The Method Of Static Functional Magnetic Resonance Study

Aim: Temporal stability during an fMRI acquisition is very important because the blood oxygen level-dependent (BOLD) effects of interest are only a few percent in magnitude. We described a protocol to test fMRI research project and make a normal range about some parameters. Method: A full description of the phantom was scaned with using a 3.0T MR scanner (GE EXCITE, Milwaukee, USA) with an 8 channel phase array head coil. After a 2D 2D-localizer scan, 26 axial slices of fMRI images were obtained (TR/TE 3000/ minimum ms, flip angle 90°, matrix 64×64, FOV 20 cm, thickness/gap 5/1 mm, total 100 volumes). CF, SNR and fMRI stable were recorded. Result:The normal range of CF is 127717097±10ppm, SNR is 1686.77±168.68 and fMRI stable is <0.6%. Conclusion: We convince that monitoring QA in this way will improve the quality of fMRI data. Aim: Most previous resting-state fMRI studies had investigated the temporal synchronization, i.e., functional connectivity. We took the power sepctrum as an index of amplitude of LFF (ALFF). Two distinct conditions, eyes closed (EC) and eyes open (EO), were used to validate this method. Material and Method: Fifteen healthy right-handed subjects (6 males and 9 females, 20-27 years) were recruited. Five subjects were excluded due to head motion > 1mm. There were four EPI (GE 3T, birdcage coil) runs for each subject, two runs for both EO and EC using both low (TR = 2000 ms, TE =30 ms, FA = 45°) and high (TR = 400 ms, TE =30 ms, FA = 30°) sampling rates. The four runs were counterbalanced across subjects. Six oblique coronal slices covering the visual areas were obtained with EPI sequence. Each run lasted 400 s. After preprocessing, the analysis included filtering (0.01-0.08Hz), FFT to power spectrum, averaged square root and normalization . Paired t-test was used to compare the ALFF differences between conditions (EO vs. EC). Results and Conclusion: In the visual area, ALFF is significantly higher in EO than in EC for both TRs of 400 ms and 2000 ms . To the contrary, ALFF is significantly higher in EC than in EO in the paracentral lobule. The higher ALFF in EO in the visual area may be due to the more external visual stimulation. The higher activation in EC than in EO in the paracentral lobule had been attributed to the more imagination in EC in the literature. The current results indicate that ALFF could be a good index to measure the regional brain activity in resting-state fMRI studies.