Simple Model to Describe Weisskoff EPI Temporal Stability Test - Analogy with Physiological Noise Model in Oxygenation-Sensitive fMRI.
Bodurka J, Bandettini P
Weisskoff introduced a simple EPI temporal stability test for fMRI. In this method, the EPI time series fluctuations are measured on the phantom and plot as a function of the square ROI length. As ROI length increases the deviation of this plot from the theoretical value (1/(n*SNR), where SNR is an image signal to noise ratio) characterized MRI scanner related instabilities. Here we have proposed a simple model and derive an analytical formula to describe the Weisskoff EPI temporal stability test. We have also shown an analogy with physiological noise model in oxygenation-sensitive fMRI. Simplicity of this analytical approach can be used to characterize and quantify MRI scanner performance for given hardware settings/imperfections and gained insight in scanner related noise contribution to human fMRI data.