bluuebunny/crossref_metadata_2025 huggingface dataset:
Study of AlN dielectric film on graphene by Raman microscopy
Authors: Jin Zhi , Su Yongbo , Chen Jianwu , Liu Xinyu , Wu Dexin
Published: December 2009

Dielectric film on graphene severely affects the performance of graphene field-effect transistors (GFETs). The authors investigated AlN dielectric film on graphene by Raman microscopy. AlN deposition led to the appearance of disorder-related peaks and to a wider Raman-active peak. The intensities of the disorder-related modes decreased exponentially with an increase in the layer number of graphene, indicating that AlN dielectric film mainly affected the surface of graphene. According to the experimental results, the authors suggested that few-layer graphene might be a better choice than single-layer graphene for the application of GFET.
Optical phase recovery in the dispersive Fourier transform
Authors: Solli D. R. , Gupta S. , Jalali B.
Published: December 2009

The dispersive Fourier transform permits real-time acquisition of optical spectra with analog-to-digital converters. The method utilizies the property that a signal’s temporal envelope matches its spectral profile if sufficiently dispersed. Unfortunately, the dispersion demand can be substantial and signal losses in highly dispersive elements represent a significant challenge, especially outside the telecommunications band. We address this problem by experimentally demonstrating that a time-domain equivalent of the Gerchberg–Saxton algorithm removes the fundamental dispersion requirement in the dispersive Fourier transform. The algorithm recovers the phase from time-domain intensity measurements.
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textured (K0.5Na0.5)(Nb0.97Sb0.03)O3 piezoelectric ceramics with high electromechanical coupling over a broad temperature range
Authors: Chang Yunfei , Poterala Stephen F. , Yang Zupei , Trolier-McKinstry Susan , Messing Gary L.
Published: December 2009

⟨ 001 ⟩ -oriented (K0.5Na0.5)(Nb0.97Sb0.03)O3 (KNNS) ceramics with a narrow orientation distribution (full width at half maximum=7.0°) were produced by templated grain growth using NaNbO3 templates. Excellent electromechanical properties were obtained from −70 °C to the polymorphic phase transition (PPT) at 160 °C. Textured KNNS ceramics show very high electromechanical coupling factors kp=0.64 and k31=0.37, high piezoelectric constants d33=208–218 pC/N and d31=−82 pC/N, and modest strain hysteresis (6.3%) at room temperature. These properties are superior to those of randomly oriented KNN-based ceramics with similar PPT temperatures.
Effect of carbon nanotube surface modification on dispersion and structural properties of electrospun fibers
Authors: Sui Xiao-Meng , Giordani Silvia , Prato Maurizio , Wagner H. Daniel
Published: December 2009

Covalent surface modification of multiwall carbon nanotubes leads to enhanced nanotube dispersion in the polymer. Despite this, the mechanical properties of electrospun fibers made of polymethylmethacrylate containing surface modified nanotubes generally fall below those of fibers with pristine nanotubes, sometimes below those of pure polymer fibers. We show that covalent functionalization produces defects in the graphene structure, leading to mechanical weakening of the nanotube and, therefore, of the nanocomposite.
The origin and evolution of V-defects in InxAl1−xN epilayers grown by metalorganic chemical vapor deposition
Authors: Miao Z. L. , Yu T. J. , Xu F. J. , Song J. , Huang C. C. , Wang X. Q. , Yang Z. J. , Zhang G. Y. , Zhang X. P. , Yu D. P. , Shen B.
Published: December 2009

Near-lattice-matched and highly compressive-strained InxAl1−xN epilayers were grown on GaN templates by metalorganic chemical vapor deposition. The V-defects associated with screw-component threading dislocations (TDs) were found in all the InxAl1−xN layers. Their origin and evolution were investigated through near-lattice-matched In0.173Al0.827N layers with different thicknesses. Furthermore, small V-defects not associated with TDs were also found in InxAl1−xN layers with high In composition (x=0.231). Stacking mismatch boundaries induced by lattice relaxation in InxAl1−xN epilayers under large strain is believed to be another mechanism forming V-defects.
Power-scaling performance of a three-dimensional tritium betavoltaic diode
Authors: Liu Baojun , Chen Kevin P. , Kherani Nazir P. , Zukotynski Stefan
Published: December 2009

Three-dimensional diodes fabricated by electrochemical etching are exposed to tritium gas at pressures from 0.05 to 33 atm at room temperature to examine its power scaling performance. It is shown that the three-dimensional microporous structure overcomes the self-absorption limited saturation of beta flux at high tritium pressures. These results are contrasted against the three-dimensional device powered in one instance by tritium absorbed in the near surface region of the three-dimensional microporous network, and in another by a planar scandium tritide foil. These findings suggest that direct tritium occlusion in the near surface of three-dimensional diode can improve the specific power production.
First-principles studies of the effect of oxygen vacancies on the electronic structure and linear optical response of multiferroic BiFeO3
Authors: Ju Sheng , Cai Tian-Yi
Published: December 2009

Oxygen vacancies (OVs) have a significant influence on the carrier mobility and optical conductivity in transition metal oxides. In this letter, using density-functional theory, we investigate the effect of OVs on the optical response in multiferroic BiFeO3. Within the generalized gradient approximation plus the on-site Coulomb repulsion, we show that the absorption edge shifts to lower energy with the increase of OV concentration, while the location of the main absorption peak does not change. The agreement between theoretical calculations and experimental measurements of the dielectric function is greatly improved when OVs are considered.
Excitation wavelength independent sensitized Er3+ concentration in as-deposited and low temperature annealed Si-rich SiO2 films
Authors: Savchyn Oleksandr , Todi Ravi M. , Coffey Kevin R. , Ono Luis K. , Cuenya Beatriz Roldan , Kik Pieter G.
Published: December 2009

