bluuebunny/crossref_metadata_2025_split huggingface dataset:
Routine 3D magnetic resonance imaging of joints
Authors: Kijowski Richard , Gold Garry E. 
Published: March 2011

AbstractDue to its high spatial resolution and excellent tissue contrast, magnetic resonance imaging (MRI) has become the most commonly used imaging method to evaluate joints. Most musculoskeletal MRI is performed using 2D fast spin‐echo sequences. However, 3D sequences have also been used for joint imaging and have the advantage of acquiring thin continuous slices through joints, which reduces the effects of partial volume averaging. With recent advances in MR technology, 3D sequences with isotropic resolution have been developed. These sequences allow high‐quality multiplanar reformat images to be obtained following a single acquisition, thereby eliminating the need to repeat sequences with identical tissue contrast in different planes. Preliminary results on the diagnostic performance of 3D isotropic resolution sequences are encouraging. However, additional studies are needed to determine whether these sequences can replace currently used 2D fast spin‐echo sequences for providing comprehensive joint assessment in clinical practice. J. Magn. Reson. Imaging 2011;33:758–771. © 2011 Wiley‐Liss, Inc.
Magnetization‐prepared IDEAL bSSFP: A flow‐independent technique for noncontrast‐enhanced peripheral angiography
Authors: Çukur Tolga , Shimakawa Ann , Yu Huanzhou , Hargreaves Brian A. , Hu Bob S. , Nishimura Dwight G. , Brittain Jean H. 
Published: March 2011

AbstractPurpose:To propose a new noncontrast‐enhanced flow‐independent angiography sequence based on balanced steady‐state free precession (bSSFP) that produces reliable vessel contrast despite the reduced blood flow in the extremities.Materials and Methods:The proposed technique addresses a variety of factors that can compromise the exam success including insufficient background suppression, field inhomogeneity, and large volumetric coverage requirements. A bSSFP sequence yields reduced signal from venous blood when long repetition times are used. Complex‐sum bSSFP acquisitions decrease the sensitivity to field inhomogeneity but retain phase information, so that data can be processed with the Iterative Decomposition of Water and Fat with Echo Asymmetry and Least‐Squares Estimation (IDEAL) method for robust fat suppression. Meanwhile, frequent magnetization preparation coupled with parallel imaging reduces the muscle and long‐T1 fluid signals without compromising scan efficiency.Results:In vivo flow‐independent peripheral angiograms with reliable background suppression and high spatial resolution are produced. Comparisons with phase‐sensitive bSSFP angiograms (that yield out‐of‐phase fat and water signals, and exploit this phase difference to suppress fat) demonstrate enhanced vessel depiction with the proposed technique due to reduced partial‐volume effects and improved venous suppression.Conclusion:Magnetization‐prepared complex‐sum bSSFP with IDEAL fat/water separation can create reliable flow‐independent angiographic contrast in the lower extremities. J. Magn. Reson. Imaging 2011;33:931–939. © 2011 Wiley‐Liss, Inc.
Effect of MRI strength and propofol sedation on pediatric core temperature change
Authors: Isaacson Diane L. , Yanosky Daniel J. , Jones Richard A. , Dennehy Nancy , Spandorfer Philip , Baxter Amy L. 
Published: March 2011

