New magnetic resonance imaging methods for cerebrovascular disease: Emerging clinical applications

During the 1990s, novel magnetic resonance imaging (MRT) techniques have em erged that allow the noninvasive and rapid assessment of normal brain funct ioning and cerebral pathophysiology. Some of these techniques, including di ffusion-weighted imaging and perfusion-weighted imaging, have already been used extensively in specialized centers for the evaluation of patients with cerebrovascular disease. Evidence is now rapidly accumulating that both di ffision- and perfusion-weighted imaging, particularly when used in combinat ion with high-speed MR angiography, will lead to improvements in the clinic al management of acute stroke patients. Other novel MR techniques, such as spectroscopic imaging, diffusion tensor imaging, and blood oxygenation leve l-dependent functional MRI, have not yet assumed a definitive role in the d iagnostic evaluation of cerebrovascular disease. However, they are promisin g research tools that provide noninvasive data about infarct evolution as w ell as mechanisms of stroke recovery. In this article, we review the basic principles underlying these novel MRI techniques and outline their current and anticipated future impact on the diagnosis and management of patients w ith cerebrovascular disease.