bluuebunny/crossref_metadata_2025_split huggingface dataset:
Intravoxel partially coherent motion technique: Characterization of the anisotropy of skeletal muscle microvasculature
Authors: Karampinos Dimitrios C. , King Kevin F. , Sutton Bradley P. , Georgiadis John G. 
Published: March 2010

AbstractPurpose:To propose a reformulation of the intravoxel incoherent motion (IVIM) technique exploiting the low b‐value diffusion‐weighted imaging regime that can characterize microcirculation of tissues perfused with partially coherent blood flow.Materials and Methods:The new methodology, termed intravoxel partially coherent motion (IVPCM) technique, is suitable for probing microcirculation in tissues with ordered microvasculature, such as skeletal muscle. We employ a subvoxel model utilizing a randomly oriented bundle of straight vessels whose orientation statistics are characterized by a Fisher axial distribution with concentration parameter K quantifying the anisotropy of the distribution (K = 0 indicates isotropic capillary orientation). The methodology is first validated with a proof‐of‐principle phantom experiment and is then applied to analyze the microvasculature of human calf muscle at rest.Results:The microcirculatory part of the diffusion‐weighted signal at b < 200 s/mm2 is anisotropic. The variation of the diffusion‐weighted signal with b‐value exhibits stronger deviation from the expected monoexponential decay when the diffusion encoding gradient is applied parallel to the mean myofiber direction in the calf muscle of three healthy volunteers. The application of the model to data from the medial gastrocnemius and the soleus of the three volunteers gives results within the expected range for the mean microvascular volume fraction, the mean microflow velocity, and the parameter K.Conclusion:The proposed methodology has the capability of characterizing the anisotropy of the capillary network in vivo in a manner analogous to the capability of high b‐value diffusion to characterize the anisotropy of muscle fibers. J. Magn. Reson. Imaging 2010;31:942–953. ©2010 Wiley‐Liss, Inc.
Multiple sclerosis: Hyperintense lesions in the brain on T1‐weighted MR images assessed by diffusion tensor imaging
Authors: Zhou FuQing , Shiroishi Mark , Gong HongHan , Zee Chi‐Shing 
Published: March 2010

AbstractPurpose:To evaluate retrospectively quantitative diffusion tensor imaging (DTI) values of hyperintense lesions on nonenhanced T1‐weighted magnetic resonance (MR) images in patients with multiple sclerosis (MS) to elucidate the degree of demyelination or remyelination associated with T1 hyperintense lesions and study their relationship to MR markers of tissue damage (brain atrophy).Materials and Methods:Institutional review board approval was obtained; informed consent was waived for this HIPAA‐compliant study, including 76 patients with MS and 20 healthy control subjects without evidence of MS clinically or on imaging. T1 lesions were compared with normal white matter on nonenhanced images and judged to be hyperintense. Quantitative DTI metrics of T1 hyperintense lesions were examined, and the relationship between DTI parameters and brain atrophy were investigated in this study.Results:At least one T1 hyperintense lesion was found in 16 patients (total, 28 lesions). Hyperintense lesions on T1‐weighted imaging (T1WI) had lower mean diffusion (MD) than others signal intensity lesions on T1WI but higher MD than normal white matter (F = 3.931; P < 0.001); Fractional anisotropy (FA; F = 3.24; P < 0.001) and volume ratio (VR; F = 1.664; P < 0.001) were higher in hyperintense lesions on T1WI than hypointense/isointense lesions on T1WI, but were lower than normal‐appearing white matter (NAWM) and normal white matter in controls. There was correlation between FA and VR (r = 0.678; P < 0.001) and inverse correlation between FA and MD (r = −0.437; P = 0.02), MD and VR (r = −0.423; P 0.025) for T1 hyperintense lesion. The MD values of T1 hyperintense lesions (r = −0.304; P < 0.001) and the VR values of T1 hyperintense lesions (r = 0.096; P = 0.042) were significantly (negative) correlated with Brain parenchymal fraction (BPF; higher BPF score); the FA values of T1 hyperintense lesions (r = −0.111; P = 0.018), the MD values of T1 hyperintense lesions (r = 0.379; P < 0.001) and the VR values of T1 hyperintense lesions (r = −0.142; P = 0.003) were significantly correlated with third ventricular width (lower width). However, the FA value of T1 hyperintense lesions was not significantly associated with BPF(r = 0.083; P = 0.08).Conclusion:The quantitative DTI values of T1 hyperintense MS plaques were between hypo‐/isointense lesions and NAWM or normal white matter, and correlated with BPF and third ventricular width. Our results supports the notion that axonal remyelination may be the reason for T1 hyperintense lesions. J. Magn. Reson. Imaging 2010;31:789–795. ©2010 Wiley‐Liss, Inc.
Assessing vascular response to exercise using a combination of real‐time spiral phase contrast MR and noninvasive blood pressure measurements
Authors: Steeden Jennifer A. , Atkinson David , Taylor Andrew M. , Muthurangu Vivek 
Published: March 2010

