bluuebunny/crossref_metadata_2025 huggingface dataset:
Intracranial Angioplasty and Stenting in the Awake Patient
Authors: Abou‐Chebl Alex , Krieger Derk W. , Bajzer Christopher T. , Yadav Jay S.
Published: October 2009

Background and Purpose. Endovascular treatment for intracranial atherosclerosis is evolving, but complications remain an issue. Most interventions are performed under general anesthesia, preventing intraprocedural clinical evaluations. We describe our approach to intracranial angioplasty and stenting, using local rather than general anesthesia, and intraprocedural neurological assessment.

Methods. We prospectively collected procedural and outcome information on all patients undergoing intracranial angioplasty and stenting. Patients underwent interventions under local anesthesia with mild intravenous sedation or analgesia only if needed. Intraoperative neurological evaluations were performed, and symptomatology was used to guide the interventional technique.

Results. Forty‐eight arteries in 40 patients with a mean age of 65.2 years were treated. Thirty‐two anterior and 16 posterior circulation segments were treated. Technical success was achieved in 100% of patients with reduction of the mean pretreatment stenosis from 85 ± 8.6% to 7 ± 10.1%. Stents were deployed in 40 segments; five patients were treated with drug‐eluting stents. The cobalt‐chromium coronary stents were the easiest to deliver. Thirty‐seven patients were treated under local anesthesia and, of those, 61.4% experienced intraprocedural symptoms that led to some alteration of the interventional technique. Headache was the most common symptom, and, when persistent, it heralded the occurrence of subarachnoid hemorrhage. There were seven total neurological complications, but only five (10.5%) led to permanent morbidity (4 strokes) or mortality (1 death).

Conclusions. Intracranial angioplasty and stenting can be successfully performed using coronary techniques and equipment including drug‐eluting stents. Local anesthesia permits neurological evaluations and often leads to the adjustment of the interventional technique, potentially making the procedure safer.
Screening for High‐grade Carotid Stenosis Using a Portable Ultrasonography Instrument
Authors: Schminke Ulf , Motsch Lillian , Lien Li‐Ming , Tan Teng‐Yeow , Bond M. Gene , Toole James F. , Tegeler Charles H.
Published: October 2009

Background and Purpose. We investigated the diagnostic performance of a brief Power Doppler Imaging (PDI) screening examination for carotid artery stenoses using a newly developed portable instrument. Methods. A highly experienced sonographer screened in total 152 carotid arteries by either continuous wave (cw) Doppler (n= 50) or a lightweight (2.4 kg) portable duplex device (n= 102) in a prospective study of 76 high‐risk patients. The screening protocols included either spectrum analysis and frequency shift measurement in both internal carotid arteries with cw‐Doppler or determination of area and diameter ratios in transverse and longitudinal views of both carotid arteries in B‐mode and with PDI, but without velocity measurement. Both protocols were evaluated against a complete routine duplex ultrasonography examination.

Results. According to the complete examination, stenoses were <50% in 73 of 102 (71.6%), 50–75% in 19 of 102 (18.6%), 75–95% in 7 of 102 (6.9%), and occluded in 3 of 102 (2.9%) arteries (PDI cohort), and <50% in 39 of 50 (78%), 50–75% in 8 of 50 (16%), 75–95% in 2 of 50 (4%), and occluded in 1 of 50 (2%) artery (cw‐Doppler cohort). Mean screening time was 8.8 ± 2.5 minute (PDI) and 9.4 ± 2.6 minute (cw‐Doppler). For stenoses >75%, Az values (area under the receiver operating characteristics curve) were 0.897 for area ratios, 0.843 for diameter ratios (PDI protocol) and 1.0 for the cw‐Doppler protocol.

Conclusions. The diagnostic performance of the cw‐Doppler protocol was superior to the PDI protocol. Nevertheless, both protocols appear suitable as inexpensive screening strategies to identify subjects with >75% stenosis measured by carotid Doppler ultrasound. However, these preliminary data need further verification.
Functional Imaging of Carotid Atheromatous Plaques
Authors: Warburton Liz , Gillard Jonathan
Published: October 2009

Atherosclerotic plaque rupture within the internal carotid artery is an important cause of transient ischemic attack (TIA) and stroke. Conventional imaging techniques such as ultrasound and angiography provide information about the structural consequences of such plaques in terms of luminal stenosis. Most clinical trials of carotid surgery and stenting and based on these imaging methods. Techniques aimed at imaging the biological ‘functional’ status of the plaque are now emerging. Most of these are based on the premise that inflammatory activity is an index of plaque stability. In this article we review potential imaging targets from the known molecular biological pathways of atherosclerosis. Both conventional imaging techniques and the newer methods are discussed. Recent data from position emission tomography (PET) imaging and from the use of superparamagnetic iron oxide particles with magnetic resonance (MR) imaging are shown.
Neuroimaging Findings in Neurosyphilis
Authors: Fadil Halim , Gonzalez‐Toledo Eduardo , Kelley Bradford J. , Kelley Roger E.
Published: October 2009

We report two cases of neurosyphilis with atypical clinical presentations that were compounded by atypical neuroimaging findings. In the first case, MRI brain scan findings were felt to be compatible with mesial temporal sclerosis or herpes simplex encephalitis. The second patient presented with a clinical picture compatible with normal pressure hydrocephalus as well as some degree of ventricular enlargement and prominent periventricular white matter changes by MRI brain scan. He actually underwent ventriculo‐peritoneal shunting prior to determination that he had active syphilitic involvement of the central nervous system. Neurosyphilis, “the great imitator,” is not only capable of mimicking various other neurological disease clinical presentations, it can also mimic neuroimaging features of various other disease processes as well.
Dynamic Vascular Analysis Shows a Hyperemic Flow Pattern in Sickle Cell Disease
Authors: Ausavarungnirun Pornpatr , Sabio Hernan , Kim Jongyeol , Tegeler Charles H.
Published: October 2009

Background. By the age of 20 years, 10% of sickle cell disease (SCD) patients have experienced a stroke. It is unclear if SCD stroke is due primarily to hemodynamic effects of intracranial stenosis, or metabolic failure from anemia. Transcranial Doppler ultrasound (TCD) identifies a SCD subgroup with high stroke risk, but high mean flow velocity (MFV) can be due to stenosis or high flow rate, as with metabolic hyperemia of severe anemia. Dynamic Vascular Analysis (DVA; New Health Sciences, Inc., Bethesda, MD) is a new way to analyze TCD data, with potential to separate structural from metabolic causes of high MFV.

