This stability (agar) phantom consists of a cylindrical phantom and agar material inside. Using this phantom a Signal to Noise Ratio, Signal Fluctuation to Noise Ratio, drift, and other imaging measures over a 100-volume or 200-volume fMRI scan can be performed. The agar phantom has characteristics similar to the T2 measures of a human head, but provides no change in signal. The T1 and T2 characteristics of the agar phantom at 3T are ~900 ms T1 and 30 ms T2.