bluuebunny/crossref_metadata_2025 huggingface dataset:
Pleistocene and Holocene glacier thicknesses, transport histories and dynamics inferred from SEM microtextures on quartz particles
Authors: MAHANEY WILLIAM C.
Published: November 2009

Recent analyses of microtextures on quartz particles (63–2000 μm) from Quaternary tills in Antarctica, Germany, southern Ontario, western Wyoming, Tibet, the Austrian Alps, and Mount Kenya show that glacial fracture and abrasion microfeatures may be used to infer the thickness, transport history and ice dynamics of Pleistocene and Holocene glaciers. Quartz sands emplaced by continental and mountain ice were studied by SEM after transport over variable distances in glaciers estimated to range from 150 m to 1500 m in thickness. Relative differences in ice thicknesses, distances of transport, and/or ice dynamics appear to have determined the frequency of occurrence and type of microtextures occurring on sand‐size particles. Subparallel fracture microfeatures tend to increase in frequency over a greater proportion of particle surfaces with increasing ice thickness and distance of transport. Conchoidal fractures, the most typical in quartz, and to some degree crescentic gouges abound on fragments emplaced by continental ice. Other possible fracture and fragmentation mechanisms, producing features of generally glacial origin, involve low velocity impacts induced by stick‐slip mechanisms, under variable cryostatic stresses, producing fracturing and abrasion across particle surfaces. Their generation implies high local contact stresses associated with high strain rates.
Impact of Nursing Unit Turnover on Patient Outcomes in Hospitals
Authors: Bae Sung‐Heui , Mark Barbara , Fried Bruce
Published: November 2009

Purpose: The aim of this study was to examine how nursing unit turnover affects key workgroup processes and how these processes mediate the impact of nursing turnover on patient outcomes.

Methods: A secondary data analysis was used to test the hypothesized model. This study used registered nurse and patient data from 268 nursing units at 141 hospitals collected as part of the Outcomes Research in Nursing Administration (ORNA II) project. Nursing units provided monthly nursing unit turnover rates for 6 consecutive months, and registered nurses completed questionnaires measuring workgroup processes (group cohesion, relational coordination, and workgroup learning). Patient outcome measures included unit‐level average length of patient stay, patient falls, medication errors, and patient satisfaction scores.

Results: Nursing units with moderate levels of turnover were likely to have lower levels of workgroup learning compared to those with no turnover (p<.01). Nursing units with low levels of turnover were likely to have fewer patient falls than nursing units with no turnover (p<.05). Additionally, workgroup cohesion and relational coordination had a positive impact on patient satisfaction (p<.01), and increased workgroup learning led to fewer occurrences of severe medication errors (p<.05).

Conclusions: The findings of this study provide specific information on the operational impact of turnover so as to better design, fund, and implement appropriate intervention strategies to prevent registered nurse exit from nursing units. Further investigation is needed to assess the turnover‐outcomes relationship as well as the mediating effect of workgroup processes on this relationship.

Clinical Relevance: Managing nursing unit turnover within appropriate levels at the nursing unit is critical to delivering high‐quality patient care.
An International Survey on Advanced Practice Nursing Education, Practice, and Regulation
Authors: Pulcini Joyce , Jelic Monika , Gul Raisa , Loke Alice Yuen
Published: November 2009

Purpose: To describe international trends on the developing role of the nurse practitioner‐advanced practice nurse (NP‐APN), including nomenclature, levels and types of NP‐APN education, practice settings, scope of practice, regulatory policies, and political environment.

Design: A cross‐sectional, descriptive Web‐based survey sent in February and March 2008 to a total of 174 key informants and active members of the International Nurse Practitioner‐Advanced Practice Nursing Network of the International Council of Nurses.

Methods: An international Web‐based survey preceded by a pilot survey.

Findings: Ninety‐one nurses from 32 countries responded. Thirteen titles were identified on nomenclature for the NP‐APN in different countries. NP‐APN education was available in 71% of the 31 countries responding to this item, with 50% identifying the master's degree as the most prevalent credential. Twenty‐three countries had formal recognition of the NP‐APN role. Of these, 48% had licensure maintenance or renewal requirements for the NP‐APN, with most requiring continuing education or clinical practice. The greatest support for the NP‐APN role came from domestic nursing organizations (92%), individual nurses (70%), and the government (68%), while opposition came primarily from domestic physician organizations (83%) and individual physicians (67%).

Conclusions: Interest in the NP‐APN role has been gaining ground worldwide. This study presents a snapshot of education, practice, and regulation for NP‐APNs as they develop their unique role in delivering health care in various countries. Areas that may require more support are highlighted.

Clinical Relevance: The NP‐APN role in healthcare systems is expanding and will benefit from international networking and support.
Precipitation Coating of Monazite on Woven Ceramic Fibers: III—Coating without Strength Degradation Using a Phytic Acid Precursor
Authors: Fair Geoff E. , Hay Randall S. , Boakye Emmanuel E. , Morgan Peter E. D. , Marzke Robert F. , Sharma Ramesh
Published: November 2009

Multiple coatings of La‐monazite (LaPO4) were applied to Nextel™ 610 and 720 oxide fibers using a heterogeneous nucleation and growth coating process with phytic acid solution precursors. The as‐processed coatings were found to be largely amorphous. Coated fibers were heat treated at 1200°C for 1–2 h, whereupon the coatings crystallized to porous LaPO4 with thin (50–100 nm) layers of AlPO4 at the fiber–coating interface. Heat‐treated fibers exhibited full strength retention, in marked contrast to fibers coated by precipitation using citric acid precursors as in a previous work. The microstructural evolution of the amorphous coatings was studied as a function of temperature. AlPO4 forms at the fiber–coating interface between 700° and 800°C, before high‐temperature outgassing of the coating as measured by TGA. NMR spectroscopy was used to study as‐precipitated powders and as‐processed coatings to gain insights into the structural nature of the materials. A possible explanation for the retention of fiber strength through the coating process is proposed and discussed in light of the experimental evidence.
Crystallization of SiO2–CaO–Na2O Glass Using Sugarcane Bagasse Ash as Silica Source
Authors: Teixeira Silvio Rainho , Romero Maximina , Rincón Jesus Ma.
Published: November 2009

