bluuebunny/crossref_metadata_2025 huggingface dataset:
Knowledge networks of ‘buzz’ in London's advertising industry: a social network analysis approach
Authors: Mould Oli , Joel Sian
Published: November 2009

There has been a plethora of literature in the last few years attempting to conceptualise how the (international) firm operates in the notion of what has been termed ‘buzz’. In this paper, we aim to highlight how the use of social network analysis (SNA) can provide a nuanced view of ‘buzz’, through a focus on London's advertising industry. In this case study, we use the data on interlocking board members of the advertising companies in London, and visualise their network maps through sociograms. This method of analysis, under‐utilised in the economic geography literature, highlights the intensity of connections between companies and particular individuals. It shows the paths of knowledge flow within the industry, and can highlight the key ‘gatekeepers’ within what is already known to be a highly networked and socialised industry. This is a specific conceptualisation of interaction and provides a quantitative conception of what has hitherto been largely evaluated through qualitative means.
Evolution of the Irrawaddy delta region since 1850
Authors: HEDLEY PETER J , BIRD MICHAEL I , ROBINSON RUTH A J
Published: November 2009

We present a time series of coastline change for the Irrawaddy delta region of Myanmar using the earliest available navigation chart from 1850, and a set of topographic maps and satellite imagery dating from 1913 to 2006. Despite the large sediment load delivered annually to the gulf by the Irrawaddy and Salween Rivers, the coastline has been largely stable for 156 years, advancing at an average rate of no more than 0.34 km per century since 1925. The long‐term average rate of increase in land area across the study area between 1925 and 2006 is 4.2 km2/year, but this masks a period of more rapid accumulation between 1925 and 1989 (8.7 km2/year), followed by a period of net erosion at a rate of 13 km2/year until 2006. Less than 9% of the sediment load delivered to the study region by the Irrawaddy, Salween and Sittoung Rivers has contributed to the observed progradation, with the remainder being exported into the Gulf of Martaban to depths below low tide level, or filling any accommodation space created due to subsidence or sea level rise. In contrast to many deltas worldwide, we suggest that the coastline encompassing the Irrawaddy delta and the Salween River is more or less in equilibrium, and that sediment deposition currently balances subsidence and sea level rise. Myanmar has fewer large dams relative to its Asian neighbours, and the Salween is currently undammed. This is forecast to change in the next 5–10 years with extensive damming projects on the mainstem of the Salween under consideration or construction, and the sediment retention will cause losses in sediment supply to the Gulf of Martaban, and retreat of the delta. This could impact the densely populated delta region and Yangon, and further exacerbate the impacts of extreme events such as Cyclone Nargis in 2008.
Electronic Prescribing at the Point of Care: A Time–Motion Study in the Primary Care Setting
Authors: Devine Emily Beth , Hollingworth William , Hansen Ryan N. , Lawless Nathan M. , Wilson‐Norton Jennifer L. , Martin Diane P. , Blough David K. , Sullivan Sean D.
Published: November 2009

Objective. To evaluate the impact of an ambulatory computerized provider order entry (CPOE ) system on the time efficiency of prescribers. Two primary aims were to compare prescribing time between (1) handwritten and electronic (e‐) prescriptions and (2) e‐prescriptions using differing hardware configurations.

Data Sources/Study Setting. Primary data on prescribers/staff were collected (2005–2007) at three primary care clinics in a community based, multispecialty health system.

Study Design. This was a quasi‐experimental, direct observation, time–motion study conducted in two phases. In phase 1 (n=69 subjects), each site used a unique combination of CPOE software/hardware (paper‐based, desktops in prescriber offices or hallway workstations, or laptops). In phase 2 (n=77), all sites used CPOE software on desktops in examination rooms (at point of care).

Data Collection Methods. Data were collected using TimerPro software on a Palm device.

Principal Findings. Average time to e‐prescribe using CPOE in the examination room was 69 seconds/prescription‐event (new/renewed combined)—25 seconds longer than to handwrite (99.5 percent confidence interval [CI] 12.38), and 24 seconds longer than to e‐prescribe at offices/workstations (99.5 percent CI 8.39). Each calculates to 20 seconds longer per patient.

Conclusions. E‐prescribing takes longer than handwriting. E‐prescribing at the point of care takes longer than e‐prescribing in offices/workstations. Improvements in safety and quality may be worth the investment of time.
The pattern of Neoglacial glacier variations in the Okstindan region of northern Norway during the last three millennia
Authors: GRIFFEY NIGEL J. , WORSLEY PETER
Published: November 2009

BOREAS Griffey, N. J. & Worsley, P. 1978 03 01: The pattern of Neoglacial glacier variations in the Okstindan region of northern Norway during the last three millennia (Okstindan Research Project Report 26). Boreas, Vol. 7, pp. 1–17. Oslo. ISSN 0300–9483.

