the spinal canal, and CSF pulse pressure is transmitted into and attenuated within the cord, causing centrifugally directed intramedullary pressure gradients, which distend the cord distal to the obstruction; 2) these centrifugally directed intramedullary pressure gradients are increased by tethering of the cord at the obstruction; 3) in Chiari I malformations, increased pulse pressure in the subarachnoid space may distend the cord by a "milking" action on the cord; and 4) if the cord is tethered, direct mechanical distension of the cord occurs by flexion of the spine.
Purpose: To assess the utility of diffusion-weighted imaging (DWI) in patients with cervical spine spondylosis.Methods: Twenty patients underwent noncontrast magnetic resonance imaging (MRI) and DWI of the cervical spine, Stenoses were measured and patients were divided into those with normal imaging findings, those with spondylosis without stenosis, and those with canal stenosis. Signal intensity in the spinal cord in all patients was assessed and compared between all sequences. Clinical correlation was obtained by review of medical records.Results: Three patients had normal findings; in these patients the spinal cord was uniformly hyperintense on DWI and also normal on MRI. Ten patients showed mild spondylosis without stenosis; in these patients the cord was of uniform size and hyperintense on DWI, and normal on MRI. Canal stenosis was present in six patients, and in two of these T-2-weighted images showed intramedullary hyperintensity at narrowed levels; DWI showed focal hypointensity in the cord ill all six. In one patient, T-2-weighted images showed intramedullary hyperintensity but DWI was normal. One patient was myelopathic, and all had pain and radiculopathy corresponding to the levels of abnormal signal on DWI.Conclusion: In these patients with symptomatic cervical stenosis, signal intensity abnormalities of the spinal cord were more pronounced on DWI than on MRI. All patients had symptoms corresponding with the abnormality noted on DWI.
The purpose of this paper is to organize the foramina of the face and cranial vault by subdividing them into ten color-coded groups according to their location in or between the bones of this region, A chart summarizes the size, content, and variations. Each ostium is shown on a schematic view of the skull and face. A companion paper on the ostia of the skull base has preceded this work (Int J Neuroradiol 1999;5:51-59).
Purpose: Coronal plane magnetic resonance imaging (MRI) is not presently part of the standard protocol for evaluating lumbar disc herniation. This review illustrates the utility of T-1-weighted coronal plane MRI for displaying the presence and site of lateral disc herniations, and a simple classification of those herniations based on their relationship to the pedicles shown on the same coronal images,Methods: Case material at City Park MRI Center, Cape Town, South Africa, and the Armed Forces Hospital, Riyadh, Saudi Arabia, was reviewed to select 42 cases of disc herniations shown on coronal plane MRI.Results: Coronal T-1 MRI displays the relationships of disc herniations to the adjacent pedicles and emerging nerve roots well, permitting simple classification of these herniations into intraspinal, extraspinal intraforaminal, and extraspinal extraforaminal locations.Conclusion: Coronal T-1 MRI contributes to MRI evaluation of lateral lumbar disc herniations.
Purpose: Although lesions of the skull vault are common, they often present difficulty in specific radiologic diagnosis. This study reviews a systematic way to evaluate these lesions by skull radiography, computed tomography (CT), and magnetic resonance imaging (MRI).Methods: Review of the case files of West Virginia University and Winthrop University Hospital provided 70 lesions with good surgical and anatomic-pathologic correlation to illustrate the criteria used in differential diagnosis.Results: Analysis of the case material and application of the diagnostic criteria provides a foundation for rational differential diagnosis by imaging techniques.Conclusion: Using the information provided herein, the radiologist is more likely to achieve a correct diagnosis or to limit the differential diagnosis more successfully.