This work reports the feasibility results of recycling sugar cane bagasse ash (SCBA) to produce glass–ceramic. The major component of this solid residue is SiO2(>89%). A 100 g batch composition containing ash, CaO and Na2O was melted and afterward, poured into water to produce a glass frit. The crystallization kinetic study by nonisothermal method was performed on powder samples (<63 μm) at five different heating rates. Wollastonite is the major phase in crystallization atT>970°C, and below this temperature there is a predominance of rankinite. The crystallization activation energies calculated by the Kissinger and Ligero methods are equivalent: 374±10 and 378±13 kJ/mol. The growth morphology parameters have equal valuesn=m=1.5 indicating that bulk nucleation is the dominant mechanism in this crystallization process, where there is a three‐dimensional growth of crystals with polyhedron‐like morphology controlled by diffusion from a constant number of nuclei. However, differential thermal analysis (DTA) curves on both monolithic and powder glass samples suggest that crystallization of the powder glass sample occurs through a surface mechanism. The divergence in both results suggests that the early stage of surface crystallization occurs through a three‐dimensional growth of crystals, which will then transform to one‐dimensional growth.
Regional Brain Atrophy Is Associated With Physical Disability in Multiple Sclerosis: Semiquantitative Magnetic Resonance Imaging and Relationship to Clinical Findings
Authors: Bakshi Rohit , Benedict Ralph H. B. , Bermel Robert A. , Jacobs Lawrence
Published: November 2009

Objectibe. Brain atrophy may occur early in the course of multiple sclerosis (MS) and may be associated with disability. Brain magnetic resonance imaging (MRI) of 114 MS patients (group A) were analyzed for regional atrophy (vs age‐/gender‐matched controls) and T1 and T2 lesions using 4‐point rating systems. Thirty‐five separate patients (group B) were analyzed for cortical atrophy (ordinal scale), third ventricular width, and total T2 hyperintense lesion volume (computer assisted). In group A, regression modeling indicated that inferior frontal atrophy (P= .0003) and T2 lesions in the pons (P= .02) predicted physical disability (Expanded Disability Status Scale [EDSS] score). Secondary progressive (SP) versus relapsing patients were predicted by inferior parietal (P= .002), superior parietal (P= .006), temporal (P= .008), inferior frontal (P= .01), superior frontal (P= .01), cerebellum (P= .01), occipital (P= .01), and midbrain (P= .02) atrophy. SP patients were also predicted by total atrophy (P= .01) and third ventricular enlargement (P= .03) but not T1 or T2 lesions. In group B, the regression model predicting EDSS score included only superior frontal atrophy (r= 0.515, P= .002). Mean kappa coefficients of ordinal ratings were 0.9 (intraobserver) and 0.8 (interobserver). Ordinal ratings correlated well with quantitative assessments. The authors conclude that brain atrophy is closely associated with physical disability and clinical course in MS patients and can be appreciated using a semiquantitative MRI regional rating system.
Use of Exponential Diffusion Imaging to Determine the Age of Ischemic Infarcts
Authors: Engelter S. T. , Provenzale J. M. , Petrella J. R. , Alberts M. J. , DeLong D. M. , MacFall J. R.
Published: November 2009

Objective. Diffusion‐weighted magnetic resonance imaging (DWI) detects acute ischemic infarcts with high lesion conspicuity. Determination of infarct age is difficult on DWI alone because infarct signal intensity (SIinfarct) on DWI is influenced by T2properties (“T2shine‐through”). Maps of the apparent diffusion coefficient (ADC) reflect pure diffusion characteristics without T2effects but have low lesion conspicuity. Thus, in clinical practice, combined use of DWI and ADC maps is required. Exponential DWI (eDWI) is an innovative means of MRI‐diffusion data analysis that merges the advantages of DWI and ADC maps. The authors hypothesized that SIinfarcton eDWI would correlate with infarct age. The authors studied 114 consecutive patients who had 120 ischemic strokes with clearly determined onset times and who underwent echo‐planar DWI. The eDWI were generated by dividing the signal intensity on DWI by that on the corresponding T2image on a pixel‐by‐pixel basis. SIinfarcton eDWI was measured in the lesion core and expressed as a percentage of contralateral control tissue. On eDWI, relative SIinfarctchanged significantly with infarct age (P < .0001). When patients were sorted in infarct‐age groups, no significant differences were found within the first 120 hours. However, for patients studied within 5 days, the mean relative SIinfarctwas significantly higher compared with patients studied ≥8 days after stroke (P < .05). For all infarcts up to 5 days old, the eDWI signal intensity was higher than control tissue (hyperintense appearance). All infarcts >10 days old had an eDWI signal intensity lower than control tissue (hypointense appearance). The authors concluded that the use of eDWI, as a single set of images, reliably differentiates acute infarcts (≤5 days old) from infarcts >10 days old. This feature would be expected to be helpful when the distinction between acute and nonacute infarction cannot be determined on clinical grounds.
Early Computed Tomography Hypodensity Predicts Hemorrhage After Intravenous Tissue Plasminogen Activator in Acute Ischemic Stroke
Authors: Dubey Neeraj , Bakshi Rohit , Wasay Mohammed , Dmochowski Jacek
Published: November 2009

