74 research outputs found

    High-Resolution Diffusion Tensor MR Imaging for Evaluating Myocardial Anisotropy and Fiber Tracking at 3T: the Effect of the Number of Diffusion-Sensitizing Gradient Directions

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    Objective: We wanted to evaluate the effect of the number of diffusion-sensitizing gradient directions on the image quality for evaluating myocardial anisotropy and fiber tracking by using in vitro diffusion tensor MR imaging (DT-MRI). Materials and Methods: The DT-MR images, using a SENSE-based echo-planar imaging technique, were acquired from ten excised porcine hearts by using a 3T MR scanner. With a b-value of 800 S/mm(2), the diffusion tensor images were obtained for 6,15 and 32 diffusion-sensitizing gradient directions at the mid-ventricular level. The number of tracked fibers, the fractional anisotropy (FA), and the length of the tracked fibers were measured for the quantitative analysis. Two radiologists assessed the image quality of the fiber tractography for the qualitative analysis. Results: By increasing the number of diffusion-sensitizing gradient directions from 6 to 15, and then to 32, the FA and standard deviation were significantly reduced (p < 0.01), and the number of tracked fibers and the length of the tracked fibers were significantly increased (p < 0.01). The image quality of the fiber tractography was significantly increased with the increased number of diffusion-sensitizing gradient directions (p < 0.01). Conclusion: The image quality of in vitro DT-MRI is significantly improved as the number of diffusion-sensitizing gradient directions is increased.Jiang Y, 2007, AM J PHYSIOL-HEART C, V293, pH2377, DOI 10.1152/ajpheart.00337.2007Wu EX, 2007, MAGN RESON MED, V58, P687, DOI 10.1002/mrm.21350Wu EX, 2007, MAGN RESON IMAGING, V25, P1048, DOI 10.1016/j.mri.2006.12.008Wu MT, 2006, CIRCULATION, V114, P1036, DOI 10.1161/CIRCULATIONHAHA.105.545863Lee JW, 2006, INVEST RADIOL, V41, P553Okada T, 2006, RADIOLOGY, V238, P668, DOI 10.1148/radiol.2382042192CHANG YM, 2005, J KOREAN RADIOL SOC, V52, P87Tanenbaum LN, 2004, AM J NEURORADIOL, V25, P1626Nagae-Poetscher LM, 2004, AM J NEURORADIOL, V25, P1325Jones DK, 2004, MAGNET RESON MED, V51, P807, DOI 10.1002/mrm.20033Jaermann T, 2004, MAGNET RESON MED, V51, P230, DOI 10.1002/mrm.10707Naganawa S, 2004, EUR RADIOL, V14, P234, DOI 10.1007/s00330-003-2163-6Zhai GH, 2003, RADIOLOGY, V229, P673, DOI 10.1148/radiol.2293021462Cercignani M, 2003, AM J NEURORADIOL, V24, P1254Tseng WYI, 2003, J MAGN RESON IMAGING, V17, P31, DOI 10.1002/jmri.10223Jeong AK, 2001, KOREAN J RADIOL, V2, P21Holmes AA, 2000, MAGNET RESON MED, V44, P157Choi SI, 2000, RADIOLOGY, V215, P863Spotnitz HM, 2000, J THORAC CARDIOV SUR, V119, P1053Pruessmann KP, 1999, MAGNET RESON MED, V42, P952Tseng WI, 1999, MAGNET RESON MED, V42, P393Scollan DF, 1998, AM J PHYSIOL-HEART C, V275, pH2308Pierpaoli C, 1996, MAGNET RESON MED, V36, P893Taber LA, 1996, J BIOMECH, V29, P745REESE TG, 1995, MAGNET RESON MED, V34, P786EDELMAN RR, 1994, MAGNET RESON MED, V32, P423RADEMAKERS FE, 1994, CIRCULATION, V89, P1174STREETER DD, 1969, CIRC RES, V24, P339

    Diffusion Tensor Imaging: Exploring the Motor Networks and Clinical Applications

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    With the advances in diffusion magnetic resonance (MR) imaging techniques, diffusion tensor imaging (DTI) has been applied to a number of neurological conditions because DTI can demonstrate microstructures of the brain that are not assessable with conventional MR imaging. Tractography based on DTI offers gross visualization of the white matter fiber architecture in the human brain in vivo. Degradation of restrictive barriers and disruption of the cytoarchitecture result in changes in the diffusion of water molecules in various pathological conditions, and these conditions can also be assessed with DTI. Yet many factors may influence the ability to apply DTI clinically, so these techniques have to be used with a cautious hand

    Chimpanzee (Pan troglodytes) Precentral Corticospinal System Asymmetry and Handedness: A Diffusion Magnetic Resonance Imaging Study

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    Most humans are right handed, and most humans exhibit left-right asymmetries of the precentral corticospinal system. Recent studies indicate that chimpanzees also show a population-level right-handed bias, although it is less strong than in humans.We used in vivo diffusion-weighted and T1-weighted magnetic resonance imaging (MRI) to study the relationship between the corticospinal tract (CST) and handedness in 36 adult female chimpanzees. Chimpanzees exhibited a hemispheric bias in fractional anisotropy (FA, left>right) and mean diffusivity (MD, right>left) of the CST, and the left CST was centered more posteriorly than the right. Handedness correlated with central sulcus depth, but not with FA or MD.These anatomical results are qualitatively similar to those reported in humans, despite the differences in handedness. The existence of a left>right FA, right>left MD bias in the corticospinal tract that does not correlate with handedness, a result also reported in some human studies, suggests that at least some of the structural asymmetries of the corticospinal system are not exclusively related to laterality of hand preference

    A Rare Neurologic Disease that Mimics Cranial Hydatid Cyst

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