bluuebunny/crossref_metadata_2025 huggingface dataset:
Interaction study of a lysozyme‐binding aptamer with mono‐ and divalent cations by ACE
Authors: Girardot Marie , Gareil Pierre , Varenne Anne
Published: January 2010

Binding between an aptamer and its target is highly dependent on the conformation of the aptamer molecule, this latter seeming to be affected by a variety of cations. As only a few studies have reported on the interactions of monovalent or divalent cations with aptamers, we describe herein the use of ACE in its mobility shift format for investigating interactions between various monovalent (Na+, K+, Cs+) or divalent (Mg2+, Ca2+, Ba2+) cations and a 30‐mer lysozyme‐binding aptamer. This study was performed in BGEs of different natures (phosphate and MOPS buffers) and ionic strengths. First, the effective charges of the aptamer in 30 mM ionic strength phosphate and MOPS (pH 7.0) were estimated to be 7.4 and 3.6, respectively. Then, corrections for ionic strength and counterion condensation effects were performed for all studies. The effective mobility shift was attributed not only to these effects, but also to a possible interaction with the buffer components (binary or ternary complexes) as well as possible conformational changes of the aptamer. Finally, apparent binding constants were calculated for divalent cations with mathematical linearization methods, and the influence of the nature of the BGE was evidenced.
A comparison of average rates of alluvial erosion between the south‐western and south‐eastern United States
Authors: Jaeger Kristin L. , Wohl Ellen , Simon Andrew
Published: January 2010

Alluvial channel bed incision and bank widening have been reported in both the south‐western and south‐eastern US throughout the past century. Distinct regional differences in climate and landscape properties likely influence the rate of erosion. This study discusses regional differences in hydraulic driving forces and substrate resistance and tests the hypothesis that regional differences exist in average rates of channel incision, bank erosion, and knickpoint retreat. Specifically, we hypothesize that erosion rates are higher in south‐western US streams and reason that this is because of greater flood magnitudes and limited substrate resistance. A review of the literature documenting incision, bank erosion, and knickpoint retreat, however, indicates that intra‐regional differences are larger than inter‐regional differences and that average rates in the south‐western US are either statistically similar or less than the rates in parts of the south‐eastern US. This could either be a result of strong intra‐regional hydroclimatic and substrate variability or because average erosion rate may not be an appropriate metric for inter‐regional comparisons because of the variability between case studies associated with the field methods to measure erosion, duration of study period, and time since disturbance to the channel. Nevertheless, these findings provide a basis for future evaluations of the relative importance of different controls on driving and resisting forces in these and other landscapes characterized by rapid channel incision and arroyo formation. Copyright © 2010 John Wiley & Sons, Ltd.
The influence of DEM resolution on simulated solar radiation‐induced glacier melt
Authors: Hopkinson Chris , Chasmer Laura , Munro Scott , Demuth Michael N.
Published: January 2010

The influence of digital elevation model (DEM) resolution to modelled glacier melt during peak melt production was evaluated by performing a clear sky GIS radiation simulation over the Peyto Glacier in the Canadian Rockies. DEMs were generated at eight resolutions ranging from 1 m to 1000 m grid spacing from airborne lidar data. When applied to the planar area (PA) of the terrain, it was found that total melt increased with DEM resolution (r2 = 0·63) by 4% over 3 orders of magnitude. This systematic scaling‐effect was mitigated at the basin scale, however, when the DEM slope variant area (SVA) was used to account for the increased divergence from PA as resolution increases. However, even after the inclusion of SVA in glacier surface melt simulations, localized melt variations with scale were still evident in the ablation and accumulation zone observations. In the ablation zone, there was a systematic increase in simulated melt (∼4%) as resolution decreased from 1 m to 1000 m (r2 = 0·89), with the opposite effect in the accumulation zone (r2 = 0·81). DEM resolution also affected the diurnal melt cycle, such that for the entire glacier there was a tendency for a morning over‐estimation and afternoon underestimation of melt rate with decreasing resolution. For the accumulation zone, there was an increased melt rate at low resolutions occurring in the afternoon, while in the ablation zone there was a tendency for increasing melt rates with decreasing resolution throughout the day. These localized spatio‐temporal variations in simulated melt are largely due to the lowering of ridges and raising of valley floors that occur as resolution decreases. This scale dependence in the representation of terrain morphology directly controls the pattern and relative proportion of direct beam shadowing over actively melting surfaces and thereby has a systematic influence on the grid cell‐level hydrological balance. It is recommended that GIS‐based glacier melt modelling routines take into account the slope area of grid cells, while noting that the choice of DEM scale can have a discernible and systematic influence on modelled runoff magnitude. It is important to note that while higher grid resolutions mitigate the effect of terrain smoothing on spatio‐temporal melt patterns, lower resolutions actually mitigate the systematic error associated with assuming all surface areas are planar. Copyright © 2010 John Wiley & Sons, Ltd and Her Majesty the Queen in right of Canada.
Are transit times useful process‐based tools for flow prediction and classification in ungauged basins in montane regions?
Authors: Soulsby C. , Tetzlaff D. , Hrachowitz M.
Published: January 2010