Parenchymal hypodensity is a proposed risk factor for hemorrhage after recombinant tissue plasminogen activator (TPA) thrombolysis for ischemic stroke. In Buffalo, NY, and Houston, TX, the authors reviewed 70 patients who were treated with intravenous TPA for acute middle cerebral artery (MCA) stroke. Two observers blinded to clinical outcome analyzed initial noncontrast head computed tomography (CT) scans. Basal ganglia CT hypodensity was quantitated in Hounsfield units (HUs). Contralateral‐ipsilateral difference in density was calculated using the asymptomatic side as a control. Ictus time to TPA averaged 2.5 hours. Six patients developed symptomatic intraparenchymal hematomas (2 fatal). The hemorrhage group had more severe basal ganglia hypodensity (mean 7.5 ± 1.4, range 6–10 HU) than the nonhemorrhage group (2.2 ± 1.4, range 0–9 HU) (P < .0001). The hemorrhage group had hypodensity of > 5 HU; the nonhemorrhage group had hypodensity of ≤4 HU, except 1 patient with hypodensity of 9 HU. In predicting hemorrhage, the positive predictive value of hypodensity > 5 HU was 86%; the negative predictive value was 100%. Prethrombolysis NIH Stroke Scale (NIHSS) deficit (P= .0007) and blood glucose (P= .005) were also higher in the hemorrhage group. Age, gender, smoking, hypertension, and ictus time to TPA infusion did not differ between the 2 groups. Logistic regression indicated that basal ganglia hypodensity was the best single predictor of hemorrhage. Hypodensity and NIHSS score together predicted all cases of hemorrhage. The authors conclude that basal ganglia hypodensity quantified by CT may be a useful method of risk stratification to select acute MCA stroke patients for thrombolytic therapy.
Reproducibility of Proton Magnetic Resonance Spectroscopy Imaging Measurements of Normal Human Hippocampus at 1.5 T: Clinical Implications
Authors: Maton B. , Londono A. , Sawrie S. , Knowlton R. , DenHollander J. , Kuzniecky R.
Published: November 2009

The authors investigate the reproducibility of metabolite signals measured with proton magnetic resonance spectroscopy1H‐MRS) acquired from the human hippocampus in controls and in a phantom. Two1H‐MRS studies separated by 3 weeks were performed in 8 healthy volunteers and in a phantom. N‐acetyl compounds (NA), choline (Ch), and creatine (Cr) peak areas and ratios were measured and compared using percentage variation, and Pearson Correlation Coefficient at the level of every voxel, the level of 1 hippocampus (5 voxels), and the level of 2 hippocampi (10 voxels). Sensitivity for observing clinically significant between‐session1H‐MRS changes was evaluated using the reliable change index. Reproducibility measures for metabolite peak areas were only moderately concordant with percentage variation ranging from 14% to 20% for NA, Cho, and Cr. Stability was much improved when NA ratios and sum of multiple voxels were considered. Between‐session NA/(Cho + Cr) changes greater than 22%, 12%, and 10% in one given participant can be detected with a 90% confidence interval when considered at the single‐voxel level, the level of a single hippocampus, or the level of both hippocampi, respectively. Left‐right asymmetry indices showed similar and limited interhemispheric asymmetry in repeated examination. This study suggests that1H‐MRS reproducibility performance is adequate for the study and monitoring of human hippocampus function when NA ratios and the sum of multiple voxels are considered. Individual metabolite peaks and single‐voxel measurements have low reproducibility at 1.5 T and should be used only with clearly established statistical parameters.
Possible Short‐term Amelioration of Basilar Plaque by High‐Dose Atorvastatin: Use of Reductase Inhibitors for Intracranial Plaque Stabilization
Authors: Callahan A. S. , Berger Brian L. , Beuter Matthew J. , Devlin Thomas G.
Published: November 2009

Regression of symptomatic intracranial atherostenosis is not known to be a common occurrence. In this case, delay of basilar reconstruction by endovascular means permitted serial angiographic assessment of plaque change. The use of high‐dose atorvastatin over a 2‐week period was associated with marked angiographic improvement. Medical programs of plaque stabilization may provide adjunctive benefit in patients with symptomatic intracranial disease.
In Vivo 1H Magnetic Resonance Spectroscopic Measurement of Brain Glycine Levels in Nonketotic Hyperglycinemia
Authors: Gabis Lidia , Parton Patricia , Roche Patricia , Lenn Nicholas , Tudorica Alina , Huang Wei
Published: November 2009

Nonketotic hyperglycinemia (NKH) is an autosomal recessive disorder of glycine metabolism. Defective glycine cleavage causes elevated concentrations of glycine in plasma, urine, and cerebrospinal fluid. A longitudinal study using magnetic resonance imaging (MRI) and single‐voxel1H magnetic resonance spectroscopy (MRS) was performed on an infant with the typical clinical picture of NKH. He was examined twice during the course of treatment with sodium benzoate and dextromethorphan. At the age of 10 months, MRI showed normal brain structure, while MRS detected a prominent glycine peak in the brain. Repeat MRS at the age of 13 months showed a small increase in glycine peak and a prominent glutamate/glutamine peak not previously detected. The MRS measurements were consistent with the slight increase in blood glycine level and the elevation in glutamine level, indicating that1H MRS can be a valuable tool in the diagnosis and monitoring of treatment effects in patients with NKH.
A Broad Diagnostic Battery for Bedside Transcranial Doppler to Detect Flow Changes With Internal Carotid Artery Stenosis or Occlusion
Authors: Christou Ioannis , Felberg Robert A. , Demchuk Andrew M. , Grotta James C. , Burgin W. Scott , Malkoff Marc , Alexandrov Andrei V.
Published: November 2009

