Diffusion MR of acute stroke

Abstract

7.17 Conclusion: Diffusion MR imaging has vastly improved evaluation of acute ischemic stroke. It is highly sensitive and specific in the detection of acute ischemic stroke at early time points when CT and conventional MR sequences are unreliable. The initial DWI lesion is thought to represent infarct core and usually progresses to infarction unless there is early reperfusion. The initial DWI lesion volume and ADC ratios correlate highly with final infarct volume as well as with acute and chronic neurologic assessment tests. ADC values may be useful in differentiating tissue destined to infarct from tissue that is ischemic but potentially salvageable with reperfusion therapy. ADC values may also be useful in determining tissue at risk of undergoing hemorrhagic transformation following reperfusion therapy. Diffusion tensor imaging can delineate the differences in responses of gray versus white matter to ischemia. Fractional anisotropy may be important in determining stroke onset time and tractography provides early detection of Wallerian degeneration that may be important in determining prognosis. Finally, diffusion MR imaging can determine which patients with transient ischemic attack are at risk for subsequent large vessel infarction and can reliably differentiate stroke from stroke mimics. With improvements in MR software and hardware, diffusion MR will undoubtedly continue to improve our management and treatment of acute stroke patients. © 2006 Springer-Verlag Berlin Heidelberg.