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This article reviews the often confusing list of brain neoplasms. With an appropriate approach and knowledge of distinguishing criteria of an intracranial mass, the differential diagnostic possibilities can be narrowed to a manageable list. [ABSTRACT FROM AUTHOR]

Background and Purpose: The pathophysiologic basis of posterior reversible encephalopathy syndrome (PRES) remains controversial. Hypertension (HTN)-induced autoregulatory failure with subsequent hyperperfusion is the leading hypothesis, whereas alternative theories suggest vasoconstriction-induced hypoperfusion as the underlying mechanism. Studies using contrast-based CT and MR perfusion imaging have yielded contradictory results supporting both ideas. This work represents one of the first applications of arterial spin labeling (ASL) to evaluate cerebral blood flow (CBF) changes in PRES., Materials and Methods: After obtaining Institutional Review Board approval, MRI reports at our institution from 07/2015 to 09/2020 were retrospectively searched and reviewed for mention of "PRES" and "posterior reversible encephalopathy syndrome." Of the resulting 103 MRIs (performed on GE 1.5 Tesla or 3 Tesla scanners), 20 MRIs in 18 patients who met the inclusion criteria of clinical and imaging diagnosis of PRES and had diagnostic-quality pseudocontinuous ASL scans were included. Patients with a more likely alternative diagnosis, technically non-diagnostic ASL, or other intracranial abnormalities limiting assessment of underlying PRES features were excluded. Perfusion in FLAIR-affected brain regions was qualitatively assessed using ASL and characterized as hyperperfusion, normal, or hypoperfusion. Additional quantitative analysis was performed by measuring average gray matter CBF in abnormal versus normal brain regions., Results: HTN was the most common PRES etiology (65%). ASL showed hyperperfusion in 13 cases and normal perfusion in 7 cases. A hypoperfusion pattern was not identified. Quantitative analysis of gray matter CBF among patients with visually apparent hyperperfusion showed statistically higher perfusion in affected versus normal appearing brain regions (median CBF 100.4 ml/100 g-min vs. 61.0 ml/ 100 g-min, p < 0.001)., Conclusion: Elevated ASL CBF was seen in the majority (65%) of patients with PRES, favoring the autoregulatory failure hypothesis as a predominant mechanism. Our data support ASL as a practical way to assess and noninvasively monitor cerebral perfusion in PRES that could potentially alter management strategies., (Copyright © 2022 The Authors. Published by Elsevier Inc. All rights reserved.)

We present a new technique using MRA instead of the usual DSA to provide guidance in the treatment of venous vascular malformations. When one performs this embolization procedure, appropriate needle positioning within the malformation must be confirmed before injection of the sclerosing agent to prevent untoward complications. Time-resolved imaging of contrast kinetics-MRA can accurately depict the angioarchitecture of the lesion, which substantially reduces the total radiation dose in these patients who are commonly in the pediatric age group and usually require numerous treatment episodes., (© 2016 by American Journal of Neuroradiology.)

We report two occurrences of high-grade tears of the lateral collateral ligament complex (LCLC), consisting of the anterolateral ligament (ALL) and fibular collateral ligament (FCL). One injury occurred in a rock climber and the other in a martial artist. Increasing awareness of isolated injuries of the LCLC will allow for appropriate diagnosis and management. We review and discuss the anatomy of the LCLC, the unique mechanism of isolated injury, as well as physical and imaging examination findings.

The authors present a case of multiple radiation-induced cavernous malformations of the cauda equina in a patient with a remote history of testicular cancer and extended field radiation therapy. Magnetic resonance imaging (MRI) demonstrated multiple nodular areas of enhancement coating the nerve roots of the cauda equina, mimicking an aggressive leptomeningeal process such as carcinomatous or infectious meningitis. Biopsy of one of these lesions revealed ectatic vascular channels devoid of intervening neuroglial tissue consistent with cavernous malformation., (Copyright © 2011 by the American Society of Neuroimaging.)

MR-spectroscopy (MRS) is a multiparameter diagnostic tool and modification of each parameter results in spectrum morphology changes. In particular, changing the echo time (TE) represents a useful tool to highlight different diagnostic elements, but also has significant impact on the spectrum morphology. Diagnostic errors can result if the role of TE is not properly considered. This article reviews the four most common TE-related pitfalls of MRS interpretation. Clinical practical methods to avoid such pitfalls are also suggested., (Published by Elsevier Masson SAS.)