Historical, lichenometrical and stratigraphical evidence is combined to establish a provisional history of Neoglacial glacier variation in a mountainous environment approx. 66oN. Attention is focussed on end moraine chronology. At five sites, derived organic materials have been located within end moraines and at two others in situ palaeosols occur buried beneath distal slopes. Organic rich samples from all the sites have been radiocarbon dated and the results permit the recognition of three major glacier expansion episodes, each of which contributes to the diachronous nature of the Okstindan outer Neoglacial limit. A widespread ‘Little Ice Age’ event with a maximum extent of probable eighteenth century age is confirmed. Limited areas of older moraine ridges peripheral to the ‘Little Ice Age’ maximal limit appear to date from about 3000‐2500 14C years B.P. and a younger period tentatively dated as about 1250‐1000 14C years B. P. which agrees with recent data from Engabreen in northwest Svartisen. No evidence for any extensive glacial activity after the inlandice wastage approx. 9000 14C years B. P. and prior to 3000 14C years B.P. was forthcoming.
Planktonic foraminiferal and oxygen isotopic stratigraphy and paleoclimatology of Norwegian Sea deep‐sea cores
Authors: KELLOGG THOMAS B. , DUPLESSY JEAN CLAUDE , SHACKLETON NICHOLAS J.
Published: November 2009

BOREAS Kellogg, T. B., Duplessy, J. C. & Shackleton, N. J. 1978 03 01: Planktonic foraminiferal and oxygen isotopic stratigraphy and paleoclimatology of Norwegian Sea deep‐sea cores. Boreas. Vol. 7, pp. 61–73. Oslo. ISSN 0300–9483.

Three Norwegian Sea deep‐sea cores, which penetrate to sediments at least 200,000 years old, were analyzed for oxygen isotope content, total calcium carbonate, and planktonic foraminifera. The oxygen isotopic stratigraphy was used to refine the time control for paleoclimatic and paleo‐oceanographic events previously described for the region. Two pulses of relatively warm subpolar water entered the region between 124,000 B.P. and 115,000 B.P. (the last interglacial), and since about 13,000 B.P. The remaining portion of the last 150,000 years was characterized by extensive ice cover. The magnitude of the change in isotopic composition between peak glacial and peak interglacial conditions is larger than can be explained by the changing isotopic content of the oceans alone suggesting that large temperature and salinity effects are recorded in isotope curves from Norwegian Sea isotope curves. The magnitude of the isotopic change from substage 5e to 5d (greater than 1%) is attributed to a combination of changing oceanic isotopic composition combined with a large temperature effect due to a sudden sea‐surface temperature decrease of about 6oC. The persistence of heavy isotope values throughout substages 5d through 5a may be related to the sea‐ice cover which prevented dilution of the isotopically heavy waters by isotopically light run‐off. Sedimentation rates calculated for each of the isotope stages show large changes from one stage to another with some tendency for odd numbered stages to have higher rates.
Palynology and sediment slumping in a high arctic Greenland lake
Authors: FREDSKILD BENT
Published: November 2009

A 103‐cm core from a high arctic lake (80°49′N, 15°00′W) on Amdrup Land, NE Greenland has been analysed for pollen and other microfossils, as well as bulk samples from 10 cores for macrofossils. AMS14C‐dating of aquatic mosses (Drepanocladus exannulatusandScorpidiurn scorpioides) revealed that the lowermost 90 cm of the core was deposited during a 1.5‐2 ka interval in the early Holocene, before the appearance ofSalix arcticawhich immigrated to N Greenlandc. 7 ka BP.Armeria scabra, now extinct in the area, larval cases and apotomes ofApatcmiu zonella, today not known north of c. 77°N, and other indices point to a climate warmer than that of today. A thin, sandy layer 13 cm below the lake bottom, accompanied by marked changes in the content of pollen and macrofossils, such as the sudden occurrence of large amounts ofSalixpollen and leaves, indicates a large hiatus. This is confirmed by the dating toc. 7 ka BP of mosses just below the sand, and ofSalixleaves just above it toc. 1 ka BP. The hiatus must be caused by sediment slumping which transported all the sediment from the intervening period to the deeper part of the lake. A similar, sandy layer in the uppermost 2–6 cm may be caused by younger, (sub‐)recent slumping, or both may be the result of the same disturbance. The possibility of a reservoir effect causing too old14C‐ages for the moss is discussed.
Palaeoecology of a Late Weichselian vertebrate fauna from Nmre Lyngby, Denmark
Authors: AARIS‐SBRENSEN KIM
Published: November 2009

Investigations at a Late Weichselian freshwater basin in northwestern Jutland, Denmark, yielded a fairly rich assemblage of vertebrate remains, mostly bones and teeth of small mammals. The remains are primarily allochthonous and the bones have been subjected to different taphonomic pathways and agents. AMS 14C‐dates on terrestrial organic remains provided ages of Middle to Late Allerød time. Identifications revealed the first fossil record in Scandinavia of Rana arvalis, Sorex minutus, Ochotona cf. pusilla, Microtus gregalis, Microtus oeconomus, and Sicista cf. betulinu. Spermophilus cf. major and Desmana moschata, previously found only once and twice respectively, were retrieved, and Sorex araneus and Arvicola terrestris were recovered for the first time beyond the Atlantic chronozone. Ecologically, the Nørre Lyngby small mammal fauna can be characterized by its very high and almost equal proportions of boreal forest and steppe elements followed by a relatively high proportion of tundra elements. The fossil species share a modern area of sympatry north of the Caspian Sea from the river Volga in the west to the southern and western slopes of the Urals. If, however, the large Allerød mammals are added, the fauna is without modern analogues. The Nørre Lyngby fauna can be seen as a last expansion of the North European glacial fauna. Provided that an absolute chronology and a differentiated sea‐level curve for the area can be established, the Nsrre Lyngby fauna could become important for studies in mammalian dispersal and migration rates.
The Role of Task Values in Adolescents' Educational Tracks: A Person‐Oriented Approach
Authors: Viljaranta Jaana , Nurmi Jari‐Erik , Aunola Kaisa , Salmela‐Aro Katariina
Published: November 2009

