PALGA, the Nationwide Histo- and Cytopathology Data Network and Archive. A Role for Digital Pathology?

With interest we have read the article of Casparie et al. on the Dutch PALGA system [1]. The paper certainly makes clear what a unique system PALGA is and what role PALGA could play in biobanking. From our point of view, one important issue with regard to national storage is however not addressed, which is the incorporation of digital images. Besides the fact that including digital macroscopic images as are currently often taken would be useful, we believe that the future of the Pathology slide archive is a digital one. Digital technology would allow to faster prepare clinicopatho-logical conferences, creates greater flexibility in location of clinicopathological conferences, allows faster consultation of colleagues (in house or remote), allows concurrent access to slides, circumvents misplaced or damaged slides and deterioration in slide quality over time, and could save archiving space. Next, it also is favorable for research purposes such as quicker (remote) revision of patient series, as well as analysis of tissue microarrays [2–7] and other digital images analysis applications [8–10]. Further, it endorses development of digital applications for virtual microscopy teaching of students. Lastly, this approach could be the stepping stone for upfront digital diagnostics in the future. Advances in scanning technology nowadays allow high throughput scanning of slides at a resolution that creates an acceptable alternative for classical mi-croscopy, and costs for mass storage have come down sufficiently to enable storing the massive number of large image files at reasonable cost. Software for managing a digital image archive and integration with present patient information management systems is available as well. We have therefore started a project to prospectively start scanning all the slides that we produce in the lab. The local infrastructure comprises two high speed slide scanners (Aperio, Vista, CA, USA) connected to a server that takes care of the management and the storage of the images. The images are transferred through a regular network connection (100 Mbit) to a Network Attached Storage (NAS) loca-tionposed of a first line 6 Terrabyte (TB) space on fast hard disks and expandable 120 TB robotic tape storage to take care of images after that. Dedicated hierarchical storage management software handles transparent image transfer between tape, hard disks (and vice versa) and workstations when requested. In view of the advantages of this digital approach to the pathology slide archive, we expect that soon other pathology labs will follow this initiative. Although local storage …