fMRI at 7 T: whole-brain coverage and signal advantages even infratentorially?
fMRI is one of the most likely applications to benefit from high field MRI. It profits from the higher signal-to-noise ratio (SNR) and increased BOLD contrast itself. However, this sensitivity to susceptibility brings with it problems, e.g. in-plane dephasing and signal dropouts near tissue-air boundaries. Therefore, most fMRI studies at 7 T focus on high resolution in supratentorial areas. Nine volunteers were measured at both 1.5 and 7 T using finger tapping with fMRI in a block design fashion. An EPI sequence with short TE (28 ms at 7 T) was chosen for covering the whole brain. A CP transmit/receive head coil was used for image acquisition. Statistical analyses were performed using SPM 02. The activated images were superimposed on both individual images and a standard T1-normalized brain dataset. All cerebral areas involved in finger tapping could be revealed using 7 T: SI, MI, SII, SMA, thalamus, and cerebellar areas. At 1.5 T the activation in the thalamus was only detectable in one subject using the same corrected p value for all analyses. Furthermore, the BOLD signal change was significantly higher at 7 T than at 1.5 T (factor 2 to 3). A well fitted response curve could be detected in all sensory-motor areas at 7 T in whole-brain coverage, even in areas suffering from susceptibility like the cerebellum. Supra- and infratentorial sensory-motor areas are consistently and reliably detectable using whole-brain fMRI at 7 T with good quality response functions and, as expected, higher signal compared to 1.5 T.
Gizewski
Elke R
ER
Department of Diagnostic and Interventional Radiology and Neuroradiology, University Hospital Essen, Hufelandstr. 55, D-45127 Essen, Germany. elke.gizewski@uni-due.de
de Greiff
Armin
A
Maderwald
Stefan
S
Timmann
Dagmar
D
Forsting
Michael
M
Ladd
Mark E
ME
D000328:Adult; D001921:Brain / Q000502:physiology*; D001931:Brain Mapping / Q000379:methods*; D019054:Evoked Potentials, Motor / Q000502:physiology*; D005260:Female; D005385:Fingers / Q000502:physiology; D006801:Humans; D007089:Image Enhancement / Q000379:methods*; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D009068:Movement / Q000502:physiology*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity