bluuebunny/crossref_metadata_2025_split huggingface dataset:
Single‐breath‐hold multiple‐slice DENSE MRI
Authors: Sigfridsson Andreas , Haraldsson Henrik , Ebbers Tino , Knutsson Hans , Sakuma Hajime 
Published: April 2010

AbstractA method to acquire multiple displacement encoded slices within a single breath hold is presented. Efficiency is improved over conventional DENSE without compromising image quality by readout of multiple slices in the same cardiac cycle, thus utilizing the position‐encoded stimulated echo available in the whole heart. The method was evaluated by comparing strain values obtained using the proposed method to strain values obtained by conventional separate breath‐hold single‐slice DENSE acquisitions. Good agreement (Lagrangian E2 strain bias = 0.000, 95% limits of agreement ± 0.04, root‐mean‐square‐difference 0.02 [9.4% of mean end‐systolic E2]) was found between the methods, indicating that the proposed method can replace a multiple breath‐hold acquisition. Eliminating the need for multiple breath holds reduces the risk of changes in breath‐hold positions or heart rate, results in higher patient comfort, and facilitates inclusion of DENSE in a clinical routine protocol. Magn Reson Med 63:1411–1414, 2010. © 2010 Wiley‐Liss, Inc.
Respiratory and cardiac self‐gated free‐breathing cardiac CINE imaging with multiecho 3D hybrid radial SSFP acquisition
Authors: Liu Jing , Spincemaille Pascal , Codella Noel C. F. , Nguyen Thanh D. , Prince Martin R. , Wang Yi 
Published: April 2010

AbstractA respiratory and cardiac self‐gated free‐breathing three‐dimensional cine steady‐state free precession imaging method using multiecho hybrid radial sampling is presented. Cartesian mapping of the k‐space center along the slice encoding direction provides intensity‐weighted position information, from which both respiratory and cardiac motions are derived. With in plan radial sampling acquired at every pulse repetition time, no extra scan time is required for sampling the k‐space center. Temporal filtering based on density compensation is used for radial reconstruction to achieve high signal‐to‐noise ratio and contrast‐to‐noise ratio. High correlation between the self‐gating signals and external gating signals is demonstrated. This respiratory and cardiac self‐gated, free‐breathing, three‐dimensional, radial cardiac cine imaging technique provides image quality comparable to that acquired with the multiple breath‐hold two‐dimensional Cartesian steady‐state free precession technique in short‐axis, four‐chamber, and two‐chamber orientations. Functional measurements from the three‐dimensional cardiac short axis cine images are found to be comparable to those obtained using the standard two‐dimensional technique. Magn Reson Med 63:1230–1237, 2010. © 2010 Wiley‐Liss, Inc.
Model predictive filtering for improved temporal resolution in MRI temperature imaging
Authors: Todd Nick , Payne Allison , Parker Dennis L. 
Published: April 2010

AbstractA novel method for reconstructing MRI temperature maps from undersampled data is presented. The method, model predictive filtering, combines temperature predictions from a preidentified thermal model with undersampled k‐space data to create temperature maps in near real time. The model predictive filtering algorithm was implemented in three ways: using retrospectively undersampled k‐space data from a fully sampled two‐dimensional gradient echo (GRE) sequence (reduction factors R = 2.7 to R = 7.1), using actually undersampled data from a two‐dimensional GRE sequence (R = 4.8), and using actually undersampled data from a three‐dimensional GRE sequence (R = 12.1). Thirty‐nine high‐intensity focused ultrasound heating experiments were performed under MRI monitoring to test the model predictive filtering technique against the current gold standard for MR temperature mapping, the proton resonance frequency shift method. For both of the two‐dimensional implementations, the average error over the five hottest voxels from the hottest time frame remained between ±0.8°C and the temperature root mean square error over a 24 × 7 × 3 × 25‐voxel region of interest remained below 0.35°C. The largest errors for the three‐dimensional implementation were slightly worse: −1.4°C for the mean error of the five hottest voxels and 0.61°C for the temperature root mean square error. Magn Reson Med 63:1269–1279, 2010. © 2010 Wiley‐Liss, Inc.
Increased anatomical detail by in vitro MR microscopy with a modified Golgi impregnation method
Authors: Zhang Xiaowei , Bearer Elaine L. , Perles‐Barbacaru Adriana T. , Jacobs Russell E. 
Published: April 2010

