1. A method for measuring fluid flow and transit times in a sample via magnetic resonance imaging, comprising: providing a labeling plane and an imaging plane for a sample; modulating the magnetization of inflowing spins at the labeling plane using a complex sequence; and obtaining transit times for the modulated spins from the labeling plane to the imaging plane from a set of acquired image slices of the sample in a single unified acquisition, wherein the complex sequence has minimal autocorrelation over time and its frequency domain transform has no zeros, and wherein the transit times are obtained by dividing the frequency domain transform of the acquired signal by the frequency domain transform of the complex sequence.