Erbium sensitization is observed in as-deposited Er3+ doped Si-rich SiO2, ruling out the involvement of Si nanocrystals in the Er3+ excitation in these samples. The Er3+ excitation cross section in this material is similar within a factor 3 to that of samples annealed at 600 °C under 355 and 532 nm excitation. The density of sensitized Er3+ ions is shown to be excitation wavelength independent, while the shape of the Er3+ excitation spectra is governed by a wavelength dependent Er3+ excitation cross section. These findings enable the use of a broad range of wavelengths for the efficient excitation of this gain medium.
The Influence of Chromophores on the Magnitude of Space-Charge Fields in Photorefractive Polymeric Composites
Authors: Moon In Kyu , Kim Do Young , Kim Nakjoong
Published: December 2009

This paper reports on the characterization of three poly(N-vinylcarbazole) (PVK)-based photorefractive composites with different non-linear optical (NLO) chromophores at an operating wavelength of 632.8 nm. The strength of the photoconductivity and the magnitude of the space-charge field (E
SC) in the photorefractive composites are strongly affected by the chromophore’s highest occupied molecular orbital (HOMO). The magnitude of E
SC increased with the lowering of the HOMO level of the NLO chromophores in the PVK composites.
Microwave-Controlled Preparation of Alkenyl-(1H)-1,2,4-triazoles: First Heck Reaction on a (1H)-1,2,4-Triazole Moiety
Authors: Díaz-Ortiz Ángel , Prieto Pilar , de Cózar Abel , Cebrián Cristina , Moreno Andrés , de la Hoz Antonio
Published: December 2009

A new synthetic approach for the preparation of alkenyl-1,2,4-triazole derivatives based on microwave-induced C–C cross-coupling Heck reactions is described. To the best of our knowledge, this is the first application of the Heck reaction to a dihalogenated 1,2,4-triazole. This approach allows the introduction of a wide range of equivalent or different alkenyl substituents in the 5- and/or 3-positions, thus extending the possibilities for the preparation of these valuable derivatives. A similar microwave-induced synthetic procedure has also been applied to the Heck reaction of 4-vinyl-1,2,3-triazoles.
Synthesis of 1,4-Diazabicyclo[3.3.1]nonan-6-ones
Authors: Kracht Daniel , Saito Susumu , Wünsch Bernhard
Published: December 2009

1,4-Diazabicyclo[3.3.1]nonanes (aza-morphans) represent conformationally constrained piperazine derivatives. Herein, we report a six-step synthesis of the benzyl and allyl substituted bicyclic ketones 3a and 3b, which represent interesting building blocks for the synthesis of conformationally restricted receptor ligands. The key steps of the synthesis are the regioselective addition of ethyl acrylate to the piperazine 8, the sodium hexamethyldisilazide-induced Dieckmann cyclization of the diesters 10, and the decarboxylation of the enol esters 11 with dilute HCl. The complete sequence is only successful when a benzyl (10a) or allyl moiety (10b) is attached to N-1, since the tosyl derivative 10f failed to give a Dieckmann cyclization product, and the decarboxylation failed with the acyl derivatives 11c and 11d.
X-ray Structural Analysis for the Prediction on the Nature of the Retro Diels - Alder Pathway: Concerted or Stepwise. Structural Studies on Nitrosobenzene Cycloadducts
Authors: Roth-Barton Jesse , White Jonathan M.
Published: December 2009

Crystal structures of nitrosobenzene cycloadducts 5–7 reveal structural effects consistent with the early stages of the retro Diels–Alder fragmentation. There is a clear differentiation between the structure parameters of cycloadduct 5, which reacts by a concerted synchronous pathway and that of cycloadduct 6, which must react by a two-step pathway. Based on these data, cycloadduct 7 is predicted to react by a highly asynchronous or two-step pathway.
Modeling and mapping wildfire ignition risk in Portugal
Authors: Catry Filipe X. , Rego Francisco C. , Bação Fernando L. , Moreira Francisco
Published: December 2009

Portugal has the highest density of wildfire ignitions among southern European countries. The ability to predict the spatial patterns of ignitions constitutes an important tool for managers, helping to improve the effectiveness of fire prevention, detection and firefighting resources allocation. In this study, we analyzed 127 490 ignitions that occurred in Portugal during a 5-year period. We used logistic regression models to predict the likelihood of ignition occurrence, using a set of potentially explanatory variables, and produced an ignition risk map for the Portuguese mainland. Results show that population density, human accessibility, land cover and elevation are important determinants of spatial distribution of fire ignitions. In this paper, we demonstrate that it is possible to predict the spatial patterns of ignitions at the national level with good accuracy and using a small number of easily obtainable variables, which can be useful in decision-making for wildfire management.
Assessing the capabilities of geospatial data to map built structures and evaluate their bushfire threat
Authors: Lowell Kim , Shamir Ron , Siqueira Andreia , White John , O'Connor Alice , Butcher Gary , Garvey Mark , Niven Michael
Published: December 2009

