Clinical fMRI: Implementation and Experience

Functional magnetic resonance imaging (fMRI) is a new tool for understanding how the brain performs cognitive functions. Paradigms of increasing sophistication such as language comprehension (Just et al., 1996a), visuospatial processing (Just et al., 1996b), and working memory (Sweeney et al., 1996a,b,c) move beyond the simple visual and motor tasks that were used to establish the robustness of the technique (Thulborn et al., 1995, 1996a,b,c,d). Not only does this technique allow the location of cognitive functions to be mapped to discrete but distributed regions of the brain but it also examines how the brain copes with tasks of increasing demands by recruiting new resources from other regions and sequencing processes across multiple regions according to the task (Just et al., 1996b; Thulborn et al., 1996a,b,c,d). A complete historical introduction of fMRI is not the purpose of this report but rather it focuses on the extension of investigations on normal volunteers in which the basic cerebrovascular physiology is assumed to be constant across individuals to patients with pathology that arise from abnormal cerebrovascular physiology. Such clinical applications are challenging because of the need to perform the study as safely and as efficiently as possible in a subject who is often distracted and anxious about his or her illness. The interpretation of the results in the setting of altered physiology must be ambiguous unless the hemodynamic and metabolic status of the brain is characterized. Technical failures must be minimized and results must be available quickly if clinical utility is to be established. The design of equipment that meets these constraints of clinical fMRI and our initial experience with patients will be described.