Database : MEDLINE
Search on : medicine [Words]
References found : 2094611 [refine]
Displaying: 1 .. 10   in format [Detailed]

page 1 of 209462 go to page                         

  1 / 2094611 MEDLINE  
              next record last record
select
to print
Photocopy
Full text

[PMID]: 27797157
[Au] Autor:Golestanirad L; Angelone LM; Iacono MI; Katnani H; Wald LL; Bonmassar G
[Ad] Address:Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA, USA. lgolestanirad@mgh.harvard.edu.
[Ti] Title:Local SAR near deep brain stimulation (DBS) electrodes at 64 and 127 MHz: A simulation study of the effect of extracranial loops.
[So] Source:Magn Reson Med;, 2016 Oct 31.
[Is] ISSN:1522-2594
[Cp] Country of publication:United States
[La] Language:ENG
[Ab] Abstract:PURPOSE: MRI may cause brain tissue around deep brain stimulation (DBS) electrodes to become excessively hot, causing lesions. The presence of extracranial loops in the DBS lead trajectory has been shown to affect the specific absorption rate (SAR) of the radiofrequency energy at the electrode tip, but experimental studies have reported controversial results. The goal of this study was to perform a systematic numerical study to provide a better understanding of the effects of extracranial loops in DBS leads on the local SAR during MRI at 64 and 127 MHz. METHODS: A total of 160 numerical simulations were performed on patient-derived data, in which relevant factors including lead length and trajectory, loop location and topology, and frequency of MRI radiofrequency (RF) transmitter were assessed. RESULTS: Overall, the presence of extracranial loops reduced the local SAR in the tissue around the DBS tip compared with straight trajectories with the same length. SAR reduction was significantly larger at 127 MHz compared with 64 MHz. SAR reduction was significantly more sensitive to variable loop parameters (eg, topology and location) at 127 MHz compared with 64 MHz. CONCLUSION: Lead management strategies could exist that significantly reduce the risks of 3 Tesla (T) MRI for DBS patients. Magn Reson Med, 2016. © 2016 International Society for Magnetic Resonance in Medicine.
[Pt] Publication type:JOURNAL ARTICLE
[Em] Entry month:1610
[Cu] Class update date: 161031
[Lr] Last revision date:161031
[St] Status:Publisher
[do] DOI:10.1002/mrm.26535

  2 / 2094611 MEDLINE  
              first record previous record next record last record
select
to print
Photocopy
Full text

[PMID]: 27797155
[Au] Autor:Lin C; Shih YY; Huang SL; Huang HM
[Ad] Address:Department of Nuclear Medicine and Center for Advanced Molecular Imaging and Translation, Chang Gung Memorial Hospital, No. 5 Fu-Shin Street, Kwei-Shan, Taoyuan County, Taiwan.
[Ti] Title:Total variation-based method for generation of intravoxel incoherent motion parametric images in MRI.
[So] Source:Magn Reson Med;, 2016 Oct 31.
[Is] ISSN:1522-2594
[Cp] Country of publication:United States
[La] Language:ENG
[Ab] Abstract:PURPOSE: Total variation (TV) method has been used widely for image restoration and reconstruction. In this work, we propose a TV-based algorithm for parametric image generation in intravoxel incoherent motion (IVIM) diffusion-weighted magnetic resonance imaging (DW-MRI). METHODS: We used simulated and real data to investigate whether the proposed TV-based method can provide reliable parametric images. Parametric images of IVIM parameters including perfusion fraction (PF), diffusion coefficient (D), and pseudo-diffusion coefficient (D*) were estimated using DW-MRI data and TV through fitting the IVIM model. The Levenberg-Marquardt (LM) method, which has often been used in the context of IVIM analysis, was employed as the standard method for comparison of the resulting parametric images. RESULTS: The simulation results show that the proposed method outperforms the LM algorithm in terms of precision, providing a 40-81%, 90-93%, and 68-84% improvement for PF, D and D*, respectively, at signal-to-noise ratio (SNR) of 30. For real data, the proposed method showed an average five-fold, three-fold, and four-fold improvement in the SNR for PF, D and D*, respectively. CONCLUSION: We introduced the use of TV to produce parametric images, and demonstrated that the proposed TV-based method is effective in improving the parametric image quality. Magn Reson Med, 2016. © 2016 International Society for Magnetic Resonance in Medicine.
[Pt] Publication type:JOURNAL ARTICLE
[Em] Entry month:1610
[Cu] Class update date: 161031
[Lr] Last revision date:161031
[St] Status:Publisher
[do] DOI:10.1002/mrm.26528