Purpose: To describe apparent misregistration seen at the periphery of acute and subacute intracerebral hematomas. Although this misregistration is similar in appearance to chemical shift, it is thought to be due to susceptibility artifact.Methods: Four patients underwent magnetic resonance imaging (MRT) for acute or early subacute intracerebral hematoma. Test tubes containing water, oil, and various blood products were placed into the same scan planes to serve as controls. The four patients and all test tubes were scanned at 1.5 T with narrow and broad bandwidths, routine and "swapped" phase and frequency-encoding axes, and with a T-1-weighted gradient echo sequence.Results: A misregistration artifact similar in appearance to chemical shift was seen at the periphery of the hematomas. This artifact was qualitatively similar to chemical shift artifact, but the degree of apparent mis-registration was less than that of fat or oil. In vitro studies using a narrow bandwidth showed that as the artifact increased it resembled the more typical "spearhead" geometric distortion due to susceptibility effect.Conclusion: The mild susceptibility artifact that appears around early hematoma can appear similar to chemical shift artifact, with a hypointense rim along one margin and a hyperintense rim along the other in the direction of the frequency-encoding axis. This may be a manifestation of subtle geometric distortion due to magnetic susceptibility. Susceptibility artifact is also known to cause misregistration along the frequency-encoding axis, This can be of diagnostic utility and help exclude other types of masses from the differential diagnosis.
Purpose: To evaluate the hypothesis that the addition of proton magnetic resonance spectroscopy (H-1 MRS) to conventional magnetic resonance imaging (MRI) would allo iv differentiation between herpes encephalitis and diffuse astrocytoma sufficiently early to institute appropriate antiviral therapy.Methods: Serial MRI studies were performed in one patient with herpes encephalitis and one patient with diffuse astrocytoma on a 1.5-T MRI instrument. The spectra were obtained as part of the conventional MRT study before contrast administration using a short-echo single-voxel technique.Results: No metabolic differences were found between acute stage herpes encephalitis and diffuse astrocytoma. In both cases, 1H MRS revealed a significant increase in choline signal, a decrease in N-acetyl-aspartate (NAA) signal, and the presence of lactate and lipids. However, in the resolution stage of herpes encephalitis, proton MRS demonstrated a significant increase of myo-inositol, a normal choline signal, and absence of both lactate and lipids.Conclusion: The cases described show that even when combined with H-1 MRS, MRI may not be able to discriminate between acute herpes encephalitis and gliomatous lesions. Early diagnosis of herpes encephalitis must still rely on a combination of clinical, laboratory, and imaging findings.
Purpose: To compare the value of a turbo fluid attenuated inversion recovery (FLAIR) sequence versus a turbo T-2-weighted spin echo (SE) sequence for assessing the extent of abnormal signal intensity associated with infiltrative intraaxial brain tumors.Methods: Three reviewers independently graded FLAIR images and the T-2-weighted images of 37 patients with surgically proven intraaxial brain tumors. The percentage of contrast and the contrast-to-noise (C/N) ratios were compared for both sequences.Results: Lesion delineation was better with FLAIR than with T-2-weighted images in 18.3 (49.5%) of the 37 cases. Flair images were particularly useful for lesions affecting the cerebral white matter, cerebral cortex, cerebellar hemisphere, and intraventricular space. T-2-weighted images were superior to FLAIR in limited regions such as the deep gray matter and the brain stem. In most cases, artifacts were either absent or were equally severe on both FLAIR and T-2-weighted images. Although measurements of C/N ratio were greater for T-2-weighted images when the white matter was used as a background, the FLAIR images tended to provide greater percent contrast than did the T-2-weighted images. Both percent contrast and C/N ratio were significantly greater for FLAIR than for T-2-weighted images when cerebrospinal fluid (CSF) was used as a background.Conclusion: Although T-2-weighted images generally are sufficient for assessing the extent of the abnormal signal associated with infiltrative brain tumors, turbo FLAIR sequences may delineate the full extent of the abnormality more accurately.