The authors present a unique case of intravascular papillary endothelial hyperplasia (IPEH) localized in the renal hilum, retroperitoneum, and spine in a patient with Wegener granulomatosis. IPEH rarely occurs in the abdomen or spine with few cases reported in the literature. No case has been reported of IPEH involving both the retroperitoneum and spine. In our case, MR imaging revealed enhancing masses in the right renal hilum and retroperitoneum as well as multiple focal enhancing lesions throughout the spine with lower thoracic ventral thecal sac compression. The diagnosis was established by resection of the renal hilum mass, and interval follow-up is deemed necessary for the remaining lesions because the long-term evolution of IPEH with conservative treatment alone is not well established.

Introduction: Our purpose was to determine the potential of metabolites other than alanine to diagnose intracranial meningiomas on proton magnetic resonance spectroscopy (MRS)., Methods: Using a 1.5-T MR system the lesions were initially identified on FLAIR, and T1- and T2-weighted images. Employing standard point-resolved spectroscopy (PRESS) for single voxel proton MRS (TR 1500 ms, TE 30 ms, 128 acquisitions, voxel size 2 x 2 x 2 cm, acquisition time 3.12 min), MR spectra were obtained from 5 patients with meningiomas, from 20 with other intracranial lesions, and from 4 normal controls. Peak heights of nine resonances, including lipid, lactate, alanine, NAA (N-acetylaspartate), beta/gamma-Glx (glutamate + glutamine), creatine, choline, myo-inositol, and alpha-Glx/glutathione, were measured in all spectra. The relative quantity of each metabolite was measured as the ratio of its peak height to the peak height of creatine., Results: Relative quantities of alpha-Glx/glutathione, beta/gamma-Glx, and total Glx/glutathione were significantly elevated in meningiomas compared to the 20 other intracranial lesions and the normal control brains. Alanine was found in four of five meningiomas, but lactate partially masked the alanine in three meningiomas. None of the other lesions or control brains showed an alanine peak. The one meningioma with no alanine and the three others with lactate had elevated Glx., Conclusion: While alanine is a relatively unique marker for meningioma, our results support the hypothesis that the combination of glutamate/creatine ratios and alanine on proton MRS is more specific and reliable for the diagnosis of meningiomas than alanine alone.

Background and Purpose: To use MR spectroscopy to aid in the diagnosis of demyelinating disease and to help differentiate tumefactive demyelinating lesions from neoplastic processes., Materials and Methods: MR imaging of the brain was obtained in 4 patients who presented clinically with focal neurologic deficits. MR imaging initially revealed parenchymal mass lesions. Single-voxel MR spectroscopy was then performed utilizing a point-resolved spectroscopy sequence protocol with a short echo time (30 msec)., Results: MR imaging revealed a focal ring-enhancing mass in one patient, multiple ring-enhancing lesions in the second patient, a large area of edema and mass effect without associated enhancement in the third patient, and multiple solid and peripherally enhancing lesions in the fourth patient. MR spectroscopic results in all 4 patients demonstrated marked elevation of the glutamate and glutamine peaks (2.1-2.5 ppm). Other nonspecific (and in a sense confounding) findings included elevation of the choline peak (3.2 ppm), elevation of the lactate peak (1.3 ppm), elevation of the lipid peak (0.5-1.5 ppm), and decrease in the N-acetylaspartate peak (2.0 ppm). All 4 patients were eventually given the diagnosis of multiple sclerosis based on CSF analysis, brain biopsy, and/or clinical follow-up., Conclusion: MR spectroscopic metabolite information may be useful in the diagnosis of demyelinating disease by demonstrating elevation of the glutamate/glutamine peaks because elevation of these peaks is typically not seen in aggressive intra-axial neoplastic processes. This is particularly beneficial in the rarer cases of tumefactive demyelinating lesions, which are very difficult to differentiate from neoplasms by imaging findings alone.

Appropriately sized 0.010- and 0.018-inch complex framing coils were placed in a wide-necked silicone aneurysm replica, and their stability was evaluated at variable physiologic flow rates using video recording. After detachment, the 0.010-inch coils demonstrated instability/prolapse that was proportional to flow rate. In contrast, 0.018-inch coils held their 3D configuration regardless of flow rate. The findings support the use of 0.018-inch coils (when possible) in aneurysms with unfavorable geometry, particularly in circulations with higher flow rates.