Bushfire threat was evaluated for built structures for three areas in Victoria (Australia) that had been impacted by the devastating 16 February 1983 Ash Wednesday fires. Structures were mapped for 1982 and 2006 using human interpretation of high-resolution (0.35-m pixels) digital orthophotographs. Damage to structures from the 1983 Ash Wednesday fires was also evaluated using human interpretation of the digital orthophotographs. Approximately 25% of the structures present were not mapped due to either interpreter error or overhanging vegetation. The majority of unmapped structures were sheds and garages. The error of omission for houses was between 7 and 10% with the error of commission for houses being less than 0.5%. Bushfire threat was modelled using information about topographic slope and aspect, forest vegetation, and prevailing wind direction during days of high fire danger. The method detected a substantial change in bushfire threat from 1982 to 2006 for one of the three study sites whereas no change in overall bushfire threat was observed for the other two. Considering the location of structures built since 1982, these results appeared reasonable. However, the 1982 bushfire threat was not related to actual structure damage sustained during the 1983 Ash Wednesday fires. Estimating bushfire threat using this methodology cost AU$6 per structure or AU$4.60 per property.
Prediction of the probability of large fires in the Sydney region of south-eastern Australia using fire weather
Authors: Bradstock R. A. , Cohn J. S. , Gill A. M. , Bedward M. , Lucas C.
Published: December 2009

The probability of large-fire (≥1000 ha) ignition days, in the Sydney region, was examined using historical records. Relative influences of the ambient and drought components of the Forest Fire Danger Index (FFDI) on large fire ignition probability were explored using Bayesian logistic regression. The preferred models for two areas (Blue Mountains and Central Coast) were composed of the sum of FFDI (Drought Factor, DF = 1) (ambient component) and DF as predictors. Both drought and ambient weather positively affected the chance of large fire ignitions, with large fires more probable on the Central Coast than in the Blue Mountains. The preferred, additive combination of drought and ambient weather had a marked threshold effect on large-fire ignition and total area burned in both localities. This may be due to a landscape-scale increase in the connectivity of available fuel at high values of the index. Higher probability of large fires on the Central Coast may be due to more subdued terrain or higher population density and ignitions. Climate scenarios for 2050 yielded predictions of a 20–84% increase in potential large-fire ignitions days, using the preferred model.
Effect of spinal degenerative changes on volumetric bone mineral density of the central skeleton as measured by quantitative computed tomography
Authors: Guglielmi G. , Floriani I. , Torri V. , Li J. , van Kuijk C. , Genant H. K. , Lang T. F.
Published: December 2009

Purpose: To evaluate the impact of degenerative changes due to osteoarthritis (OA) at the spine on volumetric bone mineral density (BMD) as measured by volumetric quantitative computed tomography (vQCT).

Material and Methods: Eighty‐four elderly women (mean age 73±6 years), comprising 33 with vertebral fractures assessed by radiographs and 51 without vertebral fractures, were studied. Trabecular, cortical, and integral BMD were examined at the spine and hip using a helical CT scanner and were compared to dual X‐ray absorptiometry (DXA) measurements at the same sites. OA changes visible on the radiographs were categorized into two grades according to severity. Differences in BMD measures obtained in the two groups of patients defined by OA grade using the described radiologic methods were compared using analysis of variance. Standardized difference (effect sizes) was also compared between radiologic methods.

Results: Spinal trabecular BMD did not differ significantly between OA grade 0 and OA grade 1. Spinal cortical and integral BMD measures showed statistically significant differences, as did the lumbar spine DXA BMD measurement (13%, P = 0.02). The QCT measurements at the hip were also higher in OA 1 subjects. Femoral trabecular BMD was 13–15% higher in OA grade 1 subjects than in OA grade 0 subjects. The cortical BMD measures in the CT_TOT_FEM and CT_TROCH ROI's were also higher in the OA 1 subjects. The integral QCT BMD measures in the hip showed difference between grades OA 1 and 0. The DXA measurements in the neck and trochanter ROI's showed smaller differences (9 and 11%, respectively). There were no statistically significant differences in bone size.

Conclusion: There is no evidence supporting that trabecular BMD measurements by QCT are influenced by OA. Instead, degenerative changes have an effect on both cortical and integral QCT, and on DXA at the lumbar spine and the hip. For subjects with established OA, assessment of BMD by volumetric QCT may be suggested.
Giant cavernous angioma of the temporal lobe: a case report and review of the literature
Authors: Gelal F. , Feran H. , Rezanko T. , Dİrİm Vİdİnlİ B.
Published: December 2009

Cavernous angiomas of the central nervous system are angiographically occult vascular lesions and are easily diagnosed by magnetic resonance imaging (MRI). Giant cavernous angiomas (GCA) are rare, with only 11 cases reported in the literature. Imaging appearance of GCAs has not been reviewed previously. We report a GCA of the temporal lobe, and discuss its computed tomography and MRI findings in the view of the literature. Imaging appearance of GCAs is variable. Some GCAs have features that are similar to those of typical cavernous angiomas, whereas some lesions may be purely cystic; and some present with significant contrast enhancement and mass effect, mimicking neoplasms. While the presence of hemosiderin, blood degradation products, and calcification may be helpful in the diagnosis of some cases, the correct diagnosis is not apparent until histopathological evaluation of the specimen is made in many instances.
Reappraisal of left‐sided gallbladder and its accompanying anomalies: a report of two cases and literature review
Authors: Wu T. ‐C. , Lee R. ‐C. , Chiang J. ‐H. , Chang C. ‐Y.
Published: December 2009

We report two cases of coexistent left‐sided gallbladder and right‐sided ligamentum teres with portal vein anomalies documented by magnetic resonance imaging (MRI) and three‐dimensional (3D) computed tomography during arterial portography (CTAP). Reformatted 3D MR and CTAP images provide an informative illustration of the accompanying portal vein anomalies. This important anatomical information is useful in preoperative work‐up of hepatobiliary surgery.
Percutaneous radiofrequency ablation of renal cell carcinoma: preliminary results
Authors: Mahnken A. H. , Rohde D. , Brkovic D. , Günther R. W. , Tacke J. A.
Published: December 2009

Purpose: To report early results in percutaneous radiofrequency ablation (RFA) of renal cell carcinoma with an expandable RF probe.