Methods. Eighty SCD patients, regardless of hemoglobin genotypes, aged 2 to 22 years, without clinical stroke or transient ischemic attack (TIA), who had TCD (1/1/02 to 1/1/04) as part of routine outpatient clinical follow‐up, with both the TCD report and study videotape available, were included. Waveforms were reviewed and marked by protocol, and DVA indices calculated including MFV, pulsatility index (PI), systolic acceleration (SA), dynamic flow index (DFI), dynamic pressure index (DPI), and dynamic compliance index (DCI). Mean and standard deviation were defined for the whole group, and for four subgroups, by age.

Results. MFV, DFI, and DPI were highest at 6‐ to 9‐year‐olds, declining thereafter. The 14‐ to 22‐year‐old group was also compared to a group of healthy young athletes (15‐ to 22 years old). SCD patients had higher MFV, lnSA, DFI, DPI, and lower PI and DCI in most segments, suggesting global hyperemia.

Conclusion. This is the first report of cross‐sectional results of DVA in a cohort of SCD outpatients without prior clinical stroke (TIA). These results suggest hyperemia without significant focal intracranial stenosis. There were also differences between asymptomatic SCD and young athletes, and the MFV, DFI, and DPI were highest at the age of 6 to 9 years, decreasing as age increased.
A Magnetization Transfer MRI Study of Deep Gray Matter Involvement in Multiple Sclerosis
Authors: Sharma Jitendra , Zivadinov Robert , Jaisani Zeenat , Fabiano Andrew J. , Singh Baljinder , Horsfield Mark A. , Bakshi Rohit
Published: October 2009

Background/Purpose: Gray matter involvement in multiple sclerosis (MS) is of growing interest with respect to disease pathogenesis. Magnetization transfer imaging (MTI), an advanced MRI technique, is sensitive to disease in normal appearing white matter (NAWM) in patients with MS.

Design/Methods: We tested if MTI detected subcortical (deep) gray matter abnormalities in patients with MS (n= 60) vs. age‐matched normal controls (NL, n= 20). Magnetization transfer ratio (MTR) maps were produced from axial proton density, conventional spin‐echo, 5 mm gapless slices covering the whole brain. Region‐of‐interest–derived MTR histograms for the caudate, putamen, globus pallidus, thalamus, and NAWM were obtained. Whole brain MTR was also measured.

Results: Mean whole brain MTR and the peak position of the NAWM MTR histogram were lower in patients with MS than NL (P < .001) and mean whole brain MTR was lower in secondary progressive (SP, n= 10) than relapsing‐remitting (RR, n= 50, P < .001) patients. However, none of the subcortical gray matter nuclei showed MTR differences in MS vs. NL, RR vs. SP, or SP vs. NL.

Conclusions: The MTI technique used in this cohort was relatively insensitive to disease in the deep gray matter nuclei despite showing sensitivity for whole brain disease in MS. It remains to be determined if other MRI techniques are more sensitive than MTI for detecting pathology in these areas.
Derivation of Power M‐Mode Transcranial Doppler Criteria for Angiographic Proven MCA Occlusion
Authors: Saqqur Maher , Hill Michael D. , Alexandrov Andrei V. , Roy Jayanta , Schebel Marcia , Krol Andrea , Garami Zsolt , Shuaib Ashfaq , Demchuk Andrew M.
Published: October 2009

Background. Stringent transcranial Doppler (TCD) criteria for diagnosing occlusion are needed for more reliable TCD performance at bedside in the acute stroke setting.

Subjects and Methods. At three academic stroke centers, we performed TCD examination for patients with symptoms of cerebral ischemia who underwent digital subtraction angiography (DSA). We used a standard insonation protocol with power M‐mode Doppler (PMD) TCD (TCD 100M, Spencer Technologies Inc., Seattle, WA). We collected mean flow velocity (MFV), pulsatility indices (PI), and power M‐mode resistance signature (absent, high, or low) in symptomatic middle (MCA), anterior (ACA), posterior (PCA), and in affected (a), ipsilateral (i), and contralateral (c‐lat) cerebral arteries. Ratios of aMCA/c‐lat MCA, aMCA/iACA, and aMCA/iPCA MFV were subsequently calculated. PMD‐TCD flow findings were evaluated with a receiver‐operating characteristic (ROC) analysis for angiographically proven MCA occlusion.

Results. We studied 120 patients with acute cerebral ischemia with PMD‐TCD examinations prior to or immediately after DSA. Lower aMCA velocities pointed to higher probability of occlusion (P= .055). The aMCA/iPCA MFV ratio was superior to the aMCA/iACA ratio and strongly predictive of occlusion at a threshold ratio of 0.5 (RR 2.31 CI95 2.13‐2.51). High resistance or absent M‐mode flow signatures in the proximal MCA were present in 87% of M1 and M2 MCA occlusions (probability 87%). In the presence of a low‐resistance PMD signature, obtaining the aMCA/iPCA MFV ratio <0.5 increases probability of occlusion to 87%. Normal MFV ratios and low‐resistance M‐mode signatures are highly predictive of a negative angiogram for MCA occlusion.