Background and Purpose. The authors establish accuracy parameters of a broad diagnostic battery for bedside transcranial Doppler (TCD) to detect flow changes due to internal carotid artery (ICA) stenosis or occlusion. Methods. The authors prospectively studied consecutive patients with stroke or transient ischemic attack referred for TCD. TCD was performed and interpreted at bedside using a standard insonation protocol. A broad diagnostic battery included major criteria: collateral flow signals, abnormal siphon or terminal carotid signals, and delayed systolic flow acceleration in the middle cerebral artery. Minor criteria included a unilateral decrease in pulsatility index (≤ 0.6 or ≤ 70% of contralateral side), flow diversion signs, and compensatory velocity increase. Angiography or carotid duplex ultrasound (CDU) was used to grade the degree of carotid stenosis using North American criteria. Sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of TCD findings were determined. Results. Seven hundred and twenty patients underwent TCD, of whom 517 (256 men and 261 women) had angiography and/or CDU within 8.8 ± 0.9 days. Age was 63.1 ± 15.7 years. For a 70% to 99% carotid stenosis or occlusion, TCD had sensitivity of 79.4%, specificity of 86.2%, PPV of 57.0%, NPV of 94.8%, and accuracy of 84.7%. For a 50% to 99% carotid stenosis or occlusion, TCD had sensitivity of 67.5%, specificity of 83.9%, PPV of 54.5%, NPV of 90.0%, and accuracy of 81.6%. TCD detected intracranial carotid lesions with 84.9% accuracy and extracranial carotid lesions with 84.4% accuracy (sensitivity of 88% and 79%, specificity of 85% and 86%, PPV of 24% and 54%, and NPV of 99% and 95%, respectively). The prevalence of the ophthalmic artery flow reversal was 36.4% in patients with ≥ 70% stenosis or occlusion. If present, this finding indicated a proximal ICA lesion location in 97% of these patients. Conclusions. In symptomatic patients, bedside TCD can accurately detect flow changes consistent with hemodynamically significant ICA obstruction; however, TCD should not be a substitute for direct carotid evaluation. Because TCD is sensitive and specific for ≥ 70% carotid stenosis or occlusion in both extracranial and intracranial carotid segments, it can be used as a complementary test to refine other imaging findings and detect tandem lesions.
Magnetic Resonance Analysis of Postsurgical Temporal Lobectomy
Authors: Alsaadi Taoufik M. , Ulmer John L. , Mitchell Michael J. , Morris George L. , Swanson Sara J. , Mueller Wade M.
Published: November 2009

Background and Purpose. The effect of temporal lobe transection area, volume of postoperative gliosis, and surgical technique on patients' seizure‐free outcome is unknown. The authors studied the effects of these variables on patients' seizure‐free outcome. Methods. A retrospective review of magnetic resonance imaging examinations acquired 3 to 18 months after temporal lobe resection was carried out for 18 patients with intractable temporal lobe seizures and known postsurgical outcomes for more than 2 years. The total volume of radiologically probable gliosis evident on axial proton‐density‐weighted images was calculated for each patient using software on an independent console. The total area of temporal lobe surface transected by the scalpel was calculated as well, using sagittal T1‐weighted images. The total volume of gliosis, the total area of transected temporal lobe, and the specific type of surgery (sparing vs no sparing of the superior temporal gyrus) were then correlated with the postsurgical outcome of the patients. An examiner with no prior knowledge of the patients' postsurgical outcomes carried out the above calculations and measurements. The patients' postoperative outcome was defined using Engel classifications, and patients were divided into two groups: group A with Engel class 1 (n= 9) and group B with Engel classes 2–4 (n= 9). Results. The mean volumes of postoperative gliosis were not significantly different between group A (3592.3 mm3) and group B (4270 mm3). The mean area of transected temporal lobe was also similar between group A (1865.2 mm2) and group B (1930 mm2). With regard to surgical technique, there were 5 subjects who had the superior temporal gyrus resected and 13 who did not. Eighty percent of patients with the superior temporal gyrus resected were Engel class 1 or 2, whereas only 20% were of Engel class 3 or 4. Conclusion. The authors found no clear association between postoperative outcome and residual temporal lobe gliosis, the surgical technique, or the total area of temporal lobe transected by the scalpel.
Intravascular Ultrasound Doppler Measurement of Blood Flow Velocity
Authors: Schumacher M. , Yin L. , Swaid S. , Oldenburger J. , Gilsbach J. M. , Hetzel A.
Published: November 2009

Background and Methods. The authors investigated the feasibility and accuracy of intravascular Doppler sonography (IVDS) with a newly developed microprobe. Methods. The known method to determine blood flow velocity by transcutaneous Doppler sonography was transferred to an intravascular usable Doppler probe. With the improved technique, a microprobe measuring 0.3 mm in diameter can be advanced through a 5F catheter used in routine diagnostic angiography to perform intravascular Doppler sonography. In a first step, the conditions for application and measurement were studied in a flow tube model and were transferred in a second step to patients undergoing routine angiography and patients with arterial stenoses. Results. Measurements with nondegassed liquids showed a high intensive acoustic signal, but no echo effect could be recorded in degassed liquids. IVDS of healthy vessels in 40 patients showed the same typical flow pulse curve as seen in transcutaneous measurements. The optimal position of the microprobe with respect to the contact of the vessel wall, the diastolic and systolic phase, and the distance to the tip of the catheter could be evaluated. In 95.6% of the 40 patients with healthy vessels, IVDS was successful. Fourteen patients with arterial stenotic diseases were investigated before and after percutaneous transluminal angioplasty, and the results of these investigations correlated well with the angiographical results. Conclusion. For percutaneously directly reachable vessels, the transcutaneous Doppler sonography is the choice for easy noninvasive and inexpensive measurement of blood flow velocity. However, for vessels that are difficult or impossible to reach percutaneously, intravascular measurement is a valid procedure.
SonoVue™ in Transcranial Doppler Investigations of the Cerebral Arteries
Authors: Kaps M. , Legemate D. A. , Ries F. , Ackerstaff R.G.A. , Markus H. , Pezzoli C. , Llull J.‐B. , Spinazzi A.
Published: November 2009

