Potential pitfalls of functional MRI using conventional gradient-recalled echo techniques.
The conventional gradient-recalled echo technique, FLASH, has widely been used for functional MRI. FLASH results at 4 T with short TEs of 10-20 ms mimic those at 1.5 T with TEs of 25-50 ms or longer. Under these conditions, large venous vessels dominate the activated area; however, the use of longer TEs at 4 T reveals activation in gray matter areas as well as large vessels. Inflow effects of large vessels can be greatly reduced with centric-reordering of phase-encoding steps and inter-image delay. Finger and toe movement paradigms show that functional activation maps are consistent with classical somatotopic maps, and are specific to the tasks. Navigator-based motion correction generates functional maps with larger activation areas by reducing physiological noise.
Kim
S G
SG
Department of Radiology, University of Minnesota Medical School, Minneapolis 55455.
Hendrich
K
K
Hu
X
X
Merkle
H
H
Uğurbil
K
K
D001921:Brain / Q000033:anatomy & histology / Q000098:blood supply / Q000502:physiology; D002550:Cerebral Veins / Q000502:physiology; D005385:Fingers / Q000502:physiology; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging / Q000379:methods*; D009044:Motor Cortex / Q000033:anatomy & histology* / Q000098:blood supply / Q000502:physiology*; D009068:Movement / Q000502:physiology; D010100:Oxygen / Q000097:blood; D012680:Sensitivity and Specificity
D010100:Oxygen