AbstractGolgi impregnation is unique in its ability to display the dendritic trees and axons of large numbers of individual neurons by histology. Here we apply magnetic resonance microscopy to visualize the neuroanatomy of animal models by combining histologic fixation chemistry with paramagnetic contrast agents. Although there is some differential uptake of the standard small‐molecular‐weight contrast agents by different tissue types, detailed discrimination of tissue architecture in MR images does not approach that of standard histology. Our modified Golgi impregnation method significantly increases anatomic detail in magnetic resonance microscopy images. Fixed mouse brains were treated with a solution containing a paramagnetic contrast agent (gadoteridol) and potassium dichromate. Results demonstrate a specific contrast enhancement likely due to diamagnetic hexavalent chromium undergoing tissue specific reduction to paramagnetic trivalent chromium. This new method dramatically improves neuroanatomical contrast compared to conventional fixation, displaying detail approximating that of histologic specimens at low (4×) magnification. Magn Reson Med 63:1391–1397, 2010. © 2010 Wiley‐Liss, Inc.
In vivo detection of PARACEST agents with relaxation correction
Authors: Jones Craig K. , Li Alex X. , Suchý Mojmír , Hudson Robert H. E. , Menon Ravi S. , Bartha Robert 
Published: April 2010

AbstractSeveral pulse sequences have been used to detect paramagnetic chemical exchange saturation transfer (PARACEST) contrast agents in animals to quantify the uptake over time following a bolus injection. The observed signal change is a combination of relaxation effects and PARACEST contrast. The purpose of the current study was to isolate the PARACEST effect from the changes in bulk water relaxation induced by the PARACEST agent in vivo for the fast low‐angle shot pulse sequence. A fast low‐angle shot–based pulse sequence was used to acquire continuous images on a 9.4‐T MRI of phantoms and the kidneys of mice following PARACEST agent (Tm3+‐DOTAM‐Gly‐Lys) injection. A WALTZ‐16 pulse was applied before every second image to generate on‐resonance paramagnetic chemical exchange effects. Signal intensity changes of up to 50% were observed in the mouse kidney in the control images (without a WALTZ‐16 preparation pulse) due to altered bulk water relaxation induced by the PARACEST agent. Despite these changes, a clear on‐resonance paramagnetic chemical exchange effect of 4‐7% was also observed. A four‐pool exchange model was used to describe image signal intensity. This study demonstrates that in vivo on‐resonance paramagnetic chemical exchange effect contrast can be isolated from tissue relaxation time constant changes induced by a PARACEST agent that dominate the signal change. Magn Reson Med 63:1184–1192, 2010. © 2010 Wiley‐Liss, Inc.
Estimation of global aortic pulse wave velocity by flow‐sensitive 4D MRI
Authors: Markl Michael , Wallis Wolf , Brendecke Stefanie , Simon Jan , Frydrychowicz Alex , Harloff Andreas 
Published: April 2010

AbstractThe aim of this study was to determine the value of flow‐sensitive four‐dimensional MRI for the assessment of pulse wave velocity as a measure of vessel compliance in the thoracic aorta. Findings in 12 young healthy volunteers were compared with those in 25 stroke patients with aortic atherosclerosis and an age‐matched normal control group (n = 9). Results from pulse wave velocity calculations incorporated velocity data from the entire aorta and were compared to those of standard methods based on flow waveforms at only two specific anatomic landmarks. Global aortic pulse wave velocity was higher in patients with atherosclerosis (7.03 ± 0.24 m/sec) compared to age‐matched controls (6.40 ± 0.32 m/sec). Both were significantly (P < 0.001) increased compared to younger volunteers (4.39 ± 0.32 m/sec). Global aortic pulse wave velocity in young volunteers was in good agreement with previously reported MRI studies and catheter measurements. Estimation of measurement inaccuracies and error propagation analysis demonstrated only minor uncertainties in measured flow waveforms and moderate relative errors below 16% for aortic compliance in all 46 subjects. These results demonstrate the feasibility of pulse wave velocity calculation based on four‐dimensional MRI data by exploiting its full volumetric coverage, which may also be an advantage over standard two‐dimensional techniques in the often‐distorted route of the aorta in patients with atherosclerosis. Magn Reson Med, 2010. © 2010 Wiley‐Liss, Inc.
B1 mapping by Bloch‐Siegert shift
Authors: Sacolick Laura I. , Wiesinger Florian , Hancu Ileana , Vogel Mika W. 
Published: April 2010