  3 / 2094611 MEDLINE  
              first record previous record next record last record
select
to print
Photocopy
Full text

[PMID]: 27797153
[Au] Autor:Ross CL
[Ad] Address:The Wake Forest Institute for Regenerative Medicine, Wake Forest Center for Integrative Medicine, Medical Center Blvd, Winston-Salem, NC. chrross@wakehealth.edu.
[Ti] Title:The use of electric, magnetic, and electromagnetic field for directed cell migration and adhesion in regenerative medicine.
[So] Source:Biotechnol Prog;, 2016 Oct 31.
[Is] ISSN:1520-6033
[Cp] Country of publication:United States
[La] Language:ENG
[Ab] Abstract:Directed cell migration and adhesion is essential to embryonic development, tissue formation and wound healing. For decades it has been reported that electric field (EF), magnetic field (MF) and electromagnetic field (EMF) can play important roles in determining cell differentiation, migration, adhesion, and evenwound healing. Combinations of these techniques have revealed new and exciting explanations for how cells move and adhere to surfaces; how the migration of multiple cells are coordinated and regulated; how cellsinteract with neighboring cells, and also to changes in their microenvironment. In some cells, speed and direction are voltage dependent. Data suggests that the use of EF, MF and EMF could advance techniques in regenerative medicine, tissue engineering and wound healing. © 2016 American Institute of Chemical Engineers Biotechnol. Prog., 2016.
[Pt] Publication type:REVIEW; JOURNAL ARTICLE
[Em] Entry month:1610
[Cu] Class update date: 161031
[Lr] Last revision date:161031
[St] Status:Publisher
[do] DOI:10.1002/btpr.2371

  4 / 2094611 MEDLINE  
              first record previous record next record last record
select
to print
Photocopy
Full text

[PMID]: 27797150
[Au] Autor:Dayem AA; Choi HY; Yang GM; Kim K; Saha SK; Kim JH; Cho SG
[Ad] Address:Department of Stem Cell & Regenerative Biotechnology, Incurable Disease Animal Model and Stem Cell Institute (IDASI), Konkuk University, Gwangjin-gu, Seoul, Korea.
[Ti] Title:The potential of nanoparticles in stem cell differentiation and further therapeutic applications.
[So] Source:Biotechnol J;, 2016 Oct 31.
[Is] ISSN:1860-7314
[Cp] Country of publication:Germany
[La] Language:ENG
[Ab] Abstract:Tissue regeneration could offer therapeutic advantages for individuals experiencing organ or tissue damage. Recently, advances in nanotechnology have provided various nanomaterials, with a wide range of applications, for modulating stem cell behavior and for further therapeutic applications in tissue regeneration. Defects in cell proliferation and differentiation, a low mechanical strength of scaffolds, and inefficient production of factors that are essential for stem cell differentiation are the current challenges in tissue regeneration. This review provides a brief explanation about the link between nanotechnology and tissue engineering, highlighting the current literature about the interaction between nanoparticles (NPs) and stem cells, the promotional effect of NPs on stem cell differentiation into various lineages, and their possible therapeutic applications. We also tried to describe the mechanism through which NPs regulate the spatial-temporal release and kinetics of vital growth and differentiation factors, enhance stem cell differentiation, and improve culture conditions for in vivo tissue regeneration. The field of nanotechnology is promising and provides novel nanomaterials and methods with valuable clinical applications in the regenerative medicine. Understanding the mechanism, as well as the toxic effects of NPs in stem cell biology will undoubtedly provide valuable insight into their clinical application in the regenerative medicine.
[Pt] Publication type:REVIEW; JOURNAL ARTICLE
[Em] Entry month:1610
[Cu] Class update date: 161031
[Lr] Last revision date:161031
[St] Status:Publisher
[do] DOI:10.1002/biot.201600453

