def get_diffusion_information(image) :
    """ Return the diffusion information from the ``image`` metadata. The 
        diffusion information is a dictionary and may contain the following keys :
        
        * ``"diffusion_bvalue"``
        * ``"diffusion_gradient_orientation"``
    """
    
    result = {}
    if "mr_diffusion_sequence" in image.metadata :
        mr_diffusion = image.metadata["mr_diffusion_sequence"][0]
        if "diffusion_bvalue" in mr_diffusion :
            result["diffusion_bvalue"] = mr_diffusion.diffusion_bvalue.value
        if "diffusion_gradient_direction_sequence" in mr_diffusion :
            diffusion_gradient_direction = mr_diffusion.\
                diffusion_gradient_direction_sequence.value[0]
            if "diffusion_gradient_orientation" in diffusion_gradient_direction :
                result["diffusion_gradient_orientation"] = \
                    diffusion_gradient_direction.diffusion_gradient_orientation.value
    
    return result