Material and Methods: In 14 patients (9 male, mean age 67.9±9.9 years) CT‐guided percutaneous radiofrequency ablation of 15 renal cell carcinomas was performed using an expandable LeVeen probe (diameter 2–4 cm) and a 200‐watt generator under general anesthesia and CT control. Tumors exceeding a diameter of 3 cm ( n = 6) were embolized within 24 h prior to RFA. Average tumor size was 3.0±1.0 cm.

Results: RFA was technically successful in all patients, resulting in a mean size of necrosis of 3.7±0.7 cm. With the exception of one reno‐cutaneous fistula, which was successfully treated conservatively, no major complications were observed. No local recurrence was observed (follow‐up: 13.9±12.4 months) while extrarenal tumor progression occurred in four patients.

Conclusion: Our preliminary data suggest that nephron sparing percutaneous RFA of renal tumors with an expandable RF probe is safe and effective.
Do dysphagic patients with an absent pharyngeal swallow have a shorter survival than dysphagic patients with pharyngeal swallow? prognostic importance of a therapeutic videoradiographic swallowing study (TVSS)
Authors: Bülow M. , Olsson R. , Ekberg O.
Published: December 2009

Purpose:To study survival in two groups of dysphagic patients – one group unable to elicit the pharyngeal stage of swallow (APS) and another group with pharyngeal swallow (WPS) – and to compare recommendations regarding nutrition and therapeutic strategies based on the therapeutic swallowing study.

Material and Methods: In this retrospective study, the records of dysphagic patients who have undergone a therapeutic videoradiographic swallowing study (TVSS) were reviewed. Forty patients without pharyngeal swallow were matched for age and gender with 40 patients with pharyngeal swallow; altogether 80 patients were included in the study. Survival was registered at 3, 12, and 72 months after the TVSS.

Results: In this study, the APS group had a significantly shorter survival time ( P = 0.0030) compared to the WPS group when followed‐up at 12 months. In the APS group, most patients (37.5% (15/40)) died within the 3 months after TVSS. At 72 months, 62.5% (25/40) of the patients in the APS group had died. In the WPS group, 5% (2/40) had died within 3 months and 47.4% (19/40) after 12 months. At 72 months, 52.5% (21/40) of the patients in the WPS group had died. Regarding nutritional and therapeutic recommendations based on TVSS, 34/40 in the APS group were recommended no oral intake. Eighteen naso‐gastric tubes were placed directly after TVSS. The therapeutic strategies recommended were head‐positioning, thermal tactile stimulation, and tongue exercises (in 8 patients). In the WPS group, all patients were recommended oral intake. Diet modification was recommended in 29 patients. The therapeutic strategies recommended were head‐positioning, thermal tactile stimulation, tongue exercises, supraglottic swallow, and effortful swallow (in 24 patients).

Conclusion: Patients unable to elicit the pharyngeal stage of swallow had a shorter survival time than patients with pharyngeal swallow, probably due to a more severe underlying disease. Tube feeding was more frequent in the APS group. Fewer therapeutic strategies were recommended compared to the WPS group. In the WPS group, diet modification was frequent. Several patients had different therapeutic strategies. At the end of the study, 8/40 patients (20%) in the APS group had recovered and regained the ability to elicit the pharyngeal stage of swallow. All eight had achieved active swallowing rehabilitation.
Cartilage metabolism in osteoarthritis and the influence of viscosupplementation and steroid: a review
Authors: Tehranzadeh J. , Booya F. , Root J.
Published: December 2009

Osteoarthritis (O.A.) is the most common type of articular disease. This is an idiopathic joint disease characterized by an imbalance between synthesis and degradation of articular cartilage and subchondral bone accompanied by capsular fibrosis, osteophyte formation and variable grade of inflammation of synovial membrane. Joint lubrication is naturally provided by Hyaluronic acid in syovial fluid. Hyaluronan is present in abundance in normal young and healthy joints. In degenerative O.A. Hyaluronan is smaller in size, molecular weight and diminished in concentration. This decrease in joint lubrication and shock absorbing mechanism in O.A. can be remedied by intraarticular viscosupplementation. Alternatively the pain and secondary inflammation in O.A. can be relieved by intraarticular injection of steroids and long acting local anesthetics. Promt and effective reduction in local inflammation occurs after intra‐articular injection of corticosteriod. This article reviews the cartilage metabolism in O.A., discusses the pros and cons of these treatments and provides a literature review of the studies which compare benefits and adverse reactions of viscosupplementation vs. intraarticular steroids with placebo treatment.
Percutaneous vertebroplasty for compression fracture: analysis of vertebral body volume by CT volumetry
Authors: Komemushi A. , Tanigawa N. , Kariya S. , Kojima H. , Shomura Y. , Sawada S.
Published: December 2009

Purpose: To evaluate the relationships between volume of vertebral bodies with compression fracture (measured by CT volumetry) before percutaneous vertebroplasty, the amount of bone cement injected, and the effect of treatment.

Material and Methods: We examined 49 consecutive patients, with 104 vertebral body compression fractures, who underwent percutaneous injection of bone cement. Vertebral body volume was measured by CT volumetry. The patient's pain level was assessed using a visual analog scale (VAS) before and after the procedure. Improvement in VAS was defined as the decrease in VAS after the procedure. Relationships between vertebral body volume, the amount of bone cement, and the effect of treatment were evaluated using Pearson's correlation coefficient test.

