Comprehensive Image Management

The integration of image data from non-radiological imaging procedures presents a challenge to most hospitals today. They should pursue the aim of storing all data in one archive - whatever its technological approach. One the one hand, the investment in the storage structures required for such a comprehensive archive is rather expensive; on the other hand, this is the only way organizations can fully tap the efficiency potentials of digitization: seamless work processes, reductions in cost by eliminating printouts as well as cutting capacity used for locating and delivery of records, optimization of patient care, reduced length of stay, and centralized support by the IT department.

 

This requires that, in addition to the radiological image data, such an image archive is able to accommodate images from all other disciplines - e.g. cardiology, surgery, neurology, ophthalmology, or pathology. Storage and display of videos, ECG, EEG, photographs, as well as third-party images from CD or film scanners need to be integrated. In many cases, compatibility and connectivity are already defined by the DICOM standard. This standard allows for the integration of much of the data generated in daily routine in such an archive already today. Even videos or pdf documents do not present an issue.

 

Hospitals should demand, however, that any type of unstructured data generated in normal daily routine be integrated in a PACS, and made seamlessly accessible in the clinical workflow. This will require extensions of the DICOM standard, e.g. for EEG data regarding image formats, as well as for typical Office documents (e.g. Word and Excel files).

Attributing an Image to a Patient

The challenge in daily hospital routine starts with data acquisition. Patient data has to be attributed precisely to the right images. Well-established methods in radiology which avoid duplicate entry of data - e.g. use of worklists which are made available via an information system - have to applied also in the acquisition of non-radiological image data. This helps achieve efficient and safe integration into the campus-wide image workflow of data which is not originally in DICOM format. This can only be realized in a reliable manner if the attribution of the data to the image is done immediately before or after generation of the image.

 

In radiology, this is a given because most modalities are worklist-enabled; positive attribution occurs of the patient and the exam which is to be carried out. The patient data is subsequently stored automatically in the DICOM header of the resulting images. For ultrasound, endoscopy, as well as ECG devices, attribution can take place via such a DICOM worklist or data entry via an additional keyboard attached to the devices. However, for documentation - e.g. of wounds or decubitus - based on a digital camera, the transfer to the PACS and patient attribution require a manual process. Portable devices, such as tablet PCs or notebooks with an integrated camera and a touchscreen, help minimize errors. A WLAN connection allows for access to the worklist and for direct attribution of the image to the patient.

 

Higher demands originate from slit lamps in ophthalmology. Integration of images including patient data is usually only possible via a frame grabber, which is basically an analog-to-digital converter for connecting image sources which do not have a common DICOM interface. Dedicated software is required to attribute the digital images to patient data via a worklist, and to transfer them to the PACS.

Campus-Wide Display of All Images

With the various images integrated into the PACS for campus-wide distribution, they need to be presented on screen. For this purpose, an omnipotent viewer is required which can be part of the PACS, and which can display all image data stored in the long-term archive. Options for reporting or postprocessing are not a must in this respect; dedicated applications -such as the classic PACS viewers for reporting or Office applications, can be used. This opens up a large area for vendors which calls for prompt action.

Compression for Image Archiving and Transfer

With today´s modalities generating ever larger amounts of data due to technologies which are increasingly sophisticated, compression of data is a key issue in archiving. Matters of quality provide the focus: at what compression rate can an image still be used for reporting? Are there differentiations required between the various organs and modalities? What is the quality needed after a certain period of time?

 

All these issues are hard to determine because quality for reporting always is subject to individual judgment - to some degree - and difficult to define on a mathematical basis. A lack of coherent norms or standards further complicates matters. Measures taken already today include the consensus conferences of the German Radiological Society which have defined recommendations for lossy compression related to exams and body regions.

 

Matters of compression are of importance, in particular, in telemedicine applications. In this context, the aim is to provide the recipient, as fast as possible, with transferred data at full diagnostic quality. In these cases, the typical approach is to use lossy compression techniques or streaming methods. This is particularly desirable for a practical transmission of images from pathology, the data volume of which is huge in comparison with other image and video data.