AbstractPurpose:To determine core body temperature variations in children undergoing MRI exams on 1.5 Tesla (T) and 3T magnetic field strengths and with and without propofol sedation.Materials and Methods:Temporal artery temperatures were prospectively collected on 400 consecutive patients undergoing 1.5 Tesla (T) or 3.0T MRI scans. A cumulative logistic regression model was created using age, weight, MRI protocol, sedation status, pre‐MRI temperature and MRI strength to assess risk of temperature change.Results:For patients with complete pre‐ and post‐MRI temperature data, mean temperatures did not significantly change (−0.0155°C, 95%CI, −0.035, 0.064; n = 385). Temperature changes differed significantly between propofol‐sedated and nonsedated patients (−0.26°C ± .44 versus 0.24°C ± 0.42;P< 0.0001), as did temperature changes for patients on the 3T (0.076°C ± 0.52) versus 1.5T (−0.06°C ± 0.48;P= 0.011). Sedation status, age, MRI strength, and MRI protocol accounted for 44.17% of temperature variance. The temperatures of 15 patients' (3.9%) decreased >1°C; 12 were on the 1.5T. All 7 patients (1.8%) who increased >1°C were non‐sedates.Conclusion:Clinically significant core body temperature change is uncommon in children undergoing MRI with different magnetic field strengths, and with and without propofol sedation. J. Magn. Reson. Imaging 2011;33:950–956. © 2011 Wiley‐Liss, Inc.
Automated ischemic lesion detection in a neonatal model of hypoxic ischemic injury
Authors: Ghosh Nirmalya , Recker Rebecca , Shah Amul , Bhanu Bir , Ashwal Stephen , Obenaus Andre 
Published: March 2011

AbstractPurpose:To develop and compare an automated detection system for ischemic lesions in a neonatal model of bilateral carotid artery occlusion with hypoxia (BCAO‐H) from T2 weighted MRI (T2WI) to the currently used “gold standard” of manual segmentation.Materials and Methods:Forty‐three P10 BCAO‐H rat pups and 8 controls underwent T2WI at 1 day and 28 days. A computational imaging method, Hierarchical Region Splitting (HRS), was developed to automatically and rapidly detect and quantify 3D lesion and normal appearing brain matter (NABM) volumes.Results:HRS quantified lesion and NABM volumes within 15 s in comparison to 3 h for its manual counterpart, with a high correlation for injury (r2 = 0. 95; P = 8.6 × 10−7) and NABM (r2 = 0. 92; P = 1.4 × 10−22). Average lesion volumes for mild, moderate, and severe injuries were 3.85%, 28.85%, and 52.98% for HRS and 0.51%, 24.22%, and 48.74% for manual detection. Lesion volumes and locations were similar for both methods (sensitivity: 0.82, specificity: 0.86, and similarity: 1.47).Conclusion:HRS is an accurate, objective, and rapid method to quantify injury evolution in neonatal hypoxic ischemic injury models. J. Magn. Reson. Imaging 2011;33:772–781. © 2011 Wiley‐Liss, Inc.
Quantification of vertebral bone marrow fat content using 3 tesla MR spectroscopy: Reproducibility, vertebral variation, and applications in osteoporosis
Authors: Li Xiaojuan , Kuo Daniel , Schafer Anne L. , Porzig Anne , Link Thomas M. , Black Dennis , Schwartz Ann V. 
Published: March 2011

AbstractPurpose:To determine the reproducibility of proton MR spectroscopy (1H‐MRS) for assessing vertebral bone marrow adiposity at 3 Tesla (T); to evaluate variation of marrow adiposity at different vertebral levels; and to demonstrate the feasibility of using 1H‐MRS at 3T for evaluating marrow adiposity in subjects with low bone density.Materials and Methods:Single voxel MRS was acquired at vertebral body L1 to L4 at 3T in 51 postmenopausal females including healthy controls (n = 13) and patients with osteoporosis/osteopenia (n = 38). Marrow fat contents were compared between vertebral levels and between groups using analysis of variance (ANOVA). Six subjects were scanned twice to evaluate technique reproducibility.Results:The average coefficient of variation of vertebral marrow fat content quantification was 1.7%. Marrow fat content significantly increased from L1 to L4. The average fat content was significantly elevated in patients with osteoporosis/osteopenia compared with controls, adjusted for age and body mass index (P < 0.05).Conclusion:In vivo MRS at high field strength provides reliable measurement of marrow adiposity with excellent reproducibility and can be a valuable tool for providing complementary information on bone quality and potentially also fracture risk. J. Magn. Reson. Imaging 2011;33:974–979. © 2011 Wiley‐Liss, Inc.
Impact of nonrigid motion correction technique on pixel‐wise pharmacokinetic analysis of free‐breathing pulmonary dynamic contrast‐enhanced MR imaging
Authors: Tokuda Junichi , Mamata Hatsuho , Gill Ritu R. , Hata Nobuhiko , Kikinis Ron , Padera Robert F. , Lenkinski Robert E. , Sugarbaker David J. , Hatabu Hiroto 
Published: March 2011