Background and Purpose. The authors investigated the safety and diagnostic potential of a new ultrasound contrast agent (SonoVue™) using transcranial color‐coded duplex sonography (TCCS). Methods. Forty patients were enrolled in a multicenter, open‐label (on‐site), blind (off‐site), randomized, dose‐ranging crossover study. SonoVue™ was administered as an intravenous bolus injection of 4 different dosages (0.3, 0.6, 1.2, and 2.4 mL). Efficacy was evaluated as (1) off‐site assessment of global quality of the Doppler investigation (based on color or power Doppler images and spectral analysis) at baseline and following each dose of SonoVue™ according to a 4‐point scale (from very poor to excellent imaging of blood flow) and (2) duration of clinically useful signal enhancement and color or power Doppler visualization of blood flow. Additional on‐site efficacy assessments performed following each dose of SonoVue™ included confidence in diagnosis and global consequences of contrast enhancement on diagnosis. Safety evaluations included clinical laboratory tests, neurological examination, injection site tolerability, and incidence of adverse events and their relationship to the study agent. Results. All doses of SonoVue™ significantly improved the global quality of Doppler examinations (P < .05). The median duration of clinically useful enhancement was dose related (P < .001) and ranged from 2 to 6 minutes at the highest dose. The administration of the contrast agent changed a nondiagnostic study to a diagnostic one in 66% of patients and increased the confidence in diagnosis in 74% of cases. No serious adverse events were recorded following SonoVue™ administration. The observed adverse reactions were all transient and mild in intensity. Conclusions. The results obtained from this multicenter study demonstrate that the administration of SonoVue™ to patients with ischemic cerebrovascular disease who undergo TCCS examination of cerebral vessels improves the visualization of intracranial arteries, providing a dose‐dependent contrast enhancement and a clinically useful duration of signal enhancement related to the dose. During this multicenter study, SonoVue™ proved to be a safe and well‐tolerated compound.
Effect of Adenosine on Cerebral Blood Flow Velocity
Authors: Zanferrari Carla , Razumovsky Alexander Y. , Lavados Pablo M. , Sen Souvik , Oppenheimer Stephen M.
Published: November 2009

Background and Purpose. Evidence suggests that adenosine (ADN) is a potent vasodilator of cerebral vessels. However, the feasibility of manipulating human cerebral vascular resistance with AND has not been assessed by means of TCD. The purpose of this study was to quantitatively estimate the change in middle cerebral artery cerebral blood flow velocity (CBFV) in response to intravenous ADN infusion in humans. Methods. Eleven patients with subacute cerebrovascular events (ischemic stroke, transient ischemic attack, or hemorrhage) undergoing adenosine‐thallium stress testing were studied before, during, and after ADN infusion to evaluate the effect of ADN on cerebral blood flow velocity. Continuous blood pressure (BP), heart rate (HR), respiration rate (RR), end‐tidal CO2(ET‐CO2), and transcranial Doppler ultrasonography monitoring of CBFV and pulsatility index (PI) in both middle cerebral arteries were performed. Results. The mean CBFVs were 65.4±19.2 cm/s before, 55.4±18.1 cm/s during, and 64.1±22.5 cm/s after ADN infusion, which represents a statistically significant decrease during ADN test compared with both baseline (P= .007) and posttest levels (P= .017). The PI was increased during the test (0.91±0.2) when compared with baseline (0.71±0.1) (P= .007). During ADN injection, mean HR increased (P= .004) and mean end‐tidal CO2levels decreased significantly (P= .003). Mean BP and RR did not change significantly. Conclusions. The authors hypothesize that any direct vasodilatory effect of ADN on the distal cerebral peripheral vasculature may be negated by an effect of ADN on depth of respiration resulting in hypocapnia and secondary distal vasoconstriction.
Helical High‐Resolution Volume‐Rendered 3‐Dimensional Computer Tomography Angiography in the Detection of Intracranial Aneurysms
Authors: Seruga Tomaz , Bunc Gorazd , Klein Guenther Erich
Published: November 2009

Background and Purpose. This study was carried out to determine whether high‐resolution three‐dimensional prospective‐volume‐rendered computed tomographic (CT) angiography can replace conventional intra‐arterial digital subtractional angiography in the diagnostic evaluation of patients with an acute subarachnoid hemorrhage (SAH) due to ruptured intracranial aneurysm. Methods. Both techniques were performed in 30 consecutive patients within 2 to 12 hours after their admission to the hospital. Results. In this group of 30 patients, CT angiography with 3‐dimensional volume‐rendered reconstruction detected 31 aneurysms in 25 patients. Two aneurysms were missed on CT angiography. Conventional angiography detected 33 aneurysms in 27 patients. The authors considered angiograms in 3 patients presenting with SAH as normal. In all cases where an aneurysm was detected on CT angiography, the finding was confirmed by conventional angiography. Conclusions. CT angiography with 3‐dimensional postprocessing is a sensitive, noninvasive method that provides a 3‐dimensional view of intracranial vessels and the aneurysm. It is also very useful in planning either surgical or endovascular treatment.
Unilateral Temporal Lobe Stroke Causing Ischemic Transient Global Amnesia: Role for Diffusion‐Weighted Imaging in the Initial Evaluation
Authors: Greer David M. , Schaefer Pamela W. , Schwamm Lee H.
Published: November 2009