The present study examined what kinds of patterns of task‐values adolescents show, and whether these patterns predict their educational and occupational expectations and school track. Six hundred and fourteen adolescents were examined twice before their transition to secondary education and once thereafter. The clustering‐by‐cases analyses identified 6 groups: (1) those who placed a high value on all school subjects, (2) those who did not value any of the subjects, (3) those who valued Finnish and social sciences, (4) those who valued in particular practical and art subjects, (5) those who valued only practical and art subjects, and (6) those who especially valued mathematics and science. The patterns of task‐values also predicted adolescents' occupational and educational expectations.
REVIEWS: A review of methods used in comprehensive, descriptive studies that relate red blood cell transfusion to clinical data
Authors: Biggin Katherine , Warner Pamela , Prescott Robin , McClelland Brian
Published: November 2009

BACKGROUND: Red blood cell (RBC) use varies greatly between countries but the underlying reasons are not well understood. Some insight might be gained from blood utilization studies that provide a complete view of the clinical conditions that place individuals at risk of transfusion. This review considers the methodology of published studies that might provide such information and proposes requirements for future studies.

STUDY DESIGN AND METHODS: A literature search was performed to identify quantitative studies of RBC use related to clinical data, for which the findings are representative of well‐defined populations. Extraction and analysis of methodologic information and epidemiologic data were performed.

RESULTS: The 13 studies identified for inclusion varied in their approach to defining the population from which the study sample was selected, classification of clinical data, and method of attributing transfusion events to clinical case groups, including the observational time frame.

CONCLUSION: Variability in methods prevents useful interpretation or comparison of the findings. Standardization and transparency of methodology and definitions are essential if future studies are to enable comparison of the factors associated with RBC transfusion in different populations and to improve understanding of the wide variations in RBC use.
BLOOD COMPONENTS: Screening of single‐donor apheresis platelets for bacterial contamination: the PASSPORT study results
Authors: Dumont Larry J. , Kleinman Steven , Murphy James R. , Lippincott Rebecca , Schuyler Robert , Houghton Jaime , Metzel Peyton
Published: November 2009

BACKGROUND: The PASSPORT study was an FDA‐mandated surveillance of outdated 7‐day apheresis platelets (APs) to assess the bacterial culture release test (RT) performance and the chance of transfusing APs containing viable bacteria compared to untested 5‐day APs.

STUDY DESIGN AND METHODS: Aerobic and anaerobic culture bottles were inoculated with 4 to 5 mL from APs 24 to 36 hours postcollection. APs were released after 24 hours if no growth was observed. Released APs were recalled for RT positives, and clinical services were notified. Day 8 APs were recultured (surveillance test [ST]). Initially positive RTs and STs were confirmed by AP reculture.

RESULTS: A total of 388,903 RTs were accrued September 2005 through January 2008 from 52 regional blood centers: RT‐positive APs interdicted before transfusion, 76 true positive (TP; 195/million; 95% confidence interval [CI], 154‐244/million) and 57 indeterminate (IN); and RT‐positive APs transfused, 14 TP and 242 IN. There were 14 reported septic transfusion reactions (STRs) from 13 AP collections (23 units) transfused on Days 3 through 7; three STRs were from Day 6 or 7 APs. There were two false‐negative RTs causing STRs in three patients. No deaths were reported. STs had four TPs of 6039 tested (662/million; 95% CI, 180‐1695/million).

CONCLUSIONS: RT culturing prevents issuance of some bacterially contaminated APs. ST culture data and clinical reports suggest that this screening fails to detect all contaminated units. No fatalities were reported related to AP transfusion. Additional actions or testing may be required to further reduce the residual STR risk of RT APs, even with a 5‐day storage limitation.
TRANSPLANTATION AND CELLULAR ENGINEERING: Prolonged isolated red blood cell transfusion requirement after allogeneic blood stem cell transplantation: identification of patients at risk
Authors: Dahl Daphne , Hahn Andreas , Koenecke Christian , Heuft Hans‐Gert , Dammann Elke , Stadler Michael , Buchholz Stefanie , Krauter Jürgen , Eder Matthias , Sykora Karl‐Walter , Klein Christoph , Ganser Arnold , Sauer Martin
Published: November 2009

BACKGROUND: Delayed donor red blood cell chimerism (DRCC), pure red blood cell aplasia (PRCA), and autoimmune hemolytic anemia (AIHA) are poorly documented complications after hematopoietic cell transplantation (HCT). The clinical variable “prolonged isolated red blood cell transfusion requirement” (PRTR) was evaluated as a trigger for an extended diagnostic workup.

STUDY DESIGN AND METHODS: PRTR was defined as the need for red blood cell (RBC) transfusions beyond Day 60 after HCT. We analyzed 487 patients transplanted between 2000 and 2006. Median age was 37 years (range, 0‐70 years). Peripheral blood stem cells (n = 344), marrow (n = 138), and cord blood (n = 5) from 278 unrelated and 209 family donors were used.

RESULTS: Univariate analysis identified age (incidence of 18.3% among elderly patients, 10.5% in adults, and 2.0% among children [p = 0.002]), ABO incompatibility (16.4% after major incompatible, 2.9% after minor incompatible, and 9.4% after ABO‐compatible transplantations [p = 0.003]), conditioning (15.2% after reduced‐intensity regimens vs. 7.3% after myeloablative conditioning; p = 0.006), donor type (13.2% after HLA‐matched unrelated, 13.6% after mismatched unrelated, 5.7% after matched related, and 0.0% after mismatched related grafts; p = 0.026), and acute graft‐versus‐host disease (aGVHD; 7.1% with aGVHD vs. 12.5% without aGVHD; p = 0.046) as predisposing factors. In multivariate analysis minor ABO incompatibility (odds ratio [OR] = 0.2, p = 0.01), younger age (OR = 0.1, p = 0.02), and matched related HCT (OR = 0.4, p = 0.02) remained independent protective factors.