AbstractPurpose:To measure the hemodynamic response to exercise using real‐time velocity mapping magnetic resonance imaging (MRI), incorporating a high temporal resolution spiral phase contrast (PC) sequence accelerated with sensitivity encoding (SENSE).Materials and Methods:Twenty healthy adults underwent MRI at rest and during supine exercise at two different exercise levels. Flow volumes were assessed in the ascending aorta using a spiral SENSE real‐time PC sequence. The sequence was validated at rest against a vendor supplied gated PC sequence, and also at rest and during exercise against left ventricular volumes assessed using a radial k‐t SENSE real‐time sequence. Combining the measured flow volumes with simultaneous oscillometric blood pressure measurements, enabled the noninvasive calculations of systemic vascular resistance (SVR) and arterial compliance (C).Results:Measured flow volumes correlated very well between the sequences at rest and during exercise. Cardiac output (CO) and heart rate were found to significantly increase during exercise, while SVR and C were found to decrease significantly.Conclusion:Hemodynamic response to exercise can be accurately quantified using a high temporal resolution spiral SENSE real‐time flow imaging. This may allow early detection of hypertension and a greater understanding of the early changes in this condition. J. Magn. Reson. Imaging 2010;31:997–1003. ©2010 Wiley‐Liss, Inc.
Accelerated slice encoding for metal artifact correction
Authors: Hargreaves Brian A. , Chen Weitian , Lu Wenmiao , Alley Marcus T. , Gold Garry E. , Brau Anja C.S. , Pauly John M. , Pauly Kim Butts 
Published: March 2010

AbstractPurpose:To demonstrate accelerated imaging with both artifact reduction and different contrast mechanisms near metallic implants.Materials and Methods:Slice‐encoding for metal artifact correction (SEMAC) is a modified spin echo sequence that uses view‐angle tilting and slice‐direction phase encoding to correct both in‐plane and through‐plane artifacts. Standard spin echo trains and short‐TI inversion recovery (STIR) allow efficient PD‐weighted imaging with optional fat suppression. A completely linear reconstruction allows incorporation of parallel imaging and partial Fourier imaging. The signal‐to‐noise ratio (SNR) effects of all reconstructions were quantified in one subject. Ten subjects with different metallic implants were scanned using SEMAC protocols, all with scan times below 11 minutes, as well as with standard spin echo methods.Results:The SNR using standard acceleration techniques is unaffected by the linear SEMAC reconstruction. In all cases with implants, accelerated SEMAC significantly reduced artifacts compared with standard imaging techniques, with no additional artifacts from acceleration techniques. The use of different contrast mechanisms allowed differentiation of fluid from other structures in several subjects.Conclusion:SEMAC imaging can be combined with standard echo‐train imaging, parallel imaging, partial‐Fourier imaging, and inversion recovery techniques to offer flexible image contrast with a dramatic reduction of metal‐induced artifacts in scan times under 11 minutes. J. Magn. Reson. Imaging 2010;31:987–996. ©2010 Wiley‐Liss, Inc.
Artifact‐reduced two‐dimensional cine steady state free precession for myocardial blood‐ oxygen‐level‐dependent imaging
Authors: Zhou Xiangzhi , Tsaftaris Sotirios A. , Liu Ying , Tang Richard , Klein Rachel , Zuehlsdorff Sven , Li Debiao , Dharmakumar Rohan 
Published: March 2010