Results: Average vertebral body volume was 26.3±8.1 cm3; average amount of bone cement was 3.2±1.1 ml; and average improvement in VAS was 4.9±2.7. The vertebral body volume was greater if a larger amount of bone cement was injected. There was a significant positive correlation between vertebral body volume and amount of bone cement ( r = 0.44; P<0.0001). However, there was no correlation between vertebral body volume and improvement in VAS, or between amount of bone cement and improvement in VAS.

Conclusion: In percutaneous vertebroplasty for vertebral body compression fracture, there is a positive correlation between vertebral body volume and amount of bone cement, but improvement in VAS does not correlate with vertebral body volume or amount of bone cement.
Three‐dimensional rotational angiography of transplanted renal arteries: influence of an extended angle of rotation on beam‐hardening artifacts
Authors: Hagen G. , Wadström J. , Eriksson L. G. , Magnusson P. , Magnusson M. , Magnusson A.
Published: December 2009

Purpose: To investigate whether three‐dimensional rotational angiography (3D‐RA) of the transplant renal artery performed with an extended angle of rotation can reduce beam‐hardening artifacts in 3D reconstructed images without image quality being lost or side effects to the transplanted kidney being increased.

Material and Methods: 3D‐RA with a C‐arm rotation of 180° was performed consecutively in 12 renal transplanted patients with suspicion of renal artery stenosis. A 1.7‐mm balloon occlusion catheter was placed using the crossover technique and this was compared to a protocol with 160° rotation and a traditional 1.4‐mm catheter in 10 patients. The occurrence of beam‐hardening artifacts was registered and the effects of the reduced contrast load on image quality and of arterial occlusion on renal function were assessed.

Results: The extended angle of rotation, from 160° to 180°, reduced the beam‐hardening artifacts. Artifacts were observed in 4/11 patients (36%) in the study group and in all 10 (100%) of the controls. There was no statistical difference regarding image quality between the two protocols. Renal function was equally affected in both protocols.

Conclusion: 3D‐RA with an extended C‐arm rotation reduced the beam‐hardening artifacts. Image quality was not reduced despite the reduced contrast medium load. The different protocols had no effect on patient outcome.
Cerebellar hematoma following transsphenoidal surgery
Authors: Miranda P. , Alén J. F. , Rivas J. , Pérez A. , Ramos A.
Published: December 2009

Cerebellar hemorrhage after supratentorial surgery is a very infrequent complication. Most cases occur following aneurysm or brain tumor surgery, or evacuation of extracerebral collections. The underlying mechanism of formation of these hematomas is unclear. We present an example of cerebellar hemorrhage following transsphenoidal resection of a pituitary adenoma. To our knowledge, this is the first case reported of hemorrhage in the posterior fossa after a transsphenoidal approach.
Diffusion‐weighted and conventional MR imaging in neurotrichinosis
Authors: Gelal F. , Kumral E. , Dirim Vidinli B. , Erdogan D. , Yucel K. , Erdogan N.
Published: December 2009

Central nervous system involvement in trichinosis is not rare. Brain lesions in trichinosis have been defined on computed tomography and magnetic resonance imaging (MRI) as multifocal small lesions located in the cerebral cortex and white matter. We present a case of trichinosis with multifocal lesions of the brain detected by MRI and diffusion weighted MRI. Evolutions of these lesions from acute through chronic stages on follow up studies are also presented. This is the first report describing sequential MRI findings and diffusion weighted imaging appearance of brain lesions in trichinosis. Sequential evaluation of conventional and diffusion MR data allowed us to conclude that multifocal lesions in the brain were related to multiple infarctions rather than true inflammatory infiltration of the brain parenchyma.
Morphological imaging in the localization of neuroendocrine gastroenteropancreatic tumors found by somatostatin receptor scintigraphy
Authors: Saga T. , Shimatsu A. , Koizumi K. , Ichikawa T. , Yamamoto K. , Noguchi S. , Doi R. , Ishibashi M. , Machinami R. , Nakamura K. , Sakahara H. , Endo K.
Published: December 2009

Purpose: To evaluate the necessity of morphological images (MI) in reading somatostatin receptor scintigraphy (SRS) in patients with suspected neuroendocrine gastroenteropancreatic (GEP) tumors.

Material and Methods: A Japanese multicenter clinical trial of SRS was conducted in 40 patients with suspected GEP tumors. Three experienced radiologists interpreted the images in three separate sessions in a blinded manner (1: SRS images alone, 2: MI alone, 3: SRS and MI analyzed simultaneously), and the reading results of each session were compared. In addition, the diagnostic abilities of SRS, MI and SRS alone and simultaneous SRS and MI readings were compared for patients where final diagnosis was obtained.

Results: SRS detected more suspected lesions (positive or inconclusive uptake) than morphological images did (51 vs 27 lesions), but included many physiological uptakes detected as positive or inconclusive uptakes. Combined reading of SRS and morphological images helped to correctly recognize these physiological uptakes, and also helped in determining the anatomical localization of the abnormal uptakes. Combined reading of SRS and morphological images gave the highest diagnostic impact.