CONCLUSIONS: PRTR could serve as a trigger for a standardized screening for DRCC, PRCA, and AIHA after HCT.
Violence Toward Nurses, the Work Environment, and Patient Outcomes
Authors: Roche Michael , Diers Donna , Duffield Christine , Catling‐Paull Christine
Published: November 2009

Purpose: To relate nurses’ self‐rated perceptions of violence (emotional abuse, threat, or actual violence) on medical‐surgical units to the nursing working environment and to patient outcomes.

Design: Cross‐sectional collection of data by surveys and primary data collection for 1‐week periods on 94 nursing wards in 21 hospitals in two states of Australia.

Methods: Nursing Work Index‐Revised (NWI‐R); Environmental Complexity Scale (ECS) PRN‐80 (a measure of patient acuity); and a nursing survey with three questions on workplace violence; combined with primary data collection for staffing, skill mix, and patient outcomes (falls, medication errors).

Findings: About one third of nurses participating (N=2,487, 80.3% response rate) perceived emotional abuse during the last five shifts worked. Reports of threats (14%) or actual violence (20%) were lower, but there was great variation among nursing units with some unit rates as high as 65%. Reported violence was associated with increased ward instability (lack of leadership; difficult MD and RN relationships). Violence was associated with unit operations: unanticipated changes in patient mix; proportion of patients awaiting placement; the discrepancy between nursing resources required from acuity measurement and those supplied; more tasks delayed; and increases in medication errors. Higher skill mix (percentage of registered nurses) and percentage of nurses with a bachelor of science in nursing degrees were associated with fewer reported perceptions of violence at the ward level. Intent to leave the present position was associated with perceptions of emotional violence but not with threat or actual assault.

Conclusions: Violence is a fact of working life for nurses. Perceptions of violence were related to adverse patient outcomes through unstable or negative qualities of the working environment. Perceptions of violence affect job satisfaction.

Clinical Relevance: In order to manage effectively the delivery of nursing care in hospitals, it is essential to understand the complexity of the nursing work environment, including the relationship of violence to patient outcomes.
Baseline Computed Tomography Changes and Clinical Outcome After Thrombolysis With Recombinant Tissue Plasminogen Activator in Acute Ischemic Stroke
Authors: Mendizabal Jorge E. , Lurie Douglas N. , Greiner Francis G. , Shah Arvind K. , Zweifler Richard M.
Published: November 2009

Objective. Intravenous recombinant tissue plasminogen activator (rt‐PA) is the only therapy of proven value for patients with acute ischemic stroke (AIS). Controversy exists with regard to the prognostic significance of early computed tomography (CT) changes in patients receiving rt‐PA for AIS. The authors retrospectively reviewed all cases of AIS who received intravenous rt‐PA for AIS in University of South Alabama hospitals between January 1996 and May 1999. A neuroradiologist, blinded to clinical outcomes, reviewed all baseline CT scans for the presence of the following signs: hyperdense middle cerebral artery (HMCA), loss of gray‐white differentiation (LGWD), insular ribbon sign (IRS), parenchymal hypodensity (PH), and sulcal effacement (SE). Modified Rankin Scale (mRS) score was recorded 90 days after thrombolysis, and clinical outcome was dichotomized as favorable (0–1) or unfavorable (2–6). The authors performed both univariate and multivariate analyses to investigate the relationship between early CT signs, baseline clinical variables, and functional outcome as measured by the 90‐day mRS scores. Any one early CT finding was detected in 23 (64%) patients. The frequency of specific findings were as follows: SE in 13 patients (36%), LGWD in 12 patients (33%), PH in 9 patients (25%), HMCA in 4 patients (11%), and IRS in 3 patients (8%) patients. There was no statistically significant association between the occurrence of these imaging findings and subsequent functional outcome after thrombolysis. The data suggest that the presence of subtle acute CT changes in AIS patients is not predictive of clinical outcome following administration of rt‐PA as per National Institute of Neurological Disorders and Stroke protocol.
Who Should Be Screened for Asymptomatic Carotid Artery Stenosis? Experience From the Western New York Stroke Screening Program
Authors: Qureshi Adnan I. , Janardhan Vallabh , Bennett Susan E. , Luft Andreas R. , Hopkins L. Nelson , Guterman Lee R.
Published: November 2009

Objective. Identification of significant asymptomatic carotid artery stenosis (ACAS) is important because of the stroke‐risk reduction observed with carotid endarterectomy. The authors developed and validated a simple scoring system based on routinely available information to identify persons at high risk for ACAS using data collected during a community health screening program at various sites in western New York. A total of 1331 unselected volunteers without previous stroke, transient ischemic attack, or carotid artery surgery were evaluated by personal interview and duplex ultrasound. The main outcome measure was carotid artery stenosis >60% by duplex ultrasound. In the derivation set (n= 887), 4 variables were significantly associated with ACAS >60%: age >65 years (odds ratio [OR] = 4.1, 95% confidence interval [CI] = 2.6–6.7), current smoking (OR = 2.0, 95% CI = 1.2–3.5), coronary artery disease (OR = 2.4, 95% CI = 1.5–3.9), and hypercholesterolemia (OR = 1.9, 95% CI = 1.2–2.9). Three risk groups (low, intermediate, and high) were defined on the basis of total risk score assigned on the basis of the strength of association. The scheme effectively stratified the validation set (n= 444); the likelihood ratio and posttest probability for ACAS in the high‐risk group were 3.0 and 35%, respectively, and in the intermediate and low‐risk groups were 1.4 and 20% and 0.4 and 7%, respectively. Routinely available information can be used to identify persons in the community at high risk for ACAS. Doppler ultrasound screening in this subgroup may prove to be cost‐effective and have an effect on stroke‐free survival.
Technetium‐99m ECD Single Photon Emission Computed Tomography in Brain Trauma: Comparison of Early Scintigraphic Findings With Long‐Term Neuropsychological Outcome
Authors: Baulieu Françoise , Fournier Patrice , Baulieu Jean‐Louis , Dalonneau Marinette , Chiaroni Patrick , Eder Véronique , Pottier Jean Marie , Legros Bernard
Published: November 2009