Transit times are being increasingly explored as process‐based tools for conceptualizing hydrological function at a range of scales. Despite this, little effort has been made to relate transit times to conventional hydrometric flow statistics. Rather, the identification of the appropriate transit time distribution (TTD) for a hydrological system and the derivation of metrics such as the mean transit time (MTT) have required quantitative assessment of input–output relationships for conservative tracers using lumped parameter models. This has allowed the main landscape controls to be identified and has facilitated the prediction of MTTs in ungauged basins in particular geomorphic provinces, though relationships with streamflow measures have been unexamined. We used estimated MTTs (with uncertainty) for 16 experimental catchments (0·5–690 km2in area) with contrasting geologic, topographic, pedologic and climatic characteristics in Scotland. The MTT was highly variable ranging from 60 days toca> 1500 days, reflecting differences in catchment soil cover, geomorphic properties and precipitation. The MTT was closely correlated with key hydrometric design statistics such as the mean annual flood (MAF) and percentiles of high (Q5) and low (Q95) flows. Analysis of MTT estimates, in conjunction with geographic information system (GIS)‐based assessment of landscape controls, showed that MTT could be predicted to within 30% for ungauged basins from catchment soil cover and drainage density. Furthermore, hydrometric design statistics for ungauged basins could also be forecast from MTT predictions with median relative errors of 14, 11 and 28% for the MAF, Q5and Q95respectively. We suggest that MTTs—predicted from mapped landscape characteristics—can be useful diagnostic metrics for ungauged montane basins, as well as a useful similarity index for process‐based catchment classification. This is important as montane headwaters are often critical, but data‐poor environments influencing the quantity, quality and ecology of downstream flows. Copyright © 2010 John Wiley & Sons, Ltd.
Osteocalcin gene polymorphisms influence concentration of serum osteocalcin and enhance fracture identification
Authors: McGuigan Fiona , Kumar Jitender , Ivaska Kaisa K , Obrant Karl J , Gerdhem Paul , Åkesson Kristina
Published: January 2010

Osteoporosis is a major health problem affecting more than 75 million people throughout Europe, the United States, and Japan. Epidemiologic studies have determined that both genetic and environmental factors contribute to the pathogenesis of osteoporosis. We have investigated the association between polymorphisms at the osteocalcin locus and variables linked to bone health. Osteocalcin provides a link between bone and energy metabolism, hence its potential importance as an osteoporosis candidate gene. In this study, we included a total of 996 women (all aged 75 years) from the Osteoporosis Prospective Risk Assessment (OPRA) cohort. We sequenced the osteocalcin gene along with flanking regions to search for novel coding polymorphisms. We also analyzed four polymorphisms selected from within and flanking regions of the osteocalcin gene to study their association with serum total osteocalcin levels (S-TotalOC), total-body (TB) bone mineral density (BMD), fracture, TB fat mass, and body mass index (BMI). The promoter polymorphism rs1800247 was significantly associated with S-TotalOC (p = .012) after controlling for BMI and TB BMD. The polymorphism rs1543297 was significantly associated with prospectively occurring fractures (p = .008). In a model taking into account rs1543297 and rs1800247, along with TB BMD, BMI, smoking, and S-TotalOC, the polymorphisms together were able to identify an additional 6% of women who sustained a fracture (p = .02). We found no association between the polymorphisms and TB BMD, BMI, or TB fat mass. In conclusion, polymorphisms in and around the osteocalcin locus are significantly associated with S-TotalOC and fracture. Genotyping at the osteocalcin locus could add valuable information in the identification of women at risk of osteoporosis. © 2010 American Society for Bone and Mineral Research
Similarities and discrepancies in subchondral bone structure in two differently induced canine models of osteoarthritis
Authors: Intema Femke , Sniekers Yvonne H , Weinans Harrie , Vianen Marieke E , Yocum Sue A , Zuurmond Anne-Marie M , DeGroot Jeroen , Lafeber Floris P , Mastbergen Simon C
Published: January 2010

In osteoarthritis (OA), cartilage degradation is accompanied by subchondral bone changes. The pathogenesis and physiology of bone changes in OA are still unclear. The changes in subchondral bone architecture and cartilage damage were compared in differently induced experimental models of OA. Experimental OA was induced bilaterally by anterior cruciate ligament transection (ACLT) or by cartilage trauma (Groove model); bilateral sham surgery served as control. Lysylpyridinoline (LP, bone resorption) and C-telopeptide of type II collagen (CTX-II, cartilage breakdown) were measured over time. At 20 weeks after surgery, the subchondral cortical plate and trabecular bone of the tibia were analyzed by micro–computed tomography (µCT) and cartilage degeneration was analyzed histologically and biochemically. In both models, cartilage degeneration and cortical subchondral plate thinning were present. CTX-II levels were elevated over time in both models. Subchondral trabecular bone changes were observed only in the ACLT model, not in the Groove model. Correspondingly, LP levels were elevated over time in the ACLT model and not in the Groove model. Interestingly, the trabecular bone changes in the ACLT model were extended to the metaphyseal area. The early decrease in plate thickness, present in both models, as was cartilage damage, suggests that plate thinning is a phenomenon that is intrinsic to the process of OA independent of the cause/induction of OA. On the other hand, trabecular changes in subchondral and metaphyseal bone are not part of a common pathway of OA development and may be induced biomechanically in the destabilized and less loaded ACLT joint. © 2010 American Society for Bone and Mineral Research
Local low-dose lovastatin delivery improves the bone-healing defect caused by Nf1 loss of function in osteoblasts
Authors: Wang Weixi , Nyman Jeffry S , Moss Heather E , Gutierrez Gloria , Mundy Gregory R , Yang Xiangli , Elefteriou Florent
Published: January 2010