Conclusion: The sensitivity of SRS with regard to GEP is high. However the specificity is very low. Morphologic imaging is necessary for the exclusion of physiological uptake and correct anatomic location of an abnormal tracer uptake. The combined reading of SRS and morphologic imaging studies gives the highest diagnostic impact.
Intravascular malignant lymphomatosis: diffusion‐weighted magnetic resonance imaging characteristics
Authors: Kinoshita T. , Sugihara S. , Matusue E. , Nomura T. , Ametani M. , Ohama E. , Ogawa T.
Published: December 2009

Intravascular malignant lymphomatosis is an unusual condition in which malignant lymphoma cells form microscopic masses within the blood vessels of the central nervous system. Occlusion of the involved blood vessels can lead to multifocal cerebral infarcts. Diffusion‐weighted magnetic resonance imaging (MRI) reveals a subacute infarction pattern (bright high signal intensity on b = 1000 s/mm2 images and intermediate apparent diffusion coefficient values) in the cerebral deep white matter. We present MRI findings of a 68‐year‐old woman with intravascular malignant lymphomatosis involving the cerebral white matter and the thoracic cord.
Intra‐arterial magnetic resonance angiography of the iliac arteries: clinical experience using two different protocols
Authors: Paetzel C. , Zorger N. , Völk M. , Herold T. , Seitz J. , Nitz W. R. , Feuerbach S. , Hamer O. , Lenhart M.
Published: December 2009

Purpose: To assess the feasibility of intra‐arterial magnetic resonance angiography (iaMRA) with two different protocols.

Material and Methods: Twenty patients were prospectively examined after digital subtraction angiography. Contrast‐enhanced iaMRA was performed using a 1.5T magnetic resonance imaging (MRI) system. Contrast agent (gadodiamide) was injected through a conventional angiography catheter placed in the abdominal aorta. The patients were randomized into two groups each comprising 10 patients. Group 1 was examined with a FLASH‐3D (fast low‐angle shot) sequence, allowing the center of the k‐space to be acquired 0.5 s after initiation of the measurement. Group 2 was examined with the identical sequence, but the center of the k‐space was acquired after 8.7 s. The increase in the intravascular signal intensity was determined and the diagnostic value of the angiograms was independently scored by 4 investigators using a 5‐point scale.

Results: Nineteen of 20 MRAs were scored as diagnostic; only 1 was scored as non‐diagnostic by 2 observers. The diagnostic value of the angiograms of group 2 was judged superior to that of group 1 owing to a more homogeneous intravascular contrast distribution.

Conclusion: Intra‐arterial MRA is feasible. The diagnostic value of angiograms using a flash sequence with center of the k‐space acquisition after 8.7 s ranged from good to excellent. This sequence is appropriate for iaMRA of iliac arteries to support MR guided intervention.
High‐resolution magnetic resonance imaging of trabecular bone in the wrist at 3 tesla: initial results
Authors: Ludescher B. , Martirosian P. , Lenk S. , Machann J. , Dammann F. , Schick F. , Claussen C. , Schlemmer H.
Published: December 2009

Purpose: To evaluate the feasibility of high‐resolution magnetic resonance imaging (MRI) of trabecular bone of the wrist at 3 Tesla (3T) in vivo and to assess the potential benefit of the increased resolution for clinical assessment of structural changes in spongy bone.

Material and Methods: High‐resolution MRI of the wrist was performed with a whole‐body 3T MR scanner using a dedicated circularly polarized transmit–receive wrist‐coil. Two 3D‐FISP sequences with a spatial resolution of 300×300×300 µm3 in a measuring time of TA = 7:51 min, and 200×200×200 µm3 in TA = 9:33 min were applied. Seven young healthy volunteers and three elderly subjects with suspected osteoporosis were examined. The signal‐to‐noise ratio (SNR) in the optimized setup at 3T was compared to measurements at 1.5T.

Results: The images at 3T allow microscopic analysis of the bone structure at an isotropic spatial resolution of 200 µm in examination times of <10 min. Differences in the structure of the spongy bone between normal and markedly osteoporotic subjects are well depicted. The SNR at 3T was found up to 16 times higher than at 1.5T applying unchanged imaging parameters.

Conclusion: The proposed high‐resolution MRI technique offers high potential in the diagnosis and follow‐up of diseases with impaired bone structure of hand and/or wrist in clinical applications.
Magnetic resonance imaging of the feto‐placentar unit after fetoscopic laser coagulation for twin‐to‐twin transfusion syndrome
Authors: Huisman T. A. G. M. , Lewi L. , Zimmermann R. , Willi U. V. , Deprest J.
Published: December 2009

Twin‐to‐twin transfusion syndrome (TTTS) is a severe complication in monochorionic twin pregnancies that results from a hemodynamical imbalance of placentar vascular anstomoses that connect the circulation of both fetuses. In TTTS, a poly/oligohydramnios sequence with high fetal morbidity and mortality rates occurs. Fetoscopic laser coagulation of the placentar anastomoses can limit or prevent fetal injury. The purpose of this report is to present and discuss fetal magnetic resonance imaging as a postoperative imaging tool after fetoscopic laser coagulation.
Book Review
Authors: Kløw Nils-Einar
Published: December 2009

Interventional Cardiology. An Atlas of investigation and therapy. Edited by B. Meier. Clinical Publishing 2004. ISBN 1 904392 11 3. Price: £74.99/$119.95.
Magnetic resonance findings of primary central nervous system t‐cell lymphoma in immunocompetent patients
Authors: Kim E. Y. , Kim S. S.
Published: December 2009

Purpose: To describe the MR findings of primary central nervous system T‐cell lymphoma (T‐PCNSL) in immunocompetent patients.