Conclusion. In acute cerebral ischemia, reliable criteria for proximal MCA occlusion have been developed based on combination of MFV ratios and M‐mode flow resistance signatures. Validation of these criteria will require multicenter studies.
Stroke Patients With Cardiac Atrial Septal Abnormalities: Differential Infarct Patterns on DWI
Authors: Santamarina Estevo , González‐Alujas M. Teresa , Muñoz Verónica , Rovira Alex , Rubiera Marta , Ribó Marc , Álvarez‐Sabin José , Molina Carlos A.
Published: October 2009

Background. Stroke mechanism in patent foramen ovale (PFO) and/or atrioseptal aneurysm (ASA) remains unclear. We aimed to study the stroke pattern on diffusion weighted imaging (DWI), in cryptogenetic stroke according to septal abnormalities.

Methods. We prospectively evaluated 314 cryptogenetic strokes. Patients were categorized according to transesophageal echocardiography (TEE) findings: PFO with ASA, PFO alone, and no abnormalities. The study group consisted of 126 patients with acute DWI lesions within the first 7 days after the stroke onset. We considered the presence of scattered lesions or a cortico‐subcortical territorial lesion as highly suggestive of an embolic pattern.

Results. PFO was identified in 77 patients (61%) and no alterations in 49 patients (39%). TEE revealed ASA in 42 patients (54.5% of PFO patients). An “embolic” pattern was depicted in 84 (66.7%) and subcortical in 42 (33.3%). An “embolic” pattern was significantly (P= .01) more frequently seen in PFO with ASA patients (n= 37;44%) as compared to PFO without ASA (n= 22; 26.2%) or no abnormalities (n= 25; 29.8%) on TEE. Univariate analysis revealed that age (P= .06), hyperlipidemia (P= .04), degree of shunt on TEE (P= .002), and the presence of an ASA (P= .008) were associated with an embolic pattern. After adjusting for sex, age, and vascular risk factors, only the presence of PFO, with ASA (OR 7.27; 95% CI 1.5‐35.22 P= .014) was independently associated with an embolic pattern.

Conclusion. In patients with cryptogenetic stroke, the presence of PFO with ASA, but not isolated PFO, is associated with an embolic pattern on DWI. These findings provide insights into the patho‐mechanism of stroke in patients with PFO.
Visualization of Venous Systems by Time‐of‐Flight Magnetic Resonance Angiography
Authors: Ko Sang B. , Kim Dong‐Eog , Kim Se H. , Roh Jae‐Kyu
Published: October 2009

Background and purpose: Time‐of‐flight (TOF) imaging technique depicts strong signal from fresh unsaturated magnetization that moves fast into the imaging region, and TOF magnetic resonance angiography (MRA) visualizes the arterial system using saturation pulse and band. However, TOF MRA can visualize the venous system when the flow direction is reversed.

Methods and patients: We consecutively enrolled patients between June 2002 and February 2003 with an internal jugular vein (IJV) and sigmoid sinus (SS) visualized by TOF MRA. Carotid Duplex ultrasonography was performed on all patients to check IJV flow directions. Gadolinium (Gd)‐enhanced MRA and conventional digital subtraction angiography were performed in selected patients.

Results: The IJVs and SSs of eight patients (left = 7, right = 1) were observed by TOF MRA. In these 8 patients, Duplex ultrasonography confirmed a reversed direction in IJVs. Four of the patients underwent Gd‐enhanced MRA, which showed proximal innominate vein steno‐occlusion.

Conclusions: This is the first description of IJV and SS visualization by TOF MRA. Clinical implications are discussed.
Ischemic Stroke in the Setting of Tuberculous Meningitis
Authors: Belorgey Laura , Lalani Irfan , Zakaria Asma
Published: October 2009

The clinical syndrome of tuberculous (TB) meningitis leading to ischemic strokes is rarely seen today in immunocompetent adults native to North America. This entity is also notoriously difficult to diagnose because the presenting symptoms are often nonspecific. The authors describe a case of a man with TB meningitis which progressed to recurrent ischemic cerebral infarcts.
Lumbar Dural Ectasia Secondary to Spinal Fusion: A Report of Two Cases
Authors: Hong Tom A. , Koenigsberg Robert A. , Brown Fraser , Dastur Cyrus K. , Kanoff Richard
Published: October 2009

Two cases of lumbar dural ectasia secondary to spinal fusion are presented. Background history of dural ectasia is discussed; computed tomography (CT) and MR imaging characteristics of dural ectasia are shown and possible causes are discussed.
Statin Use is Independently Associated with Smaller Infarct Volume in Nonlacunar MCA Territory Stroke
Authors: Shook Steven J. , Gupta Rishi , Vora Nirav A. , Tievsky Andrew L. , Katzan Irene , Krieger Derk W.
Published: October 2009

Background. Studies have shown an association between HMG‐CoA reductase inhibitors (statins) and improved stroke outcomes, possibly secondary to neuroprotective properties.

Objective. To assess whether patients taking statins prior to ischemic stroke have smaller infarcts on magnetic resonance imaging (MRI), adjusting for other relevant clinical factors.

Design. We retrospectively reviewed the Cleveland Clinic Foundation (CCF) Neurology Inpatient Database from June 2002 through June 2004. Demographics, medications, stroke subtype, diffusion‐weighted imaging (DWI) infarct volume, admission NIHSS, and hours to MRI were collected. Patients with a nonlacunar middle cerebral artery (MCA) territory infarct and MRI less than 48 hours from symptom onset were included (n= 143). A multivariable linear regression model was constructed to determine independent predictors of smaller infarct volume.