Postfracture tibial nonunion (pseudoarthrosis) leads to lifelong disability in patients with neurofibromatosis type I (NF1), a disorder caused by mutations in the NF1 gene. To determine the contribution of NF1 in bone healing, we assessed bone healing in the Nf1 ob−/− conditional mouse model lacking Nf1 specifically in osteoblasts. A closed distal tibia fracture protocol and a longitudinal study design were used. During the 21- to 28-day postfracture period, callus volume, as expected, decreased in wild-type but not in Nf1 ob−/− mice, suggesting delayed healing. At these two time points, bone volume (BV/TV) and volumetric bone mineral density (vBMD) measured by 3D micro–computed tomography were decreased in Nf1 ob−/− callus-bridging cortices and trabecular compartments compared with wild-type controls. Histomorphometric analyses revealed the presence of cartilaginous remnants, a high amount of osteoid, and increased osteoclast surfaces in Nf1 ob−/− calluses 21 days after fracture, which was accompanied by increased expression of osteopontin, Rankl, and Tgfβ. Callus strength measured by three-point bending 28 days after fracture was reduced in Nf1 ob−/− versus wild-type calluses. Importantly, from a clinical point of view, this defect of callus maturation and strength could be ameliorated by local delivery of low-dose lovastatin microparticles, which successfully decreased osteoid volume and cartilaginous remnant number and increased callus BV/TV and strength in mutant mice. These results thus indicate that the dysfunctions caused by loss of Nf1 in osteoblasts impair callus maturation and weaken callus mechanical properties and suggest that local delivery of low-dose lovastatin may improve bone healing in NF1 patients. © 2010 American Society for Bone and Mineral Research
Patients with high-bone-mass phenotype owing to Lrp5-T253I mutation have low plasma levels of serotonin
Authors: Frost Morten , Andersen Tom Erenskjold , Yadav Vijay , Brixen Kim , Karsenty Gerard , Kassem Moustapha
Published: January 2010

The Lrp5 gene is a major determinant of bone mass accrual. It has been demonstrated recently to achieve this function by hampering the synthesis of gut-derived serotonin, which is a powerful inhibitor of bone formation. In this study we analyzed plasma serotonin levels in patients with a high-bone-mass (HBM) phenotype owing to gain-of-function mutation of Lrp5 (T253I). A total of 9 HBM patients were compared with 18 sex- and age-matched controls. In HBM patients, the serotonin concentrations in platelet-poor plasma were significantly lower than in the controls (mean ± SEM: 2.16 ± 0.28 ng/mL versus 3.51 ± 0.49 ng/mL, respectively, p < .05). Our data support the hypothesis that circulating serotonin levels mediate the increased bone mass resulting from gain-of-function mutations in Lrp5 in humans. © 2010 American Society for Bone and Mineral Research.
The role of mast cells in parathyroid bone disease
Authors: Turner Russell T , Iwaniec Urszula T , Marley Kevin , Sibonga Jean D
Published: January 2010

Chronic hyperparathyroidism (HPT) is a common cause of metabolic bone disease. These studies investigated the underlying cellular and molecular mechanisms responsible for the detrimental actions of elevated parathyroid hormone (PTH) on the skeleton. Bone biopsies from hyperparathyroid patients revealed an association between parathyroid bone disease and increased numbers of bone marrow mast cells. We therefore evaluated the role of mast cells in the etiology of parathyroid bone disease in a rat model for chronic HPT. In rats, mature mast cells were preferentially located at sites undergoing bone turnover, and the number of mast cells at the bone–bone marrow interface was greatly increased following treatment with PTH. Time-course studies and studies employing parathyroid hormone–related peptide (PTHrP), as well as inhibitors of platelet-derived growth factor-A (PDGF-A, trapidil), kit (gleevec), and PI3K (wortmannin) signaling revealed that mature mast cell redistribution from bone marrow to bone surfaces precedes and is associated with osteitis fibrosa, a hallmark of parathyroid bone disease. Importantly, mature mast cells were not observed in the bone marrow of mice. Mice, in turn, were resistant to the development of PTH-induced bone marrow fibrosis. These findings suggest that the mast cell may be a novel target for treatment of metabolic bone disease. © 2010 American Society for Bone and Mineral Research
Composition of the air emission from a tobacco factory and development of the biocatalyst for odour control
Authors: Zagustina Natalya A , Krikunova Natalya I , Kulikova Albina K , Misharina Tamara A , Romanov Maxim E , Ruzhitsky Aleksander O , Terenina Margarita B , Veprizky Andrey A , Zhukov Vitaly G , Popov Vladimir O
Published: January 2010

BACKGROUND: Tobacco processing facilities produce voluminous air emissions containing a large number of smelly and potentially harmful volatile compounds that require implementation of the efficient odour control techniques. Biofiltration is the proved method for deodorisation of complex multi‐component emissions. The purpose of the present study was to identify substances present in the emission of a typical tobacco industrial facility and demonstrate efficiency of the biotrickling filter for odour control.

RESULTS:Composition of volatile compounds of leaf tobacco was investigated by capillary GC–MS. More than 80 individual compounds were identified. For evaluating the odour of individual components a GC‐sniffing analysis was employed. Laboratory‐scale trickling biofilters were used to develop a method for deodorisation of a simulated tobacco emission. Biofilters were operated for 12 months and demonstrated the absence of the ‘tobacco smell’ at the filter outlet and a stable rate of conversion of nicotine exceeding 90%.

