Report on the 2025 DICOM WSI Connectathon.

Implementation of a standard such as Digital Imaging and Communications in Medicine (DICOM) is key to all aspects of interoperability in whole-slide imaging. But the devil is in the details, so practical testing and demonstration of specific features are needed to show the path forward for practical clinical deployment, select the appropriate profile of features, and identify gaps and opportunities for improvement. The most recent Connectathon was conducted for this purpose, as a virtual Internet-mediated event. Thirty-two (32) implementers in the role of Acquisition Manager (AP-LIS) (2), Acquisition Modality (scanner) (9), Image Manager/Archive (PACS, IMS, or VNA) (7), Image Display (viewer) (15), and Evidence Creator (annotation source) (8) participated. The AP-LIS provided HL7 V2 metadata identifying and describing patients and specimens in response to a slide barcode-based query, which was then incorporated by the scanner into standard DICOM whole-slide microscopy images, which were encoded as tiled pyramids using the TILED_FULL pattern. These images were transferred to the archive using the standard DICOM protocol, and made available for virtual microscopy viewing using the standard DICOMweb mechanisms for query and retrieval of metadata and selected frames. Human and algorithm generated annotations were produced and stored in the standard DICOM annotation format, and transferred and retrieved for display, also using the standard DICOMweb mechanisms.