Results. A total of 143 patients were studied, including 38 patients taking statins at the time of their stroke. In univariate analysis, patients using statins were significantly more likely to have a history of hyperlipidemia, atrial fibrillation, and coronary artery disease and to be using coumadin, antiplatelet drugs, and angiotensin‐converting enzyme inhibitors. Patients on statins had a tendency toward smaller infarcts in univariate analysis (median 25.4 cm3 vs. 15.5 cm3, P= 0.054). In multivariable linear regression analysis statin use, patient age, and TIA within the prior 4 weeks were independently associated with smaller DWI volumes; vessel occlusion on vascular imaging, and cardioembolic stroke subtype with larger infarct size.

Conclusions. Statin use prior to the onset of nonlacunar MCA infarction was associated with a smaller infarct volume independent of other factors. Further studies utilizing both clinical and radiologic outcomes will be required to confirm these findings.
Cyberknife Radiosurgery for Basal Skull Plasmacytoma
Authors: Wong Eric T. , Lu Xing‐Qi , Devulapalli Janakiram , Mahadevan Anand
Published: October 2009

The Cyberknife delivers frameless image‐guided stereotactic radiosurgery to intracranial and extracranial tumors. We report our use of Cyberknife radiosurgery on a medullary plasmacytoma in the clivus extending into the foramen magnum. No acute toxicity was seen during or within 24 hours of treatment, and the subject had a complete and durable radiographic response on MRI 12+ months after treatment. To our knowledge, this is a first case of successful Cyberknife radiosurgery of a medullary plasmacytoma.
Delirium due to Brain Microembolism: Diagnostic Value of Diffusion‐Weighted MRI
Authors: Irimia Pablo , Martinez‐Vila Eduardo , Martinez‐Cuesta Antonio , Zulueta Javier
Published: October 2009

Delirum is a common complication in hospitalized patients and it is characterized by acute disturbances of consciousness, attention, cognition, and perception. Despite the frequency with which it is observed, ischemic stroke is generally considered as an unusual cause of delirium. A subtype of brain embolism is characterized by multiple small emboli in different vascular territories, a condition known as “brain microembolism.” Given the high contrast of acute ischemic lesions in diffusion weighted imaging (DWI) this technique is particularly helpful to detect these small infarctions. We present here a patient with pulmonary metastases who was treated with bronchial artery embolization and who subsequently developed delirium due to brain microembolism. The embolic material crossed through pulmonary arteriovenous fistulas, producing multiple areas of cerebral ischemia. The ischemic lesions could be visualized only on DWI, and they affected the periventricular region, caudate nucleus, thalamus, and cerebellum.
The Value of Diffusion‐Weighted MRI in the Diagnosis of Cerebral Fat Embolism
Authors: Eguia Pablo , Medina Antonio , Garcia‐Monco Juan Carlos , Martin Vicente , Monton Fernando I.
Published: October 2009

Fat embolism syndrome complicates open fractures involving long bones, although it occasionally follows nontraumatic conditions. Incomplete forms of the syndrome (ie, cerebral fat embolism) represent a challenge to diagnosis, and brain MRI represents a valuable diagnostic tool. We describe a patient who had a fat embolism to the brain after an isolated traumatic open fracture of the tibia. MRI with T2 and diffusion‐weighted images revealed multiple, reversible brain lesions, suggesting vasogenic edema and consistent with this entity. At present, MR imaging is the most sensitive technique to evaluate cerebral fat embolism.
Validation of Intracranial Area as a Surrogate Measure of Intracranial Volume When Using Clinical MRI
Authors: Nandigam R. N. Kaveer , Chen Yu‐Wei , Gurol Mahmut E. , Rosand Jonathan , Greenberg Steven M. , Smith Eric E.
Published: October 2009

Background and Purpose: We sought to determine whether mid‐sagittal intracranial area (ICA) is a valid surrogate of intracranial volume (ICV) when using retrospective data with relatively thick (6‐7 mm) sagittal slices. Methods: Data were retrospectively analyzed from 47 subjects who had two MRI scans taken at least nine months apart. Twenty‐three subjects had manual segmentation of ICV on the T2‐weighted sequence for comparison. Results: Intraclass correlation coefficient (ICC) for intraobserver, interobserver, and intraobserver scan‐rescan comparisons were 0.96, 0.97 and 0.95. Pearson correlation coefficients between ICV and ICA, averaging the cumulative 1, 2, 3, and 4 most midline slices, were 0.89, 0.94, 0.93, and 0.95. There was a significant marginal increase in explained variance of ICV by measuring two, rather than one, slices (P= 0.001). Conclusions: These data suggest that ICA, even measured without high‐resolution imaging, is a reasonable substitute for ICV.
Involvement of Jugular Valve Insufficiency in Cerebral Venous Air Embolism
Authors: Nedelmann Max , Pittermann Patrick , Gast Klaus Kurt , Mueller‐Forell Wibke , Dieterich Marianne
Published: October 2009

Background. Cerebral venous air entrapment is a rare finding on cranial computed tomography (CT) scan. Peripheral air embolism is discussed as a potential cause. However, the mechanism of retrograde passage through internal jugular valves and veins is unclear. Case Report. The case of a patient is reported, who had air entrapment in the left cavernous sinus. Prior to CT scanning, a peripheral intravenous line had been placed. Ultrasound revealed excessive insufficiency of the left internal jugular valve. To further study the mechanism of embolism, an echo contrast agent was injected into the cubital vein. A Valsalva maneuver resulted in retrograde transition of microbubbles across the insufficient valve. Valvular function on the unaffected right side was intact. Conclusions. This case report gives insight into the mechanism of cerebral venous air embolism. This is the firstcase describing jugular valve insufficiency as the missing link between peripheral air embolism and cerebral venous air entrapment.
Non‐HIV‐Related Progressive Multifocal Leukoencephalopathy (PML): A Tertiary Cancer Center Experience
Authors: Chowdhary Sajeel , Chalmers Lisa M. , Chamberlain Marc
Published: October 2009

