TECHNICAL APPROACHES TO FUNCTIONAL MAGNETIC-RESONANCE-IMAGING

The techniques of in vivo functional magnetic resonance imaging (fMRI) have been established over the past few years. Signal changes resulti ng from small differences in the magnetic resonance signal caused by v ariations in the oxygenation state of the venous vasculature are used to map neuronal activity of the brain. While many of the advantages fo r using MRI for functional neuroimaging are quite obvious (high spatia l and temporal resolution, direct anatomic correlation, noninvasivenes s), the underlying mechanisms and problems are not fully known. This a rticle focuses on selected topics of fMRI techniques and their problem s, such as field strength B0, different types of sequences and their p arameters, 2D and 3D data acquisition, different statistical methods a nd motion artiefacts. The authors favor the use of a 1.5 T clinical sc anner with EPI capabilities, 2D FLASH sequences with a TR < 60 ms, TE = 30-40 ms, alpha < 20-degrees for high resolution and sensitivity, fM RI and multislice EPI for high temporal and overview and fMRI as well as cross-correlation for post-processing.