A method may be provided to operate a medical system. First data may be provided for a first 3-dimensional (3D) image scan of an anatomical volume, with the first data identifying a blood vessel node in a first coordinate system for the first 3D image scan. Second data may be provided for a second 3D image scan of the anatomical volume, with the second data identifying the blood vessel node in a second coordinate system for the second 3D image scan. The first and second coordinate systems for the first and second 3D image scans of the anatomical volume may be co-registered using the blood vessel node identified in the first data and in the second data as a fiducial.