AbstractPurpose:To investigates the impact of nonrigid motion correction on pixel‐wise pharmacokinetic analysis of free‐breathing DCE‐MRI in patients with solitary pulmonary nodules (SPNs). Misalignment of focal lesions due to respiratory motion in free‐breathing dynamic contrast‐enhanced MRI (DCE‐MRI) precludes obtaining reliable time–intensity curves, which are crucial for pharmacokinetic analysis for tissue characterization.Materials and Methods:Single‐slice 2D DCE‐MRI was obtained in 15 patients. Misalignments of SPNs were corrected using nonrigid B‐spline image registration. Pixel‐wise pharmacokinetic parameters Ktrans, ve, and kep were estimated from both original and motion‐corrected DCE‐MRI by fitting the two‐compartment pharmacokinetic model to the time–intensity curve obtained in each pixel. The “goodness‐of‐fit” was tested with χ2‐test in pixel‐by‐pixel basis to evaluate the reliability of the parameters. The percentages of reliable pixels within the SPNs were compared between the original and motion‐corrected DCE‐MRI. In addition, the parameters obtained from benign and malignant SPNs were compared.Results:The percentage of reliable pixels in the motion‐corrected DCE‐MRI was significantly larger than the original DCE‐MRI (P = 4 × 10−7). Both Ktrans and kep derived from the motion‐corrected DCE‐MRI showed significant differences between benign and malignant SPNs (P = 0.024, 0.015).Conclusion:The study demonstrated the impact of nonrigid motion correction technique on pixel‐wise pharmacokinetic analysis of free‐breathing DCE‐MRI in SPNs. J. Magn. Reson. Imaging 2011;33:968–973. © 2011 Wiley‐Liss, Inc.
Diagnostic usefulness of water‐to‐fat ratio and choline concentration in malignant and benign breast lesions and normal breast parenchyma: An in vivo 1H MRS study
Authors: Thakur Sunitha B. , Brennan Sandra B. , Ishill Nicole M. , Morris Elizabeth A. , Liberman Laura , Dershaw D. David , Bartella Lia , Koutcher Jason A. , Huang Wei 
Published: March 2011

AbstractPurpose:To compare total choline concentrations ([Cho]) and water‐to‐fat (W/F) ratios of subtypes of malignant lesions, benign lesions, and normal breast parenchyma and determine their usefulness in breast cancer diagnosis. Reference standard was histology.Materials and Methods:In this HIPPA compliant study, proton MRS was performed on 93 patients with suspicious lesions (>1 cm) who underwent MRI‐guided interventional procedures, and on 27 prospectively accrued women enrolled for screening MRI. (W/F) and [Cho] values were calculated using MRS data.Results:Among 88 MRS‐evaluable histologically‐confirmed lesions, 40 invasive ductal carcinoma (IDC); 10 invasive lobular carcinoma (ILC); 4 ductal carcinoma in situ (DCIS); 3 invasive mammary carcinoma (IMC); 31 benign. No significant difference observed in (W/F) between benign lesions and normal breast tissue. The area under curve (AUC) of receiver operating characteristic (ROC) curves for discriminating the malignant group from the benign group were 0.97, 0.72, and 0.99 using [Cho], (W/F) and their combination as biomarkers, respectively. (W/F) performs significantly (P < 0.0001;AUC = 0.96) better than [Cho] (AUC = 0.52) in differentiating IDC and ILC lesions.Conclusion:Although [Cho] and (W/F) are good biomarkers for differentiating malignancy, [Cho] is a better marker. Combining both can further improve diagnostic accuracy. IDC and ILC lesions have similar [Cho] levels but are discriminated using (W/F) values. J. Magn. Reson. Imaging 2011;33:855–863. © 2011 Wiley‐Liss, Inc.
Multimode intravascular RF coil for MRI‐guided interventions
Authors: Kurpad Krishna N. , Unal Orhan 
Published: March 2011