Ischemia has been proposed as a cause of transient global amnesia (TGA), but proof has been lacking. The authors performed magnetic resonance imaging on a 77‐year‐old woman with classic TGA at 4 hours and at 6 days after the onset of symptoms. Her initial diffusion‐weighted imaging (DWI) and apparent diffusion coefficient imaging suggested an acute infarct in the left mesial temporal lobe. Follow‐up T2‐weighted imaging at 6 days confirmed the lesion as an ischemic infarct, despite resolution of her symptoms. DWI permits early detection of small ischemic lesions and may identify patients with ischemic TGA who should be evaluated for potential sources of emboli.
Intracranial Vasculitis and Multiple Abscesses in a Pregnant Woman
Authors: Cihangiroglu Mutlu , Hartker Frederick W. , Mojtahadi Saeid , Ramsey Ruth G.
Published: November 2009

Cerebral vasculitis is an unusual disorder with many causes. Infectious causes of cerebral vasculitis are predominantly bacterial or viral in nature. Purulent bacterial vasculitis is most often a complication of severe bacterial meningitis. The patient is a 25‐year‐old African American female, 25 weeks pregnant, who presented to the neurology service after a consult and referral from an outside hospital. She had a 1‐month history of right sixth nerve palsy. Initial workup included a negative lumber puncture and a noninfused magnetic resonance imaging (MRI). Three days later, the patient developed right‐sided migraine headaches and right third nerve palsy. The angiogram revealed diffuse irregularity and narrowing of the petrous, cavernous, and supraclinoid portions of the internal carotid and right middle cerebral arteries. Shortly thereafter, an MRI examination revealed diffuse leptomeningeal enhancement and abscess and a right parietal subdural empyema. Infectious vasculitis secondary to purulent meningitis has a rapidly progressive course and presents with cranial nerve palsy with involvement of the cavernous sinus. Although the association of this disease with pregnancy has not been established, it should be recognized that the early imaging studies may be negative or discordant and follow‐up imaging might be necessary.
Brain Volume Changes on Longitudinal Magnetic Resonance Imaging in Normal Older People
Authors: Tang Yong , Whitman Gregory T. , Lopez Ivan , Baloh Robert W.
Published: November 2009

Background and Purpose. The purpose of this study is to investigate the longitudinal age‐related changes in human brain volume using stereological methods. Methods. Sixty‐six older participants (34 men, 32 women, age [mean ± SD] 78.9 ± 3.3 years, range 74–87 years) with normal baseline and follow‐up examinations underwent 2 MRIs (magnetic resonance imaging) of the brain on average 4.4 years apart. The volumes of the cerebrum (defined as cortex, basal ganglia, thalamus, and white matter), lateral ventricles, and cerebellum were estimated on the 2 MRIs using an unbiased stereological method (Cavalieri principle). Results. The annual decrease (mean ± SD) of the cerebral volume was 2.1%± 1.6% (P < .001). The average volume of the lateral ventricles on the second MRI was increased by 5.6%± 3.6% per year (P < .001). The average volume of the cerebellum on the second MRI was decreased by 1.2%± 2.2% per year (P < .001). Even though the average cerebral volume was significantly different between men and women on initial MRI and second MRI, the percentage change of the age‐related cerebral volume decrease in male and female brains between initial MRI and second MRI were identical. Conclusions. The findings showed that there was age‐related atrophy of cerebrum and cerebellum and age‐related disproportional enlargement of lateral ventricles in normal older men and women.
Magnetic Resonance Reflects the Pathological Evolution of Wernicke Encephalopathy
Authors: Ho Park Seong , Kim Manho , Na Duk L. , Jeon Beom S.
Published: November 2009

Background and Purpose. Wernicke encephalopathy (WE) is an acute phase of Wernicke‐Korsakoff syndrome. Pathologic findings change between acute and chronic phases. Only a few magnetic resonance imaging (MRI) studies have been done to date. Methods. To correlate the MRI findings in acute and chronic stages of WE with the known pathologic information, 15 consecutive patients with WE were examined with MRI: 3 before thiamine treatment, 7 within 24 hours of thiamine treatment, 4 between the second and sixth day after thiamine treatment, and 1 fifty‐five days after thiamine treatment. Nine of the patients had follow‐up MRI between 2 days and 33 months. T1‐weighted, proton, and T2‐weighted axial images were obtained with additional 5‐mm‐thick T1‐weighted sagittal and coronal images to better visualize the mammillary bodies. Results. In the acute WE, MRI showed high signal intensity on T2‐weighted images in periaqueduct and medial thalamic regions. In a few patients with alcoholism, vermian and mammillary body atrophies and third ventricular enlargements were noted. In the chronic phase of WE, T2 hyperintensity disappeared but mammillary bodies and cerebellar vermis became atrophic and third ventricular enlargements were evident. High signal intensity on T2‐weighted images disappeared as early as 2 days, and atrophic changes appeared as early as 1 week. Conclusion. MRI is useful for in vivo monitoring and reflects the pathological evolution in acute and chronic phases of WE.
Segmentation of Progressive Multifocal Leukoencephalopathy Lesions in Fluid‐Attenuated Inversion Recovery Magnetic Resonance Imaging
Authors: Itti Laurent , Chang Linda , Ernst Thomas
Published: November 2009