Material and Methods: Seven patients with pathologically proven T‐PCNSL were included in our study. The number, location, shape, enhancement pattern, and signal intensity of the tumors were determined. Diffusion‐weighted images (DWI) and perfusion‐weighted images (PWI) were obtained in four and two patients, respectively. Apparent diffusion coefficients (ADCs) were generated, and regions of interest were defined in each lesion.

Results: Four patients with T‐PCNSL had a single mass, while the others had multiple lesions (four, three, and two lesions, respectively). All seven cases of T‐PCNSL had a supratentorial location: 12 in the subcortical area and 1 in the thalamus. No leptomeningeal involvement was noted. All tumors showed iso‐ to low T1 and iso‐ to slightly high T2 signal intensity to the adjacent gray matter. Rim enhancement was seen in 5 of the 7 patients (71.4%), while heterogeneous and homogeneous enhancement was seen in each of two. On DWI and ADC maps, the enhancing lesions showed slight hyperintensity in three patients (mean ADC ratio, 0.92±0.06) and iso‐intensity in the other (ADC ratio, 1.02±0.05). Cystic areas consistent with necrosis were noted in three patients. High‐signal intensity area in the cortex was noted on T1‐weighted images in three patients, suggesting hemorrhage. In two patients, the same signal intensity area was noted within the mass. The two masses on the relative cerebral blood volume (rCBV) map demonstrated either similar or slightly higher signal intensity than that of the contralateral white matter. The rCBV ratios of these two masses were 1.27±0.16 and 1.35±0.2, respectively.

Conclusion: T‐PCNSLs show a predilection for a subcortical location, a relatively high incidence of cortical or intratumoral hemorrhage, rim enhancement, or cystic areas consistent with necrosis on magnetic resonance imaging. The lower rCBV ratio of the tumor might be helpful in differentiating T‐PCNSL from other brain tumors such as high‐grade glioma.
Clinical 1h magnetic resonance spectroscopy of brain metastases at 1.5T and 3T
Authors: Sjøbakk T. E. , Lundgren S. , Kristoffersen A. , Singstad T. , Svarliaunet A. J. , Sonnewald U. , Gribbestad I. S.
Published: December 2009

Purpose: To investigate whether improvements in signal-to-noise ratio (SNR) and spectral resolution are found in spectra from patients with brain metastases obtained at higher magnetic field strengths using standard clinical instrumentation.

Material and Methods: Six patients with brain metastases, 13 healthy volunteers, and a phantom containing brain metabolites were examined using two clinical MR instruments operating at 1.5T (Siemens) and 3T (Philips) with standard clinical head coils. Spectra were obtained using a point resolved spectroscopy pulse sequence, echo times (TE) 32 ms and 144 ms, and repetition time 2000 ms from a volume-of-interest (VOI) of size 15×15×15 mm3. SNR and spectral resolution of the metabolites N-acetylaspartate, choline, and creatine compounds in spectra from 3T were compared to the 1.5T spectra.

Results: In general, spectral resolution was improved by 25–30% at higher magnetic field strength. Only minor improvements in SNR were obtained at 3T using short echo time and 20–50% at long echo time.

Conclusion: SNR and spectral resolution were improved at higher magnetic field strength, especially with TE 144 ms, including spectra from patients with heterogeneous brain tumors. However, differences in the defined effective VOI, particularly at short echo time, reduced the expected effect of increased magnetic field strength on the measured SNR.
3D imaging of the whole spine at 3T compared to 1.5T: initial experiences
Authors: Rodegerdts E. A. , Boss A. , Riemarzik K. , Lichy M. , Schick F. , Claussen C. D. , Schlemmer H. P.
Published: December 2009

Purpose: To describe our first experiences with a recently introduced 3T system for T2-weighted isotropic 3D whole-spine imaging.

Material and Methods: Magnetic resonance imaging of the whole spine was performed by implementing an isotropic 3D fast spin-echo sequence with variable flip-angle refocusing pulses at 3T and 1.5T. Signal-to-noise ratio (SNR) was compared on both systems in eight subjects.

Results: Mean values for SNR were significantly higher at 3T (346±214) for 1.0 mm voxel size compared to 1.5T (202±41), but showed considerably higher variability at 3T. At 3T, measurements with 0.9 mm voxel size were possible with similar SNR as with 1.0 mm voxel size at 1.5T.

Conclusion: High-resolution 3D imaging of the whole spine is feasible at 3T with an increased SNR compared to 1.5T. Signal gain at 3T can be used to further increase spatial resolution. Pronounced interpatient variability of SNR at 3T may be a result of inhomogeneous RF deposition due to dielectric effects.
Primary leiomyosarcoma of the oral tongue: magnetic resonance and ultrasonography findings with histopathologic correlation
Authors: Castaldi A. , Arcuri T. , Carta M. , Quilici P. , Derchi L. E.
Published: December 2009

Leiomyosarcoma is a malignant smooth muscle tumor that frequently occurs in the gastrointestinal tract and female genital tract. It is aggressive and tends to recur and metastasize. Clinical behavior is unpredictable, mostly influenced by a proper surgical approach. Oral leiomyosarcoma, in particular of the tongue, is extremely rare and poorly documented in the radiology literature. Diagnostic assessment of oral leiomyosarcoma is often challenging, mostly founded on its peculiar immunohistological features. However, imaging evaluation is essential in staging and for preoperative planning. We illustrate the case of a 52-year-old woman with 2-months history of a painless growing mass on the left hemitongue, with magnetic resonance and ultrasonographic features correlated to histopathologic examination.
A short larsen score is effective when evaluating radiographs in early rheumatoid arthritis
Authors: Palkonyai E. , Larsen A. , Geher P. , Kolarz G. , Bogye G. , Temesvari P. , Kaposi P. , Szilagyi M. , Ratko I.
Published: December 2009

Purpose: To compare the efficacy of the short Larsen score (LS 12) based on analysis of 12 areas with the original Larsen score (LS 40), which includes 40 areas for assessing radiographic changes in rheumatoid arthritis.

