INTRACRANIAL GRADIENT-ECHO AND SPIN-ECHO FUNCTIONAL MR-ANGIOGRAPHY INHUMANS

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-induce d changes in flow velocity to the functional MR imaging signal intensi ty. 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) function al MR imaging techniques were used, and the image planes were carefull y positioned with respect to the veins that responded to the motor tas k. 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 funct ional MR images were eventually processed by means of maximum intensit y 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 t o signal intensity in conventional two-dimensional GRE BOLD functional MR imaging of motor activity. CONCLUSION: Veins have a substantial ro le in BOLD functional MR imaging of motor activity.