AbstractPurpose:To minimize image artifacts in long TR cardiac phase‐resolved steady state free precession (SSFP) based blood‐oxygen‐level‐dependent (BOLD) imaging.Materials and Methods:Nine healthy dogs (four male, five female, 20–25 kg) were studied in a clinical 1.5 Tesla MRI scanner to investigate the effect of temporal resolution, readout bandwidth, and motion compensation on long repetition time (TR) SSFP images. Breath‐held 2D SSFP cine sequences with various temporal resolutions (10–204 ms), bandwidths (239–930 Hz/pixel), with and without first‐order motion compensation were prescribed in the basal, mid‐ventricular, and apical along the short axis. Preliminary myocardial BOLD studies in dogs with controllable coronary stenosis were performed to assess the benefits of artifact‐reduction strategies.Results:Shortening the readout time by means of increasing readout bandwidth had no observable reduction in image artifacts. However, increasing the temporal resolution in the presence of first‐order motion compensation led to significant reduction in image artifacts. Preliminary studies demonstrated that BOLD signal changes can be reliably detected throughout the cardiac cycle.Conclusion:Artifact‐reduction methods used in this study provide significant improvement in image quality compared with conventional long TR SSFP BOLD MRI. It is envisioned that the methods proposed here may enable reliable detection of myocardial oxygenation changes throughout the cardiac cycle with long TR SSFP‐based myocardial BOLD MRI. J. Magn. Reson. Imaging 2010;31:863–871. ©2010 Wiley‐Liss, Inc.
Predicting pathological response to neoadjuvant chemotherapy in breast cancer with quantitative 1H MR spectroscopy using the external standard method
Authors: Tozaki Mitsuhiro , Sakamoto Masaaki , Oyama Yu , Maruyama Katsuya , Fukuma Eisuke 
Published: March 2010

AbstractPurpose:To assess the efficacy of quantitative 1H MR spectroscopy (MRS) using the external standard method to predict the pathological response to neoadjuvant chemotherapy with an anthracycline‐based regimen in breast cancer patients.Materials and Methods:Sixteen patients with breast cancer were included. Tumor response to chemotherapy was evaluated after the second cycle using MRI and MRS. Final histopathology following surgery after four cycles of chemotherapy served as reference.Results:The average normalized choline (Cho) signal was 1.2 (range, 0.40 to 2.8). There were no significant differences in the baseline tumor size and normalized Cho signals between the pathological responders (n = 8) and nonresponders (n = 8). The reduction rates of the normalized Cho signal were statistically significantly different between the pathological responders and nonresponders (P = 0.004), whereas the reduction rates of the lesion size were not significantly different between the two groups. When 40–50% of the reduction rates of the normalized Cho was chosen as the cutoff value, the positive and negative predictive values of MRS were 89% (8/9) and 100% (7/7), respectively.Conclusion:The changes in Cho after the second cycle of chemotherapy as determined by quantitative MRS may be more sensitive than changes in the tumor size to predict the pathological response. J. Magn. Reson. Imaging 2010;31:895–902. ©2010 Wiley‐Liss, Inc.
Sub‐millimeter isotropic MRI for segmentation of subcortical brain regions and brain visualization
Authors: Wu Ying , Ragin Ann B. , Du Hongyan , Sidharthan Shawn , Dunkle Eugene E. , Koktzoglou Ioannis , Edelman Robert R. 
Published: March 2010

AbstractPurpose:To evaluate a rapid sub‐millimeter isotropic spoiled gradient‐echo (nonselective SPGR) to facilitate the brain subcortical segmentation and the visualization of brain volume compared with the commonly accepted inversion recovery‐prepared SPGR (SPGR‐IR) technique.Materials and Methods:The feasibility of the nonselective SPGR was evaluated for two segmentation algorithms. FAST was used to segment the brain into constituent tissue classes (white matter, gray matter, cerebrospinal fluid) and FreeSurfer was used to segment specific subcortical structures (hippocampus, caudate, putamen, and thalamus). Localized apparent signal‐to‐noise ratio (SNR) and contrast‐to‐noise ratio (CNR) values for nonselective SPGR and the SPGR‐IR were compared for the studied subcortical regions. The three‐dimensional volume rendering was generated to evaluate the nonselective SPGR and the SPGR‐IR for brain visualization.Results:In basal ganglia regions, nonselective SPGR allows for consistent segmentation results for both FAST and FreeSurfer. This sequence also better differentiated gray/white matter compared with SPGR‐IR. An approximate two‐fold improvement of image quality in apparent SNR and CNR was indicated for subcortical brain anatomical structures with nonselective SPGR versus SPGR‐IR. The nonselective SPGR improved clarity and yielded a more realistic depiction of the brain surface for visualization compared with SPGR‐IR.Conclusion:Compared with SPGR‐IR, nonselective SPGR allows for consistent segmentation results for basal ganglia regions and improved clarity for visualization of the brain. J. Magn. Reson. Imaging 2010;31:980–986. ©2010 Wiley‐Liss, Inc.
High temporal resolution SSFP cine MRI for estimation of left ventricular diastolic parameters
Authors: Krishnamurthy Ramkumar , Pednekar Amol , Cheong Benjamin , Muthupillai Raja 
Published: March 2010

