The exchange of images is a medical necessity, but there are significant challenges in utilizing images received on CDs from other institutions. We believe the most important challenge is that errors in the information on the CD may not be as readily apparent as on film—certainly they are less visible until the CD is “read” in a computer. While most picture archiving and communication systems (PACS) have the capability to import DICOM images, the true emphasis must be on the process by which this occurs. By involving the patient early (at the desk when there may be less stress) with a desk support person, we believe represents the highest likelihood of accurate confirmation. We are aware of one case in the past 5 years when an exam was imported using this process but which subsequently proved to be incorrect. In some situations (e.g., emergency transfers) requiring the patient to confirm may not be possible, but family members or transfer personnel can be a good surrogate. We recognize that this is not a perfect process, but likely addresses most of the problems.
The total significant error rate is 0.2–0.1% being the wrong patient only, and 0.1% having both the right patient and another patient’s data on the CD. While the error rate is seemingly low at 0.1% for wrong patient and also 0.1% for more than one patient, this is actually a significant problem. At the volume of exams we import, the rate of 0.1% CDs with the wrong patient means approximately one CD per day is for the wrong patient. It is infrequent enough that desk personnel who are expected to do many tasks can easily fail to detect the problem, but common enough that this cannot be ignored. We believe this is a critical problem that hospitals must carefully consider when implementing their processes and systems.
The inclusion of information for more than one patient is also a problem, but is a problem for the source hospital because it likely represents a Health Insurance Portability and Accountability Act (HIPAA) violation. The consequences of such a violation have recently become more severe with the passage of the Patient Safety and Quality Improvement Act [6
]. For this reason, hospitals should carefully study their process and software for creating CDs and take steps to avoid this risk.
Given the volume of examinations handled and the error rate, the most important consideration in dealing with images received on CD is to identify a workflow that assures high integrity of the information while not reducing clinical efficiency. The integrating healthcare enterprise (IHE) framework [3
] does identify a workflow for importing CD images—the import reconciliation work flow or IRWF—that leverages the scheduled workflow profile. The primary actor for this is the portable media importer; it creates an order so that the downstream systems can have a “handle” for dealing with the images. This allows the importation of evidence objects (which in this case is images but other information can be imported from the CD as well as other media or even the Internet). An enterprise identifier is often placed into the imported object(s) so that enterprise systems can accurately connect these objects to the patient. We note here that the import reconciliation workflow has both a scheduled and unscheduled form and these two forms are detailed in Figs. , which are adapted from the IHE website.
Fig. 3 IHE-defined IRWF profile for importation of images from media such as CD. a Shows scheduled IRWF for cases where an order is provided prior to the import of the images. b Shows unscheduled IRWF for cases where no order exists. Adapted from http://IHE.net (more ...)
While the IRWF is necessary, it is not sufficient for a clinical practice because it does not describe a clinical implementation or provide details on how a hospital may assure data integrity. These need for high data integrity can conflict with the need for clinical efficiency—developing a process and system to achieve these goals is critical.
The particular clinical setting will have a major impact on the most efficient implementation of image importation. In the case of a large group practice or hospital, we would recommend that all examinations on all CDs should be imported. We recognize that in many cases, some images on the CD will not be relevant to the care of the patient. The challenge is to predict which images will not be relevant. This is a challenge, particularly since the exam descriptions on the CD are not always obvious. Because of these challenges, it is often most efficient to simply import every valid examination on the CD. In the case of an imaging center or small imaging facility, it may be more sensible have a person decide. The right person may be a desk attendant, technologist, or even the radiologist.
The issue of image access is also critical. In the setting of a hospital or large group practice, it may be impractical to have the CD carried with the patient because teams often work in parallel and away from the patient. The result would be contention for the access to the CD. In addition, this can allow the CD to become lost. In a large practice situation, the best solution is to import the images into the EMR or PACS to allow widespread access. This has the additional advantage of letting the physicians use a graphical user interface that they are already familiar with and it also would likely be easier to compare the outside study with internal studies. In the case of an imaging center, the small physical size of the facility makes it more feasible to not import the CD and instead use either a viewer on the CD or a viewer on a local workstation without a formal import process. We simply note here that it may be more efficient to compare exams if the CD is imported, and one can allow the patient to leave the facility with the CD before the images are interpreted. If a facility does keep the CD, it must be responsible for storing or destroying it in a secure fashion.