Objective. The aim of this study was to assess the prognostic value of early brain scintigraphy in head injury in relation to long‐term neuropsychological behavior. Twenty‐four patients underwent technetium‐99m (Tc‐99m) ECD single photon emission computed tomography (SPECT) within 1 month of the trauma. Scintigraphic abnormalities were evaluated both visually and semiquantitatively using the brain‐to‐cerebellum ratio method. The clinical neuropsychological investigation was conducted to evaluate abnormalities related to motor deficit, frontal behavior, and memory and language disorders. All patients had abnormalities on SPECT scan. One year after trauma, 14 patients (58%) had neuropsychological sequelae. The brain‐to‐cerebellum ratios in the left basal ganglia and brain stem were significantly decreased in patients with memory disorders (P= .03 and P= .02, respectively). Moreover, SPECT visual analysis indicated that low uptake in the basal ganglia, thalamus, and brain stem was associated with subsequent motor deficit, frontal behavior, and language and memory disorders. The authors conclude that brain SPECT can be valuable in predicting the neuropsychological behavior of survivors of severe head injury.
Comparison Between Magnetic Resonance Phase Contrast Imaging and Transcranial Doppler Ultrasound With Regard to Blood Flow Velocity in Intracranial Arteries: Work in Progress
Authors: Seitz Johannes , Strotzer Michael , Schlaier Jürgen , Nitz Wolfgang R. , Völk Markus , Feuerbach Stefan
Published: November 2009

Objective. The authors evaluate blood flow velocities in the medial cerebral artery (MCA) and the basilar artery using magnetic resonance (MR) phase contrast technique in comparison with transcranial Doppler ultrasound (TCD). Eleven healthy male volunteers were studied. TCD of the MCA (n= 22) and basilar artery (n= 11) was performed. MR phase velocity mapping was done in each vessel at the same location where the TCD signal had been acquired. A 2‐dimensional FLASH sequence with retrospective cardiac gating and an average temporal resolution of 45 ms was used. Resistance indices (RIs) and pulsatility indices (PIs) were calculated for both modalities. The TCD insonation angle was measured retrospectively with MR, and TCD velocities were corrected based on these measurements. The comparison of flow velocities obtained with TCD and MR led to a low correlation coefficient with regard to the basilar artery and the MCA: maximum systolic velocity, r= 0.02 and r= 0.50, respectively; enddiastolic velocity, r= 0.47 and r= 0.65, respectively; mean velocity, r= 0.52 and r= 0.66, respectively. The average PIs in the basilar artery and the MCA were 0.80 and 0.81 with MR and 0.65 and 0.85 with TCD, respectively. The average RIs in the basilar artery and the MCA were 0.52 and 0.54 with MR and 0.52 and 0.55 with TCD, respectively. The TCD insonation angle differed significantly from the ideal value in the basliar artery (mean value = 32.6°) and the MCA (mean value = 26.5°). The authors find a low correlation between velocities measured with MRI and TCD but similar results with regard to the PIs and RIs. Several sources of error, such as a nonideal TCD insonation angle, were identified.
Visualization of the IXth to XIIth Cranial Nerves Using 3‐Dimensional Constructive Interference in Steady State, 3‐Dimensional Magnetization‐Prepared Rapid Gradient Echo and T2‐Weighted 2‐Dimensional Turbo Spin Echo Magnetic Resonance Imaging Sequences
Authors: Seitz Johannes , Held Paul , Fründ Rüdiger , Strotzer Michael , Nitz Wolfgang R. , Völk Markus , Haffke Thomas , Feuerbach Stefan
Published: November 2009

Objective. The purpose of this study was to evaluate the visibility of the IXth to XIIth cranial nerves using different magnetic resonance sequences. Thirty healthy volunteers underwent magnetic resonance imaging at 1.5 T using 3‐dimensional constructive interference in steady state (CISS) sequence (TR = 17 ms, TE = 8.08 ms, α= 70°), 3‐dimensional magnetization‐prepared rapid gradient echo (MP‐RAGE) sequence (TR = 11.08 ms, TE = 4.3 ms, α= 15°), and T2‐weighted (w) 2‐dimensional turbo spin echo (TSE) sequence (TR = 4000 ms, TE = 102 ms, α= 180°, slice thickness = 2 mm). Visibility of the IXth to XIIth cranial nerves in each sequence was evaluated by consensus of 2 radiologists using an evaluation scale from 1 (excellently visible) to 5 (not visible). A correlation with anatomic specimens was made. The 3‐dimensional CISS sequence provides best resolution of the IXth to XIIth cranial nerves and their relation to surrounding structures. Additional information is given by the 3‐dimensional MP‐RAGE when nerves are surrounded by soft tissues. Using the T2w 2‐dimensional TSE sequence, even whole nerves cannot be visualized due to intersection gap and partial volume effects. However, even in 3‐dimensional high‐resolution sequences, segments of nerves are not always visualized. A combination of 3‐dimensional CISS and 3‐dimensional MP‐RAGE proved to be useful to visualize the IXth to XIIth cranial nerves, whereas the 2‐dimensional technique failed. Further investigations using 3‐dimensional MP‐RAGE with contrast medium should be performed in the case of abnormality.
Differences in Functional Magnetic Resonance Imaging Activation by Category in a Visual Confrontation Naming Task
Authors: Smith C. D. , Andersen A. H. , Kryscio R. J. , Schmitt F. A. , Kindy M. S. , Blonder L. X. , Avison M. J.
Published: November 2009