Current treatment protocols using reperfusion therapy for acute ischemic stroke rely on non-contrast computed tomography (NCCT), with most indications including the absence of acute hemorrhage or large volume of infarction in the presence of clinical signs and symptoms. This predictably results in a significant incidence of the administration of reperfusion therapy to patients with "stroke mimics," such as migraine headache or Todd's paralysis after a seizure. Diffusion-weighted imaging (DWI) is a technique based on magnetic resonance imaging (MRI) that may be more sensitive and specific for acute cerebral ischemia than NCCT. In addition, data for techniques such as perfusion-weighted imaging can be acquired with minimal additional time required. This may allow better risk assessment of a clinical response to reperfusion therapy vs. the possibility of hemorrhagic complications. This article describes a methodical review of studies comparing the sensitivity, specificity, positive predictive value, and negative predictive value of DWI vs. NCCT in the evaluation of acute ischemic stroke. Data from studies meeting our screening criteria are combined to produce overall values for each.

Diffusion-weighted imaging can be used to distinguish epidermoid tumor from arachnoid cyst in the intracranial compartment. We report the use of diffusion-weighted imaging in a postoperative spine to successfully distinguish a recurrent epidermoid tumor from arachnoid cyst in a noninvasive manner. Our case illustrates the value of this readily available sequence presently not generally used in the clinical evaluation of spinal pathology.

Background and Purpose: Single-shot, fast spin-echo, fluid attenuated inversion recovery (SS-FSE-FLAIR) images are frequently used to detect disease in the brain and subarachnoid space in confused or uncooperative patients who may move during the examination. In some of these patients, high signal intensity areas are seen on good-quality images in the subarachnoid space and ventricular system in locations not associated with high CSF flow. These artifacts may simulate hemorrhage or leptomeningeal disease. The purpose of this article was to determine the cause of these artifacts, describe ways to recognize them, and find methods to reduce or eliminate them., Methods: Healthy volunteers were studied on 6 occasions with conventional multisection FSE-FLAIR images and SS-FSE-FLAIR images while at rest and while nodding and rotating their heads at different speeds. In addition, SS-FSE-FLAIR images with different section widths of the initial inverting pulse and a non-section-selective initial inversion pulse were performed with the subjects moving their heads in the same way. The scans of 30 successive patients with acute neurologic syndromes who had been studied with SS-FSE-FLAIR sequences were reviewed for evidence of high signal intensity in the CSF in regions not associated with high CSF flow., Results: Each of the volunteers showed areas of increased signal intensity in CSF at sites apart from those associated with rapid pulsatile CSF flow on SS-FSE-FLAIR images acquired during head motion. The images were otherwise virtually free of motion artifact. The use of a wider initial inversion pulse section and a non-section-selected initial inversion pulse reduced the extent of these artifacts. Nineteen of the 30 patients showed areas of high signal intensity in the CSF in regions not associated with highly pulsatile CSF flow. Six of these patients had negative lumbar punctures for blood and xanthochromia and normal CSF protein levels., Conclusion: High signal intensity artifacts may be seen in CSF as a result of head movement on otherwise artifact-free images when imaging uncooperative patients with SS-FSE-FLAIR sequences. These artifacts have a different mechanism and distribution from those caused by CSF pulsation and may simulate subarachnoid and intraventricular hemorrhage. Artifact recognition is aided by signs of patient motion during the examination. The artifacts can be reduced by use of increased section width and non-section-selective initial inversion pulses. Recognition of these artifacts is important, because the circumstances in which the SS-FSE-FLAIR sequence is used and the particular properties of the sequence may conspire to produce a trap for the unwary.

Objective: To determine if change in voxel shape and position improves the lateralization of magnetic resonance (MR) spectroscopy to the side of the MR imaging and/or electroencephalography (EEG) abnormality in mesial temporal sclerosis., Methods: In 10 patients with unilateral mesial temporal sclerosis and 5 controls, MR spectroscopy was performed. Long echo time single-voxel spectroscopy was obtained in the right and left hippocampus. First, the standard 2-cm x 2-cm x 2-cm cubic voxels were placed bilaterally. Then, 1-cm x 2-cm x 4-cm rectangular voxels were used. With this rectangular voxel shape, more of the hippocampus and less of the adjacent medial temporal lobe were included in the interrogation voxel. N-acetylaspartate-to-creatine (NAA/Cr) ratios and choline-to-creatine (Cho/Cr) ratios were obtained. The difference between the affected and unaffected sides in the patients was calculated and compared with the controls. Additionally, the mean difference and standard deviation were determined. Predictive values and Student t tests were also performed., Results: In all 10 patients, using the NAA/Cr ratios, the rectangular voxel correctly identified the abnormal side. The cubic voxel only identified the abnormal side in 6 of the 10 patients, however. Additionally, the mean difference between the affected and unaffected sides was 0.30 for the rectangular voxel but only 0.003 for the cubic voxel; that is, there was no overall significant difference when using the cubic voxel (P = 0.007). No significant correlation between the affected and unaffected sides was found using the Cho/Cr ratios. No significant difference between the right and left sides was found in the controls., Conclusion: Use of a 1-cm x 2-cm x 4-cm rectangular voxel places more of the hippocampus in the region of interrogation with less partial volume artifact from the adjacent brain parenchyma, which occurs with use of the standard 2-cm x 2-cm x 2-cm cubic voxel, resulting in improved correct lateralization of MR spectroscopy to the side of the MR imaging and/or EEG abnormality.