Background and Purpose. The authors compared the reproducibility of a manual and a semiautomated technique for the quantitation of white‐matter lesions in magnetic resonance imaging (MRI). Methods. Volumes of white‐matter lesions were determined using fluid‐attenuated inversion recovery MRI in 23 AIDS patients with progressive multifocal leukoencephalopathy. Manual outlining was compared to an automated method based on region growing and adaptive thresholding. Results. Lesion volumes from the 2 methods correlated well (61 lesions, r= 0.99, P < 10−4), although the volumes differed substantially (12.8%± 13.7%). Interscan, intrasubject reproducibility was better for the automated than the manual method (2.9%± 3.2% vs 12.4%± 16.2% volume difference, P= .02). Conclusion. The automated algorithm appeared more reproducible, which renders it superior to the manual method for longitudinal studies.
Cerebral Infarction in Conjunction With Patent Foramen Ovale and May‐Thurner Syndrome
Authors: Greer David M. , Buonanno Ferdinando S.
Published: November 2009

Stroke patients with paradoxical embolus mandate a search for deep venous thrombosis (DVT) in the lower extremities. Iliac vein compression, or May‐Thurner syndrome, places certain patients at risk for development of DVT. The authors present 3 stroke patients with patent foramen ovale and paradoxical cerebral embolism, with demonstrated iliac vein compression as the presumed source of their embolus. May‐Thurner syndrome should be considered a potential source of clot, as definitive therapy of this disorder can be curative.
Bilateral Cerebellar Infarctions Caused by a Stenosis of a Congenitally Unpaired Posterior Inferior Cerebellar Artery
Authors: Gaida‐Hommernick B. , Smekal U. v. , Kirsch M. , Schminke U. , Machetanz J. , Kessler C.
Published: November 2009

Bilateral symmetrical cerebellar infarcts in the territory supplied by the medial posterior inferior cerebellar artery (PICA) branches are extremely rare. In the few cases published, it has not been possible to clearly pinpoint the cause of this infarct pattern. The authors present the case history of a 58‐year‐old man who had acute headaches accompanied by pronounced rotatory vertigo with nausea and vomiting. The neurological examination revealed bilateral cerebellar signs. Cranial magnetic resonance imaging showed bilateral, nearly symmetrical infarcts in the territory of the medial branches of both PICAs. These bilateral PICA infarctions were caused by a stenosis of an unpaired PICA originating from the left vertebral artery supplying both cerebellar hemispheres.
Magnetic Resonance Imaging Detection of a Lesion Compatible With Central Pontine Myelinolysis in a Pregnant Patient With Recurrent Vomiting and Confusion
Authors: Valiulis Beth , Kelley Roger E. , Hardjasudarma Mardjohan , London Steven
Published: November 2009

The authors report a patient who presented with unexplained confusion. She was 15 weeks pregnant and had been having recurrent vomiting for several weeks. This was felt to possibly represent hyperemesis gravidarum, but she had several other possible contributing factors. Her serum sodium was 146 mmol/L, and her potassium was 2.6 mmol/L. She was alert but had disorientation, visual hallucinations, memory impairment, and confabulation despite being a college graduate with no history of illicit drug use or excessive alcohol consumption. Her initial magnetic resonance imaging (MRI) brain scan was interpreted as being normal. However, her follow‐up MRI brain scan revealed typical findings of central pontine myelinolysis, which correlated with hyperreflexia and positive Babinski reflexes. This patient illustrates the constellation of signs and symptoms that can be seen with a demyelinating lesion of the pons. In addition, our case illustrates how this MRI scan finding can be quite nonspecific but may help to explain the clinical findings.
Harmonic Imaging of the Brain Parenchyma in a Dog Model Following NC100100 (Sonazoid™) Bolus Injection
Authors: Meyer Karsten , Seidel Günter , Algermissen Christian
Published: November 2009

Background and Purpose. NC100100 (Sonazoid™) is a new perfluorocarbon‐based ultrasound contrast agent (UCA) that has not been introduced to transcranial harmonic imaging. Methods. In an animal study on 6 beagle dogs, the authors performed harmonic power Doppler and gray‐scale imaging (SONOS 5500, S4 probe) after bolus injection of 2 different doses of Sonazoid. Time intensity curves for brain parenchyma, masticatory muscle, and contralateral skull were generated, and the peak increase from baseline was computed. Results. With harmonic gray‐scale imaging, a dose‐dependent homogeneous increase in acoustic intensity of the brain parenchyma was observed. Evaluation of the contralateral base of the skull showed a moderate signal decrease. In harmonic power Doppler sonography, signal increase was dose dependent also, but the signal pattern was inhomogeneous, with stronger enhancement in the anterior part of the brain. Conclusion. The new UCA Sonazoid is suitable for displaying brain perfusion. As already observed for other UCAs, gray‐scale harmonic imaging with Sonazoid leads to a more homogeneous contrast increase in cerebral parenchyma compared to harmonic power Doppler imaging. Sonazoid produces a moderate shadowing effect, with signal attenuation in the underlying deeper regions of interest.
Neuroimaging Characteristics of Pseudosubcortical Laminar Heterotopia
Authors: Montenegro Maria Augusta , Min Li Li , Guerreiro Marilisa M. , Cendes Fernando
Published: November 2009

