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In an investigation of a multiresolution and multistaged approach in functional MRI, the relationship between spatial resolution and detection of functional activation is examined. The difference between functional detection and mapping is defined, and a multiresolution approach to functional detection is analyzed by constructing simple theoretical and experimental models simulating variations of in-plane resolution. Experimentally measured blood oxygenation level-dependent (BOLD) signal changes as well as BOLD contrast-to-noise ratio (CNR) with respect to different spatial resolutions are compared with results from theoretical predictions and simulation. From both an experimental and a theoretical perspective, it is shown that BOLD CNR and, thus, the concomitant detection of the functional activation are maximized when the resolution matches the size of activation., (Copyright 2001 Academic Press.)

Adaptively limiting image acquisition to areas of interest will allow more efficient data acquisition time for in-depth characterization of areas of brain activation. We designed and implemented an adaptive image acquisition scheme that uses a multiresolution-based strategy to zoom into the regions of cortical activity. Real-time pulse prescription and data processing capabilities were combined with spatially selective radiofrequency encoding. The method was successfully demonstrated in volunteers performing simple sensorimotor paradigms for simultaneous activation of primary motor and cerebellar areas. We believe that real-time adaptation of spatial and temporal sampling to task-related changes will increase the efficiency and flexibility of functional mapping experiments. Contrast-to-noise analysis in selected regions-of-interest was performed to quantitatively assess the multiresolution adaptive approach., (Copyright 1999 Academic Press.)