Ischemic stroke is a rare but serious complication of cardiac catheterization. We report a case in which systemic thrombolytic therapy was successfully utilized in treating a patient with a cerebellar stroke, leading to obtundation during elective cardiac catheterization. Underlying bilateral vertebrobasilar disease with thrombotic embolization to the basilar artery was postulated to be the pathophysiological basis for the stroke and subsequent success of thrombolytic treatment in this patient. As the consequences of this rare complication are severe, systemic thrombolytic therapy should be considered for patients suffering an acute ischemic stroke during cardiac catheterization or percutaneous coronary intervention., (Copyright 2005 Wiley-Liss, Inc.)

Our goal was to develop a system that would allow us to recreate live patient arterial pathology by using an industrial technique known as stereolithography (or rapid prototyping). In industry, drawings rendered into dicom files can be exported to a computer programmed to drive various industrial tools. Those tools then make a 3D structure shown by the original drawings. We manipulated CT scan dicom files to drive a stereolithography machine and were able to make replicas of the vascular diseases of three patients.

Our goal was to develop and prove the accuracy of a system that would allow us to re-create live patient arterial pathology. Anatomically accurate replicas of blood vessels could allow physicians to teach and practice dangerous interventional techniques and might also be used to gather basic physiologic information. The preparation of replicas has, until now, depended on acquisition of fresh cadaver material. Using rapid prototyping, it should be able to replicate vascular pathology in a live patient. We obtained CT angiographic scan data from two patients with known arterial abnormalities. We took such data and, using proprietary software, created a 3D replica using a commercially available rapid prototyping machine. From the prototypes, using a lost wax technique, we created vessel replicas, placed those replicas in the CT scanner, then compared those images with the original scans. Comparison of the images made directly from the patient and from the replica showed that with each step, the relationships were maintained, remaining within 3% of the original, but some smoothing occurred in the final computer manipulation. From routinely obtainable CT angiographic data, it is possible to create accurate replicas of human vascular pathology with the aid of commercially available stereolithography equipment. Visual analysis of the images appeared to be as important as the measurements. With 64 and 128 slice detector scanners becoming available, acquisition times fall enough that we should be able to model rapidly moving structures such as the aortic root., ((c) 2005 Wiley-Liss, Inc.)

Background and Purpose: To improve the safety and efficacy of liquid embolization, we evaluated changes in pressures in experimental aneurysms., Methods: We created three replicas of a lateral sidewall aneurysm and placed them in a physiologic flow circuit. A 3 x 10-mm nondetachable balloon was positioned in the parent vessel across the aneurysmal neck. Intra-aneurysmal pressures were measured at baseline and after balloon inflation. Fluid was infused into the sac via a 1.45F microcatheter during inflation, and maximal pressures were noted. Measurements were repeated eight times in each aneurysm., Results: After balloon inflation, average intra-aneurysmal pressures increased: 12 mm Hg (13%, sigma(n - 1) = 0.46) for aneurysm 1 (baseline mean arterial pressure [MAP], 94 mm Hg), 15 mm Hg (58%, sigma(n - 1) = 0.88) for aneurysm 2 (baseline MAP, 26 mm Hg), and 15 mm Hg (58%, sigma(n - 1) = 0.92) for aneurysm 3 (baseline MAP, 26 mm Hg). During inflation and infusion, pressures increased slightly: 1.1 (0.94%, sigma(n - 1) = 0.64), 1.6 (3.9%, sigma(n - 1) = 1.1), and 1.9 (4.6%, sigma(n - 1) = 1.2) mm Hg for aneurysms 1, 2, and 3, respectively. Despite complete balloon occlusion of the distal aneurysmal neck, a channel between the proximal aneurysmal neck and the parent-vessel lumen persisted along the microcatheter. Fluid exited the sac via this channel, preventing a concomitant, significant increase in pressure during infusion., Conclusion: Intra-aneurysmal pressure modestly increased with inflation of a parent-vessel balloon across the neck. When liquid was infused into the sac during inflation, further increases were minimal.