AbstractA novel method for amplitude of radiofrequency field (B) mapping based on the Bloch‐Siegert shift is presented. Unlike conventionally applied double‐angle or other signal magnitude–based methods, it encodes the B1 information into signal phase, resulting in important advantages in terms of acquisition speed, accuracy, and robustness. The Bloch‐Siegert frequency shift is caused by irradiating with an off‐resonance radiofrequency pulse following conventional spin excitation. When applying the off‐resonance radiofrequency in the kilohertz range, spin nutation can be neglected and the primarily observed effect is a spin precession frequency shift. This shift is proportional to the square of the magnitude of B. Adding gradient image encoding following the off‐resonance pulse allows one to acquire spatially resolved B1 maps. The frequency shift from the Bloch‐Siegert effect gives a phase shift in the image that is proportional to B. The phase difference of two acquisitions, with the radiofrequency pulse applied at two frequencies symmetrically around the water resonance, is used to eliminate undesired off‐resonance effects due to amplitude of static field inhomogeneity and chemical shift. In vivo Bloch‐Siegert B1 mapping with 25 sec/slice is demonstrated to be quantitatively comparable to a 21‐min double‐angle map. As such, this method enables robust, high‐resolution B mapping in a clinically acceptable time frame. Magn Reson Med 63:1315–1322, 2010. © 2010 Wiley‐Liss, Inc.
SWIFT detection of SPIO‐labeled stem cells grafted in the myocardium
Authors: Zhou Rong , Idiyatullin Djaudat , Moeller Steen , Corum Curt , Zhang Hualei , Qiao Hui , Zhong Jia , Garwood Michael 
Published: April 2010

AbstractWe report initial results from studies using sweep imaging with Fourier transformation (SWIFT) to detect superparamagnetic iron oxide (SPIO) particle–labeled stem cells in the rat heart. In experiments performed on phantoms containing titanium balls or SPIO–labeled cells, frequency‐shifted signals surrounding the paramagnetic objects produced a pileup artifact visualized by SWIFT. Total signal intensity was retained to a much greater extent by SWIFT as compared to gradient echo imaging. SWIFT imaging of excised and in vivo hearts showed (a) reduced blooming artifact as compared with gradient echo imaging, which helped reduce ambiguity in the detection of SPIO–labeled cells; (b) enhancement of off‐resonance signals relative to the background in the imaginary component of images; and (c) detailed myocardial anatomy in magnitude images, which provided anatomic reference. These features suggest SWIFT can facilitate the detection of SPIO–laden cells in the cardiovascular system. Magn Reson Med 63:1154–1161, 2010. © 2010 Wiley‐Liss, Inc.
q‐space and conventional diffusion imaging of axon and myelin damage in the rat spinal cord after axotomy
Authors: Farrell Jonathan A. D. , Zhang Jiangyang , Jones Melina V. , DeBoy Cynthia A. , Hoffman Paul N. , Landman Bennett A. , Smith Seth A. , Reich Daniel S. , Calabresi Peter A. , van Zijl Peter C. M. 
Published: April 2010

AbstractParallel and perpendicular diffusion properties of water in the rat spinal cord were investigated 3 and 30 days after dorsal root axotomy, a specific insult resulting in early axonal degeneration followed by later myelin damage in the dorsal column white matter. Results from q‐space analysis (i.e., the diffusion probability density function) obtained with strong diffusion weighting were compared to conventional anisotropy and diffusivity measurements at low b‐values, as well as to histology for axon and myelin damage. q‐Space contrasts included the height (return to zero displacement probability), full width at half maximum, root mean square displacement, and kurtosis excess of the probability density function, which quantifies the deviation from gaussian diffusion. Following axotomy, a significant increase in perpendicular diffusion (with decreased kurtosis excess) and decrease in parallel diffusion (with increased kurtosis excess) were found in lesions relative to uninjured white matter. Notably, a significant change in abnormal parallel diffusion was detected from 3 to 30 days with full width at half maximum, but not with conventional diffusivity. Also, directional full width at half maximum and root mean square displacement measurements exhibited different sensitivities to white matter damage. When compared to histology, the increase in perpendicular diffusion was not specific to demyelination, whereas combined reduced parallel diffusion and increased perpendicular diffusion was associated with axon damage. Magn Reson Med 63:1323–1335, 2010. © 2010 Wiley‐Liss, Inc.
Fast inversion recovery magnetic resonance angiography of the intracranial arteries
Authors: Tan Ek T. , Huston John , Campeau Norbert G. , Riederer Stephen J. 
Published: April 2010

