Current status of functional MR imaging, perfusion-weighted imaging, and diffusion-tensor imaging in Alzheimer's disease diagnosis and research.

Advanced MR techniques, such as functional MR imaging, perfusion-weighted imaging, and diffusion-tensor imaging, offer the capability of detecting early functional, hemodynamic, and microstructural alterations in Alzheimer's disease before gross anatomic alterations. Most studies of these emerging technologies are at the exploratory stage, with the purpose of increasing understanding of the underlying disease process and defining cross-sectional differences across various subject populations. Assessment of the diagnostic efficacy of these technologies in detecting early Alzheimer's disease in its preclinical and prodromal stages is ongoing.