Background and Purpose: Contrast-enhanced fluid-attenuated inversion recovery (FLAIR) imaging has been reported to have higher sensitivity for detecting leptomeningeal disease compared with contrast-enhanced T1-weighted MR imaging. The purpose of this study was to compare contrast-enhanced T1-weighted MR images with fat suppression to contrast-enhanced FLAIR images to determine which sequence was superior for depicting meningeal disease., Methods: We reviewed MR images of 24 patients (35 studies) with a variety of meningeal diseases. The MR imaging protocol included contrast-enhanced T1-weighted MR images with fat suppression (FS) and contrast-enhanced fluid-attenuated inversion recovery (FLAIR) images that were reviewed by three neuroradiologists and were assigned a rating of positive, equivocal, or negative for abnormal meningeal enhancement. The two sequences were compared side by side to determine which better depicted meningeal disease., Results: Abnormal meningeal enhancement was positive in 35 contrast-enhanced T1-weighted MR images with FS and in 33 contrast-enhanced FLAIR studies. In the first group, which had the T1-weighted sequence acquired first (21 of 33 studies), contrast-enhanced T1-weighted images with FS showed superior contrast enhancement in 11 studies (52%), inferior contrast enhancement in six studies (29%), and equal contrast enhancement in four studies (19%) compared with the contrast-enhanced FLAIR images. In the second group, which had the FLAIR sequence acquired first (12 of 33), contrast-enhanced T1-weighted images with FS showed superior contrast enhancement in seven studies (58%), inferior contrast enhancement in two studies (17%), and equal contrast enhancement in three studies (25%)., Conclusion: Contrast-enhanced T1-weighted MR imaging with FS is superior to contrast-enhanced FLAIR imaging in most cases for depicting intracranial meningeal diseases.

We present a case of multifocal enhancing lesions confined to the right cerebral hemisphere that mimicked diffuse neoplasm. MR spectroscopy revealed not only minimal elevation of the choline peak, but also marked elevation of the glutamate and glutamine peaks, findings that are more suggestive of an inflammatory process. Biopsy showed lymphocytic vasculitis, a rare variant of primary angiitis of the CNS. Following appropriate medical therapy, MR imaging demonstrated complete resolution of the lesions.

A patient with histologically proven gliomatosis cerebri presented with a normal choline level but a markedly abnormal elevated myo-inositol level on magnetic resonance (MR) spectroscopy. We describe the case presentation, imaging findings (in particular, the unique MR spectroscopic pattern), and their significance regarding the diagnosis of this relatively rare neoplasm.

Background: It is extremely rare for cancer to present first as an intramedullary spinal cord metastasis. Furthermore, because it is unlikely for spinal cord neoplasm to present acutely, an acute presentation may signify metastatic disease and should be considered in the initial differential diagnosis., Methods: The authors present a case of a 59-year-old man presenting with Brown-Sequard syndrome and in whom metastatic lung adenocarcinoma to the spinal cord was subsequently discovered. Review of the literature reveals this case to be one of only a very few where intramedullary tumor was the first manifestation of metastatic disease., Results: The mainstay of treatment for intramedullary spinal metastases remains steroids, radiation, and chemotherapy, though no well-designed study compares these modalities by long-term survival and functional results. This patient underwent local radiation and systemic chemotherapy following surgical resection., Conclusions: This patient had no preoperative signs suggesting disease in other organs, making the diagnosis of lung adenocarcinoma metastatic to the intramedullary cord surprising, especially given the extremely rare incidence of spinal intramedullary metastatic disease. However, the patient had an acute presentation, uncommon for primary neoplasm, which may be an indication of metastatic disease.

There are three reasons to create physical replicas of human anatomy: (1) to be able to better visualize the shape of a single organ, or a section of anatomy; (2) to be able to visualize the spatial relationships in three-dimensions; and (3) to use accurate replicas to practice or rehearse otherwise high-risk clinical procedures in the laboratory. This paper describes a project to fabricate a carotid artery. It discusses the gathering of data, the conversion to a volume, and the subsequent conversion to a manufacturable form.