AbstractInversion‐prepared pulse sequences can be used for noncontrast MR angiography (MRA) but suffer from long scan times when acquired using conventional nonaccelerated techniques. This work proposes a subtraction‐based spin‐labeling, three‐dimensional fast inversion recovery MRA (FIR‐MRA) method for imaging the intracranial arteries. FIR‐MRA uses alternating cycles of nonselective and slab‐selective inversions, leading to dark‐blood and bright‐blood images, respectively. The signal difference between these images eliminates static background tissue and generates the angiogram. To reduce scan time, segmented fast gradient recalled echo readout and parallel imaging are applied. The inversion recovery with embedded self‐calibration method used allows for parallel acceleration at factors of 2 and above. An off‐resonance selective inversion provides effective venous suppression, with no detriment to the depiction of arteries. FIR‐MRA was compared against conventional three‐dimensional time‐of‐flight angiography at 3 T in eight normal subjects. Results showed that FIR‐MRA had superior vessel conspicuity in the distal vessels (P < 0.05), and equal or better vessel continuity and venous suppression. However, FIR‐MRA had inferior vessel sharpness (P < 0.05) in four of nine vessel groups. The clinical utility of FIR‐MRA was demonstrated in three MRA patients. Magn Reson Med, 2010. © 2010 Wiley‐Liss, Inc.
Patient reported outcomes: The ICIQ and the state of the art
Authors: Coyne Karin , Kelleher Con 
Published: April 2010

AbstractIntroductionFollowing the first International Consultation on Incontinence (ICI) in 1998, a multidisciplinary committee was established to develop a universally applicable, brief urinary incontinence patient‐reported outcome (PRO) questionnaire: the ICIQ‐UI Short Form. The project was expanded to recommend and develop high quality, validated questionnaires for all lower pelvic dysfunction related to incontinence. The ICI Modular Questionnaire project (ICIQ) was then established to include a wider spectrum of urinary, bowel and vaginal symptoms and their impact on health related quality of life (HRQL). Three aims underpin the ICIQ project:

To recommend high quality, validated PRO questionnaires.
To promote wider use of questionnaires to standardize assessment of lower pelvic dysfunction and its impact on HRQL.
To facilitate communication in different patient settings and patient groups.

ConclusionThe authors, both ICIQ committee members, debated the title. If the conceptualization of the ICIQ is correct, the PROs recommended by the ICIQ need to be under constant evolution and improvement to ensure the aims of the ICIQ project. A modular questionnaire design, recognized and implemented internationally, would add greatly to the universal inclusion, interpretation and understanding of PRO data in clinical practice and clinical research. However, in order to achieve the goals of the ICIQ project, we must ensure that the scientific quality of PRO development, documentation and validation meets current scientific standards, as well as societal and governmental regulatory guidelines. These topics are discussed along with recommendations for future areas of research and need for the ICIQ committee to explore these issues. Neurourol. Urodynam. 29:645–651, 2010. © 2010 Wiley‐Liss, Inc.
Is the urothelium intelligent?
Authors: Birder L.A. , Kanai A.J. , Cruz F. , Moore K. , Fry C.H. 
Published: April 2010

AbstractThe urothelium separates the urinary tract lumen from underlying tissues of the tract wall. Previously considered as merely an effective barrier between these two compartments it is now recognized as a more active tissue that senses and transduces information about physical and chemical conditions within the urinary tract, such as luminal pressure, urine composition, etc. To understand this sensory function it is useful to consider the urothelium and suburothelium as a functional unit; containing uroepithelial cells, afferent and efferent nerve fibers and suburothelial interstitial cells. This structure responds to alterations in its external environment through the release of diffusible agents, such as ATP and acetylcholine, and eventually modulates the activity of afferent nerves and underlying smooth muscles. This review considers different stresses the urothelium/suburothelium responds to; the particular chemicals released; the cellular receptors that are consequently affected; and how nerve and muscle function is modulated. Brief consideration is also to regional differences in the urothelium/suburothelium along the urinary tract. The importance of different pathways in relaying sensory information in the normal urinary tract, or whether they are significant only in pathological conditions is also discussed. An operational definition of intelligence is used, whereby a system (urothelium/suburothelium) responds to external changes, to maximize the possibility of the urinary tract achieving its normal function. If so, the urothelium can be regarded as intelligent. The advantage of this approach is that input–output functions can be mathematically formulated, and the importance of different components contributing to abnormal urinary tract function can be calculated. Neurourol. Urodynam. 29:598–602, 2010. © 2010 Wiley‐Liss, Inc.
Urgency: All or none phenomenon?
Authors: De Wachter Stefan , Hanno Phil 
Published: April 2010