CONCLUSION:

Composition of volatile substances of the leaf tobacco was investigated and compounds responsible for ‘tobacco smell’ were identified. A trickling biofiltration technique was shown to be an efficient method for control of tobacco odours. The results of the study have been scaled up to the pilot level to control emissions of an operating tobacco factory. Copyright © 2010 Society of Chemical Industry
Gum Arabic coated magnetic nanoparticles with affinity ligands specific for antibodies
Authors: Batalha Iris L. , Hussain Abid , Roque A. C. A.
Published: January 2010

A novel magnetic support based on gum Arabic (GA) coated iron oxide magnetic nanoparticles (MNP) has been endowed with affinity properties towards immunoglobulin G (IgG) molecules. The success of the in situ triazine ligand synthesis was confirmed by fluorescence assays. Two synthetic ligands previously developed for binding to IgG, named as ligand 22/8 (artificial Protein A) and ligand 8/7 (artificial Protein L) were immobilized on to MNPs coated with GA (MNP_GA). The dimension of the particles core was not affected by the surface functionalization with GA and triazine ligands. The hydrodynamic diameters of the magnetic supports indicate that the coupling of GA leads to the formation of larger agglomerates of particles with about 1 µm, but the introduction of the triazine ligands leads to a decrease on MNPs size. The non‐functionalized MNP_GA bound 28 mg IgG/g, two times less than bare MNP (60 mg IgG/g). MNP_GA modified with ligand 22/8 bound 133 mg IgG/g support, twice higher than the value obtained for ligand 8/7 magnetic adsorbents (65 mg/g). Supports modified with ligand 22/8 were selected to study the adsorption and the elution of IgG. The adsorption of human IgG on this support followed a Langmuir behavior with a Qmáx of 344 mg IgG/g support and Ka of 1.5 × 105 M. The studies on different elution conditions indicated that although the 0.05 M citrate buffer (pH 3) presented good recovery yields (elution 64% of bound protein), there was occurrence of iron leaching at this acidic pH. Therefore, a potential alternative would be to elute bound protein with a 0.05 M glycine‐NaOH (pH 11) buffer. Copyright © 2010 John Wiley & Sons, Ltd.
Quantitative MR in multi‐center clinical trials
Authors: Ashton Edward
Published: January 2010

MRI has a wide variety of applications in the clinical trials process. MR has shown particular utility in the early phases of clinical development, when trial sponsors are interested in demonstrating proof of concept and must make decisions about allocation of resources to a particular compound based on the results from a small number of experimental subjects. This utility is largely due to the many different imaging endpoints that can be measured using MR, ranging from structural (tumor burden, hippocampal volume) to functional (blood flow, vascular permeability) to molecular (hepatic fat fraction, glycosaminoglycan content). The unique flexibility of these systems has proven to be both a blessing and a curse to those attempting to deploy MR in multi‐center clinical trials, however, as differences among scanner manufacturers and models in pulse sequence implementation, hardware capabilities, and even terminology make it increasingly difficult to ensure that results obtained at one center are comparable to those at another. These problems are compounded by the differences between the procedures used in clinical trials and those used in routine clinical practice, which make trial‐specific training for site technologists and radiologists a necessity in many cases. This article will briefly review the benefits of including quantitative MR imaging in clinical trials, then explore in detail the challenges presented by the need to develop and deploy a detailed MR protocol that is both effective and implementable across many different MR systems and software versions. J. Magn. Reson. Imaging 2010; 31: 279–288. © 2010 Wiley‐Liss, Inc.
Evaluation of multicoil breast arrays for parallel imaging
Authors: Marshall Helen , Devine Patrick M. , Shanmugaratnam Nishanthan , Fobel Ryan , Siegler Peter , Piron Cameron A. , Plewes Donald B.
Published: January 2010

Purpose:

To evaluate three multicoil breast arrays for both conventional and SENSE‐accelerated imaging.

Materials and Methods:

Two commercially available 8‐element coils and a prototype 16‐element coil were compared. One 8‐element array had adjustable coils located next to the breast tissue and the other had a fixed coil arrangement; both were designed to allow parallel imaging in the left–right direction. The 16‐element coil was designed to have coil sensitivity variation in both the left–right and superior–inferior directions, and also had adjustable coils. Their performance was assessed in terms of signal‐to‐noise ratio (SNR), g‐factor, and uniformity with a custom‐built phantom.

Results:

The 16‐element array with adjustable coils provided the highest SNR, while the 8‐element coil with a fixed coil arrangement had the best uniformity. All coils performed well for SENSE acceleration in the left–right direction. The 8‐element coils did not have the capability for acceleration in the superior–inferior direction across the whole volume. The 16‐element coil enabled acceleration in the superior–inferior direction in addition to the left–right direction.

Conclusion:

Smaller, adjustable coil elements located next to breast tissue can provide greater SNR than larger, fixed coil elements. A multicoil breast array with high intrinsic SNR and low g‐factors enables high‐quality parallel imaging. J. Magn. Reson. Imaging 2010; 31: 328–338. © 2010 Wiley‐Liss, Inc.
Decreased incidence of NSF in patients on dialysis after changing gadolinium contrast‐enhanced MRI protocols
Authors: Martin Diego R. , Krishnamoorthy Saravanan K. , Kalb Bobby , Salman Khalil N. , Sharma Puneet , Carew John D. , Martin Phillip A. , Chapman Arlene B. , Ray Gaye L. , Larsen Christian P. , Pearson Thomas C.
Published: January 2010

Purpose:

To retrospectively determine the incidence of nephrogenic systemic fibrosis (NSF) in patients on dialysis administered either a lower dose high‐relaxivity linear gadolinium‐chelate, gadobenate dimeglumine (MultiHance, MH), compared to a standard dose linear gadolinium chelate, gadodiamide (Omniscan, OM).