Objective. Cortical processing involved in seemingly similar tasks may differ in important ways. The authors mapped cortical regions engaged in a commonly performed picture naming task, seeking differences by semantic category. Functional magnetic resonance imaging was used during presentation of standardized line drawings in 18 healthy right‐handed female participants, comparing living versus nonliving entities. During visual naming, across categories there was strong activation of left frontal (BA45/47), bilateral temporo‐occipital junction (BA19), and inferior temporal regions (BA36/37). Activation of right inferior temporal cortex (BA19 & 37) was greater during naming of living versus nonliving category items. No category differences in activation strength in the left temporal lobe were observed. The authors conclude that visual semantic operations may involve visual association cortex in the right temporal lobe in women.
Cerebral Hemodynamics Changes During Retrograde Brain Perfusion in Dogs
Authors: Razumovsky Alexander Y. , Tseng Elaine E. , Hanley Daniel F. , Baumgartner William A.
Published: November 2009

The objective of this study was to examine cerebral hemodynamics changes during hypothermic circulatory arrest (HCA) with and without retrograde cerebral perfusion (RCP). Thirteen colony‐bred hound dogs were placed on cardiopulmonary bypass (CPB) and cooled to 18°C. Five dogs underwent 2 hours of HCA without RCP and 8 with RCP. The animals were then rewarmed on CPB until normothermic and weaned. Cerebral blood flow velocity (CBFV) and Gosling Pulsatility Index (PI) in the middle cerebral artery (MCA) were studied using transcranial Doppler (TCD) ultrasound. At baseline and during pre‐ and postarrest CPB, there was anterograde direction of blood flow in the MCA. During HCA with RCP, there was retrograde direction of blood flow in the MCA. There was no difference in CBFV between pre‐, during, and postarrest CPB in the group with RCP; however, there was significantly increased CBFV during postarrest CPB in the group without RCP compared to the dogs with RCP. Later, at 3 hours after postarrest CPB, there was decreased CBFV in all animals accompanied by increased PI (2.4 ± 0.4 and 2.2 ± 0.6 for animals with RCP and without RCP, respectively) and abnormal TCD waveform changes including decreased diastolic compartment and sharp systolic peak. During hypothermic circulatory arrest, RCP provides CBFV in the MCA comparable to MCA CBFV during CPB. HCA dogs without RCP showed immediate hyperemia on reperfusion. The decreased CBFV and increased PI at 1 hour after postarrest CPB could be an indicator of progressive ischemic injury due to the increased intracranial pressure despite the implementation of RCP.
Effect of Hyperventilation on Cerebral Blood Flow Velocity in Preeclamptic Pregnancies: Is There Evidence for an Altered Cerebral Vasoreactivity?
Authors: Zatik J. , Aranyosi J. , Molnár C. , Páll D. , Borsos A. , Fülesdi B.
Published: November 2009

The purpose of this study was to investigate cerebral arteriolar vasoreactivity function in preeclampsia. Preeclamptic (n= 26) and healthy pregnant (n= 22) women underwent transcranial Doppler sonography of the middle cerebral artery at rest and after 60 seconds of hyperventilation (HV). Systolic, diastolic, and mean blood flow velocities were recorded. The percentage change of the blood flow velocities after HV was calculated. Mean blood flow velocity of the middle cerebral artery was higher in preeclamptic women as compared with healthy pregnant women. No difference could be detected in percentage change of middle cerebral artery blood flow velocities after HV between the two groups. There is no evidence of a small‐vessel vasoconstriction among preeclamptic patients. The role of vasoconstriction of the large cerebral arteries and vasodilation of the resistance arterioles, as well as a combination of these 2 pathomechanisms, in determining cerebral blood flow in preeclampsia and eclampsia should be investigated in further studies.
Isolated Petrous Carotid Stenosis and Transient Ischemic Attack
Authors: Levine Ross L. , Hafeez Faizan , Khasru Muhammed A. , Dulli Douglas A.
Published: November 2009

Although anterior circulation transient ischemic attacks (TIAs) tend to be more common in patients with extracranial carotid arterial disease than in those with intracranial carotid or middle cerebral arterial disease, the authors recently encountered 4 patients with both recurrent, stereotypical TIAs as well as isolated stenosis of their petrous internal carotid artery (ICA). While the gold standard for establishing the diagnosis of intracranial large‐artery disease has always been conventional angiography, magnetic resonance angiography changes, confirmed with intra‐arterial digital subtraction angiography in 2 of these patients, were quite sufficient to define the occlusive disease in each of the cases. Petrous ICA stenosis is not uncommon, but it has often been overshadowed by the search for extracranial ICA disease that might be amenable to surgical reconstruction.
Transcranial Color‐Coded Sonography of a Vein of Galen Arteriovenous Malformation in an Adult
Authors: Strowitzki Martin , Fox Thomas , Hamann Gerhard
Published: November 2009

