1. A method for producing a time-resolved three-dimensional image of a subject, the method comprising: acquiring image projection data from the subject using a medical imaging system during a single contrast injection, the medical imaging system including a single source/single detector system; generating a time-series of two-dimensional images from at least a portion of the acquired image projection data; reconstructing a three-dimensional image substantially without temporal resolution from at least a portion of the acquired image projection data; and producing a time-resolved three-dimensional image having a signal-to-noise ratio substantially higher than a signal-noise-ratio of the acquired image projection data by selectively combining the three-dimensional image substantially without temporal resolution and the time-series of two-dimensional images; wherein a subtracted vessel-only time-series of two-dimensional images is generated by subtracting at least one of a time frame of the time-series and an average of time frames of the time-series acquired before arrival of contrast from frames of the time-series acquired after an arrival of contrast during the single contrast injection; and further comprising: registering the reconstructed three-dimensional image substantially without temporal resolution to the subtracted vessel-only time-series of two-dimensional images; convolving the subtracted vessel-only time-series of two-dimensional images using a two-dimensional spatial kernel; projecting a value of each pixel in the subtracted vessel-only time-series of two-dimensional images along a line extending through each respective pixel in a direction perpendicular to a plane of the time-series of two-dimensional images; and multiplying the three-dimensional image substantially without temporal resolution with the projected value of each pixel for each time frame of the subtracted vessel-only time-series of two-dimensional images to produce the time-resolved three-dimensional image; wherein a signal in the time-resolved three-dimensional image corresponding to undesired vascular structures in a region being imaged is zeroed by multiplication of the three-dimensional image substantially without temporal resolution with the projected value of each pixel for each time frame of the subtracted vessel-only time-series of two-dimensional images, which is substantially free of signals corresponding to undesired vascular structures in the region being imaged; wherein multiplying the three-dimensional image is repeated at additional angles; wherein: i) the final image is derived from the minimum values resulting from image estimates obtained by multiplication at two or more angles; or ii) the method further comprises: calculating one or more voxel intensity curves as a function of multiple projection angles for the time resolved three dimensional image; identifying at least one anomaly in at least one voxel intensity curve; and for the voxel corresponding to the anomaly, averaging the voxel intensity over multiple projection angels.