1. A method for producing an image of a subject's brain positioned in a field of view (FOV) of a magnetic resonance imaging (MRI) system, the steps comprising: a) acquiring with the MRI system a set of projection views at each of a plurality of intervals following an event that produces brain activity in the subject; b) producing a composite image with projection views acquired during the plurality intervals wherein the projection views are interleaved with each other; c) reconstructing an image frame at each interval by: c)i) backprojecting a set of projection views acquired at the interval into the FOV and weighting the value backprojected into each image pixel by the value of the corresponding pixel in the composite image; and c)ii) summing the backprojected values for each image pixel.