In the course of 1 year at a tertiary cancer center, 3 patients (2 men; 1 woman; age 51‐75 years) were seen in neurological consultation (1.5% of all consultations). Clinical course in all patients was of a progressive neurologic disorder not consistent with either a primary or secondary malignancy. Magnetic resonance (MR) imaging was most informative with respect to diagnosis and subsequent management. Brain biopsy was performed in all patients to assist in both diagnosis and prognostication. All patients were determined to have progressive multifocal leukoencephalopathy (PML) by brain biopsy.
PET OEF Reactivity for Hemodynamic Compromise in Occlusive Vascular Disease
Authors: Nemoto Edwin M. , Yonas Howard , Pindzola Ronda R. , Kuwabara Hiroto , Sashin Donald , Chang Yuefang , Jovin Tudor
Published: October 2009

Background and Purpose. Hemodynamic compromise in symptomatic patients with occlusive vascular disease (OVD) identified by cerebrovascular reserve (CVR) and oxygen extraction fraction (OEF) is an independent predictor of high stroke risk. However, up to 60% of patients compromised by CVR have normal OEF indicating a high rate of discordance. CVR is measured with an acetazolamide challenge, and OEF reactivity (OEFR) to acetazolamide, ie, a hemodynamic challenge, may reveal hemodynamic compromise and less discordance with measurements of CVR. Methods. Nine symptomatic patients with OVD were studied by positron emission tomography before and 15 minutes after 15 mg/kg intravenous acetazolamide in the middle cerebral artery territories of each hemisphere. Results. A close correlation between hemispheric CVR and OEFR was observed. Two hemispheres from two different patients showed an increase in OEF to acetazolamide challenge despite a normal baseline OEF. The two hemispheres showing an increase in OEF in response to acetazolamide were also associated with the lowest CVR and severest white matter hyperintensities. Conclusions. These observations suggest that positive OEFR may distinguish hemispheres in hemodynamic compromise despite normal OEF and show less discordance with CVR. However, these preliminary observations require confirmation in a larger study.
The Spencer's Curve: Clinical Implications of a Classic Hemodynamic Model
Authors: Alexandrov Andrei V.
Published: October 2009

Merrill P Spencer and John M Reid applied the Hagen‐Poiseuille law, continuity principle, and cerebrovascular resistance to describe a theoretical model of the relationship between the flowvelocity, flowvolume, and decreasing size of the residual vessel lumen. The model was plotted in a graph that became widely known as the Spencer's curve. Although derived for a smooth and axis‐symmetric arterial stenosis of a short length in a segment with no bifurcations being perfused at stable arterial pressures and viscosity, this model represents a milestone in understanding cerebral hemodynamics with long‐lasting practical and research implications. This review summarizes several hemodynamic principles that determine velocity and flowvolume changes, explains how the model aids interpretation of cerebrovascular ultrasound studies, and describes its impact on clinical practice and research.
Practice Standards for Transcranial Doppler Ultrasound: Part I—Test Performance
Authors: Alexandrov Andrei V. , Sloan Michael A. , Wong Lawrence K.S. , Douville Colleen , Razumovsky Alexander Y. , Koroshetz Walter J. , Kaps Manfred , Tegeler Charles H. ,   for the American Society of Neuroimaging Practice Guidelines Committee
Published: October 2009

Indications for the clinical use of transcranial Doppler (TCD) continue to expand while scanning protocols and quality of reporting vary between institutions. Based on literature analysis and extensive personal experience, an international expert panel started the development of guidelines for TCD performance, interpretation, and competence. The first part describes complete diagnostic spectral TCD examination for patients with cerebrovascular diseases. Cranial temporal bone windows are used for the detection of the middle cerebral arteries (MCA), anterior cerebral arteries (ACA), posterior cerebral arteries (PCA), C1 segment of the internal carotid arteries (ICA), and collateralization of flow via the anterior (AComA) and posterior (PComA) communicating arteries; orbital windows—for the ophthalmic artery (OA) and ICA siphon; the foraminal window—for the terminal vertebral (VA) and basilar (BA) arteries. Although there is a significant individual variability of the circle of Willis with and without disease, the complete diagnostic TCD examination should include bilateral assessment of the M2 (arbitrarily located at 30‐40 mm depth), M1 (40‐65 mm) MCA [with M1 MCA mid‐point at 50 mm (range 45‐55 mm), average length 16 mm (range 5‐24 mm), A1 ACA (60‐75 mm), C1 ICA (60‐70 mm), P1‐P2 PCA (average depth 63 mm (range 55‐75 mm), AComA (70‐80 mm), PComA (58‐65 mm), OA (40‐50 mm), ICA siphons (55‐65 mm), terminal VA (40‐75 mm), proximal (75‐80), mid (80‐90 mm), and distal (90‐110 mm) BA]. The distal ICA on the neck (40‐60 mm) can be located via submandibular windows to calculate the VMCA/VICA index, or the Lindegaard ratio for vasospasm grading after subarachnoid hemorrhage. Performance goals of diagnostic TCD are to detect and optimize arterial segment‐specific spectral waveforms, determine flow direction, measure cerebral blood flow velocities and flow pulsatility in the above‐mentioned arteries. These practice standards will assist laboratory accreditation processes by providing a standard scanning protocol with transducer positioning and orientation, depth selection and vessel identification for ultrasound devices equipped with spectral Doppler and power motion Doppler.
Spinal Cord Pilomyxoid Astrocytoma: An Unusual Tumor
Authors: Mendiratta‐Lala Mishal , Kader Ellika Shehanaz , Gutierrez Jorge A. , Patel Suresh C. , Jain Rajan
Published: October 2009

We present the imaging findings of a case of spinal pilomyxoid astrocytoma in a 29‐year‐old woman with history of neck and back pain and weakness of bilateral upper extremities. A contrast‐enhanced magnetic resonance (MR) imaging study revealed an extensive intradural extramedullary lesion occupying most of the thecal sac extending from mid cervical up to the lumbosacral region with extensive contrast enhancement. Spinal pilomyxoid astrocytoma is rare with only three reported cases in pediatric population in the literature. This report illustrates the MR findings of an unusual case of intradural extramedullary spinal pilomyxoid tumor in an adult patient.
Rhombencephalosynapsis Associated with Dandy‐Walker Malformation
Authors: Sener R. Nuri
Published: October 2009

