[Echo-planar imaging of the brain]

In this review, the clinical utility of echoplanar techniques in MRI of the brain is discussed. Comparison of high-resolution EPI with SE/turbo-SE shows high image quality of EPI in the supratentorial brain. In the infratentorial region, however, susceptibility artifacts limit image quality. For the assessment of neuronal brain activation utilizing the intrinsic contrast of blood (BOLD), EPI has definite advantages over other techniques of functional MRI. Due to its superior temporal resolution and multislice capabilities, EPI allows for analysis of complex neuronal activation patterns. Diffusion imaging benefits from the lack of bulk motion artifacts and serves primarily to detect early stroke. Three methods of perfusion imaging (rel. blood volume, rel. blood flow) are discussed: the susceptibility artifact method (T2*), the relaxitivity method (T1), and the signal-labelling technique (STAR). Perfusion imaging may have a clinical impact in the assessment of brain tumors and cerebral ischemia.