Background and Purpose: The main issue with use of a liquid embolic agent is one of safety. To determine and improve the efficacy of potential neuroendovascular treatment regimens, particularly the use of liquid embolic agents, we evaluated the changes in aneurysm flow dynamics resulting from alterations of parent vessel flow., Methods: We created silicone replicas of a laboratory-created aneurysm model and a basilar artery aneurysm cast from a human cadaver. Replicas were placed in a circuit of pulsatile non-Newtonian fluid, and flows were adjusted to simulate human physiologic flow velocity, profile, and volume. Individual fluid slipstreams were opacified with isobaric dyes. Images were obtained of the unaltered vascular replica; after placement of a nondetachable balloon in the parent vessel at multiple locations proximal to, across, and distal to the aneurysm neck; and after placement of a stent across the aneurysm neck. Aneurysms were then occluded with a cyanoacrylate liquid embolic agent in association with each device., Results: In the unaltered replica, flow entered the distal aneurysm neck and impacted against the distal lateral aneurysm wall. Disturbed, but nonturbulent, flow then continued along the aneurysm wall in a vortex pattern and exited at the proximal aspect of the aneurysm neck. With the balloon partially inflated in the parent vessel, the slipstream velocity increased. This resulted in more rapid flow in the aneurysm sac, a less favorable condition for deposition of liquid embolic material. The effect was more pronounced with greater degrees of balloon inflation (resulting in greater parent vessel narrowing) and when the balloon was proximal to the aneurysm neck compared with more distal parent vessel positioning. Only with complete occlusion of the parent vessel lumen, either proximal to, across, or distal to the aneurysm sac, was there intraaneurysmal flow reduction (ie, stasis), a more favorable condition for liquid embolic material deposition. Also, with the balloon positioned across the aneurysm neck, not only did the liquid agent remain in the aneurysm sac, but also the surface could be molded to re-create a normal parent vessel lumen. A stent placed across the aneurysm neck caused the slipstreams to lose their coherence as they passed through the stent mesh. This prevented slipstream impact against the aneurysm sidewall and decreased the intraaneurysmal fluid velocity. During deposition of liquid embolic agent through the stent sidewall into the aneurysm sac, the stent mesh appeared to provide a barrier to passage of the embolic agent into the adjacent parent vessel, also a more favorable condition for liquid embolic material deposition., Conclusion: Knowledge of aneurysm flow dynamics and the changes incurred after endovascular parent vessel flow alteration provides a basis for safer aneurysm obliteration by using a liquid embolic agent with a neurointerventional technique.

Objective and Importance: Reported is a case of a thoracic intramedullary astrocytoma with a lipomatous component, a so-called astrolipoma. This is the only known case of a single intraspinal astrolipoma in an otherwise healthy patient., Clinical Presentation: The patient was a 36-year-old woman with dorsal thoracic pain of more than 1 month's duration, mild lower extremity weakness, and incomplete sensory loss to the T10 level., Intervention: Magnetic resonance imaging of the thoracolumbar spine revealed a fusiform mass at the T9-T11 level. The patient underwent T9-T11 laminectomies and complete resection of the tumor. In the initial postoperative period, the patient's symptoms worsened. However, 3 months after surgery, the patient was clinically improved and was able to walk without assistance. Twelve months after surgery, imaging revealed no evidence of tumor., Conclusion: The current treatment plan and recommendation, assuming this tumor will behave like a low-grade glioma or lipoma, is continued radiographic surveillance after gross total resection. Reresection is recommended for tumor recurrence or significant regrowth. The long-term prognosis for astrolipoma is unknown.

The authors describe a 36-year-old man with Sturge-Weber syndrome who presented with focal seizures and subsequently developed a temporary post-ictal hemianopia. Magnetic resonance imaging of the brain demonstrated focal leptomeningeal enhancement, which subsequently resolved.

We report a case of a patient who developed a left posterior cerebral artery aneurysm 5 years after balloon occlusion of the right internal carotid artery for a giant cavernous aneurysm. The location of the new aneurysm was outside of the primary collateral pathways to the contralateral, proximally occluded, anterior circulation, illustrating the complexity of hemodynamic factors contributing to the development of intracranial saccular aneurysms. The appearance of an aneurysm in this setting supports the hypothesis that degenerative factors and hemodynamic stresses are important in the etiology of intracranial aneurysms.

Background and Purpose: Currently, no specific method exists to measure arteriovenous malformation (AVM) nidus size, a requirement in assessing the success of treatment. Additionally, the commonly used evaluation provides only a linear one-dimensional measurement of this three-dimensional entity. The purpose of this study was to devise an improved method for measuring AVM nidus size, an irregularly shaped radiologic entity, that provides objective and reproducible results., Methods: The procedure involved digitizing angiograms obtained before and after treatment, making the gray scale uniform, printing images on standard bond paper, delineating the nidus area, measuring the nidus area with a polar planimeter, and finally, correcting for geometric magnification. Three observers made the measurements. The corrected nidus areas were tabulated, and the mean, standard deviation, interobserver variability, and confidence intervals (CIs) were calculated., Results: On both anteroposterior and lateral views, the Kendall coefficient of concordance (a measure of interobserver variability) was equal to 0.97, signifying excellent agreement. Additionally, these values were within the 95% CIs; this result showed that they were unlikely the result of chance., Conclusion: Precise measurements of an AVM nidus are required to properly analyze changes in the lesion after endovascular embolization (ie, to evaluate treatment success). Because of the irregular contours of an AVM nidus, measuring an area with planimetry, rather than with the usual linear dimensions, should yield more exact results.