  5 / 2094611 MEDLINE  
              first record previous record next record last record
select
to print
Photocopy
Full text

[PMID]: 27797114
[Au] Autor:Landheer K; Schulte R; Geraghty B; Hanstock C; Chen AP; Cunningham CH; Graham SJ
[Ad] Address:Department of Medical Biophysics, University of Toronto, Ontario, Canada. landheer@sri.utoronto.ca.
[Ti] Title:Diffusion-weighted J-resolved spectroscopy.
[So] Source:Magn Reson Med;, 2016 Oct 31.
[Is] ISSN:1522-2594
[Cp] Country of publication:United States
[La] Language:ENG
[Ab] Abstract:PURPOSE: To develop a novel diffusion-weighted magnetic resonance spectroscopy (DW-MRS) technique in conjunction with J-resolved spatially localized spectroscopy (JPRESS) to measure the apparent diffusion coefficients (ADCs) of brain metabolites beyond N-acetylaspartic acid (NAA), creatine (Cr), and choline (Cho) at 3T. This technique will be useful to probe tissue microstructures in vivo, as the various metabolites have different physiological characteristics. METHODS: Two JPRESS spectra were collected (high b-value and low b-value), and the ADCs of 16 different metabolites were estimated. Two analysis pipelines were developed: 1) a 2D pipeline that uses ProFit software to extract ADCs from metabolites not typically accessible at 3T and 2) a 1D pipeline that uses TARQUIN software to extract the metabolite concentrations from each line in the 2D dataset, allowing for scaling as well as validation. RESULTS: The ADCs of 16 different metabolites were estimated from within six subjects in parietal white matter. There was excellent agreement between the results obtained from the 1D and 2D pipelines for NAA, Cr, and Cho. CONCLUSION: The proposed technique provided consistent estimates for the ADCs of NAA, Cr, Cho, glutamate + glutamine, and myo-inositol in all subjects and additionally glutathione and scyllo-inositol in all but one subject. Magn Reson Med, 2016. © 2016 International Society for Magnetic Resonance in Medicine.
[Pt] Publication type:JOURNAL ARTICLE
[Em] Entry month:1610
[Cu] Class update date: 161031
[Lr] Last revision date:161031
[St] Status:Publisher
[do] DOI:10.1002/mrm.26514

  6 / 2094611 MEDLINE  
              first record previous record next record last record
select
to print
Photocopy
Full text

[PMID]: 27797113
[Au] Autor:Platt MJ
[Ad] Address:Norwich Medical School, University of East Anglia, Norfolk, UK.
[Ti] Title:Counting cases of cerebral palsy.
[So] Source:Dev Med Child Neurol;, 2016 Oct 31.
[Is] ISSN:1469-8749
[Cp] Country of publication:England
[La] Language:ENG
[Pt] Publication type:JOURNAL ARTICLE
[Em] Entry month:1610
[Cu] Class update date: 161031
[Lr] Last revision date:161031
[St] Status:Publisher
[do] DOI:10.1111/dmcn.13304

  7 / 2094611 MEDLINE  
              first record previous record next record last record
select
to print
Photocopy
Full text