AbstractUrgency is the key symptom of a very prevalent symptom complex, the overactive bladder syndrome. Addressing urgency as a hallmark for detrusor overactivity is for physicians very comfortable, but appears to be an oversimplification of a very complex symptom entity. This overview tries to put the relevant literature on urgency against the question whether urgency is an all or none phenomenon, and summarizes the current views on how urgency is perceived. Neurourol. Urodynam. 29:616–617, 2010. © 2010 Wiley‐Liss, Inc.
Continence products: Research priorities to improve the lives of people with urinary and/or fecal leakage
Authors: Fader Mandy , Bliss Donna , Cottenden Alan , Moore Katherine , Norton Christine 
Published: April 2010

AbstractAlthough many successful treatments for incontinence exist they are not effective or suitable for all people. Inconspicuous and dependable management with continence products and devices plays a crucial part in maintaining quality of life. We aim to briefly review what is known and not known in the field of continence products and devices and set out suggested priorities for research and development. The field of continence product research encompasses techniques and designs from basic laboratory science, through to clinical trials of products and to evaluations of service delivery models. Priorities for research include determining prevalence and costs of product use, development of patient reported outcomes, and development of methods for measuring skin health and for quantifying urine/faecal leakage. Product development priorities include better washable pads for women, absorbent products for fecal incontinence and flatus filters. Clinical trials of different product categories (e.g., devices for men) are needed, as are qualitative studies of patient experiences of product use. Neurourol. Urodynam. 29:640–644, 2010. © 2009 Wiley‐Liss, Inc.
Performance of a Petrov–Galerkin algebraic multilevel preconditioner for finite element modeling of the semiconductor device drift‐diffusion equations
Authors: Lin Paul T. , Shadid John N. , Tuminaro Ray S. , Sala Marzio 
Published: April 2010

AbstractThis study compares the performance of a relatively new Petrov–Galerkin smoothed aggregation (PGSA) multilevel preconditioner with a nonsmoothed aggregation (NSA) multilevel preconditioner to accelerate the convergence of Krylov solvers on systems arising from a drift‐diffusion model for semiconductor devices. PGSA is designed for nonsymmetric linear systems, Ax=b, and has two main differences with smoothed aggregation. Damping parameters for smoothing interpolation basis functions are now calculated locally and restriction is no longer the transpose of interpolation but instead corresponds to applying the interpolation algorithm to AT and then transposing the result. The drift‐diffusion system consists of a Poisson equation for the electrostatic potential and two convection–diffusion‐reaction‐type equations for the electron and hole concentration. This system is discretized in space with a stabilized finite element method and the discrete solution is obtained by using a fully coupled preconditioned Newton–Krylov solver. The results demonstrate that the PGSA preconditioner scales significantly better than the NSA preconditioner, and can reduce the solution time by more than a factor of two for a problem with 110 million unknowns on 4000 processors. The solution of a 1B unknown problem on 24 000 processor cores of a Cray XT3/4 machine was obtained using the PGSA preconditioner. Copyright © 2010 John Wiley & Sons, Ltd.
A Lagrangian finite element approach for the analysis of fluid–structure interaction problems
Authors: Cremonesi M. , Frangi A. , Perego U. 
Published: April 2010

AbstractA Lagrangian finite element method for the analysis of incompressible Newtonian fluid flows, based on a continuous re‐triangulation of the domain in the spirit of the so‐called Particle Finite Element Method, is here revisited and applied to the analysis of the fluid phase in fluid–structure interaction problems. A new approach for the tracking of the interfaces between fluids and structures is proposed. Special attention is devoted to the mass conservation problem. It is shown that, despite its Lagrangian nature, the proposed combined finite element‐particle method is well suited for large deformation fluid–structure interaction problems with evolving free surfaces and breaking waves. The method is validated against the available analytical and numerical benchmarks. Copyright © 2010 John Wiley & Sons, Ltd.