AbstractPurpose:To demonstrate the feasibility of using a single intravascular radiofrequency (RF) probe connected to the external magnetic resonance imaging (MRI) system via a single coaxial cable to perform active tip tracking and catheter visualization and high signal‐to‐noise ratio (SNR) intravascular imaging.Materials and Methods:A multimode intravascular RF coil was constructed on a 6F balloon catheter and interfaced to a 1.5T MRI scanner via a decoupling circuit. Bench measurements of coil impedances were followed by imaging experiments in saline and phantoms.Results:The multimode coil behaves as an inductively coupled transmit coil. The forward‐looking capability of 6 mm was measured. A greater than 3‐fold increase in SNR compared to conventional imaging using optimized external coil was demonstrated. Simultaneous active tip tracking and catheter visualization was demonstrated.Conclusion:It is feasible to perform 1) active tip tracking, 2) catheter visualization, and 3) high SNR imaging using a single multimode intravascular RF coil that is connected to the external system via a single coaxial cable. J. Magn. Reson. Imaging 2011;33:995–1002. © 2011 Wiley‐Liss, Inc.
Improved spatial coverage for brain 3D PRESS MRSI by automatic placement of outer‐volume suppression saturation bands
Authors: Ozhinsky Eugene , Vigneron Daniel B. , Nelson Sarah J. 
Published: March 2011

AbstractPurpose:To develop a technique for optimizing coverage of brain 3D 1H magnetic resonance spectroscopic imaging (MRSI) by automatic placement of outer‐volume suppression (OVS) saturation bands (sat bands) and to compare the performance for point‐resolved spectroscopic sequence (PRESS) MRSI protocols with manual and automatic placement of sat bands.Materials and Methods:The automated OVS procedure includes the acquisition of anatomic images from the head, obtaining brain and lipid tissue maps, calculating optimal sat band placement, and then using those optimized parameters during the MRSI acquisition. The data were analyzed to quantify brain coverage volume and data quality.Results:3D PRESS MRSI data were acquired from three healthy volunteers and 29 patients using protocols that included either manual or automatic sat band placement. On average, the automatic sat band placement allowed the acquisition of PRESS MRSI data from 2.7 times larger brain volumes than the conventional method while maintaining data quality.Conclusion:The technique developed helps solve two of the most significant problems with brain PRESS MRSI acquisitions: limited brain coverage and difficulty in prescription. This new method will facilitate routine clinical brain 3D MRSI exams and will be important for performing serial evaluation of response to therapy in patients with brain tumors and other neurological diseases. J. Magn. Reson. Imaging 2011;33:792–802. © 2011 Wiley‐Liss, Inc.
Fast monitoring of T1, T2, and relative proton density (M0) changes in skeletal muscles using an IR‐TrueFISP sequence
Authors: de Sousa Paulo Loureiro , Vignaud Alexandre , Fleury Servanne , Carlier Pierre G. 
Published: March 2011

