DICOM – The Industry’s Equivalent of a .pdf File

The word DICOM has a certain buzz about it in the medical imaging community. A substantial part of IXICO’s business revolves around DICOM data analysis. However, despite the large amount of information available in DICOM format, we can testify from experience that it still remains hazy to many. Below is a short description that explains how DICOM came about and its relevance to the imaging community.

DICOM stands for Digital Imaging and Communications in Medicine. It was developed in the 1980s and eventually adopted by the medical imaging community to allow for ease of communication and data transfer. DICOM can be thought of as the medical imaging field’s equivalent of a .pdf file or the lingua franca for imaging systems.

The development of a universal industry standard was imperative as digital imaging began to be widely used. Although the 1980s saw the proliferation of magnetic resonance imaging and computed tomography, both of which allowed for an unparallel level of image detail, the emphasis is now on easy connectivity and seamless communication between different imaging devices to boost efficiency and workflow.

The imaging devices were initially designed as isolated equipment with their unique printing and archiving methods. Equipment vendors were thus free to use their own propriety formats for storing imaging data. An image from one vendor could not be viewed using another’s viewer. Adding to this, it came to the point that the vendors would alter formats such that images from older devices could not be read by newer ones. Slight changes in image formats made it a nightmare for display workstations as they were forced to accommodate each new format.

DICOM was born out of the need to develop an imaging standard that would simplify data transfer and archiving between the many vendors. The DICOM format is now a universal imaging standard that is compatible with different brands, modalities, and models of imaging devices. A DICOM committee of radiologists, imaging equipment manufacturers, and engineers are tasked with periodically producing technical guidelines regarding transfer between devices, archives, printers and display workstations. Major imaging equipment manufacturers are also encouraged to produce DICOM conformance statements for their equipment.

DICOM is now the industry standard for medical images. It has made things easier for devices to communicate, raised awareness for connectivity amongst consumers, immensely enhanced collaboration between manufacturers to improve their products, and had a dramatic impact on clinical workflows.

Trial Wire – Organizing DICOM Images in a Disorderly World

IXICO recently made available for free a tool called Trial Wire. This is a tool that is routinely used by us in-house to transfer medical image files between clinical trial sites and IXICO servers. Nearly all medical imaging scanners in hospitals can store and transfer image files as a series of slices, or cross sections, using the industry-standard DICOM format. DICOM stands for digital imaging and communications in medicine. It was adopted by the medical imaging community to allow for ease of communication and data transfer, independent of the manufacturer or type of scanner involved. You can think of DICOM as the medical imaging field’s equivalent of a .pdf file.

The DICOM format is designed for communication of image data between scanners, imaging workstations, and hospital image archive (known as Picture Archival and Communication Systems or PACS). But for research studies and clinical trials, handling of DICOM data can be painful!
Among several clever features of Trial Wire, one that is sometimes overlooked is its ability to organize DICOM files into series of sub-directories. This seemingly trivial feature is in fact very complicated for most DICOM data users.

The problem lies with the imaging systems and equipment that are made by the likes of GE, Siemens, and Philips. When a patient is given an MR or CT scan, say, the imaging system can transmit the images to a computer in either a random or systematic fashion. Although the images are still fully DICOM compliant, the manufacturers do not have a standard way of organizing the data. This can result in several image slices being stored in dozens of sub-directories in what to many users can be a very confusing fashion. To manually structure the images is tedious and time-consuming.

Trial Wire uses an algorithm that is able to specifically tackle this problem. When a directory is specified, Trial Wire searches that particular directory and any sub-directory for any DICOM data. It then automatically imposes a directory structure into one of the three options set by the user:

1. Subject/Study/Series
   In this structure, the data is organized first by subject (which can be de-identified by Trial Wire) then by study name and then by image series. This allows for easy review in a trial-centric manner, meaning that someone interested in retrieving the data can now easily search by subject, study, or series. This approach will generally appeal most to those conducting clinical trials.
2. Flat directory
   In this structure, all the files are copied into one target collection. They are also all renamed to have a unique 8-character filename and a DICOMDIR file is created to describe them. This approach will most often be used by those who want to maintain large volumes of data that can be further organized later according to changing needs.
3. Mirror the original structure
   The original directory structure will be kept. This also means that any name on the files (which may contain personal information) is kept. This approach will most likely be used in a clinical setting where patient data is a necessary part of communication between physicians, such as conferring physicians within a hospital centre.

The organizing feature offered by Trial Wire gives the option to structure its files the way our experts do it here at IXICO or preserve the original structure. This provides the maximum flexibility for end users to organize DICOM data for storage or transfer. And a key benefit is that data from different scanners can all be stored together in a coherent structure to allow for easier sharing and analysis of the data.