Standardization of Digital Microscopy Instruments Ensures Reproducible Diagnostic Data

Methods have been developed to generate high-quality reproducible clinical diagnostic data that precisely relates to biomarker concentrations in tissue sections.

For tissue specimens stained for a biomarker such as HER2, physicians and patients expect the same quantitative result regardless of the digital microscopy instrument used.

Sources of variability in digital scanning microscopy instrumentation were evaluated. One source of variability is the light source; a second is the path traveled by the light through each instrument.

By correcting for each of these sources of variability high levels of reproducibility were achieved for an assay previously thought to be incapable of true standardization: with AQUA technology, the same slide of breast cancer specimens stained for HER2 analyzed across five instruments standardized by this method attained a coefficient of variance of less than 5% (where typical variances are ~20%).

AQUA technology is an automated, quantitative IHC testing method that enables measurement of protein biomarkers in tissue as an aid to a pathologist's diagnosis. Such precise determination of the location within the tumor cell and the amount in each location is not possible with conventional testing methods, such as standard IHC.

HistoRx (Branford, CT, USA) has been issued two US patents covering key features necessary for achieving reproducible, standardized image analysis results. The patents protect the company's methods for standardization of digital microscopy instruments, methods required to generate high-quality reproducible clinical diagnostic data that precisely relates to biomarker concentrations in tissue sections.

Exposure times are most commonly determined to optimize contrast and visual appeal of the image, and may be determined “by eye.” The human eye is a poor judge of intensity, and images generated by conventionally determined exposure times are commonly too overexposed for generating quantitative results. The patented methods automatically determine the appropriate exposure time to maximize for a broad range of pixel intensities in the image, thereby maximizing the dynamic range of quantitative measurements achievable from subsequent image analysis.
A second patent pertains to hardware that can be inserted into the digital imaging fluorescent microscopy system, similar to filter cubes used in fluorescence microscopy, and provides for the monitoring of the light source and its fluctuation.

HistoRx, Inc. products and services are based on proprietary analysis of tissue biomarkers using AQUA technology. AQUA technology is the only platform capable of precisely measuring protein biomarker concentration with sub-cellular resolution in tissue sections, enabling fully objective, standardized, reproducible, and automated analysis to guide diagnosis, drug development, and therapeutic decision-making. HistoRx is commercializing a pipeline of proprietary diagnostic products targeting improved treatment decision-making and patient outcomes in cancer care.

AQUA technology in the clinical diagnostic setting was first used in 2010 by Genoptix Inc. (Carlsbad, CA, USA). The company launched diagnostic tests based on AQUA technology licensed from HistoRx. AQUA technology is currently available on the ScanScope FL from Aperio (Vista, CA, USA) and will be available later this year on the Vectra system from Caliper Life Sciences (Hopkinton, MA, USA).

Related Links:
HistoRx, Inc.
Genoptix Inc.
Aperio