Coexistence of rhombencephalosynapsis and Dandy‐Walker malformation has previously been documented in a fetus by autopsy. In addition, there are three cases in the imaging literature suggesting this combination. This paper reports an 8‐month‐old girl with clear MR imaging evidence of association of these two anomalies. The vermis was absent, and there was fusion of the cerebellar hemispheres, characteristic for rhombencephalosynapsis. The fourth ventricle showed cystic dilatation associated with an enlarged posterior fossa, characteristic for Dandy‐Walker malformation. These findings suggest that rhombencephalosynapsis and Dandy‐Walker malformation can coexist.
Spinal Cord Compression Secondary to Epidural Bilharzioma: Case Report
Authors: Maia Antonio C.M. , Silva Luciano R.F. , Guimarães Matheus D. , Gomes Francinaldo L. , Bichuetti Denis B. , Stávale João N. , Prandini Mirto N.
Published: October 2009

A case of an epidural granuloma due to Schistosoma mansoni compressing the spinal cord at T7‐T9 is presented. The patient, a 35‐year‐old Brazilian man, started complaining of recurrent back pain since 2003. A magnetic resonance imaging (MRI) scan showed a large epidural mass extending from T7 to T9 and causing mild spinal cord compression. Through a bilateral laminectomy the bilharzioma was subtotally removed without significant bleeding. The histopathology confirmed the diagnosis of granuloma due to S. mansoni. The patient recovered completely. Although the MRI is nonspecific, this differential diagnosis should be included in homogeneous epidural lesions without bone involvement, more than ever in endemic countries or during the evaluation of travelers to those regions.
Internal Carotid Aplasia/Hypoplasia and Intracranial Saccular Aneurysms: Series of Three New Cases and Systematic Review of the Literature
Authors: Zink Walter E. , Komotar Ricardo J. , Meyers Phillip M.
Published: October 2009

Background and Purpose. Abnormal arterial flow dynamics and intracranial collateral pathways can be seen in patients with congenital internal carotid artery (ICA) aplasia or hypoplasia. Here we seek to evaluate whether ICA aplasia/hypoplasia is associated with an increased prevalence of intracranial saccular aneurysm relative to carotid rete mirabile. Methods. We combined our experience of three cases with 148 previous publications to form a retrospective series including 132 cases of ICA aplasia, 33 cases of ICA hypoplasia, and 34 cases of carotid rete mirabile. Results. After excluding cases lacking angiograms, ICA aplasia/hypoplasia was more commonly associated with aneurysm (45/158, 27.8%) compared with rete mirabile (2/34, 5.9%). A significantly greater overall aneurysm prevalence was seen among ICA aplasia/hypoplasia patients age 30 years or older (38/101, 36.6%) than in younger individuals (7/48, 14.6%). Conclusions. Intracranial saccular aneurysm is more strongly associated with ICA aplasia/hypoplasia than rete mirabile. An increased aneurysm prevalence among older individuals with ICA aplasia/hypoplasia suggests an acquired etiology. Magnetic resonance angiography (MRA) is recommended in the initial evaluation of ICA aplasia/hypoplasia to evaluate for intracranial saccular aneurysm, particularly after the third decade of life.
Meckel's Cave Tuberculoma with Unusual Infratemporal Extension
Authors: Kesavadas Chandrasekharan , Somasundaram S. , Rao Ravi M. , Radhakrishnan VV
Published: October 2009

The authors describe a rare case of intracranial tuberculoma of the Meckel's cave and cavernous sinus with extension into the infratemporal fossa causing widening of the foramen ovale and adjacent bone destruction. The rarity of the lesion and the unusual extension of the lesion are presented with a brief review of literature.
Moyamoya Disease with Cerebral Arteriovenous Malformation Presenting as Primary Subarachnoid Hemorrhage
Authors: Somasundaram Sivaraman , Thamburaj Krishnamoorthy , Burathoki Sandeep , Gupta Arun K.
Published: October 2009

The authors report a rare combination of definite moyamoya disease and brain arteriovenous malformation (AVM) presenting with primary subarachnoid hemorrhage (SAH) unheard of in the literature. The authors review the radiographic findings of this unique case with a brief review of literature.
Neuroimaging and Neurologic Complications after Organ Transplantation
Authors: Živković Saša
Published: October 2009

Neurologic complications are common after transplantation and affect 30‐60% of transplant recipients. The etiology of most of the posttransplant neurologic disorders is related to the opportunistic infections, both systemic and involving central nervous system (CNS), toxicity of immunosuppressive medications, and the metabolic insult created by the underlying primary disease and the transplant procedure. Neuroimaging studies are one of the key tools in the evaluation and enable early diagnosis of neurologic complications in transplant patients, especially posterior reversible leukoencephalopathy syndrome, central pontine myelinolysis, intracerebral hemorrhage, and fungal and bacterial abscesses. Magnetic resonance imaging (MRI) is the preferred technique, but each of the available neuroimaging techniques offers a unique insight into the pathophysiologic mechanisms underlying neurologic complications of transplantation. The role of neuroimaging in this population includes early detection of calcineurin inhibitor neurotoxicity, opportunistic infections, neoplasia, metabolic disorders, or cerebrovascular diseases. In addition, we can monitor longitudinal progression of disease and treatment response.
Mechanical Disruption of Thrombus Following Intravenous Tissue Plasminogen Activator for Ischemic Stroke
Authors: Qureshi Adnan I. , Janjua Nazli , Kirmani Jawad F. , Harris‐Lane Pansy , Suri M. Fareed K. , Zhou Jingying , Divani Afshin A.
Published: October 2009