Arachnoid cysts are relatively common occurrences, with the majority being asymptomatic. The safety of an epidural blood patch in a patient with an arachnoid cyst has not been reported. Our patient had a known thoracic arachnoid cyst and required epidural blood patch for a postdural puncture headache. Magnetic resonance imaging obtained following the epidural blood patch demonstrated no alterations of the cyst or spinal cord compression.

Summary: A replica of a lethal wide-necked basilar artery aneurysm was created by casting a deceased patient's brain vessels and then placing the replica in a circuit of pulsating optically clear non-Newtonian fluid. Individual fluid slipstreams were opacified with isobaric dyes, and images were recorded on film. Studies were completed on the vascular replica, then were repeated, first after placement of a stent across the aneurysm neck and then after placement of Guglielmi detachable coils into the aneurysm sac through the stent. The slipstreams entered the untreated aneurysm via the distal aneurysm neck (the inflow zone), impacting against the distal lateral aneurysm wall. When the stent was placed across the aneurysm neck, the slipstreams lost coherence and did not strike the aneurysm sidewall. Placing the coils further disturbed and reduced aneurysmal flow, especially when the coils filled the inflow zone at the distal lateral aneurysm sac.

The authors present a rare case of oligodendrogliomatosis in a child, which they believe originated from a primary spinal cord tumor. At 2.5 years of age this boy developed poor balance, neck stiffness, and a regression in developmental milestones. A computerized tomography (CT) scan of the head initially revealed ventriculomegaly and multiple cystic cerebellar lesions. In addition, magnetic resonance (MR) imaging revealed a cystic intramedullary lesion involving the cervical spinal cord. A CT scan of the head and an MR image obtained 3 years later demonstrated diffuse small cysts on the surface of the brainstem, cerebellum, medial temporal and inferior frontal cortices, subcortical white matter, and corpus callosum suggestive of leptomeningeal tumor spread. Analysis of pathological specimens obtained at surgery showed neoplastic glial cells with small, uniform nuclei and perinuclear clear zones. The cells appeared to migrate along the subpial space but no tumor cells were present in the subarachnoid space. These findings were compatible with a diagnosis of oligodendrogliomatosis cerebri. Despite having a complicated course, chemotherapy with carboplatin has provided the patient with long-term palliation and a high quality of life. This case may represent the fifth report in the literature of oligodendrogliomatosis occurring in a child but only the third occurring with a spinal primary tumor.

We describe and analyze the flow dynamics in replicas of a human anterior communicating artery aneurysm. The replicas were placed in a circuit of pulsating non-Newtonian fluid, and flows were adjusted to replicate human physiologic parameters. Individual slipstreams were opacified with isobaric dyes, and images were recorded on film and by CT/MR angiography. When flow in the afferent (internal carotid) and efferent (anterior and middle cerebral) arteries was bilaterally equal, slipstreams rarely entered the aneurysm. When flow in either the afferent or efferent vessels was not symmetrical, however, slipstreams entered the aneurysm neck, impinged upon the aneurysm dome, and swirled within the aneurysm. Unequal flow in carotid or cerebral systems may be necessary to direct pathologic, fluid slipstreams into an aneurysm.

Replicas of ruptured posterior communicating and basilar artery aneurysms were created from cadaveric specimens and then were placed in a circuit of pulsating non-Newtonian fluid. Individual fluid slipstreams were opacified with isobaric dyes, and images were recorded on film. The slipstreams entered the distal aneurysm neck with impact against the distal lateral wall of the aneurysm. They then swirled slowly in a reverse vortical pattern within the aneurysm sac. Fluid exited the aneurysm at the proximal neck. The flow pattern clearly shows the impact zone of entering slipstreams (the point of aneurysm rupture) and provides information pertaining to aneurysm growth and formation.