Materials and Methods:

This study was Health Insurance Portability and Accountability Act (HIPAA)‐compliant and Institutional Review Board (IRB)‐approved. As per institution standardized contrast‐enhanced magnetic resonance imaging (MRI) protocols, patients on dialysis were imaged using either MH, between 2/2007 to 9/2008, or OM between 10/2003 and 1/2007. Rates of NSF were compared using 95% score‐based confidence intervals (CI). The Wilcoxon rank sum test was used to test similarity/difference between contrast doses given to each patient group.

Results:

Overall, 312 patients on dialysis received OM and eight (2.6%) developed NSF (95% CI: 1.30%–4.98%). In all, 784 patients on dialysis received MH at a mean cumulative dose of 0.11 mmol/kg (0.05–0.75 mmol/kg) and no cases of NSF were identified (upper 95% confidence bound of 0.45%). The mean cumulative dose of OM was 0.16 mmol/kg (0.1–0.9 mmol/kg) for all patients and 0.28 mmol/kg (0.1–0.8 mmol/kg) for the patients with NSF. The median OM dose was greater in patients who developed NSF (P = 0.03), and was greater than the median MH dose (P < 0.005).

Conclusion:

NSF incidence in at‐risk patients receiving contrast‐enhanced MRI can be reduced after changing contrast administration protocols that includes changing the type and dose of contrast agent. J. Magn. Reson. Imaging 2010; 31: 440–446. © 2010 Wiley‐Liss, Inc.
High resolution noncontrast MRI of the hip
Authors: Potter Hollis G. , Schachar Jennifer
Published: January 2010

The relatively thin cartilage of the hip joint, as well as its complex geometry, poses challenges for standardized, reproducible assessment of cartilage and the acetabular labrum. With appropriate pulse sequence parameters, however, accurate, reproducible assessment of cartilage and the labrum is feasible. More detailed evaluation of cartilage biochemistry may be obtained with techniques aimed at noninvasively evaluating the integrity of collagen and/or proteoglycan components in the articular cartilage. One of the benefits of noncontrast techniques lie in the ability to visualize the native synovium, and thereby detect the presence of synovial proliferative disorders, the clinical symptoms of which may mimic a labral tear or traumatic cartilage injury. Standard cartilage evaluation allows for the detection of surface delamination and osteoarthritis in the setting of femoroacetabular impingement, as well as subtle areas of subchondral collapse and secondary delamination of cartilage in the setting of osteonecrosis. This preserves the use of hip arthroscopy as a therapeutic rather than a diagnostic tool. J. Magn. Reson. Imaging 2010; 31: 268–278. ©2010 Wiley‐Liss, Inc.
Measuring perfusion and permeability in renal cell carcinoma with dynamic contrast‐enhanced MRI: A pilot study
Authors: Notohamiprodjo Mike , Sourbron Steven , Staehler Michael , Michaely Henrik J. , Attenberger Ulrike I. , Schmidt Gerwin P. , Boehm Holger , Horng Annie , Glaser Christian , Stief Christian , Reiser Maximilian F. , Herrmann Karin A.
Published: January 2010

Purpose:

To retrospectively assess an improved quantitative methodology with separate assessment of perfusion and permeability for characterization of primary renal cell carcinoma (RCC) and monitoring antiangiogenic treatment.

Materials and Methods:

Fifteen RCC patients before surgery, 6 RCC patients before and after neoadjuvant antiangiogenic therapy, and 15 patients without renal disease underwent dynamic contrast‐enhanced (DCE)‐MRI of the kidney with integrated retrospective respiratory triggering and an individual arterial input function. Tracer kinetic analysis was performed with a two‐compartment‐filtration‐model for the kidney data and a two‐compartment‐exchange‐model for the tumor data, providing four independent parameters: the perfusion‐parameters plasma flow (FP) and plasma volume (VP), and the permeability‐parameters extraction flow (FE) and extravascular‐extracellular volume (VE).

Results:

In tumors FP and FE were significantly lower than in normal kidneys. Tracer kinetic analysis displayed hemodynamic alteration caused by vessel infiltration or necrosis. Papillary RCC could be differentiated from clear‐cell variants by a distinct perfusion pattern. In antiangiogenically treated RCC VE was not significantly decreased, while the perfusion parameters VP and FP were significantly diminished.

Conclusion:

DCE‐MRI with integrated motion compensation enables evaluation of primary RCC and detects distinct perfusion patterns. Quantification with a two‐compartment‐exchange‐model produces a separate perfusion‐ and permeability characterization and may become a diagnostic tool to monitor antiangiogenic treatment. J. Magn. Reson. Imaging 2010; 31: 490–501. © 2010 Wiley‐Liss, Inc.
Measurement of brain iron distribution in Hallevorden‐Spatz syndrome
Authors: Szumowski Jerzy , Bas Erhan , Gaarder Kirsten , Schwarz Erwin , Erdogmus Deniz , Hayflick Susan
Published: January 2010

Purpose:

To investigate spatial distribution of iron accumulation in the globus pallidus (GP) in patients with Hallevorden‐Spatz syndrome (HSS) using phase imaging. We compared sensitivity of a phase imaging technique to relaxation rate measurement methods (R1,R2,R2*) for iron quantification.

Materials and Methods:

R1, R2, and R2* were measured in GP structure of the brain of eight pantothenate kinase‐associated neurodegeneration (PKAN) patients and a healthy volunteer using a 3T magnetic resonance imaging (MRI) scanner. The phase of gradient‐echo images was preprocessed to eliminate phase 2π wrapping and filtered to remove phase background variations. Phase gap across GP structure was used as a metric for iron effects quantification.