Background and Purpose: We prospectively evaluated the safety of aggressive mechanical disruption of thrombus following full‐dose intravenous (IV) recombinant tissue plasminogen activator (rt‐PA) to treat ischemic stroke in 24 patients with an initial National Institutes of Health stroke scale (NIHSS) score of ≥10. Methods: Clinical evaluations were performed at presentation and 24 hours, 7 to 10 days, and 1 to 3 months (using modified Rankin scale) after treatment. These end points were compared to matched historical controls treated with IV rt‐PA alone. Results: Of the 24 patients, mechanical disruption was undertaken in 17 patients with persistent angiographic occlusion using microcatheter exploration (n= 3), angioplasty (n= 5), snare maneuvers (n= 7), and combination of both (n= 2). Partial or complete recanalization was observed in 10 of the 17 patients. Neurological improvement at 24 hours (≥4 point reduction in NIHSS score) was observed in 11 of 17 patients. Comparisons with matched controls suggest potential equivalence for symptomatic ICH (0% vs 12%), asymptomatic ICH (18% vs 15%), and early neurological improvement (65% vs 53%). Conclusion: The study shows that aggressive mechanical thrombus disruption in large artery occlusion in the setting of acute ischemic stroke is safe with acceptable rates of ICH and promotes angiographic recanalization.
Spatial Profiling of the Corticospinal Tract in Amyotrophic Lateral Sclerosis Using Diffusion Tensor Imaging
Authors: Wong John C.T. , Concha Luis , Beaulieu Christian , Johnston Wendy , Allen Peter S. , Kalra Sanjay
Published: October 2009

Background and Purpose: Diffusion tensor imaging (DTI) was used as a noninvasive method to evaluate the anatomy of the corticospinal tract (CST) and the pattern of its degeneration in amyotrophic lateral sclerosis (ALS). Methods. Fourteen patients with ALS and 15 healthy controls underwent DTI. Parameters reflecting coherence of diffusion (fractional anisotropy, FA), bulk diffusion (apparent diffusion coefficient, ADC), and directionality of diffusion (eigenvalues) parallel to (λ∥) or perpendicular to (λ⊥) fiber tracts were measured along the intracranial course of the CST. Results: FA and λ∥ increased, and ADC and λ⊥ decreased progressively from the corona radiata to the cerebral peduncle in all subjects. The most abnormal finding in patients with ALS was reduced FA in the cerebral peduncle contralateral to the side of the body with the most severe upper motor neuron signs. λ∥ was increased in the corona radiata. Internal capsule FA correlated positively with symptom duration, and cerebral peduncle ADC positively with the Ashworth spasticity score. Conclusion: There is a spatial dependency of diffusion parameters along the CST in healthy individuals. Evidence of intracranial CST degeneration in ALS was found with distinct diffusion changes in the rostral and caudal regions.
Pattern of Cortex and White Matter Involvement in Severe Middle Cerebral Artery Ischemia
Authors: Stoeckel Maria Cornelia , Wittsack Hans‐Jörg , Meisel Stephanie , Seitz Rüdiger J.
Published: October 2009

Background and Purpose. In middle cerebral artery (MCA) stroke, ischemia usually is unevenly distributed within the MCA territory. We sought to investigate which brain structures are critical for the acute neurological deficit in severe MCA stroke. Methods. We used magnetic resonance (MR) imaging and statistical parametric mapping in 64 consecutive stroke patients (64 ±13 years) to study the pattern of the initial perfusion abnormality. Results. Patients with lesion progression had more severe time‐to‐peak (TTP) abnormalities (P < .0001) in the inferior frontal gyrus, superior temporal gyrus, insula, and underlying hemispheric white matter than those with lesion regression. Also, patients with lesion progression had more severe T2 abnormalities on day 8 than those with lesion regression. In contrast, the changes of water diffusion were similar among the two groups resulting in a perfusion–diffusion mismatch in lesion progression. TTP‐lesions were related to the neurological deficit score (rs=−0.563, P < .0001), T2‐lesions (r= 0.686, P < .0001), and cerebral artery abnormalities assessed on MR‐angiography (rs= 0.399, P < .01). Conclusions. In major MCA, stroke ischemia was most severe in the central portion of the MCA territory. It is suggested that involvement of hemispheric white matter accentuated the neurological deficit probably by affecting cortico‐cortical and cortico‐subcortical fibers.
Distinguishing Air From Solid Emboli Using Ultrasound: In‐Vitro Study of the Effect of Doppler Carrier Frequency
Authors: Rodriguez Rosendo A. , Rodriguez Carlos D. , Mesana Thierry , Nathan Howard J.
Published: October 2009

Objective. To compare the ability of the signal relative‐intensity and sample‐volume‐length (SVL) to discriminate air bubbles from solid spheres in an in‐vitro model using two different carrier frequencies of the Doppler transducer. Methods. A gel ultrasound phantom was connected to a circuit in which blood‐mimicking fluid circulated. Air bubbles (100‐140 μm) and latex spheres (125 ± 10 μm) were injected into the circuit and interrogated using 1‐ and 2‐MHz transducers. High‐intensity‐transient‐signals (HITS) were recorded with a dual‐gated transcranial Doppler (TCD) system. Receiver‐Operating‐Characteristic curves determined the best cut‐off points that would distinguish between embolic materials. Results. HITS from air bubbles had higher intensities and longer SVL than solid spheres with either transducer (P < .0001). Air bubbles (P < .0001) and microspheres (P= .049) showed higher intensities with the 1‐MHz relative to the 2‐MHz transducer. The intensity increase with the 1‐MHz transducer was greater for air bubbles than microspheres (P < .0001). The discriminating efficacy of both the relative‐intensity and SVL was similar between transducers (intensity, P= .201; SVL, P= .98). Conclusions. The relative‐intensity and SVL are equally effective to distinguish solid from air emboli using 1‐ and 2‐MHz transducers. Our study indicates that using a lower carrier frequency does not improve the discrimination of air from solid emboli.
Transcranial Doppler Microembolic Signal Monitoring is Useful in Diagnosis and Treatment of Carotid Artery Dissection: Two Case Reports
Authors: Roy Jayanta , Akhtar Naveed , Watson Timothy , Demchuk Andrew M. , Saqqur Maher
Published: October 2009