AbstractPurpose:To obtain high temporal resolution (HTR) magnetic resonance (MR) steady‐state free‐precession (SSFP) cine cardiac images by using multichannel radiofrequency (RF) hardware and parallel imaging techniques; to study the effect of temporal resolution; and to compare the derived left ventricular (LV) diastolic filling parameters with echocardiographic results.Materials and Methods:HTR images were acquired in 13 healthy volunteers using a 1.5 T scanner with 32 RF channels and sensitivity encoding (SENSE) and k‐t broad‐use linear‐acquisition speedup technique (k‐t BLAST) imaging techniques. LV diastolic parameters were calculated and compared to conventional echocardiographic indices such as the isovolumic relaxation time (IVRT) and E/A ratio. The need for HTR was assessed and the MR results were compared with echocardiographic results.Results:The HTR (≈6‐ms) images yielded higher peak filling rates, peak ejection rates, and peak atrial filling rates. A progressive decline in filling and ejection rates was observed with worsening temporal resolution. The IVRTs and E/A ratios measured with MR versus echocardiography were in broad agreement. Also, SENSE and k‐t BLAST yielded similar diastolic functional parameters.Conclusion:With SENSE or k‐t BLAST and modern hardware, HTR cine images can be obtained. The lower temporal resolutions (30–50 ms) used in clinical practice reduce LV filling rates by ≤30% and may hinder characterization of transient phenomena such as the IVRT. J. Magn. Reson. Imaging 2010;31:872–880. ©2010 Wiley‐Liss, Inc.
Breathheld autocalibrated phase‐contrast imaging
Authors: Lew Calvin , Alley Marcus T. , Spielman Daniel M. , Bammer Roland , Chan Frandics P. 
Published: March 2010

AbstractPurpose:To compare generalized autocalibrating partially parallel acquisitions (GRAPPA), modified sensitivity encoding (mSENSE), and SENSE in phase‐contrast magnetic resonance imaging (PC‐MRI) applications.Materials and Methods:Aliasing of the torso can occur in PC‐MRI applications. If the data are further undersampled for parallel imaging, SENSE can be problematic in correctly unaliasing signals due to coil sensitivity maps that do not match that of the aliased volume. Here, a method for estimating coil sensitivities in flow applications is described. Normal volunteers (n = 5) were scanned on a 1.5 T MRI scanner and underwent PC‐MRI scans using GRAPPA, mSENSE, SENSE, and conventional PC‐MRI acquisitions. Peak velocity and flow through the aorta and pulmonary artery were evaluated.Results:Bland–Altman statistics for flow in the aorta and pulmonary artery acquired with mSENSE and GRAPPA methods (R = 2 and R = 3 cases) have comparable mean differences to flow acquired with conventional PC‐MRI. GRAPPA and mSENSE PC‐MRI have more robust measurements than SENSE when there is aliasing artifact caused by insufficient coil sensitivity maps. For peak velocity, there are no considerable differences among the mSENSE, GRAPPA, and SENSE reconstructions and are comparable to conventional PC‐MRI.Conclusion:Flow measurements of images reconstructed with autocalibration techniques have comparable agreement with conventional PC‐MRI and provide robust measurements in the presence of wraparound. J. Magn. Reson. Imaging 2010;31:1004–1014. ©2010 Wiley‐Liss, Inc.
Bone matrix imaged in vivo by water‐ and fat‐suppressed proton projection MRI (WASPI) of animal and human subjects
Authors: Wu Yaotang , Hrovat Mirko I. , Ackerman Jerome L. , Reese Timothy G. , Cao Haihui , Ecklund Kirsten , Glimcher Melvin J. 
Published: March 2010

