Neuroimaging clinics of North America
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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.
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Diffusion-weighted imaging of the musculoskeletal system including the spine is a new MR imaging method. Several studies have shown significantly different diffusivities for various pathologic conditions such as edema and tumor. The specificity of diagnosis may be increased and therapeutic effects may be monitored. ⋯ In general, those patients do not pose problems in differential diagnosis. New sequence developments and higher magnetic field gradients should be able to increase spatial resolution and decrease problems from motion artifacts. Studies with larger patient groups and sequences that quantify the results with ADCs are the necessary next steps.
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Diffusion-tensor MR imaging is a promising tool to evaluate white-matter integrity by quantitative and graphic maps including neural fiber tractogram. Current challenges afoot are to obtain higher quality diffusion-weighted MR images (high SNR, isotropic voxel, and high spatial resolution), to create a robust mathematical framework to process the data, to construct a user-friendly computer-based algorithm, to reveal determinants of diffusion process, and to establish analytical methodology.