Results:

Among the relaxation rates the most sensitive to iron accumulation was the R2* rate. The R1 and R2 rates demonstrated only small variations in this group of subjects. Up to an order of magnitude phase gap changes were measured between one PKAN patient and an age‐matched healthy volunteer. Assuming that phase gap differences scale linearly with iron concentration we estimate that up to 2 mg Fe/g ww accumulates in GP of these patients.

Conclusion:

Our results demonstrate significantly higher sensitivity of the phase measurements for quantitative assessment of iron concentration compared to the relaxation rate measurements. Phase measurements could potentially be used for monitoring a progression and a response to therapy in PKAN. J. Magn. Reson. Imaging 2010; 31: 482–489. © 2010 Wiley‐Liss, Inc.
Comparison of gadodiamide‐enhanced MR angiography to intraarterial digital subtraction angiography for evaluation of renal artery stenosis: Results of a phase III multicenter trial
Authors: Garovic Vesna D. , Achauer Manuela A. , Kittner Thomas , Horák David , Sheng Rubin , Stanson Anthony W.
Published: January 2010

Purpose:

To evaluate the efficacy and safety of 0.1 mmol/kg gadodiamide administration for contrast‐enhanced magnetic resonance angiography (MRA) in detecting hemodynamically relevant renal artery stenosis (RAS) when compared with intraarterial digital subtraction angiography (IA‐DSA) as the gold standard.

Materials and Methods:

In a multicenter, controlled study, 395 patients with suspected or known RAS were included. Three independent readers evaluated the MRA images. Two readers evaluated the IA‐DSA images and subsequently achieved consensus. The sensitivities and specificities of gadodiamide‐enhanced MRA were analyzed at the per‐patient and per‐vessel levels (exact 1‐sided binomial test at α = 0.025 with 95% confidence interval).

Results:

A total of 335 patients who had available standard of truth and MRA tests were included in the all‐subjects efficacy population: 55.5% (186/335) men and 44.5% women with a mean age of 63 ± 13 years (range 17–85 years). The sensitivities and specificities ranged from 81% to 86% for all independent readers at the per‐patient analysis based on subjects with the diagnostic images. Similar results were achieved with per‐vessel level analysis. Fewer than 1% of patients had adverse event associated with gadodiamide administration. There were no cases of nephrogenic systemic fibrosis (NSF) reported.

Conclusion:

Gadodiamide administration at the labeled dose of 0.1 mmol/kg for contrast‐enhanced MRA achieved equivalent results compared to IA‐DSA in evaluation of RAS and was well tolerated. J. Magn. Reson. Imaging 2010; 31: 390–397. © 2010 Wiley‐Liss, Inc.
Quantification of 3D regional myocardial wall thickening from gated magnetic resonance images
Authors: Prasad Mithun , Ramesh Amit , Kavanagh Paul , Tamarappoo Balaji K. , Nakazato Ryo , Gerlach James , Cheng Victor , Thomson Louise E.J. , Berman Daniel S. , Germano Guido , Slomka Piotr J.
Published: January 2010

Purpose:

To develop 3D quantitative measures of regional myocardial wall motion and thickening using cardiac magnetic resonance imaging (MRI) and to validate them by comparison to standard visual scoring assessment.

Materials and Methods:

In all, 53 consecutive subjects with short‐axis slices and mid‐ventricular 2‐chamber/4‐chamber views were analyzed. After correction for breath‐hold‐related misregistration, 3D myocardial boundaries were fitted to images and edited by an imaging cardiologist. Myocardial thickness was quantified at end‐diastole and end‐systole by computing the 3D distances using Laplace's equation. 3D thickening was represented using the standard 17‐segment polar coordinates. 3D thickening was compared with 3D wall motion and with expert visual scores (6‐point visual scoring of wall motion and wall thickening; 0 = normal; 5 = greatest abnormality) assigned by imaging cardiologists.

Results:

Correlation between ejection fraction and thickening measurements was (r = 0.84; P < 0.001) compared to correlation between ejection fraction and motion measurements (r = 0.86; P < 0.001). Good negative correlation between summed visual scores and global wall thickening and motion measurements were also obtained (rthick = −0.79; rmotion = −0.74). Additionally, overall good correlation between individual segmental visual scores with thickening/wall motion (rthick = −0.69; rmotion = −0.65) was observed (P < 0.0001).

Conclusion:

3D quantitative regional thickening and wall motion measures obtained from MRI correlate strongly with expert clinical scoring. J. Magn. Reson. Imaging 2010; 31: 317–327. © 2010 Wiley‐Liss, Inc.
PC HYPR flow: A technique for rapid imaging of contrast dynamics
Authors: Velikina Julia V. , Johnson Kevin M. , Wu Yijing , Samsonov Alexey A. , Turski Patrick , Mistretta Charles A.
Published: January 2010

Purpose:

To improve spatial and temporal resolution and signal‐to‐noise ratio (SNR) in three‐dimensional (3D) radial contrast‐enhanced (CE) time‐resolved MR angiography by means of a novel hybrid phase contrast (PC) and CE MRA acquisition and HYPR reconstruction (PC HYPR Flow).

Materials and Methods:

PC HYPR Flow consists of a CE exam immediately followed by a PC scan used to constrain the HYPR reconstruction of the time series. Temporal resolution of the new method was studied in computer simulations. The feasibility of the new technique was studied in healthy subjects and patients with brain arteriovenous malformations and in a canine model of aneurysms.

Results:

Simulations demonstrated preservation of contrast agent dynamics in proximal vessels, showing better performance than peer methods for acceleration up to 20 in 2D. In vivo, PC HYPR Flow yielded 3D time series with frame rate of 0.5 s and significantly outperformed two peer methods by means of a major increase in spatial resolution (0.8 × 0.8 × 0.8 mm3) and arterial/venous ratio, while maintaining necessary temporal waveform fidelity and high SNR.