AbstractPurpose:To demonstrate water‐ and fat‐suppressed proton projection MRI (WASPI) in a clinical scanner to visualize the solid bone matrix in animal and human subjects.Materials and Methods:Pig bone specimens and polymer pellets were used to optimize the WASPI method in terms of soft‐tissue suppression, image resolution, signal‐to‐noise ratio, and scan time on a 3T MRI scanner. The ankles of healthy 2–3‐month‐old live Yorkshire pigs were scanned with the optimized method. The method was also applied to the wrists of six healthy adult human volunteers to demonstrate the feasibility of the WASPI method in human subjects. A transmit/receive coil built with proton‐free materials was utilized to produce a strong B1field. A fast transmit/receive switch was developed to reduce the long receiver dead time that would otherwise obscure the signals.Results:Clear 3D WASPI images of pig ankles and human wrists, showing only the solid bone matrix and other tissues with high solid content (eg, tendons), with a spatial resolution of 2.0 mm in all three dimensions were obtained in as briefly as 12 minutes.Conclusion:WASPI of the solid matrix of bone in humans and animals in vivo is feasible. J. Magn. Reson. Imaging 2010;31:954–963. ©2010 Wiley‐Liss, Inc.
Silicon planar detectors adapted to slow neutron detection
Authors: Guardiola C. , Fleta C. , Lozano M. , Pellegrini G. 
Published: March 2010

AbstractMost neutron detectors use some type of conversion material to convert the incident neutrons into secondary charged particles, which can be detected inside the detector bulk afterwards. In these reactions, charged particles and recoil nuclei are emitted, with energies high enough to be distinguished from the gamma ray background. In this way, semiconductor detectors incorporating a layer of a neutron reactive material on top of the substrate can be used as neutron detectors. Based on their experience in the fabrication of radiation detectors, CNM‐IMB (National Center of Microelectronics in Barcelona, Spain) has started a new research line in solid‐state neutron detectors for imaging or dosimetry. The Geant4 Monte–Carlo simulation package has been used to predict the detection efficiency of planar silicon detectors with a neutron converter layer. At the same time, preliminary tests of silicon pad detectors covered with neutron converters have been carried out in the Autonomous University of Barcelona with a neutron source (241Am‐Be). Copyright © 2010 John Wiley & Sons, Ltd.
Long bone fracture repair in mice harboring GFP reporters for cells within the osteoblastic lineage
Authors: Ushiku Chikara , Adams Douglas J. , Jiang Xi , Wang Liping , Rowe David W. 
Published: March 2010

AbstractGFP reporter mice previously developed to assess levels of osteoblast differentiation were employed in a tibial long bone fracture model using a histological method that preserves fluorescent signals in non‐decalcified sections of bone. Two reporters, based on Col1A1 (Col3.6GFPcyan) and osteocalcin (OcGFPtpz) promoter fragments, were bred into the same mice to reflect an early and late stage of osteoblast differentiation. Three observations were apparent from this examination. First, the osteoprogenitor cells that arise from the flanking periosteum proliferate and progress to fill the fracture zone. These cells differentiate to osteoblasts, chondrocytes, to from the outer cortical shell. Second, the hypertrophic chondrocytes are dispersed and the cartilage matrix mineralized by the advancing Col3.6+ osteoblasts. The endochondral matrix is removed by the following osteoclasts. Third, a new cortical shell develops over the cartilage core and undergoes a remodeling process of bone formation on the inner surface and resorption on the outer surface. The original fractured cortex undergoes resorption as the outer cortical shell remodels inward to become the new diaphyseal bone. The fluorescent microscopy and GFP reporter mice used in this study provide a powerful tool for appreciating the molecular and cellular processes that control these fundamental steps in fracture repair, and may provide a basis for understanding fracture nonunion. Published by Wiley Periodicals, Inc. J Orthop Res 28:1338–1347, 2010
Raman microscopy study of synthetic cobalt blue spinels used in the field of art
Authors: Bouchard Michel , Gambardella Alessa 
Published: March 2010

AbstractThis study aims to provide a better understanding of the Raman spectra of cobalt‐based pigments in works of art. Systematic analyses of 21 industrial blue cobalt‐based pigments were carried out by using elemental energy dispersive spectroscopy and phase analyses by X‐ray diffraction (XRD) and Raman microspectroscopy, which led to the identification of 17 spinel Co‐based pigments. All the minerals contained in each pigment were characterised by all three techniques and subsequently attributed to diluents, extenders, mineralisers or unreacted reagents or to the main mineral phase, whether it was pure or contained doping or lattice modifier elements. In the particular case where doping elements were in low concentration in the host mineral lattice, their distinction by XRD from non‐doped spinel was impossible. On the contrary, Raman microspectroscopy turned out to be a perfect tool for detecting the presence of the doping agents in the spinel lattice. The determination of the elemental and mineralogical composition of the industrial blue cobalt‐based pigments commercially available for artists and studied in this survey represents a significant increase in the amount of analytical data available for this type of pigment as well as a valuable addition in the characterisation by Raman microspectroscopy of these compoundsin situ, on works of art. Copyright © 2010 John Wiley & Sons, Ltd.