Intracranial gradient-echo and spin-echo functional MR angiography in humans

PURPOSE: To investigate the predominance of venous signal intensity at 1.5-T gradient-echo (GRE) functional magnetic resonance (MR) imaging of motor activity and to demonstrate the contribution from task-induced changes in flow velocity to the functional MR imaging signal intensity. MATERIALS AND METHODS: Functional MR imaging of motor activity was performed in healthy volunteers. In a first examination, conventional two-dimensional GRE blood oxygenation level-dependent (BOLD) functional MR imaging techniques were used, and the image planes were carefully positioned with respect to the veins that responded to the motor task. In a second examination, two- dimensional spin-echo (SE) techniques were used, and the image planes were oriented axially and measured in a sequential multisection manner. The areas of hyperintensity on functional MR images were eventually processed by means of maximum intensity projection. RESULTS: Functional MR angiograms were obtained in both examinations. The possibility to generate SE functional MR angiograms demonstrates that venous inflow effects may contribute substantially to signal intensity in conventional two- dimensional GRE BOLD functional MR imaging of motor activity. CONCLUSION: Veins have a substantial role in BOLD functional MR imaging of motor activity.SCOPUS: ar.j