Tissue-based diagnosis includes all diagnosis procedures to analyze spatial configurations of biological functional units. Most frequently cells, cellular agglutinations such as vessels, nerves, glands, etc. are being investigated. Additional structures such as gene sequences, cellular movements, or membrane potentials are covered in advanced studies [1
From the medical point of view it can be distinguished between several categories, namely
a) conventional or "classical histological and cytological" diagnosis,
b) "prospective" diagnosis,
c) "indicative" diagnosis, and
d) "risk-assigned" diagnosis [8
The different categories of diagnosis require different technologies to be applied, and will lead to different clinical impacts as shown in <table >.
Diagnosis categories and medical application
The classical diagnosis is a prerequisite for any reliable treatment of chronic diseases such as cancer or chronic inflammatory lesions, and, by the way, is by far the cheapest diagnostic medical procedure [8
]. It is also quite independent from its medical environment, i.e., the specialization of a hospital or pathology institution in contrast to the other diagnosis types.
That of prognosis-associated information requires detailed clinical information in addition to molecular pathology investigations [8
The recognition of a "risk-associated disease" such as the genetic predisposition to developing breast cancer is the duty of highly specialized (molecular genetic) institutions or departments.
Therefore, institutions involved in tissue-based diagnosis should have access to a variety of sources for data, information, and knowledge, to enable working in an efficient manner. At the same time they can provide integrated and highly abstracted information of the disease and direct the necessary treatment. This central embedding of diagnostic pathology has opened new doors in medical communication.
It started with telepathology providing on-line and off-line procedures to electronically transfer diagnostic useful information, and continued with image analysis applications available via the Internet. The essential tools are depicted in (figure ). On-line telepathology can be assumed as a static and asynchronous approach sending information upfront without the flexibility for the "sender" to immediately react to the reviewer's advice. User's had to "synchronize" their email communications in telephone conferences [10
The essential tools to performing telepathology include microscope with mounted digital camera, interactive submission of clinical data and images, computerized transfer stations, and acoustic telecommunication.
Another on-line technology for telepathology is the Remote Controlled Microscope. This is used by small surgical units, which do not host a surgical pathologist. The installed remote control microscopes require also "visually controlled tissue sampling and cutting tables". The systems permit intra-operative diagnosis of pathologists working with a congruent control and survey system installed in a remote pathology department or institution [24
Different to these on-line telepathology systems the so-called off-line telepathology has been developed. Specific servers have been implemented to enable expert consultation, secondary advices, or to provide even a "virtual pathology institution" capability [9
]. These systems are usually completely embedded into the Internet. Three main systems have been implemented so far, the iPATH [10
] in Basel, Switzerland; the UICC-TPCC (Telepathology Consultation Center of the Union International Contre Cancer in Berlin, Germany [40
], and the Telepathology service of the Armed Forces Institute of Pathology (AFIP), located in Bethesda, Maryland, USA [40
]. These platforms allow sending information between distributed users; however, there is no interaction with communication systems or to grant access to computation facilities or specific data bases.
Another system, the Electronic Automated Measurement User System (EAMUS™, [47
]) automatically measures the staining intensities and derived features of images acquired from immunohistochemically stained glass slides. It is an open system and can be accessed via the Internet [48
Obviously, these systems are all build on a specific purpose and cannot interact with each other. They can be considered to be precursors of more advanced and broader designed networks meeting the characteristics of a virtual network, a Grid.
All these systems require digital images acquired from a histological glass slide that are a prerequisite to using these tools. Today, still images of limited size (SVHS, or other formats of approximately 1000 × 1000 pixels) serve for these purposes. The glass slides are still archived in the conventional manner. However, since about two years glass slide scanning technologies are available, which acquire a complete glass slide and also provide interfaces for digital archives and support advanced Internet Communication between pathologists for interactive remote consultation [48
]. In a next step diagnostic pathology would move on from image acquisition generating "Digital Slides", into Virtual Networking, i.e. – using a Grid.
Grids are based on open standards like PACS (Picture Archiving and Communication System) for Medical Imaging and provide a simple, fast, resilient and open framework. They are designed to generate an easy to use platform for delivering intra- and interdisciplinary collaborative medicine. Images would be one core, and Health Care Systems can share pathology, cardiology, radiology and other digital images across sites.
Grid Technology enables physicians to access and use all compute and storage resources available in a virtual network. Users are granted physical freedom from the underlying technology, enabling fast remote access. Healthcare providers can leverage computing and storage resources across multiple departments and sites. By sharing resources, Grid technology will help to eliminate hardware vendor 'lock-in' via vendor agnostic architectures.
Obviously, immediate access to different diagnostic resources will improve the patients' care and physicians' diagnosis ability. Naturally, the network has to provide security and privacy to protect the patients' confidentiality.
What are the features of a Grid? Which Grids related to tissue-based diagnosis do already exist, and which specificities can be implemented in computational diagnostic pathology? Is the design of the existing telepathology services appropriate to be migrated into an advanced Grid system? Which features are promising, which ones have to be modified, or even neglected?
This article tries to give some answers from the technological and medical point of view to these questions. In addition, we want to describe the basics of Grid technology in relation to future changes in tissue-based diagnosis, which will most likely occur, in our opinion.