Neuroimaging clinics of North America
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Diffusion MR imaging provides unique information about the physiologic state of ischemic tissue. It is highly sensitive and specific in the detection of acute and hyperacute ischemic stroke and has greatly improved the diagnosis and treatment of acute stroke. ⋯ Diffusion combined with perfusion MR imaging provides information about the operational ischemic penumbra and final infarct size. Diffusion MR imaging seems to be promising in the evaluation of candidates for thrombolysis.
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Diffusion-weighted imaging is of limited value in the MR imaging diagnosis of various tumor pathologies, except in differentiating between dermoids/epidermoids and arachnoid cysts. Diffusion tractography, on the other hand, allows accurate depiction of important white-matter tracts adjacent to brain tumors. This technique uses data derived from diffusion tensor imaging.
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Spinal cord DWI may be useful in providing information not available with conventional MR imaging. More work, however, is required to explain what the qualitative and quantitative results actually represent. Computer simulations and detailed radiologic-histologic correlations will therefore be necessary.
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Diffusion imaging is a useful technique for the evaluation of many normal and pathologic processes occurring in the neonate and often provides complementary information for conventional MR and other imaging techniques.
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Perhaps one of the greatest benefits of the development of high b-value technology has been the insight provided into the physiologic basis of diffusion imaging. The multiexponential features of the diffusion process are revealed on scans obtained with high b-value. The subsequent isotropic diffusion images have the distinct advantage of more accurately reflecting the intrinsic ADC of the tissues examined. ⋯ The degree to which this is proved to be clinically relevant is dependent on future investigation, but initial results are promising. The clinical potential of high b-value imaging at higher field strength remains to be explored. The greater signal to noise afforded by the use of 3-T scanners will likely make higher b-value imaging more practical with less costly scan time penalties necessary at lower field strengths.