AbstractPurpose:To investigate the feasibility of fast and simultaneous assessment of T1, T2, and M0 (relative proton density) changes in skeletal muscle studies using an inversion recovery true fast imaging with steady‐state precession (TrueFISP) sequence.Materials and Methods:NMR signal dynamics in calf muscles were analyzed under four different conditions: intravenous injection of a low‐molecular weight Gd contrast agent (CA), postarterial occlusion reactive hyperemia, local cooling, and an exercise bout. Experiments were conducted on a clinical 3T whole‐body scanner.Results:At rest, average muscle T1 and T2 values obtained from the IR‐TrueFISP experiments were 1.34 ± 0.13 seconds and 45 ± 5 msec, respectively (median ± standard deviation). 1) Noticeable T1 decreases (ΔT1 max ≈−30%) were measured in the calf muscles after CA injection, while no significant changes were observed for T2 and M0. 2) T2 increased rapidly during reactive hyperemia and reached a peak value (+6%) at about 1 minute postischemia. During ischemia, a significant decrease was observed only in the soleus muscle. No significant paradigm‐related changes in M0 and T1 were noted in all muscle groups, except in the m. soleus (ΔT1 ≈+1% during reactive hyperemia). 3) Opposite variations in muscle T1 (ΔT1 max ≈−30%) and M0 (ΔM0 max ≈+25%) associated with local cooling were detected. 4) Concomitant changes in T1 (ΔT1 max ≈+15%), T2 (ΔT2 max ≈+35%), and M0 (ΔM0 max ≈+16%) were observed in the activated muscles following the exercise bout.Conclusion:IR‐TrueFISP was sufficiently fast and sensitive to detect small and transient T1, T2, and M0 changes in the calf muscles under different experimental conditions. The sequence offers a time‐resolution adequate to track rapid physiological adaptations in skeletal muscle. J. Magn. Reson. Imaging 2011;33:921–930. © 2011 Wiley‐Liss, Inc.
Choline metabolism, proliferation, and angiogenesis in nonenhancing grades 2 and 3 astrocytoma
Authors: McKnight Tracy R. , Smith Kenneth J. , Chu Philip W. , Chiu King S. , Cloyd Colleen P. , Chang Susan M. , Phillips Joanna J. , Berger Mitchel S. 
Published: March 2011

AbstractPurpose:To study choline metabolism in biopsies from nonenhancing Grade 2 (AS2) and Grade 3 (AS3) astrocytomas to determine whether (1) phosphocholine (PC) dominates in AS3, and (2) PC is associated with proliferation or angiogenesis. PC and glycerophosphocholine (GPC) are involved in phospholipid metabolism that accompanies mitosis. PC is the predominant peak in Grade 4 astrocytoma (GBM) while GPC dominates in AS2.Materials and Methods:We used high resolution magic angle spinning magnetic resonance spectroscopy to compare the concentrations of 10 metabolites in 41 biopsies (16 AS2 and 25 AS3) from 24 tumors. Immunohistochemistry was performed on paired biopsies to determine the cell density, Ki‐67 proliferation index, and vascular endothelial growth factor (VEGF) angiogenic marker expression.Results:AS3 had higher PC than AS2; however, the PC:GPC was less than 1 in all cases irrespective of tumor grade. Within tumors, GPC increased with Ki‐67 and PC and tCho increased with cell density. There was no association between any choline compound and VEGF.Conclusion:These data suggest that PC:GPC less than 1 is not unique to low grade glioma. Furthermore, the PC concentration that is a marker of aggressive glial tumors is not tightly linked to cell proliferation or angiogenesis in nonenhancing astrocytomas. J. Magn. Reson. Imaging 2011;33:808–816. © 2011 Wiley‐Liss, Inc.
Predictive model to describe water migration in cellular solid foods during storage
Authors: Voogt Juliën A , Hirte Anita , Meinders Marcel BJ 
Published: March 2011