Summary: We describe and analyze pressure measurements across vascular stenoses in an atherosclerotic human carotid bulb replica using catheters of different diameters. Replicas of an atherosclerotic human carotid bulb were created using the lost wax technique, and were placed in a circuit of pulsating nonnewtonian fluid. Flows were adjusted to replicate human physiologic flow profiles. Common carotid artery total flow volume of 600 milliliters/minute was studied. A pressure recording device was calibrated; data were received from catheters placed longitudinally in the common carotid artery and internal carotid artery. The internal carotid artery pressures were obtained both through the stenosis as is usually performed in the angiography suite and through the vessel side-wall beyond the stenosis as a control. Internal carotid artery flow volumes were also measured with and without the catheter through the stenosis. Multiple pressure recordings and volume measurements were obtained in the replica using 7 French, 5 French, and 2.5 French catheters. Measurements of the replica showed a 58% diameter stenosis and an 89% area stenosis of the carotid bulb. All longitudinal pressure measurements in the common carotid artery agreed with control values regardless of the diameter of the catheter used. Pressure measurements were also in agreement with control values in the internal carotid artery using the 2.5 French catheter. However, when larger diameter catheters were employed, pressures measured with the catheter through the stenosis fell when compared to control values. Additionally, internal carotid artery flow volumes were also decreased when the larger diameter catheters were placed across the stenosis. Large diameter catheters when placed across vascular stenoses may cause an occlusive or near-occlusive state and artifactually increase the measured transstenotic vascular pressure gradient as well as decrease forward vascular flow.

Summary: The flow dynamics and pressure relationships in an ulcerated atherosclerotic carotid bulb obtained at post-mortem were studied and correlated with angiographic findings in a similar live patient. Using the lost wax technique, we created replicas of an ulcerated atherosclerotic carotid bulb from a fresh cadaver, and placed those replicas in a circuit of pulsating non-Newtonian fluid. Flow profiles were adjusted to replicate human physiologic flows, and flow rates of 400, 600, and 800 milliliters per minute were evaluated. In the replicas, the slipstreams were opacified with isobaric dyes, and images were recorded both on 35 mm film and on SuperVHS high speed video. Data were collected from needles placed radially in the common carotid artery, in the region of the maximal atherosclerotic narrowing, and in the internal carotid artery. Though pressure relationships could not be obtained in the live human for ethical reasons, angiography in a similar stenosis was evaluated for slipstream dynamics. The post-mortem replica had a 55% diameter stenosis (88% area stenosis) of the carotid bulb with a shallow 3 mm ulcer. Flow in the common carotid artery showed undisturbed slipstreams, but as these slipstreams entered the narrow bulb, they crowded together, accelerating dramatically, with a jet continuing distally beyond the maximal narrowing for at least 2 vessel diameters, where flow again became normal. As fluid entered the narrowed bulb, radial pressures decreased and within the ulcer a vortex circulation was found. Similar findings were observed on the angiographic images of the live patient. This combination of events, the slowly swirling fluid in the ulcer, which would allow platelet aggregates to form, and the intermittent low pressure of the Bernoulli effect which could pull the aggregates into the adjacent rapidly flowing blood may help explain how ulcerated carotid plaques lead to embolic stroke.

Purpose: We describe and analyze flow dynamics and pressure relationships in an ulcerated atherosclerotic human carotid bulb., Methods: Replicas of an ulcerated atherosclerotic human carotid bulb were created using the lost wax technique. The resulting replicas were placed in a circuit of pulsating non-Newtonian fluid and flows were adjusted to replicate human physiological flow profiles. Common carotid artery total flow volumes of 400, 600, and 800 mL/min were studied. Slipstreams were opacified with isobaric dyes. Images were recorded on 35 mm film and on super VHS video. A pressure recording device was calibrated; data were received from needles placed radially and longitudinally in the common carotid artery, narrowed bulb/ulcer, and internal carotid artery. Multiple pressure recordings were obtained in the replicas., Results: Measurements of the replica showed a 59% diameter stenosis and an 88% area stenosis of the carotid bulb with a shallow 3.3-mm ulcer. Analysis of flow in the common carotid artery showed undisturbed slipstreams, but as these streams entered the narrowed carotid bulb they crowded together and accelerated significantly. This accelerated jet continued for at least two vessel diameters into the more normal portions of the internal carotid artery, where flow remained disturbed peripherally and often assumed a helical pattern but was nonturbulent. As fluid entered the narrowed bulb, radial pressures decreased. Most important, at peak systole, lower radial pressure with a vortex circulation was found at the ulceration., Conclusion: This combination of events (ie, slowly swirling fluid within the ulcer, allowing platelet aggregates to form, and the intermittent Bernoulli effect, pulling the aggregates into the rapidly flowing blood) may help explain how ulcerated carotid plaques lead to embolic stroke.