RETROSPECTIVE ESTIMATION AND CORRECTION OF PHYSIOLOGICAL FLUCTUATION IN FUNCTIONAL MRI

Image-to-image fluctuation due to physiological motion is a major limi tation to the accurate detection of neuronal activity with functional MRI. In this paper, a new and general technique for the estimation and compensation of the physiological effects is presented. By simultaneo usly monitoring the respiration and heart beat during the acquisition of imaging data, and retrospectively synchronizing the imaging data wi th physiological activity, physiological effects are estimated and rem oved. This technique does not rely on the periodicity of the respirati on or the heart beat, does not affect the signal changes arising from neuronal activation, and is beneficial to images acquired with any spe ed. Experimental studies performed with FLASH and EPI sequences have d emonstrated that the new technique is effective in reducing physiologi cal fluctuation acid improving the sensitivity of functional MRI and i s generally applicable.