Conclusion:

This initial study indicates that PC HYPR Flow simultaneously provides 3D isotropic sub‐millimeter spatial resolution, sub‐second temporal reconstruction windows and high SNR level, which may benefit a wide range of CE MRA applications. J. Magn. Reson. Imaging 2010; 31: 447–456. © 2010 Wiley‐Liss, Inc.
Topography mapping of whole body adipose tissue using A fully automated and standardized procedure
Authors: Würslin Christian , Machann Jürgen , Rempp Hansjörg , Claussen Claus , Yang Bin , Schick Fritz
Published: January 2010

Purpose:

To obtain quantitative measures of human body fat compartments from whole body MR datasets for the risk estimation in subjects prone to metabolic diseases without the need of any user interaction or expert knowledge.

Materials and Methods:

Sets of axial T1‐weighted spin‐echo images of the whole body were acquired. The images were segmented using a modified fuzzy c‐means algorithm. A separation of the body into anatomic regions along the body axis was performed to define regions with visceral adipose tissue present, and to standardize the results. In abdominal image slices, the adipose tissue compartments were divided into subcutaneous and visceral compartments using an extended snake algorithm. The slice‐wise areas of different tissues were plotted along the slice position to obtain topographic fat tissue distributions.

Results:

Results from automatic segmentation were compared with manual segmentation. Relatively low mean deviations were obtained for the class of total tissue (4.48%) and visceral adipose tissue (3.26%). The deviation of total adipose tissue was slightly higher (8.71%).

Conclusion:

The proposed algorithm enables the reliable and completely automatic creation of adipose tissue distribution profiles of the whole body from multislice MR datasets, reducing whole examination and analysis time to less than half an hour. J. Magn. Reson. Imaging 2010; 31: 430–439. © 2010 Wiley‐Liss, Inc.
3 tesla MRI of patients with a vagus nerve stimulator: Initial experience using a T/R head coil under controlled conditions
Authors: Gorny Krzysztof R. , Bernstein Matt A. , Watson Robert E.
Published: January 2010

Purpose:

To assess safety of clinical MRI of the head in patients with implanted model 100, 102, and 103 vagus nerve stimulation (VNS) Therapy Systems (Cyberonics, Inc., Houston, TX) in 3.0 Tesla MRI (GE Healthcare, Milwaukee, WI).

Materials and Methods:

The distributions of the radiofrequencyB1+‐field produced by the clinically used transmit/receive (T/R) head coil (Advanced Imaging Research Incorporated, Cleveland, OH) and body coil were measured in a head and shoulders phantom. These measurements were supplemented by temperature measurements on the lead tips and the implantable pulse generator (IPG) of the VNS devices in a head and torso phantom with the same two coils. Clinical 3T MRI head scans were then acquired under highly controlled conditions in a series of 17 patients implanted with VNS.

Results:

Phantom studies showed only weakB1+fields at the location of the VNS IPG and leads for MRI scans using the T/R head coil. The MRI‐related heating on a VNS scanned in vitro at 3T was also found to be minimal (0.4–0.8°C at the leads, negligible at the IPG). The patient MRI examinations were completed successfully without any adverse incidents. No patient reported any heating, discomfort, or any other unusual sensation.

Conclusion:

Safe clinical MRI head scanning of patients with implanted VNS is shown to be feasible on a GE Signa Excite 3T MRI system using one specific T/R head coil. These results apply to this particular MRI system configuration. Extrapolation or generalization of these results to more general or less controlled imaging situations without supporting data of safety is highly discouraged. J. Magn. Reson. Imaging 2010; 31: 475–481. © 2010 Wiley‐Liss, Inc.
Hepatocellular carcinoma: Assessment of response to transarterial chemoembolization with image subtraction
Authors: Kim Sooah , Mannelli Lorenzo , Hajdu Cristina H. , Babb James S. , Clark Timothy W.I. , Hecht Elizabeth M. , Taouli Bachir
Published: January 2010

Purpose:

To assess the diagnostic accuracy of image subtraction compared with nonsubtracted images obtained with contrast‐enhanced T1‐weighted imaging (CE T1WI) for the diagnosis of hepatocellular carcinoma (HCC) necrosis after transarterial chemoembolization (TACE), using liver explant as the reference standard.

Materials and Methods:

Thirty‐four patients who underwent TACE within 90 days of liver transplantation and CE MRI scans were assessed by two independent observers who determined the percentage of tumor necrosis using nonsubtracted and subtracted postcontrast phases. Histopathologic percentage of necrosis was retrospectively determined by an experienced pathologist. Spearman rank correlation test was used to correlate the percentages of necrosis from MR evaluation and from pathology. Receiver operating characteristics curve analysis was performed to determine the performance of subtracted versus nonsubtracted datasets for the diagnosis of complete tumor necrosis.

Results:

There were 57 HCCs (mean size, 2.4 cm; range, 1.2–4.2 cm) diagnosed at explant and identified on MRI, including 16 completely necrotic HCCs. Subtraction demonstrated better interobserver agreement than nonsubtraction dataset for the diagnosis of tumor necrosis. There was a strong correlation between image subtraction and histopathologic assessment of necrosis (r = 0.80–0.86, depending on the phase, P < 0.0001). Subtraction demonstrated significantly higher sensitivity and accuracy for the diagnosis of complete tumor necrosis compared with nonsubtracted dataset.