The case of an adult harboring a vein of Galen arteriovenous malformation (VGAM) is reported. Diagnosis was established by computed tomography (CT) and digital subtraction angiography and confirmed afterwards by transcranial color‐coded sonography (TCCS). The patient's course after endovascular treatment was then consecutively monitored by TCCS until complete occlusion was achieved. The results of TCCS were validated by angiography, with which they showed good correlation. Thus, it can be concluded that TCCS may be a useful adjunct to CT and angiography to noninvasively monitor adults with VGAM.
HIV‐2 Infection With Cerebral Toxoplasmosis and Lymphomatoid Granulomatosis
Authors: Issakhanian M. , Chang L. , Cornford M. , Witt M. , Speck O. , Goldberg M. , Ernst T.
Published: November 2009

A Nigerian man had acute onset of headache and vertigo due to a cerebellar mass. A brain biopsy of the mass revealed toxoplasmosis despite repeated negative HIV‐1 serology. The presence of an opportunistic infection and his country of origin raised the suspicion for HIV‐2; this was confirmed by positive HIV‐2 serology. Despite his preliminary pathological diagnosis, results of physiological magnetic resonance imaging (MRI) (perfusion MRI and proton magnetic resonance spectroscopy) were not typical for toxoplasmosis. The lesion showed a biochemical and perfusion pattern that was intermediate for infectious and neoplastic processes. Further neuropathology confirmed a secondary diagnosis of lymphomatoid granulomatosis.
Transcranial Doppler Pulsatility Indices as a Measure of Diffuse Small‐Vessel Disease
Authors: Kidwell Chelsea S. , El‐Saden Suzie , Livshits Zhanna , Martin Neil A. , Glenn Thomas C. , Saver Jeffrey L.
Published: November 2009

Background and Purpose. Elevation in pulsatility indices (PIs) as measured by transcranial Doppler (TCD) have been postulated to reflect downstream increased vascular resistance caused by small‐vessel ischemic disease. Methods. The authors retrospectively compared TCD PIs and magnetic resonance imaging (MRI) manifestations of small‐vessel disease in 55 consecutive patients who underwent TCD studies and brain MRI within 6 months of each other during a 2‐year period. Results. Correlations between TCD middle cerebral artery PIs and MRI measures were as follows: periventricular hyperintensity (PVH) = 0.52 (P < .0001), deep white matter hyperintensity (DWMH) = 0.54 (P < .0001), lacunar disease = 0.31 (P= .02), and combined PVH/DWMH/lacunes = 0.54 (P < .0001). Correlation between pontine ischemia and vertebrobasilar PIs was 0.46 (P= .0004). Univariate analysis showed that age, elevated PI, and hypertension strongly correlated with white matter disease measures. After adjusting for these factors in a multivariate Poisson regression analysis, PI remained an independent predictor of white matter disease. Receiver operator curve analyses identified PI cut points that allowed discrimination of PVH with 89% sensitivity and 86% specificity and discrimination of DWMH with 70% sensitivity and 73% specificity. Conclusions. Elevation in PIs as measured by TCD shows strong correlation with MRI evidence of small‐vessel disease. TCD may be a useful physiologic index of the presence and severity of diffuse small‐vessel disease.
Single Photon Emission Computed Tomography, Magnetic Resonance Imaging Hyperintensity, and Cognitive Impairments in Patients With Vascular Dementia
Authors: Cohen Ronald A. , Paul Robert H. , Zawacki Tricia M. , Sethi Manish , Ott Brian R. , Moser David J. , Stone William , Noto Richard , Gordon Norman
Published: November 2009

Background. The relationship between subcortical hyperintensity (SH) on magnetic resonance imaging (MRI), cortical perfusion on single photon emission computed tomography (SPECT), and cognitive function is not well understood. The authors examined these relationships in individuals with vascular dementia (VaD), paying particular attention to frontal lobe function to determine whether the presence of SH on MRI was associated with frontal hypoperfusion on SPECT, which in turn would be associated with impairments of executive‐attention function. Methods. Patients with vascular dementia (n= 26) were assessed on neurocognitive tests and brain MRI and SPECT. SH volume was quantified from the axial T2‐weighted fluid attenuated inversion recovery MRI. Total counts of activation across voxels for 12 cortical regions of interest were determined from SPECT. Perfusion ratios of both total cortical and frontal activation relative to cerebellum activation were derived, and regression analyses were performed to determine the relationships between cognitive, MRI, and SPECT indices. Results. SH volume on MRI was significantly associated with frontal lobe perfusion, but not with global cortical perfusion as measured by SPECT. Frontal lobe perfusion did not consistently correlate with performance on measures of executive function, although both total and frontal perfusion ratios were significantly associated with other cognitive functions. Conclusions. These results suggest that a functional “disconnection” between the frontal lobes and subcortical structures does not fully account for the magnitude of global cognitive impairment in VaD. Cortical perfusion as measured by SPECT appears to be associated with cognitive performance, but not specifically executive‐attention dysfunction. Additional studies are needed to further examine the relationship between subcortical and cortical function in VaD.
A Computed Tomography Score for Assessment of Mass Effect in Space‐Occupying Cerebellar Infarction
Authors: Jauss M. , Müffelmann B. , Krieger D. , Zeumer H. , Busse O.
Published: November 2009

