Choose a whole slide imaging system as a complete diagnostic workflow, not as a scanner purchase. The right system must preserve the information a pathologist needs, fit the laboratory's specimen mix, and keep cases moving when scanning or network services fail.

Digital pathology is the larger clinical system for creating, managing, viewing, and interpreting digital slide images. Whole slide imaging is the scanning step inside it. Neither term means AI.

Whole Slide Imaging Is One Component

A whole slide imaging system converts a prepared glass slide into a high-resolution digital image. The FDA's product classification describes a system that includes an image management system, scanner and software, and display monitor. It also says the WSI system itself does not include automated image-analysis functions.

The first system authorized in the United States for primary diagnosis was the Philips IntelliSite Pathology Solution in 2017. The FDA reviewed it through the De Novo process after a study of roughly 2,000 surgical pathology cases found diagnoses made from the digital slides comparable to diagnoses made from glass slides.

Digital Pathology Is The Larger Workflow

The FDA defines digital pathology around acquisition, visualization, analysis, transfer, storage, and interpretation. In practice that includes slide preparation, scanning, image quality control, storage, case assignment, a diagnostic viewer, display hardware, access controls, and a reliable link to the laboratory record.

Each part can affect the final image. Focus, tissue folds, staining, scanner settings, compression, display conditions, and network performance become workflow variables. The question is not whether a scanner produces a beautiful image. It is whether the complete system preserves the information needed for the intended specimen and use.

Eight Checks Before You Choose A System

  1. Clinical scope: list the specimen types, stains, frozen sections, cytology work, and diagnostic uses the laboratory expects the system to support.
  2. Real throughput: measure slide volume, scan time, rescans, loading work, and peak demand with the laboratory's own case mix.
  3. Image quality: test focus, tissue detection, color, compression, z-stacking needs, and how staff catch missing or poorly scanned tissue.
  4. Local validation: define the cases, users, displays, preparation methods, and acceptance criteria required before routine diagnosis.
  5. Viewer and display: confirm navigation speed, annotation, measurement, color consistency, monitor requirements, and ergonomics for a full reading day.
  6. Storage and integration: map image size, retention, network load, laboratory-system links, case assignment, identity matching, and access controls.
  7. AI compatibility: verify that any planned model accepts the local image format, stain, scanner output, and preparation workflow covered by its evidence.
  8. Downtime plan: decide how cases move when the scanner, viewer, storage service, network, or AI function is unavailable.

Validation Comes Before Routine Diagnosis

The College of American Pathologists maintains guidance for validating whole slide imaging for diagnostic purposes. The principle is practical: a laboratory validates the system for its intended clinical use before it replaces or supplements the microscope in routine diagnosis.

Local validation matters because the deployed system includes local specimens, preparation methods, scanners, displays, users, and workflows. An FDA marketing authorization for the product does not perform that implementation work for the laboratory.

Where AI Enters The System

Once slides are digital, software can support quality control, detect or segment tissue, count cells, quantify biomarkers, flag suspicious regions, or generate a score for a narrow intended use. Those functions require their own evidence. A validated WSI workflow proves that digital slides can support the intended diagnostic work. It does not validate every model later applied to those images.

For the difference between digitization and an authorized algorithm, see why pathology has so few cleared AI devices. The concise definitions remain in digital pathology and whole slide imaging.

Primary Sources

See the FDA's technical performance guidance for WSI devices, Digital Pathology Program, and the CAP validation guideline.