Another important consideration for workflow is the naming of the procedures. There is as yet, no universal standard for how to describe imaging procedures in radiology. As a result, the study description in the DICOM header is variable and it may not be easy for all physicians, particularly non-radiologists, to know what study was done. We have found that a simple string lookup and mapping can provide a correct match in approximately 80% of the cases that we have seen. However, a significant fraction of the remaining 20% is much more difficult to determine. For these, it is probably necessary to use the description unmodified.
Given the frequency at which errant CDs are seen, we believe that that is a good argument for having a high-quality import process. We should note that if the “distribute the CD” approach is taken, it means that even though one team might identify a problem with the CD, other teams may not be aware that incorrect data is present on the CD, and the problem could be propagated.
At the time the image CD importation application was implemented, we decided to not import non-DICOM data because the other image formats do not encode patient information into the image file itself. Given the error rates noted above, we feel this is the most prudent course of action. This is a policy decision that we have made and one that we believe other healthcare facilities should consider. We also recognize that in some cases, CDs have the same images in both JPEG and DICOM format, but that is less common than having only non-DICOM images.
Another issue that we have seen with images on CDs is inappropriate compression of image data. While the vast majority of images are either not compressed or compressed using lossless methods, occasionally we do see lossy- or irreversibly compressed images on CDs. Even among those, the majority are compressed at a reasonable rate and do not pose a problem. However, there are occasional cases where there are clear artifacts present on images, likely because there is no single compression rate that can reliably be applied to images which also achieves a reasonable savings.
As noted previously, we do see CDs that are not readable. More frequently in the past, this was caused by CD creation software which allowed one to eject the disk before “closing it.” This problem seems to be less frequent now but we do see issues with CDs with fingerprints, being scratched, or otherwise becoming unreadable. We also see that there is some variation in readers across computers and we would recommend that one attempt to read a disk and on other computers.
An important policy decision is whether images from outside institutions should be archived. There is no one universal answer for every facility. We have seen that the average size for examination today is approximately 211 MB and that the average CD has approximately 2.3 examinations. We have noted that this trend is clearly increasing and as DVDs become more common, allowing greater storage capacity, the number of images as well as size of studies will likely increase. We are currently in the process of implementing a system in which any physician (radiologist or clinician) can request archiving as well as interpretation of an outside imaging examination. Those images not selected for archival or interpretation would be erased several months after the discharge of the patient.
The use of CDs for image exchange is pervasive, and a workflow that promotes high accuracy while not impeding clinical efficiency is critical. While there are efforts to develop systems for direct network-based image exchange, it is clear that CDs will be used for several years. Therefore, it is effort well spent to understand and address important issues in CD-based image exchange. It is also important to note that network transfer will also suffer from similar challenges, and that the process will be a bigger challenge. If a patient carries a CD, then it presents an opportunity for the patient to say “yes that is me.” With networks, the usual mechanism relies on some sort of “profiling” to match identifiers between organizations. This may be highly reliable, but it is not clear that it is perfect—reports on accuracy are currently lacking.
Given the issues with data integrity, this is a good opportunity to emphasize that since it is a relatively simple problem to produce a CD, one should make the effort to do it well. The consequences of producing an errant CD are potentially very large and can only produce embarrassment for your facility. Another part of producing a high-quality CD is to have a viewer on it that is usable by most physicians. The IHE basic image review profile is attempting to improve the standardization of the user interface elements used in viewing images. We also emphasize here that 0.1% of CDs have information for more than one patient, which likely represents a HIPAA violation, and the penalties for breaches are becoming more severe.
Most would agree that CD-based image exchange is a suboptimal stop-gap measure. Transfer of images using the Internet seems a superior option [3
], but there are important challenges in realizing that goal. Some of the challenges include privacy—when images are transferred by network, one must assure that only
the individuals or organizations that should
see the images can
see the images. Encryption methods that protect the information during transfer is likely sufficient. The bigger challenge is assuring that only the right party receives the information, and that they know who it belongs to. HIPAA rules and regulations demand that this be done in a well-controlled fashion. The advantage of the CD over network is that the source hospital gives the CD to the patient, and the patient then gives the CD to whichever hospital(s) they wish, thus avoiding HIPAA concerns.
This model is now being applied to network transfer of images. There are now personal health records (PHRs) supplied by several vendors. These are designed to accept data from hospitals on a given patient. The patient may then review and give access to this information. Images can be transferred to a PHR capable of handling DICOM data. While there are some issues with this model—particularly in how a hospital might then “pull” the image data from the PHR into their system—just having a viewing capability from a PHR would be an advantage in many situations.