Purpose: To investigate the value of contrast-enhanced fluid attenuated inversion recovery (FLAIR) imaging in the diagnosis of metastatic brain tumors.Methods: Spin echo (SE) T-2-weighted images, noncontrast and contrast-enhanced T-1-weighted SE images, and noncontrast and contrast-enhanced FLAIR images from 32 patients with brain metastases were reviewed to compare lesion detectability on contrast-enhanced FLAIR versus contrast-enhanced T-1-weighted SE imaging, and on contrast-enhanced FLAIR versus noncontrast SE T-2-weighted imaging.Results: All 32 patients exhibited enhancing lesions on contrast-enhanced FLAIR imaging. Of the 145 lesions detected by any sequence, 19 were not detected on the contrast-enhanced FLAIR images (13.1%). There was no significant difference in lesion detectability between FLAIR and T-1-weighted sequences. In 21 of the 32 patients (66%), the contrast-enhanced FLAIR images showed the tumor margin more clearly than did the contrast-enhanced T-1-weighted images. In each patient, contrast-enhanced FLAIR images demonstrated accompanying edema better than did T-2-weighted SE images.Conclusion: Contrast-enhanced FLAIR images are inferior to contrast-enhanced T-1-weighted SE images for detection of brain metastases, but remain useful for depicting both the peritumoral edema and the tumor margin on a single image.
Subcortical brain injuries are commonly encountered in the clinical setting. The purpose of this paper is to summarize the often-overlooked neuropsychiatric symptoms that may result from injury to the globus pallidus, putamen, caudate, thalamus, fornix, amygdala, hypothalamus, mamillary bodies, hippocampus, substantia nigra, and pens. A knowledge of these deficits can help in assessing prognosis and planning rehabilitation in these patients.
Purpose: To study the arteries and veins supplying the developing choroidal plexus during the embryonic period. With these data, a new review on the development of the medial vein of the prosencephalon, considered to be the precursor of the vein of Galen, is offered.Methods: Study of serial cuts of 11 embryos with crown-rump length (CRL) from 15 to 30 mm.Results: The medial vein of the prosencephalon appears approximately at the stage of 19 mm as a conspicuous vein draining anteriorly both choroidal plexi toward the channels of the sagittal plexus, A branch of both anterior cerebral arteries supplies the choroidal plexus of the embryo and early fetus from the seventh-week of gestation.Conclusion: Vein of Galen malformations (VGM) have a clear embryologic or fetal origin, which seems to be related to the choroidal plexus vascularization, Its unique anatomic situation can explain the kind of dilatation that occurs in VGM, and the arterial aferents of these malformations.
Purpose: To report unusual enhancement patterns of brain lesions in patients with multiple sclerosis (MS).Methods: Seven patients (3 male patients and 4 female patients) ranging from 15 to 33 years of age (mean age 29 years) were included in the study. Five patients had clinical evidence of MS and were examined with 1.5T magnets both before and after gadolinium enhancement. The other two patients only had contrast computed tomography (CT) examination, and both had brain biopsy with pathologic confirmation. The patients were selected because of positive laboratory findings and MS lesions with specific enhancement patterns.Results: Three types of enhancing patterns were identified: complete or incomplete concentric rings (type A; n = 2 of 7), semilunar (type B; n = 5 of 7), and typical ring lesions previously described in the literature (type C; n = 3 of 7) in association with type A or B.Conclusion: Recognition of these types of enhancement involving MS lesions confirms the clinical and laboratory diagnosis of MS and precludes unnecessary invasive operative procedures. The ring sign (type C) previously described in the literature is seen in other pathologic processes and is less specific for MS.
Conventional and computer reconstructed angiography can be transformed into pairs of images for stereoscopic viewing. The first paper in this series explains how to produce these images and provides a basic stereoscopic atlas of normal cerebral vascular anatomy. The second paper (see pp. 000-000) presents stereoscopic anatomy on image pairs of the posterior fossa circulation on conventional angiograms.