Background and Purpose. Patients with cerebellar infarction are threatened by infratentorial herniation and impaired circulation of cerebrospinal fluid if mass effect in posterior fossa develops. Clinical assessment is often impaired in patients with disturbances of consciousness. Therefore, computed tomography (CT) examination is essential in the diagnosis of complication and decision for operative treatment. Methods. Mass effect of cerebellar infarction was quantitatively assessed using a three‐item CT score: width of fourth ventricle, compression of quadrigeminal cistern, and width of lateral ventricle. Retest and interrater reliability was determined. Validity of assessment of mass effect was examined using 185 CT scans from a cerebellar infarction study, and the effect of operative treatment on CT score was determined. Results. The correlation coefficients for retest and interrater reliability were .94 and .75, respectively. The authors found a significant difference for the CT sum score and all CT items except “compression of the fourth ventricle” between patients with different levels of consciousness. Effect of operative treatment was documented by improvement of CT score. Conclusions. The proposed CT score is of high interrater and retest reliability, supplements the clinical assessment of the patient, and is able to monitor the efficacy of decompressive treatment.
1H Spectroscopy in Patients With Amyotrophic Lateral Sclerosis
Authors: Kenn Werner , Ochs Guenther , Pabst Thomas Alois , Hahn Dietbert
Published: November 2009

Background and Purpose. The authors investigate changes in brain metabolites among patients with amyotrophic lateral sclerosis (ALS). Twelve patients diagnosed with definite ALS (and 2 subgroups with either pronounced upper motoneuron signs or less obvious, probable upper motoneuron involvement) and 10 controls were examined.1H studies were performed on a 1.5‐T Siemens Magnetom Vision with single voxel (SV). A voxel (TR = 1500 ms, TE = 270 ms, 512 acquisitions, VOI = 8 cm3) was placed bilaterally in the precentral gyrus. In addition, chemical shift imaging (CSI) (VOI = 1 × 1 × 1.5 cm, TR = 1500 ms, TE = 135 ms) was performed. Ratios of peak integrals (N‐acetyl‐aspartate/choline, N‐acetyl‐aspartate/creatine, and creatine/choline) were determined. A Mann‐Whitney U Test and a Wilcoxon Matched Pairs Test were applied. Methods. The statistical analysis failed to demonstrate any significant differences between the ALS patients and the controls with respect to ratio measures. Using CSI, it was found that patients with clinically pronounced upper motoneuron signs had significantly lower (P= .037) N‐acetyl‐aspartate/choline ratios in the more affected hemisphere. Conclusions. The authors conclude that CSI is more effective at detecting lower N‐acetyl‐aspartate/choline levels among ALS patients than is SV.
Pharmacokinetics of Echocontrast Agent Infusion in a Dog Model
Authors: Kaps M. , Seidel G. , Algermissen C. , Gerriets T. , Broillet A.
Published: November 2009

Ultrasound contrast agents (UCAs) have a distinct diagnostic impact on transcranial Doppler (TCD) and duplex sonography. In addition to the properties of the UCA and ultrasound imaging modes, the duration of contrast enhancement depends on the administration mode. Infusion of UCAs may be appropriate for prolonging the diagnostically useful time of elevated Doppler intensity. Five sedated dogs were investigated by TCD during infusion with SonoVue™, a new UCA consisting of sulfur hexafluoride microbubbles. The infusion rate was varied, and the time‐intensity curves were analyzed. Infusion rate of 70 ml/h provided a stable mean level of increased Doppler intensity up to 24 to 26 dB over baseline, whereas a rate of 35 ml/h did not result in a stable plateau (range 8–19 dB over baseline [5 minutes after starting time]). The maximum increases in Doppler mean intensity (18.2 dB [35 ml/h] and 25.6 dB [70 ml/h]) were significantly different (P= .025). Pharmacokinetic analysis of SonoVue™ during inflow (by exponential functional fitting of the time‐mean intensity curves) and elimination (by linear regression analysis) revealed no dose‐related differences. This study demonstrated a dose‐dependent level of increased Doppler mean intensity within the brain circulation during infusion of SonoVue™. Unlike the bell‐shaped course of Doppler signal enhancement seen after bolus injection, infusion generates a stable plateau, which is an important prerequisite for more advanced contrast applications.
Selective Arterial Distribution of Cerebral Hyperperfusion in Fabry Disease
Authors: Moore David F. , Herscovitch Peter , Schiffmann Raphael
Published: November 2009

Fabry disease is an X‐linked recessive deficiency of lysosomal α‐galactosidase A associated with an increased risk of early onset cerebrovascular disease. The disorder is reported to affect the posterior circulation predominantly. This hypothesis was investigated directly by the measurement of regional cerebral blood flow with positron emission tomography (PET). Resting regional cerebral blood flow (rCBF) in 26 hemizygous patients with Fabry disease and 10 control participants was examined using H215O and PET. Statistical parametric mapping (SPM{t}, SPM99) and PET images of patients and controls were produced. Significantly increased SPM{t} clusters were then color coded and blended with a coregistered T1 magnetic resonance imaging (MRI) template. Cerebral arterial territory maps were digitized and rescaled. Custom OpenGL and ImageVision Library C++ code was written to allow a first‐order affine transformation of the blended SPM{t} and MRI template onto the arterial territory map. The affine transformation was constrained by choosing corresponding cerebral landmark “tie points” between the SPM{t}∪ MRI template images and the cerebral arterial territory maps. The data demonstrated that the posterior circulation is the predominant arterial territory with a significantly increased rCBF in Fabry disease. No arterial distribution had a decreased rCBF.