Aperio, a Vista, Calif., maker of systems that digitize medical images for use in the diagnosis of disease, raised $10.6 million from existing investors. It last raised $17 million in a second round of funding in Nov. 2005, and has now garnered a total of $33 million in equity capital. The company’s release is here.

Aperio makes systems that digitally scan microscope slides of tissue samples in high resolution and then allow diagnostic specialists, or pathologists, to view and analyze them in detail. The systems are currently offered for research purposes only, as they have not been cleared or approved by the FDA for patient care.

The round was led by Galen Partners and Advanced Technology Ventures, with participation by other existing investors.