A method of recording data in a file, the data being associated with the operation of a combined ultrasound and optoacoustic imaging system. The method generates a sinograms each reflective an of an optoacoustic return signal responsive to a light event, and associates each sinogram with a value that can be used to determine its temporal order. The method also generates ultrasound images each reflective an of an ultrasound return signal responsive to generated ultrasound, and associates each ultrasound image with a value that can be used to determine its temporal order. The sinogram and ultrasound data are stored in frames without concern for the precise order of the frames in the file, the frames including the values associating the sinograms and ultrasound images with their temporal order, so that the order and timing of the data underlying the frames can be reconstructed from the information in the file.