Material and Methods: The radiographs of the hands, wrists, and feet of 122 patients with early rheumatoid arthritis were evaluated by two radiologists using both the LS 40 and LS 12 methods. Cross-sectional analysis of radiographs of 122 patients and longitudinal analysis in 68 patients were performed.

Results: There was no significant difference between the mean LS 40 and mean LS 12 in the cross-sectional study. LS 12 correlated strongly ( r = 0.93, P<0.01) with LS 40 at the baseline, and the rate of progression was similar in both methods ( r = 0.89, P<0.01) in the longitudinal study.

Conclusion: The short Larsen score was as efficient as the original method.
Impact of extended written information on patient anxiety and image motion artifacts during magnetic resonance imaging
Authors: Törnqvist E. , Månsson Å. , Larsson E.-M. , Hallström I.
Published: December 2009

Purpose: To evaluate whether increased written information to patients prior to magnetic resonance imaging (MRI) decreases patient anxiety and image motion artifacts.

Material and Methods: A two-group controlled experimental design was used. Of 242 patients, 118 received routinely given basic written information (control group) while 124 were given increased written information (intervention group). To measure patient anxiety before and during scanning, the self-report psychometric test State-Trait Anxiety Inventory (STAI) was used. After MR examination, the patients answered a questionnaire on satisfaction with the written information. The images were assessed with regard to motion artifacts.

Results: Motion artifacts were present in fewer patient images in the intervention group than in the control group (4.0% versus 15.4%; P = 0.003). There was no significant difference between the control and the intervention group regarding patient anxiety and satisfaction with the information. Women in both groups showed a higher level of anxiety than the men did.

Conclusion: Increased information about the MRI scanning procedure and expected experiences during the scan may help patients to lie still during the sequences, with a decrease in motion artifacts. However, further research is needed to evaluate the effect of other interventions on patient anxiety during MRI scanning.
Huge retrovesical hydatid cyst with pelvic localization as the primary site: a case report
Authors: Halefoglu A. M. , Yasar A.
Published: December 2009

We present a patient with symptoms of abdominal pain and frequent urination due to a huge mass in the retrovesical region. All imaging modalities revealed a cystic mass containing small daughter cysts located between the urinary bladder and rectum. Its characteristics led us to suspect the presence of a hydatid cyst, and an indirect hemagglutination test for Echinococcus granulosus was found positive. No other involvement of hydatid cystic disease was detected. The primary site for the hydatid disease was therefore regarded as the pelvis, on which only a few cases have been reported previously. The patient started albendazole therapy, but refused operation. Hydatid cyst should always be considered in the differential diagnosis of abdominopelvic masses in endemic regions of the world.
Pulmonary cement embolism: a complication of percutaneous vertebroplasty
Authors: Duran C. , Sirvanci M. , Aydoğan M. , Ozturk E. , Ozturk C. , Akman C.
Published: December 2009

Background: Percutaneous vertebroplasty (PV) has recently become a very common procedure for vertebral compression fractures. Extravasation of cement, a common event associated with vertebroplasty, may lead to cement emboli in the lungs.

Purpose: To determine the frequency of pulmonary cement embolism after percutaneous vertebroplasty.

Material and Methods: Between 2002 and 2006, 128 percutaneous vertebroplasties were performed in 73 patients (56 women and 17 men) in our institution. Postprocedural chest radiographs were obtained for all patients and assessed for the presence of pulmonary cement emboli.

Results: Pulmonary cement embolism was detected on chest radiographs and confirmed with chest computed tomography (CT) in four patients treated with percutaneous vertebroplasty for osteoporotic collapse and one patient treated for multiple myeloma. The imaging finding of pulmonary cement embolism was solitary or multiple fine radiodense lines with occasional branching patterns. The frequency of pulmonary cement embolism was 6.8%.

Conclusion: An incidence of pulmonary cement embolism of 6.8% during PV was found. Close clinical follow-up, postprocedural chest radiographs, and chest CT scans, if necessary, are important for the detection of pulmonary cement embolism at an early stage.
Percutaneous needle biopsy of the spine
Authors: Tehranzadeh J. , Tao C. , Browning C. A.
Published: December 2009

The purpose of this review article is to provide a brief overview of the recent literature on the two main types of percutaneous biopsy methods done in the spinal column: fine needle aspiration biopsy (FNAB) and core needle biopsy (CNB). FNAB is the process of obtaining a sample of cells and bits of tissue for examination by applying suction through a fine needle attached to a syringe. Core needle biopsy involves extracting a cylindrical sample of tissue using a large, hollow needle. The decision for needle biopsy is a joint effort between the clinician, pathologist, radiologist, surgeon, and patient. Specific techniques and approaches with varying needle systems are described for each spinal region. Percutaneous image-guided spine biopsy is a safe and effective procedure. It is the procedure of choice in definitive diagnosis of pathologic lesions of the spine.
In the Shadow of Mugabe
Authors: Kwenda Stanley
Published: December 2009

The new coalition government in Zimbabwe has so far failed to deliver on its promise of greater media freedom, says Stanley Kwenda
Stopping the Killers
Authors: Simon Joel
Published: December 2009

Impunity is an urgent issue facing press freedom campaigners. Joel Simon of the Committee to Protect Journalists outlines a roadmap for action