Attaching images to e-mail: DICOM is (almost) ready

April 19, 2000

My dentist routinely makes a digital photograph of each tooth before and after he treats it. When I asked whether he gets reimbursed for taking that picture, he told me that because the photos eliminate

My dentist routinely makes a digital photograph of each tooth before and after he treats it. When I asked whether he gets reimbursed for taking that picture, he told me that because the photos eliminate any argument with the insurance company as to whether a restoration should have been performed means the process pays for itself.

A similar practice is being used in surgery. I was given a picture of my daughter’s appendix before and after it was removed so that, again, there would be no doubt about the necessity of the surgical procedure.

Electronic images are increasingly being used as procedure documentation, as a communication tool, and also for obtaining second opinions. How best to exchange these images is still a question, however. Currently, most applications convert them into a “Web-friendly” format such as GIF or TIFF. Unfortunately, such conversions effect a loss of image fidelity and eliminate the ability to use the full data range and manipulate window widths and levels.

What can be done to ensure full image fidelity and retain all image header information when sending an image from one system to another, especially as an e-mail attachment? The solution is actually simple: The receiving application must be able to recognize the information in the same manner it recognizes, say, a Microsoft Word attachment, so that it can prompt the appropriate application. This is done using MIME, which specifies the data type of the information in the e-mail. Thus, in order to ensure full-fidelity image exchange, we need a MIME type just for DICOM images. That is exactly what the DICOM working group has come up with, and they recently approved a submission to the Internet authority for registration of this type.

There is also a proposal on how information within an e-mail message should be formatted. DICOM is a communication protocol, not a file specification. However, a file format for exchange media had already been specified—for storing images and other DICOM objects on a disk such as a CD. By considering the Internet as a virtual disk, it was easy to extend that specification for the purpose of file exchange. That does not necessarily mean that your version of Netscape or Microsoft Explorer will be able to view the DICOM images you receive attached to your e-mail, but the good news is that at least the interface is well defined.

This part of the DICOM standard is not yet finalized but can be expected within the next couple of months. This solution has already been implemented by a small start-up company in Europe and is strongly supported by European representatives. Whether this peer-to-peer “push” model is going to evolve as the method of choice, rather than a model that uses a central server where information is posted and subscribers can fetch the information when needed, is still open to debate.

Comments/questions: Herman Oosterwijk

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