[PMID]: 27797111
[Au] Autor:Ilicak E; Senel LK; Biyik E; Çukur T
[Ad] Address:Department of Electrical and Electronics Engineering, Bilkent University, Ankara, Turkey.
[Ti] Title:Profile-encoding reconstruction for multiple-acquisition balanced steady-state free precession imaging.
[So] Source:Magn Reson Med;, 2016 Oct 31.
[Is] ISSN:1522-2594
[Cp] Country of publication:United States
[La] Language:ENG
[Ab] Abstract:PURPOSE: The scan-efficiency in multiple-acquisition balanced steady-state free precession imaging can be maintained by accelerating and reconstructing each phase-cycled acquisition individually, but this strategy ignores correlated structural information among acquisitions. Here, an improved acceleration framework is proposed that jointly processes undersampled data across N phase cycles. METHODS: Phase-cycled imaging is cast as a profile-encoding problem, modeling each image as an artifact-free image multiplied with a distinct balanced steady-state free precession profile. A profile-encoding reconstruction (PE-SSFP) is employed to recover missing data by enforcing joint sparsity and total-variation penalties across phase cycles. PE-SSFP is compared with individual compressed-sensing and parallel-imaging (ESPIRiT) reconstructions. RESULTS: In the brain and the knee, PE-SSFP yields improved image quality compared to individual compressed-sensing and other tested methods particularly for higher N values. On average, PE-SSFP improves peak SNR by 3.8 ± 3.0 dB (mean ± s.e. across N = 2-8) and structural similarity by 1.4 ± 1.2% over individual compressed-sensing, and peak SNR by 5.6 ± 0.7 dB and structural similarity by 7.1 ± 0.5% over ESPIRiT. CONCLUSION: PE-SSFP attains improved image quality and preservation of high-spatial-frequency information at high acceleration factors, compared to conventional reconstructions. PE-SSFP is a promising technique for scan-efficient balanced steady-state free precession imaging with improved reliability against field inhomogeneity. Magn Reson Med, 2016. © 2016 International Society for Magnetic Resonance in Medicine.
[Pt] Publication type:JOURNAL ARTICLE
[Em] Entry month:1610
[Cu] Class update date: 161031
[Lr] Last revision date:161031
[St] Status:Publisher
[do] DOI:10.1002/mrm.26507

  8 / 2094611 MEDLINE  
              first record previous record next record last record
select
to print
Photocopy
Full text

[PMID]: 27797110
[Au] Autor:Ahmed Z; Levesque IR
[Ad] Address:Medical Physics Unit, McGill University, Montreal, QC, Canada. zaki.ahmed@mail.mcgill.ca.
[Ti] Title:Increased robustness in reference region model analysis of DCE MRI using two-step constrained approaches.
[So] Source:Magn Reson Med;, 2016 Oct 31.
[Is] ISSN:1522-2594
[Cp] Country of publication:United States
[La] Language:ENG
[Ab] Abstract:PURPOSE: Reference region models (RRMs) can quantify tumor perfusion in dynamic contrast-enhanced MRI without an arterial input function. Inspection of the RRM reveals that one of the free parameters in the fit is uniquely linked to the reference region and is common to all voxels. A two-step approach is proposed that takes this constraint into account. METHODS: Three constrained RRM (CRRM) approaches were devised and evaluated. Simulations were performed to compare their accuracy and precision over a range of noise and temporal resolutions. The CRRM was also applied on a virtual phantom that simulates different perfusion values. In vivo evaluation was performed on data from breast cancer and soft tissue sarcoma. RESULTS: In simulations, the CRRM consistently improved precision and had better accuracy at low signal-to-noise ratio (SNR). In virtual phantom, the CRRMs were able to fit voxels that had similar kinetics to the reference tissue, whereas the unconstrained models failed to accurately fit these voxels. In the in vivo data, the constrained approaches produced parameter maps that had less variability and were in better agreement with the Tofts model. CONCLUSION: These findings indicate that the two-step fitting approach of the CRRM can reduce the variability of perfusion estimates for quantifying perfusion with dynamic contrast-enhanced (DCE) MRI. Magn Reson Med, 2016. © 2016 International Society for Magnetic Resonance in Medicine.
[Pt] Publication type:JOURNAL ARTICLE
[Em] Entry month:1610
[Cu] Class update date: 161031
[Lr] Last revision date:161031
[St] Status:Publisher
[do] DOI:10.1002/mrm.26530

  9 / 2094611 MEDLINE  
              first record previous record next record last record
select
to print
Photocopy
Full text

