(Re) Defining the High-Power Field for Digital Pathology.

Area of Science:

• Digital pathology
• Histopathology
• Image analysis

Background:

• Microscope high-power field (HPF) is crucial for histopathology diagnostics like mitotic figure quantification and tumor grading.
• Traditional light microscopy evaluates HPFs at ×400 magnification across 10 fields of view.
• Digital pathology introduces new variables affecting HPF evaluation.

Purpose of the Study:

• To determine parameters influencing high-power field (HPF) evaluation in whole slide images (WSIs).

Main Methods:

• Compared glass slides scanned on various devices to digital slides viewed on different WSI viewer software and an in-house viewer.
• Reviewed WSIs at "×40" equivalent HPF on monitors with varying sizes, resolutions, and aspect ratios.
• Calculated and compared digital and microscopic HPF areas.

Main Results:

• Significant variation in HPF area was observed across different monitor sizes and display resolutions.
• Minor differences in HPF area were noted between WSI viewers.
• No significant differences were found based on the scanner or WSI scanning resolution.

Conclusions:

• Microscopic HPF at ×400 magnification is not equivalent to "×40" digital HPF areas.
• Digital HPF quantification is influenced by monitor size, display resolution, and WSI viewers.
• Further clinical validation and development of new digital metrics are needed for accurate HPF evaluation.