Digital storage of pathology slides on the Internet: techniques and issues

Vincenzo Della Mea1, Francesca Demichelis3,Vito Roberto2

1) Dept. of Medical Morphological Research, 2) Dept of Computer ScienceUniversity of Udine, Italy

3) ITC/Irst, Trento, ItalyPer vedere questa immagineoccorre QuickTime™ e undecompressore GIF.

MEDNET2001 - Udine, Italy

Per vedere questa immagineoccorre QuickTime™ e undecompressore GIF.Telepathology on the Internet

It’s a mammuth (frozen sections)

Fast diagnosis during surgery Needs realtime

main application: remote consultation Second opinion diagnosis On a peer-to-peer basis just like in traditional mail-based

consultation of expertsGrowing field: education

Access to microscope images without microscope

Self-learningQuality control

Proficiency testing

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Internet telepathology implementation

Store-and-forward Email Server-mediated (on the WWW) Proprietary tools

Realtime Remotely driven robotized microscope Videoconference-like tool

Della Mea V. Pre-recorded telemedicine. In: An introduction to telemedicine (Wootton R, Craig J eds.), RSM Press, London, 2000

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Acquisition devices: storage sizes

Resolution Storage size Compressed*

Analog cameras 800x600 1.4 MB 100 KB

Digitalphotocameras

1800x1200 6.3 MB 400 KB

Photoscanners 3400x2700 26.2 MB 1.7 MB

Digital glass slide Thousandsof images

1-5 GB ~300 MB

*Foran et al. Compression guidelines for diagnostic telepathology. IEEE Trans IT in Biomedicine, 1997; 1:55-60

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Human-computer interface problems

The usual computer screen has up to 1024x768-1600x1200 pixels; Images are larger than the display

The pathologist has specific habits coming from the use of the microscope, which are not often respected by computer systems

Per vedere questa immagineoccorre QuickTime™ e undecompressore GIF.The pathologist’ behaviourDouble observation pattern:

First, a low magnification slide overview Then, a high magnification study of the

possibly diagnostic details (Tsuchihashi et al. The basic diagnostic approaches used in

robotic still-image telepathology. J Telemed Telecare 5(S1) (1999), 115-117)

Apart from cytology, useful details represent a minimum part of the total specimen area

Looking at images with a browser does not satisfy this constraints!

Per vedere questa immagineoccorre QuickTime™ e undecompressore GIF.Interaction with the glass slide

Per vedere questa immagineoccorre QuickTime™ e undecompressore GIF.S&F Telepathology

Usually on selected imagesPractical, not expensive, but…

Limited: pathologists do not like diagnose on selected images (even when good diagnostic quality is demonstrated)

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Digital storage of Pathology slides

Idea: we acquire the whole glass slide using a high magnification objective

Issues: Maximum (useful) resolution Storage size - thousands of images!!! speed

Per vedere questa immagineoccorre QuickTime™ e undecompressore GIF.Microscope resolution

Depends on Numerical Aperture (NA) of the objective, and wavelength

At 100x, oil objective, up to 0.2 micron2 pixel/point => 10 pixel per micron

Per vedere questa immagineoccorre QuickTime™ e undecompressore GIF.Histological sample size

10 mm2 - 3 cm2

1cm2 = 10000 x 10000 micronThis corresponds to an image of:

100000x100000 pixels 10GB uncompressed 500 MB

safely compressed

Not easy to manage !

Per vedere questa immagineoccorre QuickTime™ e undecompressore GIF.Approaches

CD rom distribution Still more physical storage needed than the glass

slide

Online: exploitation of the double pattern used by pathologists (i.e., sending just what is needed) Need for protocols

Establishment of microscope-like interfaces

Per vedere questa immagineoccorre QuickTime™ e undecompressore GIF.Current status of storage

Very fashioned nowFolder-based storage

Dublin, Trento, Nikon(?)..

Proprietary, patented systems Flashpix BacusLab’s Webslide™

Proposals: Adapting DICOM

Per vedere questa immagineoccorre QuickTime™ e undecompressore GIF.Current status of protocols

Adapted from other uses IIP (Internet Imaging Protocol)

Open source protocols: iPath

(available on the Web, ipath.sourceforge.net)

Proposals: DICOM again?

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A possible correspondence: changing magnification ~ changing

resolution Moving the microscope stage ~image pan

Advantages: Slide overview available Transmission only of the needed details

Per vedere questa immagineoccorre QuickTime™ e undecompressore GIF.Standardization

One of the major lacks of telepathology is standards

A protocol is needed for dynamic telepathologyStatic and dynamic telepathology with the same

softwareSome extension would make the protocol

better, i.e., for managing focus or at least some focus plane

iPath? IIP? DICOM for virtual slides?

Per vedere questa immagineoccorre QuickTime™ e undecompressore GIF.IIP in the Italian Network After these evaluations,

we recently added IIP access to images in all network databases

It is viewable with almost all Java-compliant browsers

Implementation: Apache (web server) Jserv (servlet engine) IIP reference

implementation running as an applet

Standard JPEG images

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The Trento SteMySys system

Per vedere questa immagineoccorre QuickTime™ e undecompressore GIF.An iPath-based protocol

Mic. API Virtual Microscope Protocol

Stored cases

XML model of the robotized microscope features

Transport:•SOAP/XML_RPC•IP•HTTP•...

Per vedere questa immagineoccorre QuickTime™ e undecompressore GIF.Developments

Cytology needs more than one focus plane: IIP -as is- is not sufficient, need to extension

Client software: a separate slide overview might be useful (no need for protocol changes)

We are trying to develop a dynamic server for doing static as well dynamic telepathology with the same protocol) Starting from IIP and the iPath protocol

Per vedere questa immagineoccorre QuickTime™ e undecompressore GIF.Conclusions

Digital storage of glass slides seems promising for Education Quality control Sometimes telediagnosis

In the future, even as a substitute for legal storage of diagnostic material At present, glass is better than magnetic/optical

technologies...