[PMID]: 27797109
[Au] Autor:Twieg M; Griswold MA
[Ad] Address:Department of Electrical Engineering and Computer Science, Case Western Reserve University, Cleveland, Ohio, USA.
[Ti] Title:High efficiency radiofrequency power amplifier module for parallel transmit arrays at 3 Tesla.
[So] Source:Magn Reson Med;, 2016 Oct 31.
[Is] ISSN:1522-2594
[Cp] Country of publication:United States
[La] Language:ENG
[Ab] Abstract:PURPOSE: The purpose of this study is to develop an in-bore radiofrequency (RF) power amplifier (RFPA) module with high power efficiency and density for use in parallel transmit (pTX) arrays at 3 Tesla. METHODS: The modules use a combination of current mode class D, class S, and class E amplifiers based on enhancement-mode gallium nitride-on-silicon field-effect transistors. Together the amplifiers implement envelope elimination and restoration to achieve amplitude modulation with high efficiency over a wide operating range. The static nonlinearity and power efficiency of the module were measured using pulsed RF measurements over a 37 dB dynamic range. Thermal performance was also measured with and without forced convection cooling. RESULTS: The modules produces peak RF power up to 130 W with an overall efficiency of 85%. When producing 100 W RF pulses at a duty cycle of 10%, maximum junction temperatures did not exceed 80 °C, even without the use of heatsinks or forced convection. CONCLUSION: The small size and low cost of the modules promise lower cost implementation of pTX systems compared with linear RFPAs located remotely. Further work must be done on control of the RF output in the presence of nonlinearities and coupling. Magn Reson Med, 2016. © 2016 International Society for Magnetic Resonance in Medicine.
[Pt] Publication type:JOURNAL ARTICLE
[Em] Entry month:1610
[Cu] Class update date: 161031
[Lr] Last revision date:161031
[St] Status:Publisher
[do] DOI:10.1002/mrm.26510

  10 / 2094611 MEDLINE  
              first record previous record
select
to print
Photocopy
Full text

[PMID]: 27797108
[Au] Autor:Sanaei Nezhad F; Anton A; Parkes LM; Deakin B; Williams SR
[Ad] Address:Centre for Imaging Science, Manchester Academic Health Science Centre, University of Manchester, Manchester, United Kingdom.
[Ti] Title:Quantification of glutathione in the human brain by MR spectroscopy at 3 Tesla: Comparison of PRESS and MEGA-PRESS.
[So] Source:Magn Reson Med;, 2016 Oct 31.
[Is] ISSN:1522-2594
[Cp] Country of publication:United States
[La] Language:ENG
[Ab] Abstract:PURPOSE: Glutathione (GSH) is an important intracellular antioxidant in the brain. A number of studies report its measurement by localized (1) H spectroscopy using PRESS and STEAM. This study evaluates the reliability and accuracy of GSH measurements from PRESS at 3 Tesla (T) and compares the results to those obtained with MEGA-PRESS. METHODS: Phantoms containing brain metabolites, identical except for variable GSH concentration between 0 and 24 mM, were scanned using PRESS (echo time (TE) = 35 ms) and MEGA-PRESS (optimized TE = 130 ms) at 3 T. Spectra of the anterior cingulate cortex and occipital cortex in seven healthy volunteers were also acquired. RESULTS: Phantom GSH concentrations from 0 to 3mM were unreliably quantified using PRESS, although at 4 mM and above there was a linear relationship between measured and true concentrations (R(2) = 0.99). Using MEGA-PRESS, there was no signal detected at 0 mM GSH, plus a linear relationship (R(2) = 0.99) over the full range from 0-24 mM. In brain, concentrations calculated from MEGA-PRESS and PRESS were significantly different in occipital cortex (P < 0.001). Moreover, only MEGA-PRESS reported significant differences in GSH between the two brain regions (P = 0.003). CONCLUSION: Due to uncertainties in GSH quantification raised by the study, the authors conclude that physiological concentrations (<4 mM) of GSH cannot be reliably quantified from PRESS (TE = 35 ms) spectra at 3 T. Magn Reson Med, 2016. © 2016 The Authors Magnetic Resonance in Medicine published by Wiley Periodicals, Inc. on behalf of International Society for Magnetic Resonance in Medicine.
[Pt] Publication type:JOURNAL ARTICLE
[Em] Entry month:1610
[Cu] Class update date: 161031
[Lr] Last revision date:161031
[St] Status:Publisher
[do] DOI:10.1002/mrm.26532


page 1 of 209462 go to page                         
   


Refine the search
  Database : MEDLINE Advanced form   

    Search in field  
1  
2
3
 
           



Search engine: iAH v2.6 powered by WWWISIS

BIREME/PAHO/WHO - Latin American and Caribbean Center on Health Sciences Information