Simultaneous perfusion and BOLD imaging using reverse spiral scanning at 3T: characterization of functional contrast and susceptibility artifacts.

Abstract

Reverse spiral scanning with arterial spin-labeling was developed at 3T to simultaneously detect perfusion and BOLD signals in the brain by subtracting or adding the control and labeled images, respectively, in the same dataset. BOLD contrast was improved with the longer effective echo time achieved in the reverse spiral scan compared to conventional forward spiral scans. Susceptibility artifacts near air-tissue interfaces in the brain were substantially reduced in the reverse spiral images due to their early data acquisition time and, hence, less signal attenuation. Brain activation experiments with the reverse spiral scan were performed on normal subjects and were compared to forward spiral imaging in the same subjects. The experiments demonstrated that reverse spiral imaging was able to detect perfusion and BOLD signals simultaneously and reliably, even in the brain regions with severe susceptibility-induced local gradients, while forward spiral scans were either not optimal for detecting the two functional signals at the same time or were vulnerable to susceptibility artifacts.