Arterial dissection is the underlying stroke mechanism in approximately 2.5% of all strokes and the second leading cause of stroke in patients younger than 45 years of age. Controversy exists regarding the medical management of carotid dissection. Both anticoagulants and antiplatelet agents have been used with no compelling data supporting one therapy over the other. Transcranial Doppler (TCD) emboli monitoring may help in establishing the diagnosis and guide the treatment by measuring the frequency of microembolic signals (MES). We present two cases of carotid dissection where TCD monitoring for MES helped in establishing the diagnosis and proved useful in identifying that standard anticoagulation treatment was not preventing emboli. Both cases were also monitored for emboli count reduction with subsequent antiplatelet therapy.
Verbal Working Memory and Atherosclerosis in Patients with Cardiovascular Disease: An fMRI study
Authors: Haley Andreana P. , Sweet Lawrence H. , Gunstad John , Forman Daniel E. , Poppas Athena , Paul Robert H. , Tate David F. , Cohen Ronald A.
Published: October 2009

Background and Purpose. Intimal–medial thickening (IMT) of the carotid wall is an accepted peripheral marker of atherosclerosis. It is associated with increased risk for myocardial infarction and stroke, and lower attention‐executive‐psychomotor functioning. The purpose of this study was to examine the relationship between IMT and brain activity during a verbal working memory (VWM) task in patients with cardiovascular disease (CVD). Methods. Thirteen CVD patients underwent functional magnetic resonance imaging (fMRI) during a 2‐Back VWM task, and B‐mode ultrasound of the carotid arteries. IMT was calculated using an automated algorithm based on a validated edge‐detection technique. The relationship between IMT and 2‐Back‐related brain activity was modeled using partial correlations controlling for age and small vessel disease as measured by white matter signal hyperintensities on MRI (WMH). Results. Higher IMT was associated with lower 2‐Back‐related signal intensity and in the right middle frontal gyrus, independent of age and WMH. Conclusions. IMT may be one mechanism contributing to brain dysfunction in CVD. The blood oxygenation level‐dependent (BOLD) contrast appears to be highly sensitive to peripheral vascular health as measured by IMT. Future studies should examine the sensitivity and specificity of the BOLD response for predicting cognitive decline in CVD.
Intracranial Hemorrhage Sparing Meningioma in an Anticoagulated Patient
Authors: Romero José Rafael , Sakai Osamu , Rice Mary Berlik , Babikian Viken L.
Published: October 2009

Background and Purpose. The risk of intracerebral hemorrhage (ICH) in patients receiving antithrombotic therapy is well known. However, there is sparse literature regarding the risk of intracerebral hemorrhage in patients receiving warfarin, who have an intracranial meningioma. Methods and Results. We report a case of a 66‐year‐old man who developed multifocal ICHs in the context of supratherapeutic anticoagulation. There was sparing of the intracranial meningioma despite the development and growth of multiple intraparenchymal hemorrhages that resulted in death. We also review the literature evaluating the risk of ICH in anticoagulated patients with an intracranial meningioma. Conclusions. The findings of this case lend further support to the gradually developing notion of relative safety of anticoagulation in patients with meningioma. They also underscore the importance of close monitoring of the INR.
Neuroimaging Characteristics in Subgroup of GBMs with p53 Overexpression
Authors: Mut Melike , Turba Ulku C. , Botella Anali Conesa , Baskurt Erol , Lopes M. Beatriz S. , Shaffrey Mark E.
Published: October 2009

Glioblastoma multiforme (GBM) is a heterogeneous group of tumors, and neuroimaging characteristics have not been well‐defined in molecular subgroups. Eighty‐five patients with GBM were analyzed regarding imaging characteristics and correlation to p53 expression. The p53 positivity was graded according to percentage of positive cells (Grade 0, for < 10%; Grade 1, for <25%; Grade 2, for 26–50%; Grade 3, for >50% labeled cells). Imaging characteristics evaluated in the preoperative MRI were location and number of lesions, dimensions of enhancing lesion and of surrounding edema, mass effect, tumor borders, enhancement pattern after intravenous contrast administration, and tumor necrosis. Eighteen tumors had p53 expression >50% in immunohistochemical staining. Preoperative MRI of patients harboring those tumors with high p53 positivity revealed typical lesions with ring enhancement pattern and well‐defined borders in T1‐weighted images with contrast, and they were significantly different from other groups of p53 expression. There was no difference in terms of location and number of the lesions, dimensions of enhancing lesion and surrounding edema, mass effect, and the tumor necrosis between four different groups of p53 expression. A special subgroup of GBMs with p53 overexpression has ring enhancement pattern and well‐defined border on MRI that may be influential in preoperative planning and postoperative management of adjunct therapy.
Hyperechogenicity of the Substantia Nigra in Parkinson's Disease
Authors: Ressner Pavel , Školoudík David , Hluštík Petr , Kaňovský Petr
Published: October 2009

Substantia nigra (SN) was assessed by transcranial sonography (TCS) in 47 Parkinson's disease (PD) patients and in 39 healthy volunteers. A semiquantitative echogenicity scale was created with arbitrary values ranging from 1 to 5, zones with grade ≥3 and larger than 0.19 cm2 were recorded as hyperechogenic SN. TCS examination of SN as a diagnostic test for PD in our study showed 87.2% sensitivity and 94.9% specificity.