Subcortical laminar heterotopia (SLH) is a subtype of malformation of cortical development characterized by laminar gray matter between the cortex and ventricles, which can vary in thickness and may be continuous or discontinuous. The objective of this study is to describe a normal finding of high‐resolution magnetic resonance imaging that may simulate an SLH. SLH is isointense to cortex on both T1‐ and T2‐weighted/FLAIR images, usually both anteriorly and posteriorly in location. Conversely, pseudo‐SLH is a normal variant present only at the posterior aspect of the brain, and with dark signal on both T1‐ and T2‐weighted/FLAIR images.
Angioplasty and Stenting for Symptomatic Basilar Artery Stenosis
Authors: Gondim Francisco de Assis Aquino , Cruz‐Flores Salvador , Moore Joseph , Al‐Joundi Taman
Published: November 2009

A 71‐year‐old man with symptomatic basilar artery stenosis refractory to antiplatelet therapy and anticoagulation underwent angioplasty and stenting of the basilar artery. The patient was discharged symptom‐free on clodiprogel 75 mg qd and aspirin 325 mg qd. One month later, he presented with a right frontal intracerebral hemorrhage. Angioplasty with stenting for symptomatic basilar artery stenosis is feasible. Its role in the therapy of symptomatic basilar artery stenosis is not yet defined. Furthermore, the best medical treatment postprocedure is yet to be established.
Ictal and Interictal Single Photon Emission Computed Tomography in a Patient With Benign Familial Infantile Convulsions
Authors: Nagase Tomoko , Takahashi Yukitoshi , Iida Satoko , Masue Michiya , Okamoto Hiroyuki , Kondo Naomi
Published: November 2009

Ictal and interictal single photon emission computed tomography (SPECT) and ictal electroencephalography (EEG) were studied in a 3‐month‐old girl with benign familial infantile convulsions (BFIC) to reveal the epileptic focus. There was bilateral diffuse propagation from a left frontal lobe focus on the ictal EEG. Perfusion in the left frontal region was increased on ictal SPECT and decreased on interictal SPECT. Epileptic foci of BFIC showed the same characteristics as foci of symptomatic partial epilepsy.
Misinterpretation of Parahippocampal Herniation for a Posterior Fossa Tumor: Imaging and Intraoperative Findings
Authors: Horowitz Michael , Kassam Amin , Levy Elad , Lunsford L. Dade
Published: November 2009

Tumors of the hippocampal and parahippocampal gyrus are not uncommon, nor are lesions of the cerebellopontine and ambient cisterns. Lesions in these areas include astrocytomas, meningiomas, gangliogliomas, hamartomas, neurilemomas, epidermoids, and dermoids. Preoperative imaging is an important tool that can help distinguish lesions, making surgical therapy more targeted and appropriate. The authors report a case of a 41‐year‐old man with right‐sided atypical trigeminal neuralgia and a left ambient cistern abnormality that was radiologically interpreted as a mesial temporal lobe or extramedullary ambient cistern mass lesion. Surgical exploration for biopsy revealed an abnormal posterior fossa anatomy and a parahippocampal herniation into the perimesencephalic cistern. Biopsy confirmed the finding of normal brain.
Flumazenil Responsive Ornithine Transcarbamylase Deficiency Encephalopathy: Clinical and Radiographic Features
Authors: Meyer Michael A. , Gavrilova Ralitza H.
Published: November 2009

A 22‐year‐old woman with a negative urine drug screen and somnolence rapidly reversed by intravenous flumazenil was found to have elevated ammonia levels and punctate calcifications of the subcortical frontal white matter. Abnormally high levels of orotic acid were found in serum and urine, confirming the diagnosis of ornithine transcarbamylase deficiency. Although computed tomography findings are non‐specific, young patients with unexplained hyperammonemic states of somnolence reversed by flumazenil should be screened for this X‐linked recessive metabolic disorder.
Isolated Septum Pellucidum Agenesis in an Adult
Authors: Cihangiroglu Mutlu , Bulut Serpil , Yilmaz Saim
Published: November 2009

Septum pellucidum agenesis is frequently associated with other cerebral malformations. Its isolated agenesis is quite rare. In the literature, all reported cases were diagnosed in early childhood. The authors present an unusual case of isolated septum pellucidum agenesis detected in adulthood with computed tomography and magnetic resonance imaging.
Clinical Investigative Studies: Relationship Between Absolute Mean Cerebral Transit Time and Absolute Mean Flow Velocity on Transcranial Doppler Ultrasound After Ischemic Stroke
Authors: Wardlaw Joanna M. , Dennis Martin S. , Merrick Malcolm V. , Warlow Charles P.
Published: November 2009

Background and Purpose. Previous studies of transcranial Doppler (TCD) sonography in acute stroke have used the relative difference between the symptomatic and asymptomatic arteries to assess arterial occlusion. However, a simple measure of absolute mean flow velocity might provide a direct assessment of “perfusion reserve” in acute ischemic stroke. Methods. In a prospective study, 62 patients with ischemic stroke had TCD and a mean cerebral transit time examination within 48 hours of stroke. Absolute intracranial arterial mean flow velocities were correlated with the corresponding absolute mean transit times. Results. The authors found a significant correlation between middle cerebral artery (MCA) mean flow velocity and transit time in the symptomatic (Spearman rank correlation coefficient [ρ] =−0.65, P < .01) but not in the asymptomatic (ρ=−0.04, P=ns) MCA territory. Equations relating absolute mean flow velocity to absolute transit time were derived. Conclusion. The findings suggest that in the normal hemisphere (with intact autoregulation on the horizontal portion of the autoregulation curve), flow velocity and transit time are not closely related to each other, but in the symptomatic hemisphere (on the downward slope of the autoregulation curve), flow velocity is directly proportional to the transit time and, therefore, to its inverse, perfusion reserve. The use of absolute mean flow velocity values on TCD should be further explored as a simple way of assessing “perfusion” in acute ischemic stroke.