AbstractBACKGROUND: Water migration in cellular solid foods during storage causes loss of crispness. To improve crispness retention, physical understanding of this process is needed. Mathematical models are suitable tools to gain this physical knowledge.RESULTS: Water migration in cellular solid foods involves migration through both the air cells and the solid matrix. For systems in which the water migration distance is large compared with the cell wall thickness of the solid matrix, the overall water flux through the system is dominated by the flux through the air. For these systems, water migration can be approximated well by a Fickian diffusion model. The effective diffusion coefficient can be expressed in terms of the material properties of the solid matrix (i.e. the density, sorption isotherm and diffusion coefficient of water in the solid matrix) and the morphological properties of the cellular structure (i.e. water vapour permeability and volume fraction of the solid matrix). The water vapour permeability is estimated from finite element method modelling using a simplified model for the cellular structure.CONCLUSION: It is shown that experimentally observed dynamical water profiles of bread rolls that differ in crust permeability are predicted well by the Fickian diffusion model. Copyright © 2011 Society of Chemical Industry
Interactive effects of vegetation structure and composition describe bird habitat associations in mixed broadleaf–conifer forest
Authors: Seavy Nathaniel E. , Alexander John D. 
Published: March 2011

AbstractThe effects that changes in forest structure and composition have on wildlife have often been considered independently, such that the potential for interactive effects has received relatively little attention. We investigated the importance of vegetation structure, floristic composition, and their interaction for predicting bird distribution in mixed broadleaf–conifer forest. We collected vegetation and bird data at 979 stations in a watershed in southern Oregon in the spring of 2001. At each station, we described the vegetation using measures of structure (total vegetation volume) and of floristic composition (broadleaf–conifer composition). We then used logistic regression to model the probability of occurrence of bird species as a function of these 2 variables, their quadratic terms, and their interaction. Using stepwise model selection we identified the best model for each species and used area under the curve (AUC) scores to evaluate model performance. Of the 44 bird species we investigated, 20 had models with AUC scores ≥0.70. Of the best models for these 20 species, 1 included vegetation composition alone, 12 included just the main effects of vegetation composition and structure, and 7 included both the main effects and interaction terms. In summer of 2001 a wildfire burned 2,500 ha of the study area, resulting in substantial changes in the vegetation structure and composition. We used 4 yr of postfire bird and vegetation surveys to test the predictive performance of the habitat models for 9 species that occurred at >15% of the burned stations. Models for 3 of these species performed poorly (AUC < 0.7) in all 4 yr. For the other 6 species, predictive performance was low in the first year after fire and improved during subsequent years, suggesting a lagged response to changes in vegetation structure and composition. Quantifying the interactive effects of vegetation structure and composition improves our understanding of how birds respond to forest management and large‐scale disturbances, such as wildfires. © 2011 The Wildlife Society.
Spread of plague among black‐tailed prairie dogs is associated with colony spatial characteristics
Authors: Johnson Tammi L. , Cully Jack F. , Collinge Sharon K. , Ray Chris , Frey Christopher M. , Sandercock Brett K. 
Published: March 2011

AbstractSylvatic plague (Yersinia pestis) is an exotic pathogen that is highly virulent in black‐tailed prairie dogs (Cynomys ludovicianus) and causes widespread colony losses and individual mortality rates >95%. We investigated colony spatial characteristics that may influence inter‐colony transmission of plague at 3 prairie dog colony complexes in the Great Plains. The 4 spatial characteristics we considered include: colony size, Euclidean distance to nearest neighboring colony, colony proximity index, and distance to nearest drainage (dispersal) corridor. We used multi‐state mark–recapture models to determine the relationship between these colony characteristics and probability of plague transmission among prairie dog colonies. Annual mapping of colonies and mark–recapture analyses of disease dynamics in natural colonies led to 4 main results: 1) plague outbreaks exhibited high spatial and temporal variation, 2) the site of initiation of epizootic plague may have substantially influenced the subsequent inter‐colony spread of plague, 3) the long‐term effect of plague on individual colonies differed among sites because of how individuals and colonies were distributed, and 4) colony spatial characteristics were related to the probability of infection at all sites although the relative importance and direction of relationships varied among sites. Our findings suggest that conventional prairie dog conservation management strategies, including promoting large, highly connected colonies, may need to be altered in the presence of plague. © 2011 The Wildlife Society