"Virtual flow cytometry" of immunostained lymphocytes on microscopic tissue slides: iHCFlow tissue cytometry

Hernani D Cualing1, Eric Zhong, Lynn Moscinski

  • 1H. Lee Moffitt Cancer Center and Research Institute, University of South Florida, Tampa, Florida, USA. cualinhd@moffitt.usf.edu

Insights

A new digital microscopy technique, iHCFlow Tissue Cytometry (TC), automates lymphocyte analysis from tissue samples. This virtual flow cytometry approach offers a clinically valid alternative to traditional methods for cancer diagnosis and prognosis.

Area of Science:

  • Digital pathology
  • Immunohistochemistry
  • Flow cytometry
  • Cytomics

Background:

  • A novel method, iHCFlow Tissue Cytometry (TC), has been developed for automated measurement of immunostained lymphocytes in tissue sections.
  • This technique utilizes digital color microscopy and advanced cell analysis, converting immunohistochemistry (IHC) data into a flow cytometry-like dot-plot display, termed virtual flow cytometry.
  • Seven technical challenges for virtual flow cytometry were identified and addressed.

Purpose of the Study:

  • To present validation data for population statistics of immunostained lymphocytes using tissue cytometry (TC).
  • To introduce a new paradigm in tissue cytometry that converts IHC staining of lymphocytes into automated, flow cytometry-like results.
  • To establish iHCFlow TC as a potential clinical surrogate for diagnostic and prognostic analyses.

Main Methods:

  • Image segmentation of 512 x 474 RGB images and statistical result tabulation were performed using proprietary algorithms in 12-15 seconds.
  • A panel of seven antibodies (CD3, CD4, CD8, Bcl-1, Ki-67, CD20, CD5) was used for validation on 14 mantle cell lymphoma cases.
  • Results from TC were compared against manual counts by expert observers and flow cytometric immunophenotyping of the same specimens.

Main Results:

  • High concordance was observed between manual counts, flow cytometry, and TC results, with correlation coefficients of r = 0.9365 (Manual vs. TC) and r = 0.9537 (FC vs. TC).
  • The system successfully evaluated 2,027 image frames, encompassing 810,800 cell objects.
  • Technical issues were resolved, and the solutions were evaluated and presented.

Conclusions:

  • The iHCFlow TC technology demonstrates potential as a clinically valid surrogate for manual and flow cytometry analyses when only tissue IHC is available.
  • This automated system facilitates objective, rapid counting of immunostained cells in tissues, providing percentage results for cancer diagnosis, monitoring, and prognosis.
  • The intuitive dot plot histogram display offers pathologists an automated tool for rapid characterization of cell populations, satisfying criteria for Cytomics.
Abstract