Conclusion:

Image subtraction enables accurate assessment of necrosis of HCC after TACE with the best accuracy observed at the arterial phase. J. Magn. Reson. Imaging 2010; 31: 348–355. © 2010 Wiley‐Liss, Inc.
Correlations between in vivo 1H MRS and ex vivo 1H HRMAS metabolite measurements in adult human gliomas
Authors: Opstad Kirstie S. , Wright Alan J. , Bell B. Anthony , Griffiths John R. , Howe Franklyn A.
Published: January 2010

Purpose:

To assess how accurately ex vivo high‐resolution magic angle spinning (HRMAS) proton magnetic resonance spectroscopy (1H MRS) from small biopsy tissues relate to in vivo 1H MRS (from larger tumor volumes) in human astrocytomas.

Materials and Methods:

In vivo (PRESS, TE = 30 msec) and ex vivo (presaturation) 1H spectra of 17 human astrocytomas (4 grade II, 1 grade III and 12 glioblastomas) were quantified using LCModel. Concentrations of 11 metabolites and 2 lipid/macromolecules were retrospectively compared, with histogram analysis of the in vivo MRI data used to evaluate tumor heterogeneity.

Results:

For homogeneous‐appearing tumors, significant correlations were found between in vivo and ex vivo 1H MRS concentrations of those metabolites known to be metabolically stable in postmortem tissues (eg, creatine, myo‐inositol, total cholines, and the ≈1.3 and 0.9 ppm lipids). Anaerobic glycolysis during biopsy surgical removal depletes the tissue of glucose, increasing alanine and lactate, and resulted in no correlation between these in vivo and ex vivo metabolite concentrations.

Conclusion:

Within defined limitations, ex vivo astrocytoma biopsy HRMAS 1H spectra have similar metabolic profiles to that obtained in vivo and therefore detailed ex vivo characterization of glioma biopsies can directly relate to the original tumor. J. Magn. Reson. Imaging 2010; 31: 289–297. © 2010 Wiley‐Liss, Inc.
Improved blood suppression in three‐dimensional (3D) fast spin‐echo (FSE) vessel wall imaging using a combination of double inversion‐recovery (DIR) and diffusion sensitizing gradient (DSG) preparations
Authors: Makhijani Mahender K. , Hu Houchun H. , Pohost Gerry M. , Nayak Krishna S.
Published: January 2010

Purpose:

To provide improved blood suppression in three‐dimensional inner‐volume fast spin‐echo (3D IV‐FSE) carotid vessel wall imaging by using a hybrid preparation consisting of double inversion‐recovery (DIR) and diffusion sensitizing gradients (DSG).

Materials and Methods:

Multicontrast black‐blood MRI is widely used for vessel wall imaging and characterization of atherosclerotic plaque composition. Blood suppression is difficult when using 3D volumetric imaging techniques. DIR approaches do not provide robust blood suppression due to incomplete replacement of blood spins, and DSG approaches compromise vessel wall signal, reducing the lumen‐wall contrast‐to‐noise ratio efficiency (CNReff). In this work a hybrid DIR+DSG preparation is developed and optimized for blood suppression, vessel wall signal preservation, and vessel‐wall contrast in 3D IV‐FSE imaging. Cardiac gated T1‐weighted carotid vessel wall images were acquired in five volunteers with 0.5 × 0.5 × 2.5 mm3 spatial resolution in 80 seconds.

Results:

Data from healthy volunteers indicate that the proposed method yields a statistically significant (P < 0.01) improvement in blood suppression and lumen‐wall CNReff compared to standard DIR and standard DSG methods alone.

Conclusion:

A combination of DIR and DSG preparations can provide improved blood suppression and lumen‐wall CNReff for 3D IV‐FSE vessel wall imaging. J. Magn. Reson. Imaging 2010; 31: 398–405. © 2010 Wiley‐Liss, Inc.
MRI measurements of carotid plaque in the atherosclerosis risk in communities (ARIC) study: Methods, reliability and descriptive statistics
Authors: Wasserman Bruce A. , Astor Brad C. , Sharrett A. Richey , Swingen Cory , Catellier Diane
Published: January 2010

Purpose:

To measure carotid plaque components using MRI and estimate reliability in the population‐based Atherosclerosis Risk in Communities (ARIC) study.

Materials and Methods:

Contrast‐enhanced high‐resolution (0.51 × 0.58 × 2 mm3) MRI images were acquired through internal (ICA) and common carotid arteries (CCA) of 2066 ARIC participants at four sites. Sixty‐one exams were repeated and 164 pairs had repeated interpretations. Plaque component thicknesses, areas and volumes over eight slices (1.6‐cm segment) were measured. Intraplaque hemorrhage was recorded. Reliability was evaluated by intraclass correlations and κ statistics.

Results:

There were 1769 successful MRI exams (mean age 71 years; 57% females; 81% white; 19% African‐Americans). Repeat scan reliability was highest for CCA lumen area (0.94) and maximum wall thickness (0.89), ICA lumen area (0.89) and maximum wall thickness (0.77) and total wall volume (0.79), and lowest for small structures—core volume (0.30) and mean cap thickness (0.38). Overall reliability was primarily related to reader variability rather than scan acquisition. K's for presence of core, calcification and hemorrhage were fair to good. White men had the thickest plaques (average maximum ICA wall thickness = 2.3 mm) and the most cores (34%).

Conclusion:

The most important limiting factor for MRI measurements of plaque components is reader variability. Measurement error depends largely on the analyzed structure's size. J. Magn. Reson. Imaging 2010; 31: 406–415. © 2010 Wiley‐Liss, Inc.